CN113691152A - Power conversion device and abnormality detection method - Google Patents

Abstract

The invention provides a power conversion apparatus and an abnormality detection method. A power conversion device (100) is provided with: a first index calculation unit that calculates a first index for diagnosing whether or not the dc voltage detector is abnormal, based on an index using a detection value of the dc voltage detector; a second index calculation unit that calculates a second index that indicates a change in the index when a detection abnormality occurs in which a detection value changes in a predetermined direction in either one of the first direct-current voltage detector (25) and the second direct-current voltage detector (26); a comprehensive diagnosis index calculation unit that calculates a comprehensive diagnosis index from the second index; and an abnormality determination unit (72) that performs, on the DC voltage detectors, an operation of switching the detection value of the DC voltage detector assumed to be abnormal to an output estimation value estimated from the detection values of the other DC voltage detectors, and determines which of the first DC voltage detector and the second DC voltage detector has an abnormality based on a change in the comprehensive diagnosis index.

Description

Power conversion device and abnormality detection method

Technical Field

The invention relates to a power conversion device and an abnormality detection method.

Background

There is known a power conversion device that converts power from an ac power supply into power of variable voltage and variable frequency. In the power converter, a dc circuit includes a smoothing capacitor and a dc voltage detector that measures a voltage across the smoothing capacitor, and the dc voltage is controlled to be constant by power transmission and reception of an ac system interconnected with the power converter.

For example, as a technique for confirming the soundness of a dc voltage detector, a technique for determining an abnormality from a plurality of signals during operation is known (see patent document 1).

Patent document 1 discloses a technique for creating a plurality of diagnostic indexes from the behavior of a dc voltage during operation and comparing the plurality of diagnostic indexes with a reference value to determine an abnormality in order to check the soundness of a dc voltage detector, but does not disclose a technique for setting a reference value when the circuit constants of a motor and a transformer connected to the outside of a power conversion device to which the application is directed are unknown. In the technique of patent document 1, even if the circuit constants of the motor and the transformer connected to the outside of the power converter to which the application target is applied are known, the index change amount with respect to the abnormality of the dc voltage detector is different depending on the circuit constant, and therefore, it is necessary to set the reference value for each application target. The dc voltage detector is necessary to control the dc voltage of the power conversion device, and an abnormality of the dc voltage detector may cause instability of the system operation, and in the worst case, the system may be unexpectedly stopped, causing a large damage.

Patent document 1: japanese patent laid-open publication No. 2019-195231

Disclosure of Invention

The present invention has been made in view of such circumstances, and provides a technique capable of appropriately detecting an abnormality of a dc voltage detector in a power conversion device even if a circuit constant of a circuit connected to the outside of the power conversion device is unknown.

In order to solve the above problem, a power conversion device according to one aspect includes: a converter that converts alternating current into a first potential, a second potential lower than the first potential, and a third potential lower than the second potential; and an inverter that converts voltages of the first potential, the second potential, and the third potential into alternating current, the power conversion device including: a first smoothing capacitor connected between the first potential and the second potential; a second smoothing capacitor connected between the second potential and the third potential; a first direct current voltage detector that detects a potential difference between potentials to which the first smoothing capacitor is connected; a second dc voltage detector that detects a potential difference between potentials to which the second smoothing capacitor is connected; a first index calculation unit that calculates a first index for diagnosing whether or not there is an abnormality in the dc voltage detector, based on an index using a detection value of the dc voltage detector, when a detection abnormality occurs in either one of the first dc voltage detector and the second dc voltage detector, the detection abnormality changing in a predetermined direction, the detection value of the dc voltage detector being based on a voltage relational expression established in a circuit including a potential difference between potentials connected to the first smoothing capacitor and a potential difference between potentials connected to the second smoothing capacitor; a second index calculation unit that calculates a second index showing a change in an index when a detection abnormality occurs in which a detection value changes in a predetermined direction in one of the first direct-current voltage detector and the second direct-current voltage detector; a comprehensive diagnosis index calculation unit that calculates a comprehensive diagnosis index obtained by scalar synthesis or vector synthesis of 1 or 2 or more second-type indices; and an abnormality determination unit that performs an operation of switching a detection value of the dc voltage detector assumed to be abnormal to an output estimation value estimated from a detection value of another dc voltage detector for 1 or 2 or more dc voltage detectors, from among the first dc voltage detector and the second dc voltage detector, assuming that 1 dc voltage detector is abnormal, and determines which of the first dc voltage detector and the second dc voltage detector is abnormal, based on a change in a comprehensive diagnosis index after the operation of switching to the output estimation value.

According to the present invention, even if the circuit constant of the circuit connected to the outside of the power conversion device is unknown, it is possible to appropriately detect an abnormality of the dc voltage detector in the power conversion device.

Drawings

Fig. 1 is an overall configuration diagram of a power conversion system according to a first embodiment of the present invention.

Fig. 2 is a configuration diagram of the abnormality determiner of the first embodiment.

Fig. 3 is a configuration diagram of the index creating unit according to the first embodiment.

Fig. 4 is a configuration diagram of the first index creating unit according to the first embodiment.

Fig. 5 is a configuration diagram of the second pointer creating unit according to the first embodiment.

Fig. 6 is a configuration diagram of the third index creating unit according to the first embodiment.

Fig. 7A is a first diagram (1 thereof) for explaining the 2 nd harmonic in the first embodiment.

Fig. 7B is a first diagram (2) for explaining the 2 nd harmonic in the first embodiment.

Fig. 8A is a second diagram (1 thereof) for explaining the 2 nd harmonic in the first embodiment.

Fig. 8B is a second diagram (2) for explaining the 2 nd harmonic in the first embodiment.

Fig. 9 is a configuration diagram of a fourth index creating unit according to the first embodiment.

Fig. 10 is a configuration diagram of a fifth pointer generating unit according to the first embodiment.

Fig. 11 is a configuration diagram of the sixth index creating unit according to the first embodiment.

Fig. 12 is a configuration diagram of a seventh index creating unit according to the first embodiment.

Fig. 13 is a diagram illustrating extraction of a judgment cross section in the first embodiment.

Fig. 14A is a table showing the abnormality detector and the gain of the abnormality detector and the change in the index 201 according to the first embodiment.

Fig. 14B is a table showing the abnormality detector and the gain of the abnormality detector and the change in the index 202 in the first embodiment.

Fig. 14C is a table showing the abnormality detector and the gain of the abnormality detector and the change in the indices 203 and 204 in the first embodiment.

Fig. 15A is a table showing the abnormality detector and the gain of the abnormality detector and the change in the index 205 in the first embodiment.

Fig. 15B is a table showing the abnormality detector and the gain of the abnormality detector and the change in the indices 206 and 207 in the first embodiment.

Fig. 16 is a diagram summarizing the relationship among the abnormality detector, the index, the converter-side index, and the inverter-side index according to the first embodiment.

Fig. 17 is a configuration diagram of the dc voltage signal generating unit according to the first embodiment.

Fig. 18 is a flowchart of an abnormal part diagnosis process performed by the abnormality determiner of the first embodiment.

Fig. 19 is a flowchart of an abnormal part diagnosis process performed by the abnormality determiner of the first embodiment.

Fig. 20 is a diagram showing the state of the dc voltage detector in the case where the dc voltage detector is abnormal within each time range of the abnormality determiner of the first embodiment, the numbers of the corresponding flowcharts, and the inputs to the correction unit.

Fig. 21A is a diagram showing an example of temporal changes in the index 201 according to the abnormality determiner of the first embodiment.

Fig. 21B is a diagram showing an example of temporal change of the index 203 (converter-side index) according to the abnormality determiner of the first embodiment.

Fig. 21C is a diagram showing an example of temporal change of the index 206 (inverter-side index) according to the abnormality determiner of the first embodiment.

Fig. 21D is a diagram showing an example of temporal changes in the comprehensive diagnostic index 250 according to the abnormality determiner of the first embodiment.

Fig. 22 is a diagram showing an operation example in the case where the dc voltage detector of the first embodiment is abnormal.

Fig. 23A is a diagram showing an example of temporal change of the index 201 in the case where the dc voltage detector of the first embodiment is abnormal.

Fig. 23B is a diagram showing an example of temporal change of the index 203 (converter-side index) in the case where the dc voltage detector of the first embodiment is abnormal.

Fig. 23C is a diagram showing an example of temporal change of the index 206 (inverter-side index) in the case where the dc voltage detector of the first embodiment is abnormal.

Fig. 23D is a diagram showing an example of temporal changes in the comprehensive diagnostic index in the case where the dc voltage detector of the first embodiment is abnormal.

FIG. 24A shows a normal state (t) of the DC voltage detector according to the second embodiment of the present invention₀～t₁) A map of a vector of the integrated diagnostic index of (1).

FIG. 24B shows a case where the DC voltage detector of the second embodiment is abnormal and the estimated value is not used (t)₂～t₃) A map of a vector of the integrated diagnostic index of (1).

FIG. 24C shows a case where the DC voltage detector of the second embodiment is abnormal and uses E_{FBH_CP}When (t)₃～t₄) A map of a vector of the integrated diagnostic index of (1).

FIG. 24D shows the second embodimentWhen the DC voltage detector of the embodiment is abnormal, the method uses E_{FBH_CN}When (t)₅～t₆) A map of a vector of the integrated diagnostic index of (1).

FIG. 24E shows a case where the DC voltage detector of the second embodiment is abnormal and uses E_{FBH_IP}When (t)₇～t₈) A map of a vector of the integrated diagnostic index of (1).

FIG. 24F shows an abnormal state of the DC voltage detector of the second embodiment and uses E_{FBH_IN}When (t)₉～t₁₀) A map of a vector of the integrated diagnostic index of (1).

FIG. 25A shows a normal state (t) of the DC voltage detector according to the second embodiment of the present invention₀～t₁) A map of a vector of the integrated diagnostic index of (1).

FIG. 25B shows a case where the DC voltage detector of the second embodiment is abnormal and the estimated value is not used (t)₂～t₃) A map of a vector of the integrated diagnostic index of (1).

FIG. 25C shows a case where the DC voltage detector of the second embodiment is abnormal and uses E_{FBH_CP}When (t)₃～t₄) A map of a vector of the integrated diagnostic index of (1).

FIG. 25D shows a case where the DC voltage detector of the second embodiment is abnormal and uses E_{FBH_CN}When (t)₅～t₆) A map of a vector of the integrated diagnostic index of (1).

FIG. 25E shows the second embodiment of the DC voltage detector in abnormal condition and uses E_{FBH_IP}When (t)₇～t₈) A map of a vector of the integrated diagnostic index of (1).

FIG. 25F shows an abnormal state of the DC voltage detector of the second embodiment and uses E_{FBH_IN}When (t)₉～t₁₀) A map of a vector of the integrated diagnostic index of (1).

Fig. 26 is a flowchart of an abnormal part diagnosis process performed by the abnormality determiner of the power conversion apparatus according to the third embodiment of the present invention.

Fig. 27 is a flowchart of an abnormal portion diagnosis process performed by the abnormality determiner of the power conversion apparatus according to the third embodiment.

Fig. 28 is a diagram showing an example of the operation of the power converter according to the third embodiment.

Fig. 29A is a diagram showing an example of temporal changes in the index 201 relating to the abnormality determiner of the power conversion apparatus according to the third embodiment.

Fig. 29B is a diagram showing an example of a temporal change in the index 203 (converter-side index) of the power conversion device according to the third embodiment.

Fig. 29C is a diagram showing an example of temporal change of the index 206 (inverter-side index) of the power conversion device according to the third embodiment.

Fig. 29D is a diagram showing an example of temporal changes in the comprehensive diagnosis index of the power conversion device according to the third embodiment.

Fig. 30 is a flowchart of an abnormal part diagnosis process performed by the abnormality determiner of the power conversion apparatus according to the fourth embodiment of the present invention.

Fig. 31 is a flowchart of an abnormal portion diagnosis process performed by the abnormality determiner of the power conversion apparatus according to the fourth embodiment.

Fig. 32A is a diagram showing an example of temporal changes in the index 201 relating to the abnormality determiner of the power conversion apparatus according to the fourth embodiment.

Fig. 32B is a diagram showing an example of a temporal change in the index 203 (converter-side index) of the power conversion device according to the fourth embodiment.

Fig. 32C is a diagram showing an example of temporal change of the index 206 (inverter-side index) of the power conversion device according to the fourth embodiment.

Fig. 32D is a diagram showing an example of temporal changes in the comprehensive diagnosis index of the power conversion device according to the fourth embodiment.

Fig. 33 is a diagram showing a first operation example of the power converter according to the fourth embodiment.

Fig. 34A is a diagram showing an example of temporal changes in the index 201 relating to the abnormality determiner of the power conversion apparatus according to the fourth embodiment.

Fig. 34B is a diagram showing an example of a temporal change in the index 203 (converter-side index) of the power conversion device according to the fourth embodiment.

Fig. 34C is a diagram showing an example of temporal change of the index 206 (inverter-side index) of the power conversion device according to the fourth embodiment.

Fig. 34D is a diagram showing an example of temporal changes in the comprehensive diagnosis index of the power conversion device according to the fourth embodiment.

Fig. 35 is a diagram showing a second operation example of the power converter according to the fourth embodiment.

Fig. 36 is an overall configuration diagram of a power conversion system according to a fifth embodiment of the present invention.

Fig. 37 is an overall configuration diagram of a power conversion system according to a sixth embodiment of the present invention.

Fig. 38 is a configuration diagram of the abnormality determiner of the sixth embodiment.

Fig. 39 is a configuration diagram of the index creating unit according to the sixth embodiment.

Fig. 40 is a configuration diagram of an eighth index creating unit according to the sixth embodiment.

Fig. 41A is a first diagram illustrating a change in the index associated with a detector abnormality in the sixth embodiment, and is a diagram illustrating a dc voltage detector having an abnormality, a direction of gain abnormality, and a direction of change in the index 202 in the case where a failure occurs in any one of the dc voltage detectors.

Fig. 41B is a first diagram illustrating a change in the index associated with a detector abnormality in the sixth embodiment, and is a diagram showing a direction of a gain abnormality of a dc voltage detector having an abnormality when a failure occurs in any one of the dc voltage detectors, and a direction of a change in the indices 203 and 204.

Fig. 41C is a first diagram illustrating a change in the index associated with a detector abnormality in the sixth embodiment, and is a diagram illustrating a dc voltage detector having an abnormality, a direction of gain abnormality, and a direction of change in the index 205 when a failure occurs in any one of the dc voltage detectors.

Fig. 42A is a second diagram illustrating a change in the index associated with a detector abnormality in the sixth embodiment, and is a diagram illustrating a direction of a dc voltage detector having an abnormality, a direction of a gain abnormality, and a direction of a change in the indices 206 and 207 when a failure occurs in either of the dc voltage detectors 43 and 44.

Fig. 42B is a second diagram illustrating a change in the index associated with a detector abnormality in the sixth embodiment, and is a diagram illustrating a dc voltage detector having an abnormality when a failure occurs in either of the dc voltage detectors 43 and 44, the direction of the gain abnormality, and the direction of change in the index 208.

Fig. 43 is a configuration diagram of the estimation unit according to the sixth embodiment.

Fig. 44 is a flowchart of an abnormal part diagnosis process performed by the abnormality determiner of the sixth embodiment.

Fig. 45 is a flowchart of an abnormal part diagnosis process performed by the abnormality determiner of the sixth embodiment.

Fig. 46A shows an estimated value use ratio K in the case where the dc voltage detector of the sixth embodiment is abnormal_CIPThe figure (a).

Fig. 46B shows an estimated value use ratio K in the case where the dc voltage detector of the sixth embodiment is abnormal_CINThe figure (a).

Fig. 46C is a diagram showing an indicator 209 in the case where the dc voltage detector according to the sixth embodiment is abnormal.

Fig. 46D is a diagram showing a comprehensive diagnostic index in the case where the dc voltage detector of the sixth embodiment is abnormal.

Fig. 47A is a diagram showing an estimated value use ratio K in the case where the dc voltage detector of the sixth embodiment is abnormal_CIPThe figure (a).

Fig. 47B shows an estimated value usage ratio K in the case where the dc voltage detector of the sixth embodiment is abnormal_CINThe figure (a).

Fig. 47C is a diagram showing an indicator 209 in the case where the dc voltage detector according to the sixth embodiment is abnormal.

Fig. 47D is a diagram showing a comprehensive diagnostic index in the case where the dc voltage detector of the sixth embodiment is abnormal.

Fig. 48 is a configuration diagram of an index creation unit of the power conversion device according to the modification of the first embodiment.

Fig. 49 is a diagram showing an example of the configuration of the ninth index creating unit of the power converter according to the modification of the first embodiment.

Fig. 50A is a diagram showing an analysis result of the Q-axis current in the normal state of the dc voltage detector relating to the ninth index creating unit of the power converter according to the modification of the first embodiment.

Fig. 50B is a diagram showing an analysis result of the Q-axis current at the time of abnormality relating to the ninth index creation unit of the power conversion device according to the modification of the first embodiment.

Fig. 51 is a diagram showing an example of a configuration diagram of a tenth index creating unit of the power converter according to the modification of the first embodiment.

Fig. 52A is a diagram showing an analysis result of the Q-axis current in the normal state of the dc voltage detector relating to the tenth index creation unit of the power conversion device according to the modification of the first embodiment.

Fig. 52B is a diagram showing an analysis result of the Q-axis current at the time of abnormality relating to the tenth index creation unit of the power conversion device according to the modification of the first embodiment.

Fig. 53A is a table showing the abnormality detector, the gain of the abnormality detector, and the change in the index 209 of the power conversion device according to the modification of the first embodiment.

Fig. 53B is a diagram showing the abnormality detector, the gain of the abnormality detector, and the change in the index 210 of the power conversion device according to the modification of the first embodiment.

Description of the symbols

2 converter unit (converter),

3 inverter unit (inverter),

4 motor,

5a converter control device,

6 inverter control device,

7 current detector,

8 speed detector,

9a current detector,

11 voltage detector,

12 a transformer,

21 converter power conversion unit,

A smoothing capacitor on the 22P side (first smoothing capacitor: converter-side first smoothing capacitor),

Smoothing capacitors (second smoothing capacitor, converter-side second smoothing capacitor) on the 23N side,

24. 34 neutral point resistance,

25 DC voltage detectors (first DC voltage detector, converter-side first DC voltage detector),

26 DC voltage detectors (second DC voltage detector, converter-side second DC voltage detector),

27. 35, 36, 43, 44 DC voltage detectors,

31 inverter power conversion unit,

32. 33 a smoothing capacitor,

51 DC voltage command generator,

52 DC voltage controller,

53 current controller,

54 pulse generator,

A 55 neutral point voltage controller,

61 speed command generator,

62 speed controller,

63 a current controller,

64 pulse generator,

65 neutral point voltage controller,

72. 75, 76 abnormality determiner (abnormality determining section),

75c an index creating unit (a first index calculating unit, a second index calculating unit, and a comprehensive diagnosis index calculating unit),

73 a display,

74 output estimator,

202-207 index (the second index: one of the comprehensive diagnosis indexes),

250 comprehensive diagnosis index,

201. 209 indexes (first indexes),

100. 101, 102, 103, 104 power conversion devices,

729 a ninth index producing section,

730 tenth index creating part,

1000. 1001 power conversion system.

Detailed Description

Several embodiments are described with reference to the accompanying drawings. The embodiments to be described below do not limit the invention according to the scope of patent protection, and all of the elements and combinations thereof described in the embodiments are not necessarily essential to the solving means of the invention.

(first embodiment)

A power conversion system according to a first embodiment of the present invention will be described with reference to fig. 1 to 25F.

Fig. 1 is an overall configuration diagram of a power conversion system according to a first embodiment.

The power conversion system 1000 includes: an ac power supply 1 that supplies ac power; a power conversion device 100 that converts ac power supplied from an ac power supply 1 into desired ac power and outputs the ac power; and a motor 4 that operates using the ac power output from the power conversion device 100. The power conversion device 100 and the motor 4 are connected via an ac cable, for example.

The power conversion device 100 includes: a transformer 12 for transforming ac power; a converter unit (also referred to as a converter) 2 interconnected with the ac power supply 1 via a transformer 12, converting ac power from the ac power supply 1 into dc power; an inverter unit (also referred to as an inverter) 3 that converts the dc power output from the converter unit 2 into desired ac power and outputs the converted ac power to the motor 4; a converter control device 5 that controls the converter unit 2; and an inverter control device 6 that controls the inverter unit 3.

The converter unit 2 is a neutral point clamped 3-level converter, and converts an ac voltage into a dc voltage having a positive potential (first potential) level, a neutral point (zero) potential (second potential) level, and a negative potential (third potential) level. The inverter unit 3 is a so-called 3-level inverter, and converts a direct-current voltage of a positive potential (first potential) level, a neutral point (zero) potential (second potential) level, and a negative potential (third potential) level into an alternating-current voltage for the motor 4. The converter unit 2 and the inverter unit 3 are connected by a P-wiring 40 at a positive potential level, a C-wiring 41 at a neutral point potential level, and an N-wiring 42 at a negative potential level.

The converter unit 2 has: converter power conversion unit 21, smoothing capacitor 22 on the P side of converter 2 for suppressing fluctuations in the dc voltage (first smoothing capacitor: converter side first smoothing capacitor), smoothing capacitor 23 on the N side of converter 2 (second smoothing capacitor, converter side second smoothing capacitor), dc voltage detector 25 for measuring the inter-terminal voltage of smoothing capacitor 22 (first dc voltage detector, converter side first dc voltage detector), dc voltage detector 26 for measuring the inter-terminal voltage of smoothing capacitor 23 (second dc voltage detector, converter side second dc voltage detector), and converter neutral point resistance 24 for suppressing dc resonance. Converter neutral point resistor 24 is connected to C line 41. Note that, in fig. 1, only the configuration for the 1-phase of the converter unit 2 is shown (except for the converter neutral point resistor 24, the dc voltage detector 25, and the dc voltage detector 26), but the same configuration is also provided for the other phases.

The inverter unit 3 includes: the inverter power converter 31, a P-side smoothing capacitor 32 (first smoothing capacitor, inverter-side first smoothing capacitor) of the inverter 3, an N-side smoothing capacitor 33 (second smoothing capacitor, inverter-side second smoothing capacitor) of the inverter 3, a dc voltage detector 35 (first dc voltage detector, inverter-side first dc voltage detector) for measuring an inter-terminal voltage of the smoothing capacitor 32, a dc voltage detector 36 (second dc voltage detector, inverter-side second dc voltage detector) for measuring an inter-terminal voltage of the N-side smoothing capacitor 33 of the inverter 3, and an inverter neutral point resistance 34 for suppressing dc resonance. The inverter neutral point resistor 34 is connected to the C line 41. Note that, in fig. 1, only the configuration for phase 1 of the inverter unit 3 is shown (except for the inverter neutral point resistor 34, the dc voltage detector 35, and the dc voltage detector 36), but the same configuration is also provided for other phases.

The converter control device 5 controls the converter power conversion unit 21 so that the converted dc power has a desired value. The inverter control device 6 controls the inverter power conversion unit 31 so that the output torque and the speed of the motor 4 satisfy desired characteristics.

The power conversion apparatus 100 further includes: a current detector 7, which is an example of an alternating current detector, that detects and outputs a current flowing between the converter unit 2 and the alternating current power supply 1; a voltage detector 11, which is an example of an ac voltage detector, that detects and outputs an output voltage of the ac power supply 1; a speed detector 8 directly connected to the motor 4, for detecting and outputting a speed of the motor 4; a current detector 9 that detects and outputs an output current of the inverter unit 3; a voltage detector 10 that detects and outputs an output voltage of the inverter unit 3; an abnormality determiner 72 (abnormality determining section) as an example of the abnormality determining section; and a display 73.

Signals (output signals) of detection values detected by the current detector 7 and the dc voltage detectors 25 and 26 are input to the converter control device 5. The converter control device 5 performs various arithmetic processes based on the input detection value, and outputs a signal for controlling the converter power conversion unit 21.

Signals (output signals) of detection values detected by the speed detector 8, the current detector 9, and the dc voltage detectors 35 and 36 are input to the inverter control device 6. The inverter control device 6 performs various arithmetic processes based on the input detection value, and outputs a signal for controlling the inverter power conversion unit 31 to the inverter power conversion unit 31.

The signals (output signals) of the detection values detected by the current detector 7, the speed detector 8, the current detector 9, the voltage detector 11, the dc voltage detectors 25 and 26, and the dc voltage detectors 35 and 36 are input to the abnormality determiner 72.

The converter control device 5 includes: a dc voltage command generator 51, a dc voltage controller 52, a current controller 53, a pulse generator 54, and a neutral point voltage controller 55 as an example of a converter neutral point control device.

The dc voltage command generator 51 outputs a dc voltage command value indicating a voltage value of the dc voltage output from the converter unit 2 to the dc voltage controller 52. Specifically, the dc voltage command generator 51 outputs a command value of the voltage between P and N output from the converter 2 as a fixed value.

The dc voltage controller 52 calculates a converter output effective current command value based on the dc voltage command value input from the dc voltage command generator 51 and the detected value of the dc voltage input from the dc voltage detectors 25 and 26, and outputs the calculated value to the current controller 53. Specifically, the dc voltage controller 52 calculates the converter output effective current command value so that the total value of the detected values of the dc voltages input from the dc voltage detectors 25 and 26 coincides with the dc voltage command value.

Neutral point voltage controller 55 calculates ac output voltage correction value AVzR such that neutral point voltage becomes zero based on the difference between detected values of dc voltages input from dc voltage detectors 25 and 26, respectively_{OUT_C}And output to the current controller 53.

The current controller 53 calculates a converter ac voltage command value so that a detection value (converter output current detection value) input from the current detector 7 matches a converter output effective current command value input from the dc voltage controller 52, and outputs the converter ac voltage command value to the pulse generator 54. At this time, the current controller 53 outputs the ac output voltage correction value AVzR input from the neutral point voltage controller 55_{OUT_C}The converter AC voltage command value is calculated by adding an AC output voltage command value, which is an output of a predetermined current control operation.

The pulse generator 54 calculates a pulse signal for controlling on and off of each switching element of the converter power conversion unit 21 by pulse-width modulating the triangular wave as the carrier wave and the converter ac voltage command value so that the ac output voltage of the converter power conversion unit 21 matches the converter ac voltage command value input from the current controller 53, and outputs the pulse signal to the converter power conversion unit 21.

The inverter control device 6 includes: a speed command generator 61, a speed controller 62, a current controller 63, a pulse generator 64, and a neutral point voltage controller 65 as an example of an inverter neutral point control device.

The speed command generator 61 outputs a speed command value indicating a speed at which the motor 4 is operated to the speed controller 62. In the present embodiment, the speed command value is a predetermined value set in advance.

The speed controller 62 calculates an inverter output current command value so that a detection value (speed detection value) input from the speed detector 8 matches the speed command value input from the speed command generator 61, and outputs the inverter output current command value to the current controller 63.

Neutral point voltage controller 65 calculates ac output voltage correction value AVzR such that neutral point voltage becomes zero based on the difference between detected values of dc voltages input from dc voltage detectors 35 and 36, respectively_{OUT_I}And output to the current controller 63.

The current controller 63 calculates an inverter ac voltage command value so that the inverter output current detection value input from the current detector 9 matches the inverter output current command value input from the speed controller 62, and outputs the calculated value to the pulse generator 64. At this time, the current controller 63 outputs the ac output voltage correction value AVzR input from the neutral point voltage controller 65_{OUT_I}The inverter AC voltage command value is calculated by adding an AC output voltage command value, which is an output of a predetermined current control operation.

The pulse generator 64 calculates a pulse signal for controlling on and off of each switching element of the inverter power conversion unit 31 by pulse-width modulating the triangular wave as the carrier wave and the inverter ac voltage command value so that the output voltage of the inverter power conversion unit 31 matches the inverter ac output voltage command value input from the current controller 63, and outputs the pulse signal to the inverter power conversion unit 31.

The abnormality determiner 72 determines whether or not there is an abnormality in each of the dc voltage detectors 25, 26, 35, and 36 based on the detection values detected by the various detectors, the input values from the calculators 52, 53, 54, and 55 of the converter control device 5, and the input values from the calculators 62, 63, 64, and 65 of the inverter control device 6, and sends the determination results to the display 73. Here, the various detectors are, for example, dc voltage detectors 25, 26, 35, and 36, current detector 7, speed detector 8, current detector 9, voltage detector 10, and voltage detector 11.

The abnormality determiner 72, when detecting an abnormality of the dc voltage detector, causes the display 73 to display information (for example, a device number) of the dc voltage detector capable of specifying the abnormality and a message recommending inspection, replacement, or the like. The abnormality determiner 72 may be configured by a processor, not shown, executing a program stored in a memory. The display 73 is a display device capable of displaying information, such as a liquid crystal display.

Next, the abnormality determiner 72 will be described in detail.

Fig. 2 is a configuration diagram of the abnormality determiner of the first embodiment.

The abnormality determiner 72 has: a signal storage unit 72a, a setting storage unit 72b, an index creation unit 72c, an abnormal portion determination unit 72d, and a dc voltage signal generation unit 72e, which are examples of the first-type index calculation unit, the second-type index calculation unit, and the comprehensive diagnosis index calculation unit.

The signal storage unit 72a stores, as time-series data, signals of detection values input from the various detectors 25, 26, 35, 36, 7, 8, 9, 10, 11, input values from the calculators 52, 53, 54, 55 of the converter control device 5, and input values from the calculators 62, 63, 64, 65 of the inverter control device 6.

The setting storage unit 72b stores filter constants and reference values for determining abnormality of the voltage detectors 25, 26, 35, and 36.

The index creating unit 72c creates a plurality of indexes for detecting an abnormality of the voltage detectors 25, 26, 35, and 36. Specifically, the index creating unit 72c reads a signal used for calculation of the index from the signal storage unit 72a, and calculates a plurality of indexes by performing filter calculation or the like with the filter constant read from the setting storage unit 72b on the read value.

The index creation unit 72c functions as a comprehensive diagnostic index calculation unit that calculates a comprehensive diagnostic index obtained by scalar synthesis or vector synthesis of 1 or 2 or more second-type indices.

The abnormal portion diagnosing unit 72d diagnoses an abnormality of the dc voltage detector based on the index calculated by the index creating unit 72c and the signal read from the signal storage unit 72a, and outputs an estimated value use ratio and an abnormality diagnosis result. The abnormal part specifying unit 72d includes an index storage unit 720 that stores each index (201, 202, 203, 204, 205, 206, 207) (described later).

The dc voltage signal generator 72e corrects and outputs the detector signals input from the voltage detectors 25, 26, 35, and 36 based on the estimated value use ratio input from the voltage detector 72 d.

Next, the index creating unit 72c will be described.

Fig. 3 is a configuration diagram of the index creating unit according to the first embodiment.

The index creating unit 72c receives the filter constants stored in the setting storage unit 72b, and performs a calculation including a low-pass filter calculation using the filter constants, thereby creating each index from each signal read from the signal storage unit 72 a. The index creating unit 72c includes: a first index creating unit 721 for creating the index 201, a second index creating unit 722 for creating the index 202, a third index creating unit 723 for creating the index 203, a fourth index creating unit 724 for creating the index 204, a fifth index creating unit 725 for creating the index 205, a sixth index creating unit 726 for creating the index 206, and a seventh index creating unit 727 for creating the index 207. Details of the respective indices 201, 202, 203, 204, 205, 206, 207 and the respective index generating units 721, 722, 723, 724, 725, 726, 727 will be described later.

In addition, all of the indices 201, 202, 203, 204, 205, 206, and 207 need not be used for abnormality diagnosis. That is, abnormality diagnosis is performed using at least 1 of the index 201, the converter-side indices (index 202, index 203, index 204), and at least 1 of the inverter-side indices (index 205, index 206, index 207). In the later-described embodiment of fig. 17 and the following, the abnormality diagnosis operation in the case where the index 201, the index 203, and the index 206 are used will be described.

Before the description of each index, the respective detection values of the dc voltage detectors 25, 26, 35, and 36 will be described, and the correlation between the respective detection values will be described.

The relationship between the detection values of the dc voltage detectors 25, 26, 35, and 36 and the true values is expressed by the following equations (1) to (4).

E_{FB_CP}＝G_CP×E_{T_CP}…(1)

E_{FB_CN}＝G_CN×E_{T_CN}…(2)

E_{FB_IP}＝G_IP×E_{T_IP}…(3)

E_{FB_IN}＝G_IN×E_{T_IN}…(4)

Here, E in the formula_{FB_**}The detected value of the DC voltage detector indicating the position corresponding to the index G_**Denotes the gain of the DC voltage detector corresponding to the index, E_{T_**}The true value of the detected dc voltage value corresponding to the index x is shown. C in the subscript indicates the converter side, I indicates the inverter side, P indicates the P side, and N indicates the N side. Thus, CP denotes a converter-side and P-side dc voltage detector, i.e., dc voltage detector 25, CN denotes a converter-side and N-side dc voltage detector, i.e., dc voltage detector 26, IP denotes an inverter-side and P-side dc voltage detector, i.e., dc voltage detector 35, and IN denotes an inverter-side and N-side dc voltage detectorA side dc voltage detector, i.e. dc voltage detector 36.

When all of the dc voltage detectors 25, 26, 35, and 36 are normal, the detection value E of each dc voltage detector_FBAnd true value E_TEqual and therefore the value of the gain G is 1. On the other hand, when dc voltage detectors 25, 26, 35, and 36 are abnormal (for example, when gain abnormality occurs), detection value E is detected_FBAnd true value E_TThe gain G is not equal but is other than 1 (e.g., 0.9 or 1.1).

The detection values (E) of the dc voltage detectors 25, 26, 35, and 36_{FB_CP}、E_{FB_CN}、E_{FB_IP}、E_{FB_IN}) The correlation of (A) is as follows.

Since converter power conversion unit 21 is controlled by neutral point voltage controller 55 of converter 2 so that the neutral point potential becomes zero, the following relationship of equation (5) is stably established. Further, since the neutral point voltage controller 65 of the inverter 3 controls the inverter power conversion unit 31 so that the neutral point potential becomes zero, the following relationship of the equation (6) is stably established.

E_{FB_CP}＝E_{FB_CN}…(5)

E_{FB_IP}＝E_{FB_IN}…(6)

The DC voltage controller 52 of the converter 2 detects the value E_{FB_CP}And a detection value E_{FB_CN}The sum of (a) and the DC voltage command value V outputted from the DC voltage command generator 51_{DC_REF}Since the converter power conversion unit 21 is controlled in a uniform manner, the relationship shown in the following equation (7) is established.

E_{FB_CP}+E_{FB_CN}＝V_{DC_REF}…(7)

Further, the equations (5) and (7) hold the equations (8) and (9).

E_{FB_CP}＝V_{DC_REF}/2…(8)

E_{FB_CN}＝V_{DC_REF}/2…(9)

Further, as shown in fig. 1, since the smoothing capacitor 22 and the smoothing capacitor 32 are connected by the P wiring 40 and the smoothing capacitor 23 and the smoothing capacitor 33 are connected by the N wiring 42, the following formula (10) is established.

E_{T_CP}+E_{T_CN}＝E_{T_IP}+E_{T_IN}…(10)

Next, the first index creating unit 721 will be described.

Fig. 4 is a configuration diagram of the first index creating unit according to the first embodiment.

The first index creating unit 721 calculates the index 201(═ DI)₁). The index 201 is an index for detecting an abnormality of the dc voltage detector by utilizing a difference between a P-N dc voltage detection value on the converter 2 side and a P-N dc voltage detection value on the inverter 3 side when the dc voltage detector is abnormal, and is an index (an inter-inverter and converter voltage detection value difference index, a first index) related to a difference between the P-N dc voltage detection value on the converter 2 side and the P-N dc voltage detection value on the inverter 3 side.

The first index creating unit 721 includes an index calculating unit 7211 and a filter 7212.

The index calculation unit 7211 performs the calculation shown in formula (11).

DI₁＝(E_{FB_IP}+E_{FB_IN})-(E_{FB_CP}+E_{FB_CN})…(11)

Here, index 201 (DI) in the case where a failure (abnormality) occurs in dc voltage detector 25_{1_25}) The description is given. In addition, the abnormal gain G of the DC voltage detector 25 is adjusted_CPSetting the gain G of the DC voltage detectors 26, 35, 36 to a value other than 1 (e.g., 0.9 or 1.1)_CN、G_IP、G_INIs set to 1.

When the following formula (12) is obtained by substituting the formulas (1) to (4) into the formula (11) and using the relationship of the formula (10).

DI_{1_25}＝(E_{FB_IP}+E_{FB_IN})-(E_{FB_CP}+E_{FB_CN})

＝(G_IP×E_{T_IP}+G_IN×E_{T_IN})-(G_CP×E_{T_CP}+G_CN×E_{T_CN})

＝(E_{T_IP}+E_{T_IN})-(E_{T_CP}+E_{T_CN})+(1-G_CP)×E_{T_CP}

＝(1-G_CP)×E_{T_CP}

＝(1-G_CP)×E_{FB_CP}/G_CP…(12)

According to the formula (12), if E is equal to_{FB_CP}、G_CPSet to positive, then at gain G_CPIndex 201 (DI) when changing in a direction less than 1 (e.g., 0.9)_{1_25}) Is positive at G_CPIndex 201 (DI) when changing in a direction greater than 1 (e.g., 1.1)_{1_25}) Is negative.

Note that the index 201 in the case where a failure occurs in any of the dc voltage detectors 26, 35, and 36 can also be obtained in the same manner as in equation (12). That is, the index 201 when the dc voltage detector 26 has failed is formula (13), the index 201 when the dc voltage detector 35 has failed is formula (14), and the index 201 when the dc voltage detector 36 has failed is formula (15).

DI_{1_26}＝(1-G_CN)×E_{FB_CN}/G_CN…(13)

DI_{1_35}＝(G_IP-1)×E_{FB_IN}/G_IP…(14)

DI_{1_36}＝(G_IN-1)×E_{FB_IN}/G_IN…(15)

Further, the equations (12), (13), (14) and (15) can be modified to have gains on the left side as shown in the equations (16), (17), (18) and (19).

G_CP＝E_{FB_CP}/(E_{FB_CP}+DI_{1_25})…(16)

G_CN＝E_{FB_CN}/(E_{FB_CN}+DI_{1_26})…(17)

G_IP＝E_{FB_IP}/(E_{FB_IP}-DI_{1_35})…(18)

G_IN＝E_{FB_IN}/(E_{FB_IN}-DI_{1_36})…(19)

That is, by using the index 201 (DI)₁) Value of (A) and E_{FB_CP}、E_{FB_CN}、E_{FB_IP}、E_{FB_IN}The value of (2) is substituted into the formula (16), the formula (17), the formula (18), and the formula (19), and it is possible to estimate how much the value of the gain of the abnormal voltage detector deviates from 1.

When any one of the dc voltage detectors fails, the relationship among the dc voltage detector having abnormality, the direction of gain abnormality (greater than 1 or less than 1), and the direction of change of the index 201 is as shown in fig. 14A.

Specifically, in the dc voltage detector 25, a gain G is generated_CPIf the abnormality is less than 1, the index 201 is positive (increased), and the gain G is generated_CPIf the abnormality is greater than 1, the index 201 is negative (decreased). In addition, in the dc voltage detector 26, a gain G is generated_CNIf the abnormality is less than 1, the index 201 is positive (increased), and the gain G is generated_CNIf the abnormality is greater than 1, the index 201 is negative (decreased). In addition, in the dc voltage detector 35, a gain G is generated_IPIf the abnormality is less than 1, the index 201 is negative (decreased), and the gain G is generated_IPIf the abnormality is greater than 1, the index 201 is positive (increased). In addition, in the dc voltage detector 36, a gain G is generated_INIf the abnormality is less than 1, the index 201 is negative (decreased), and the gain G is generated_INIf the abnormality is greater than 1, the index 201 is positive (increased).

Even if an abnormality occurs in either one of the dc voltage detector 25 and the dc voltage detector 26, if the direction of the gain abnormality is the same, the index 201 shows a change in the same direction. In addition, even if an abnormality occurs in either one of the dc voltage detector 35 and the dc voltage detector 36, if the direction of the gain abnormality is the same, the index 201 shows a change in the same direction. Further, between the dc voltage detector 25 and the dc voltage detector 26, and between the dc voltage detector 35 and the dc voltage detector 36, if the direction of the gain abnormality is the same, the index 201 shows a change in the opposite direction.

The dc voltage detection value input to the index calculation unit 7211 includes switching ripples and noise, and the influence of these fluctuation components is applied to the value output from the index calculation unit 7211. Therefore, the filter 7212 performs filtering processing for reducing the influence of the fluctuation component on the value output from the index calculation unit 7211. The filter 7212 may be a first-order lag filter having the filter constant input from the setting storage unit 72b as a time constant. The filter 7212 is not limited to the first-order lag filter, and may be an averaging filter or a low-pass filter, for example.

Next, the second pointer generation unit 722 will be described.

Fig. 5 is a configuration diagram of the second pointer generation unit according to the first embodiment.

The second index creating unit 722 calculates the index 202(═ DI)₂). Index 202 is a correction value AVzR of the AC output voltage from the neutral point voltage controller 55 when the DC voltage detector is abnormal_{OUT_C}When the change occurs, an index of abnormality of the DC voltage detectors 25 and 26 is detected, and the difference Δ E between the detection values of the DC voltage is used_{FB_C}(＝E_{FB_CN}-E_{FB_CP}) Zero AC output voltage correction value AVzR_{OUT_C}The indexes (converter neutral point voltage control signal index, second type index, converter side index) are set. Calculating the AC output voltage correction value AVzR_{OUT_C}So that the difference Delta E between the detection values of the DC voltage detector_{FB_C}(＝E_{FB_CN}-E_{FB_CP}) The method of zero can use, for example, the technique disclosed in japanese patent application laid-open No. 2008-011606.

The second pointer creation unit 722 has a filter 7221. The filter 7221 performs removal of the ac output voltage correction value AVzR input from the neutral point voltage controller 55_{OUT_C}Filtering the fluctuation component of (2). The function of the filter 7221 is the same as that of the filter 7212 shown in fig. 4.

The index 202 will be explained.

When the dc voltage detectors 25 and 26 are normal, the detection values substantially match the true values (E)_{FB_CP}＝E_{T_CP}、E_{FB_CN}＝E_{T_CN}) Thus, the neutral point voltage ((E)_{T_CN}-E_{T_CP}) /2) is substantially zero. On the other hand, when the dc voltage detector is abnormal, the detection value does not match the true value (E)_{FB_CP}≠E_{T_CP}、E_{FB_CN}≠E_{T_CN}) Thus, the neutral point voltage V_{T_CZ}((E_{T_CN}-E_{T_CP}) And/2) is biased to either positive or negative in a steady state.

With the formulas (1), (2), and (5), only the neutral point voltage V in the case where the dc voltage detector 25 fails is the neutral point voltage V_{T_CZ}As shown in the following equation (20), the neutral point voltage V in the case where only the dc voltage detector 26 fails_{T_CZ}As shown in the following equation (21).

V_{T_CZ}＝E_{FB_CP}(1-1/G_CP)/2…(20)

V_{T_CZ}＝E_{FB_CP}(1/G_CN-1)/2…(21)

When the gain abnormality of the dc voltage detector 25 is in the state shown in equation (22), the neutral point voltage V is obtained from equation (20)_{T_CZ}Is negative. When the gain abnormality of the dc voltage detector 25 is in the state shown by the formula (24), the neutral point voltage V is expressed by the formula (20)_{T_CZ}Is positive.

On the other hand, when the gain abnormality of the dc voltage detector 26 is in the state shown in equation (23), the neutral point voltage V is obtained from equation (21)_{T_CZ}Is negative. When the gain abnormality of the dc voltage detector 26 is in the state shown by equation (25), the neutral point voltage V is expressed by equation (21)_{T_CZ}Is positive.

G_CP＜1…(22)

G_CN＞1…(23)

G_CP＞1…(24)

G_CN＜1…(25)

The true value (E) of the voltage of the capacitor is caused by the abnormality shown in any one of the formulas (22) to (25)_{T_CP}、E_{T_CN}) Micro-fluidics from the system in the case of asymmetryA charging current that is a true value of the capacitor voltage. In contrast, the neutral point voltage controller 55 continuously outputs the ac output voltage correction value AVzR_{OUT_C}To balance the capacitor voltage detection value (E) of the DC voltage detector in which the malfunction has occurred_{FB_CP}、E_{FB_CN}). For example, at neutral point voltage V_{T_CZ}In the case of an abnormality represented by the negative formula (22) or the negative formula (23), the true value V of the neutral point voltage is maintained negative_{T_CZ}The neutral point voltage controller 55 continuously outputs the negative ac output voltage correction value AVzR_{OUT_C}。

When a failure occurs in either of the dc voltage detectors 25 and 26, the relationship between the dc voltage detector having an abnormality, the direction of the gain abnormality, and the direction of change of the index 202 is as shown in fig. 14B.

Specifically, in the dc voltage detector 25, a gain G is generated_CPIf the abnormality is less than 1, the index 202 is negative (decreased), and the gain G is generated_CPIf the abnormality is greater than 1, the index 202 is positive (increased). In addition, in the dc voltage detector 26, a gain G is generated_CNIf the abnormality is less than 1, the index 202 is positive (increased), and the gain G is generated_CNIf the abnormality is greater than 1, the index 202 is negative (decreased). Note that the index 202 does not change with respect to the abnormality of the dc voltage detectors 35 and 36.

When an abnormality occurs in either one of the dc voltage detector 25 and the dc voltage detector 26, if the direction of change of the gain is the same, the indicator 202 shows a change in a different direction (reverse direction).

Next, the third index creating unit 723 will be described.

Fig. 6 is a configuration diagram of a third index creating unit according to the first embodiment.

The third index creating unit 723 calculates the index 203(═ DI)₃). The index 203 is a value obtained by using the detected value I of the AC current to the converter 2 side when the DC voltage detector is abnormal_{FB_C}The index for detecting abnormality of the dc voltage detector by superimposing the 2 nd harmonic component is calculated for the ac side connection point 13The reference even-order harmonic waveform of the current (c) is based on an index (converter-side even-order harmonic current index, second index, converter-side index) of the product of the reference even-order harmonic waveform and the current value detected by the current detector 7. Here, the ac side connection point 13 is a point at a position between the transformer 12 and the converter 2.

First, for the 2 nd harmonic current I_{FB_C2}Superimposed on the value of the detected AC current I_{FB_C}And 2 harmonic current I_{FB_C2}The characteristics of (a) are explained.

Fig. 7A to 7B are first diagrams illustrating the 2 nd harmonic in the first embodiment. FIG. 7A shows the true value E of the DC voltage on the P side due to the failure of the DC voltage detector 25 or 26, with time on the horizontal axis_{T_CP}Greater than the true value E of the DC voltage on the N side_{T_CN}(E_{T_CP}＞E_{T_CN}) Ac output voltage V of ac side connection point 13 of state (1)_{PWM_C}Fig. 7B shows an example of the ac output voltage V of the ac side connection point 13_{PWM_C}Fundamental wave V of_{PWM_C1}And 2 th harmonic V_{PWM_C2}Of the synthetic wave V_{PWM_C12}An example of the method.

Fig. 8A to 8B are second diagrams illustrating the 2 nd harmonic in the first embodiment. FIG. 8A shows the true value E of the DC voltage on the P side when the DC voltage detector 25 or 26 fails and the horizontal axis is time_{T_CP}True value E of DC voltage smaller than N side_{T_CN}Ac output voltage V of ac side connection point 13 of state (1)_{PWM_C}Fig. 8B shows an example of the ac output voltage V of the ac side connection point 13 in the case shown in fig. 8A_{PWM_C}Fundamental wave V of_{PWM_C1}And 2 th harmonic V_{PWM_C2}Of the synthetic wave V_{PWM_C12}An example of the method.

True value E of DC voltage on P side due to abnormality of DC voltage detector 25 or 26_{T_CP}Greater than the true value E of the DC voltage on the N side_{T_CN}State (E)_{T_CP}＞E_{T_CN}) Lower, AC output voltage V_{PWM_C}The time waveform of (a) is shown in fig. 7A. The power conversion is obtained by multiplying a switching signal obtained by pulse width modulating an AC output voltage by a DC capacitor voltageThe ac voltage command value of the converter 21. True value E of the DC voltage on the P side_{T_CP}And true value E of DC voltage on N side_{T_CN}In different cases (E)_{T_CP}≠E_{T_CN}In the case of (1), even if the ac output voltage command value has a waveform with positive and negative symmetry, the ac voltage ac output voltage V output from the power conversion unit 21_{PWM_C}Also a positive and negative asymmetrical waveform. Thus, the AC voltage is the AC output voltage V_{PWM_C}Including even harmonics (2 nd, 4 th, 6 th, etc.).

AC output voltage V_{PWM_C}Fundamental wave V of_{PWM_C1}And 2 th harmonic V_{PWM_C2}Of the synthetic wave V_{PWM_C12}(V_{PWM_C1}+V_{PWM_C2}) As shown in fig. 7B, the composite wave V_{PWM_C12}Represented by equation (26).

V_{PWM_C12}＝V_C1cos(ωt)+V_C2cos(2ωt)…(26)

Here, V_C1Is a composite wave V_{PWM_C12}Voltage fundamental wave component of V_C2Is a composite wave V_{PWM_C12}Voltage 2 harmonic component of (a).

According to the formula (26), the 2 nd harmonic V_{PWM_C2}Phase of and fundamental wave V_{PWM_C1}Are in phase.

On the other hand, the AC output voltage V is detected by an abnormality of the DC voltage detector 25 or 26_{PWM_C}The time waveform of (a) is shown in fig. 8A. AC output voltage V_{PWM_C}Fundamental wave V of_{PWM_C1}And 2 th harmonic V_{PWM_C2}Of the synthetic wave V_{PWM_C12}(V_{PWM_C1}+V_{PWM_C2}) As shown in fig. 8B, the composite wave V_{PWM_C12}Represented by equation (27).

V_{PWM_C12}＝V_C1cos(ωt)+V_C2cos(2ωt+π)

＝V_C1cos(ωt)-V_C2cos(2ωt)…(27)

As can be seen from fig. 7A to 7B and fig. 8A to 8B, equation (26) and equation (27): synthetic wave V_{PWM_C12}True value E of DC voltage having phase of 2-th harmonic component on P side_{T_CP}Greater than the true value E of the DC voltage on the N side_{T_CN}State (E)_{T_CP}＞E_{T_CN}) And the true value E of the DC voltage on the P side_{T_CP}True value E of DC voltage smaller than N side_{T_CN}State (E)_{T_CP}＜E_{T_CN}) The difference is 180 degrees.

At E_{T_CP}＞E_{T_CN}In the case of a failure (state shown by the formula (26)), the ac current detection value I_{FB_C}As shown in the following equation (28), at E_{T_CP}＜E_{T_CN}In the case of a failure (state shown by the formula (27)), the ac current detection value I_{FB_C}As shown in the following equation (29).

I_{FB_C}＝I_C1cos(ωt-φ₁)+I_C2cos(2ωt-φ₂)…(28)

I_{FB_C}＝I_C1cos(ωt-φ₁)-I_C2cos(2ωt-φ₂)…(29)

Here, I_C1Is a detected value of alternating current I_{FB_C}Fundamental wave component of current, I_C2Is a detected value of alternating current I_{FB_C}Current 2 harmonic component of phi₁Is the phase difference between the phase of the fundamental wave voltage at the AC side connection point 13 and the phase of the fundamental wave current at the current detector 7, phi₂The phase difference is the phase difference between the fundamental wave voltage phase at the ac side connection point 13 and the 2 nd harmonic current phase at the current detector 7.

Phase difference phi₂In the case where the magnitude of the 2 nd harmonic of the voltage waveform contained in the ac power supply 1 is small enough to be ignored, it can be calculated by the real part and the imaginary part of the impedance of the transformer 12. For example, the impedance of the transformer 12 is dominated by the inductive component, and therefore φ₂Is pi/2. Further, I is obtained from the amplitude of the fundamental wave voltage at the AC side connection point 13 and the impedance of the transformer 12_C1. Further, phi is obtained from the phase of the fundamental wave voltage at the ac side connection point 13 and the impedance of the transformer 12₁. Further, I is obtained from the amplitude of the 2 nd harmonic voltage applied to the AC side connection point 13 and the impedance of the transformer 12_C2。

As can be seen from equations (28) and (29): at E_{T_CP}＞E_{T_CN}When a failure occurs, and E_{T_CP}＜E_{T_CN}Fault ofThe phase of the 2 nd harmonic current differs by pi.

Therefore, E is known from the phase difference of the 2 nd harmonic current_{T_CP}And E_{T_CN}Can be according to I_C2Estimate of the size of E_{T_CP}And E_{T_CN}The deviation of (2).

In the above example, the 2 nd harmonic was explained as an example, but the 4 th order and 6 th order low even harmonic currents other than the 2 nd order are applied to E in the same manner as described above_{T_CP}And E_{T_CN}With different values, the 2 nd harmonic currents are 180 degrees out of phase. Therefore, even if harmonics of even orders other than 2 are used, E can be performed in the same manner as the 2 nd order harmonics_{T_CP}And E_{T_CN}And estimating the voltage deviation.

Next, the third index creating unit 723 will be described in detail.

The third index creating unit 723 includes: a fundamental wave phase detection unit 7231, a reference 2-order harmonic cosine wave calculation unit 7232, a product calculation unit 7233, a moving average calculation unit 7234, and a filter 7235.

The fundamental wave phase detection unit 7231 obtains the phase of the fundamental wave voltage (fundamental wave voltage phase) at the ac side connection point 13 from the waveform of the voltage input from the voltage detector 11, the impedance Xc of the transformer 12 acquired from the setting storage unit 72b, and the waveform of the current input from the current detector 7.

Specifically, the fundamental wave phase detection unit 7231 calculates the fundamental wave voltage phase of the ac power supply 1 by performing pll (phase Locked loop) operation on the detection value input from the voltage detector 11. Next, the fundamental wave phase detection unit 7231 calculates a current d-q converted value by d-q converting the detection value of the current detector 7 using the fundamental wave phase, and calculates a voltage vector of the ac-side connection point 13 by vector-synthesizing the voltage d-q converted value obtained by d-q converting the detection value of the voltage detector 11 based on the current d-q converted value and the inductance Xc.

Next, the fundamental wave phase detection unit 7231 calculates a phase difference from the fundamental wave voltage phase of the ac power supply 1 based on the voltage vector, thereby calculating the voltage phase of the ac side connection point 13.

Here, when inductance Xc of transformer 12 is small, detected value V of voltage detected value 11 is detected_{AC_C}Fundamental wave voltage V of_{AC_C1}And an AC output voltage V from an AC side connection point 13_{PWM_C}Fundamental wave voltage V of_{PWM_C1}Since the voltage values substantially match, only the detection value V of the voltage detection value 11 may be used_{AC_C}The phase of the fundamental wave voltage at the ac side connection point 13 is approximately obtained. The phase of the fundamental wave voltage at the ac-side connection point 13 may be determined from a converter ac voltage command value output from the current controller 53 of the converter control device 5.

The reference 2-order harmonic cosine wave calculation unit 7232 calculates a reference 2-order harmonic cosine wave α_{BASE_C}. For example, when the 2 nd harmonic cos (2 ω t) having the same phase as the fundamental wave cos (ω t) of the ac side connection point 13 is set as the reference, the phase of the 2 nd harmonic of the current detected by the current detector 7 lags behind the phase of the ac side connection point 13 by Φ₂. Therefore, the reference 2 nd harmonic cosine wave α is obtained by the following formula (30)_{BASE_C}。

α_{BASE_C}＝cos(2ωt-φ₂)…(30)

Phase difference phi₂For example, can be calculated from the real and imaginary parts of the impedance of the transformer 12. Further, the reference 2 nd harmonic cosine wave α in this example_{BASE_C}Phase of (E)_{T_CP}＞E_{T_CN}The phases of the 2 nd harmonics of the current generated at the time of the fault are equal. The reference 2 nd harmonic cosine wave α may be obtained by a phase difference between the phase of the converter output effective current command value output from the dc voltage controller 52 of the converter control device 5 and the phase of the ac side connection point 13_{BASE_C}Phase phi of₂。

The product operation unit 7233 detects the ac current I of the current detector 7_{FB_C}Multiplying by a reference 2 harmonic cosine wave alpha_{BASE_C}. In this case, the alternating current I_{FB_C}At E_{T_CP}＞E_{T_CN}In the case of failure (in the state shown in FIGS. 7A to 7B), as shown by the formula (28), E_{T_CP}＜E_{T_CN}(in the state shown in FIGS. 8A to 8B)As shown in equation (29). Therefore, the operation result (α) of the product operation unit 7233_{BASE_C}×I_{FB_C}) At E_{T_CP}＞E_{T_CN}At the time of failure of (3), as shown in the following formula (31), at E_{T_CP}＜E_{T_CN}The failure time (2) is as shown in the following equation (32).

α_{BASE_C}×I_{FB_C}＝I_C1cos(2ωt-φ₂)cos(ωt-φ₁)

+I_C2cos(2ωt-φ₂)cos(2ωt-φ₂)…(31)

α_{BASE_C}×I_{FB_C}＝I_C1cos(2ωt-φ₂)cos(ωt-φ₁)

-I_C2cos(2ωt-φ₂)cos(2ωt-φ₂)…(32)

The moving average calculation unit 7234 calculates the calculation result (α) of the product calculation unit 7233_{BASE_C}×I_{FB_C}) I.e., a moving average of 1 cycle amount of formula (31) or formula (32) (index 203). When the moving average of 1 cycle is calculated for formula (31) and formula (32), the first terms of formula (31) and formula (32) are zero from the orthogonality of the trigonometric functions. Therefore, the moving average for equation (31) is positive and the moving average for equation (32) is negative.

The filter 7235 removes noise that cannot be removed by the moving average calculation unit 7234. The function of the filter 7235 is the same as the filter 7212 shown in fig. 4.

When a failure occurs in either of the dc voltage detectors 25 and 26, the relationship between the direction of the abnormal gain and the direction of change of the index 203 in the dc voltage detector with abnormality is shown in fig. 14C.

Specifically, in the dc voltage detector 25, a gain G is generated_CPIf the abnormality is less than 1, the index 203 is positive (increased), and the gain G is generated_CPIf the abnormality is greater than 1, the index 203 is negative (decreased). In addition, in the dc voltage detector 26, a gain G is generated_CNIf the abnormality is less than 1, the index 203 is negative (decreased), and the gain G is generated_CNIn the case of an abnormality greater than 1,index 203 is positive (increasing). The index 203 does not change with respect to the abnormality of the dc voltage detectors 35 and 36.

When an abnormality occurs in either one of the dc voltage detector 25 and the dc voltage detector 26, if the direction of change of the gain is the same, the index 203 shows a change in a different direction (reverse direction).

Next, the fourth index creating unit 724 will be described.

Fig. 9 is a configuration diagram of a fourth index creating unit according to the first embodiment.

The fourth index creating unit 724 calculates the index 204(═ DI)₄). The index 204 is an index for detecting an abnormality of the dc voltage detector by superimposing a 2 nd harmonic component on the voltage waveform on the converter 2 side when the dc voltage detector is abnormal, and is an index (converter-side even harmonic voltage index, second index, converter-side index) for calculating a reference even harmonic waveform for the voltage at the ac-side connection point 13 and based on the product of the reference even harmonic waveform and the voltage value.

The fourth index creating unit 724 includes: a waveform calculation unit 7241, a fundamental waveform detection unit 7242, a reference 2-order harmonic cosine wave calculation unit 7243, a product calculation unit 7244, a moving average 7245, and a filter 7246. The fourth index creating unit 724 performs a process locally different from that performed by the third index creating unit 723.

The fourth index creating unit 724 is different from the third index creating unit 723 in that the ac output current multiplied by the ac side connection point 13 in the product calculating unit 7233 is multiplied by the ac output voltage of the ac side connection point 13 in the product calculating unit 7244. Since the index 204 and the index 203 have substantially the same properties, a detailed description thereof will be omitted, and a point different from the third index creating unit 723 will be described.

The waveform computing unit 7241 calculates the ac output voltage V at the ac side connection point 13 by calculating the difference between the detection value of the voltage detector 11 and the voltage drop obtained from the product of the detection value of the current detector 7 and the impedance Xc of the transformer 12_{PWM_C}The waveform of (2). Note that the intersection may be calculated instead of the calculation performed by the waveform calculating unit 7241Current output voltage_{PWM_C}Further, a voltage detector for detecting the voltage at the ac side connection point 13 is provided, and the voltage at the ac side connection point 13 is directly measured.

The fundamental wave phase detection unit 7242 calculates the ac output voltage V from the waveform calculation unit 7241_{PWM_C}The phase of the fundamental wave of the voltage waveform at the ac side connection point 13 is detected. Specifically, the fundamental wave phase detection unit 7242 detects the ac output voltage V at the ac-side connection point 13_{PWM_C}The phase of the fundamental wave voltage at the ac side connection point 13 is calculated by performing PLL operation on the value of (d).

When the inductance of the transformer 12 is small, the detection value V of the voltage detector 11 is set to be small_{AC_C}Fundamental wave voltage V of_{AC_C1}And an AC output voltage V from an AC side connection point 13_{PWM_C}Fundamental wave voltage V of_{PWM_C1}Since the phases are substantially identical, the fundamental wave phase at the ac side connection point 13 may be approximately obtained from only the voltage waveform of the voltage detector 11. The fundamental wave phase of the voltage waveform at ac-side connection point 13 may be determined from a converter voltage command value output from current controller 53 of converter control device 5.

When a failure occurs in either of the dc voltage detectors 25 and 26, the relationship between the dc voltage detector having an abnormality, the direction of the gain abnormality, and the direction of change in the index 204 is as shown in fig. 14C.

Specifically, in the dc voltage detector 25, a gain G is generated_CPIf the abnormality is less than 1, the index 204 is positive (increased), and the gain G is generated_CPIf the abnormality is greater than 1, the index 204 is negative (decreased). In addition, in the dc voltage detector 26, a gain G is generated_CNIf the abnormality is less than 1, the index 204 is negative (decreased), and the gain G is generated_CNIf the abnormality is greater than 1, the index 204 is positive (increased). Note that the index 204 does not change with respect to the abnormality of the dc voltage detectors 35 and 36.

When an abnormality occurs in either one of the dc voltage detector 25 and the dc voltage detector 26, if the direction of change of the gain is the same, the indicator 204 shows a change in a different direction (reverse direction). The size of the index 204 is proportional to the size of the 2 nd harmonic of the voltage at the ac side connection point 13.

Next, the fifth pointer generation unit 725 will be described.

Fig. 10 is a configuration diagram of a fifth pointer generating unit according to the first embodiment.

The fifth index generation unit 725 calculates the index 205(═ DI)₅). Index 205 is an ac output voltage correction value AVzR by using neutral point voltage controller 65 at the time of abnormality of dc voltage detector_{OUT_I}When the change occurs, an index of abnormality of the DC voltage detectors (35, 36) is detected, and the difference Delta E between the detection values of the DC voltage detectors is used_{FB_I}(＝E_{FB_IN}-E_{FB_IP}) Zero AC output voltage correction value AVzR_{OUT_I}An index (an index of the inverter neutral point voltage control signal: a second index: an index on the inverter side) is set.

The fifth index making section 725 has a filter 7251. The fifth pointer generation unit 725 and the second pointer generation unit 722 have the same processing as the first pointer generation unit, but have different output destinations of the input ac output voltage correction values. The filter 7251 performs a correction value AVzR for removing the ac output voltage inputted from the neutral point voltage controller 65_{OUT_I}Filtering the fluctuation component of (2). The function of the filter 7251 is the same as the filter 7212 shown in fig. 4.

When a failure occurs in either of the dc voltage detectors 35 and 36, the relationship between the direction of the abnormal dc voltage detector, the abnormal gain, and the direction of change in the index 205 is as shown in fig. 15A.

Specifically, in the dc voltage detector 35, a gain G is generated_IPIf the abnormality is less than 1, the index 205 is negative (decreased), and the gain G is generated_IPIf the abnormality is greater than 1, the index 205 is positive (increased). In addition, in the dc voltage detector 36, a gain G is generated_INIf the abnormality is less than 1, the index 205 is positive (increased), and the gain G is generated_INIf the abnormality is greater than 1, the index 205 is negative (decreased). In addition, it meansThe target 205 does not change with respect to the abnormality of the dc voltage detectors 25 and 26.

When an abnormality occurs in either one of the dc voltage detector 35 and the dc voltage detector 36, if the direction of change of the gain is the same, the indicator 205 appears as a change in a different direction (reverse direction).

Next, the sixth index creating unit 726 will be described.

Fig. 11 is a configuration diagram of a sixth index creating unit according to the first embodiment.

The sixth index creation unit 726 calculates the index 206(═ DI)₆). The indicator 206 is a value obtained by using the detected ac current I on the inverter 3 side when the dc voltage detector is abnormal_{FB_I}The index for detecting an abnormality of the dc voltage detector 35 or 36 by superimposing the 2 nd harmonic component is an index (inverter-side even harmonic current index, second index, inverter-side index) for calculating a reference even harmonic waveform of a current to a connection point at the subsequent stage of the inverter 3 and based on a product of the reference even harmonic waveform and a current value detected by the current detector 9. The connection point of the subsequent stage of the inverter 3 may be, for example, the position of the current detector 9.

The sixth index creating unit 726 includes: a fundamental wave phase detection unit 7261, a reference 2-order harmonic cosine wave calculation unit 7262, a product calculation unit 7263, a moving average calculation unit 7264, and a filter 7265. Each part of the sixth index creating unit 726 basically has the same function as the part of the third index creating unit 723 having the same name except for the points described below. Hereinafter, differences between the parts of the sixth index generating unit 726 and the parts of the third index generating unit 723 will be described.

The product operation unit 7263 receives the detection value (current waveform) of the current detector 9 instead of the detection value of the current detector 7 received from the product operation unit 7233, and uses the result in multiplication.

The fundamental wave phase detection unit 7261 detects the phase of the fundamental wave current from the detection value of the current detector 9. The phase of the fundamental wave current may be detected from the phase of the inverter output current command value output from the speed controller 62, or may be detected from the phase of the inverter voltage command value output from the current controller 63 and the phase difference caused by the impedance of the motor 4.

When a failure occurs in either of the dc voltage detectors 35 and 36, the relationship between the dc voltage detector having an abnormality, the direction of the gain abnormality, and the direction of change of the index 206 is as shown in fig. 15B.

Specifically, in the dc voltage detector 35, a gain G is generated_IPIf the abnormality is less than 1, the indicator 206 is positive (increased), and the gain G is generated_IPIf the abnormality is greater than 1, the index 206 is negative (decreased). In addition, in the dc voltage detector 36, a gain G is generated_INIf the abnormality is less than 1, the index 206 is negative (decreased), and the gain G is generated_INIf the abnormality is greater than 1, the index 206 is positive (increased). Note that the index 206 does not change with respect to the abnormality of the dc voltage detectors 25 and 26.

When an abnormality occurs in either one of the dc voltage detector 35 and the dc voltage detector 36, if the direction of change of the gain is the same, the indicator 206 shows a change in a different direction (reverse direction).

Next, the seventh index creating unit 727 will be described.

Fig. 12 is a configuration diagram of a seventh index creating unit according to the first embodiment.

The seventh index creating unit 727 calculates the index 207(═ DI)₇). The index 207 is a detected value (V) using the AC line voltage between the U phase and the V phase when the DC voltage detector is abnormal_{FB_IUV}) And a detected value of the AC line voltage between the V phase and the W phase (V)_{FB_IVW}) The error index (ac line voltage index, second index, inverter-side index) of the dc voltage detector 35 or 36 is detected by detecting the timing of the positive/negative deviation of the difference value of (a).

Index 207 is a detected value (V) of the ac line voltage on the inverter side_{FB_IUV}、V_{FB_IVW}) Is represented by formula (33).

DI₇＝V_{FB_IUV}-V_{FB_IVW}…(33)

The principle of determining the failure of the dc voltage detectors 35 and 36 by the index 207 will be described.

Detected value (V) of AC line voltage_{FB_IUV}、V_{FB_IVW}) From an alternating phase voltage (U-phase voltage V)_{FB_IU}Voltage of V phase_{FB_IV}W phase voltage V_{FB_IW}) When expressed, the expression is expressed by the formula (34) and the formula (35).

V_{FB_IUV}＝V_{FB_IU}-V_{FB_IV}…(34)

V_{FB_IVW}＝V_{FB_IV}-V_{FB_IW}…(35)

When the formula (34) and the formula (35) are substituted into the formula (33), the formula (36) is obtained.

DI₇＝V_{FB_IUV}-V_{FB_IVW}＝V_{FB_IU}-2V_{FB_IV}+V_{FB_IW}…(36)

Here, the inverter 3 is a 3-level inverter. Therefore, the ac phase voltage (V) of the inverter 3_{FB_IU}、V_{FB_IV}、V_{FB_IW}) Is a positive potential level V_{LV1_I}(first potential), neutral point potential level V_{LV2_I}(second potential), negative potential level V_{LV3_I}(third potential) is not limited. Each voltage level (V)_{LV1_I}、V_{LV2_I}、V_{LV3_I}) Using the true value E of the voltage of the smoothing capacitor 32_{T_IP}True value E of voltage of smoothing capacitor 33_{T_IN}And neutral point potential V of inverter-side neutral point 14_{T_IZ}＝(E_{T_IN}-E_{T_IP}) The expression,/2, is as shown in the expressions (37) to (39).

V_{LV1_I}＝E_{T_IP}+V_{T_IZ}…(37)

V_{LV2_I}＝V_{T_IZ}…(38)

V_{LV3_I}＝-E_{T_IN}+V_{T_IZ}…(39)

AC phase voltage (V)_{FB_IU}、V_{FB_IV}、V_{FB_IW}) Can respectively take V_{LV1_I}、V_{LV2_I}、V_{LV3_I}These 3 values, and therefore the combination of the ac phase voltages is 27Group (═ 3 to power). In this combination, the detected value (V) of the AC line voltage_{FB_IUV}、V_{FB_IVW}) All of which are positive alternating phase voltages (V)_{FB_IU}、V_{FB_IV}、V_{FB_IW}) The combination of (c) is only the case shown in equation (40). In addition, the detected value (V) of the AC line voltage_{FB_IUV}、V_{FB_IVW}) All of which are negative alternating phase voltages (V)_{FB_IU}、V_{FB_IV}、V_{FB_IW}) The combination of (c) is only the case shown in equation (41). Here, Λ is a logical product (AND).

(V_{FB_IU}＝E_{T_IP}+V_{T_IZ-})∧(V_{FB_IV}＝V_{T_IZ})

∧(V_{FB_IW}＝-E_{T_IN}+V_{T_IZ})…(40)

(V_{FB_IU}＝-E_{T_IN}+V_{T_IZ})∧(V_{FB_IV}＝V_{T_IZ})

∧(V_{FB_IW}＝E_{T_IP}+V_{T_IZ})…(41)

When the formula (40) is satisfied, the detected value (V) of the AC line voltage_{UV_I}、V_{VW_I}) As shown in equation (42). When the formula (41) is satisfied, the detected value (V) of the AC line voltage is obtained_{UV_I}、V_{VW_I}) As shown in equation (43).

(V_{FB_IUV}＝E_{T_IP})∧(V_{FB_IVW}＝E_{T_IN})…(42)

(V_{FB_IUV}＝-E_{T_IN})∧(V_{FB_IVW}＝-E_{T_IP})…(43)

When equation (42) is satisfied, index 207 is as shown in equation (44). When equation (43) is satisfied, index 207 is also expressed by equation (44).

DI₇＝E_{T_IP}-E_{T_IN}…(44)

Here, the true value of the voltage (E)_{T_IP}、E_{T_IN}) According to formula (3) and formula (4), respectively, as shown in formula (45) and formula (46).

E_{T_IP}＝E_{FB_IP}/G_IP…(45)

E_{T_IN}＝E_{FB_IN}/G_IN…(46)

When the formula (45) and the formula (46) are substituted into the formula (44), the formula (47) is obtained.

DI₇＝(E_{FB_IP}/G_IP)-(E_{FB_IN}/G_IN)…(47)

When the formula (6) indicating the correlation between the detection values of the dc voltage detectors 35 and 36 is used, the formula (47) can be modified as shown in the formula (48).

DI₇＝E_{FB_IP}(1/G_IP-1/G_IN)…(48)

According to equation (48), when a failure occurs in any one of dc voltage detectors 35 and 36, index 207 has a relationship between the direction of the abnormal dc voltage detector, the direction of the gain abnormality, and the direction of change in index 207, as shown in fig. 15B.

Specifically, in the dc voltage detector 35, a gain G is generated_IPIf the abnormality is less than 1, the indicator 207 is positive (increased), and the gain G is generated_IPIf the abnormality is greater than 1, the index 207 is negative (decreased). In addition, in the dc voltage detector 36, a gain G is generated_INIf the abnormality is less than 1, the index 207 is negative (decreased), and the gain G is generated_INIf the abnormality is greater than 1, the index 207 is positive (increased). Note that the index 207 does not change with respect to the abnormality of the dc voltage detectors 25 and 26.

If an abnormality occurs in either one of the dc voltage detector 35 and the dc voltage detector 36, the indicator 207 shows a change in a different direction (opposite direction) if the direction of change in the gain is the same.

The seventh index creating unit 727 includes: a determination section extraction unit 7271, an index calculation unit 7272, and a filter 7273.

The determination cross section extraction unit 7271 extracts a time cross section (determination cross section) in which the formula (40) or the formula (41) is satisfied.

Fig. 13 is a diagram illustrating extraction of a judgment cross section in the first embodiment. Fig. 13 shows temporal changes in pulse signals for controlling on and off of the switching elements of the inverter power conversion unit 31, which are output from the pulse generator 64 for each phase.

The determination cross section extraction unit 7271 extracts a time cross section in which the formula (40) or the formula (41) is satisfied from the time change of the pulse signal for on/off control of each switching element of the inverter power conversion unit 31, which is output from the pulse generator 64 for each phase. Further, a time section in which the formula (42) or the formula (43) is satisfied may be extracted from the detection value of the voltage detector 10. In this case, true value E_{T_IP}Sum true value E_{T_IN}And gain G_IPAnd gain G_INAccordingly, the detected value V of the AC line voltage is changed_{UV_I}And a detected value V of the line voltage between the alternating current lines_{VW_I}Instead of using the formula (42) and the formula (43), a certain range as shown in the formula (49) and the formula (50) may be used.

((E_{FB_IP}×G_L)＜V_{FB_IUV}＜(E_{FB_IP}×G_H))

∧((E_{FB_IN}×G_L)＜V_{FB_IVW}＜(E_{FB_IN}×G_H))…(49)

((-E_{FB_IN}×G_H)＜V_{FB_IUV}＜(-E_{FB_IN}×G_L))

∧((-E_{FB_IP}×G_H)＜V_{FB_IVW}＜(-E_{FB_IP}×G_L))…(50)

Here, G_H、G_LIs a constant number, G_H＞1，0＜G_L＜1。

The index calculation unit 7272 obtains a detected value (V) of the ac line-to-line voltage of the time section extracted by the judgment section extraction unit 7271 from the voltage detector 10_{FB_IUV}、V_{FB_IVW}). The index calculation unit 7272 obtains a detected value (V) of the ac line voltage_{FB_IUV}、V_{FB_IVW}) The index 207 is calculated by substituting into equation (33). The filter 7273 removes noise from the index 207 calculated by the index calculation unit 7272. The function of the filter 7273 is the same as the filter 7212 shown in fig. 4.

Fig. 14A to 14C and fig. 15A to 15B are diagrams showing the abnormality detector, the gain of the abnormality detector, and the index change as tables. Fig. 14A shows changes in the gain and index 201 of the abnormality detector, the gain and index 202 of the abnormality detector, and fig. 14C shows changes in the gain and index 203 and index 204 of the abnormality detector and abnormality detector. Fig. 15A shows changes in the gains and indices 205 of the abnormality detector and the abnormality detector, and fig. 15B shows changes in the gains and indices 206 and 207 of the abnormality detector and the abnormality detector.

When any of the dc detectors 25, 26, 35, and 36 is an abnormality detector, the normality (gain is 1) changes, and the abnormality detector can be determined from the change in the index.

Fig. 16 is a diagram summarizing the relationship between the abnormality detector, the index 201, the converter-side index, and the inverter-side index from fig. 14A to 14C and fig. 15A to 15B.

In the case where there is no abnormality detector, the index 201, the converter-side index, and the inverter-side index are near 0.

On the other hand, when the detector 25 or the detector 26 is abnormal, the index 201 and the converter-side index increase or decrease, and the inverter-side index does not change.

On the other hand, when the detector 35 or the detector 36 is abnormal, the index 201 or the inverter-side index increases or decreases, and the converter-side index does not change.

By using the first to seventh indexes, the soundness of the dc voltage detector can be diagnosed by the method described in patent document 1. However, when the circuit constant of a motor or a transformer connected to the outside of the power conversion device as the application target is unknown, it is difficult to set the reference value. Even if the circuit constants of the motor and the transformer connected to the outside of the power converter as the application target are known, the index change amount for the abnormality of the dc voltage detector is different depending on the circuit constant, and therefore, it is necessary to set the reference value for each application target.

In order to solve this problem, the abnormality diagnosis process shown in fig. 18 to 19 is performed by the abnormality determiner 72 including the dc voltage signal generating unit shown in fig. 17, whereby the soundness of the dc voltage detector can be easily diagnosed.

Fig. 17 is a configuration diagram of the dc voltage signal generating unit 72 e.

In the estimation unit 7200, the estimation values of the detection values of the dc voltage detectors 25, 26, 35, and 36 are calculated using the equations (51) to (54). For example, at E_{FB_CN}、E_{FB_IP}、E_{FB_IN}Under normal conditions, E_{FB_CP}Estimated value of E_{FBH_CP}Represented by equation (51). Likewise, in E_{FB_CP}、E_{FB_IP}、E_{FB_IN}Under normal conditions, E_{FB_CN}Estimated value of E_{FBH_CN}Represented by formula (52). Likewise, in E_{FB_CP}、E_{FB_CN}、E_{FB_IN}Under normal conditions, E_{FB_IP}Estimated value of E_{FBH_IP}Represented by equation (53). Likewise, in E_{FB_CP}、E_{FB_CN}、E_{FB_IP}Under normal conditions, E_{FB_IN}Estimated value of E_{FBH_IN}Represented by equation (54).

E_{FBH_CP}＝(E_{FB_IP}+E_{FB_IN})-E_{FB_CN}…(51)

E_{FBH_CN}＝(E_{FB_IP}+E_{FB_IN})-E_{FB_CP}…(52)

E_{FBH_CP}＝(E_{FB_CP}+E_{FB_CN})-E_{FB_IN}…(53)

E_{FBH_CP}＝(E_{FB_CP}+E_{FB_CN})-E_{FB_IP}…(54)

In the correction units 7201, 7202, 7203, and 7204, correction values are calculated using equations (55) to (58).

E_{FBC_CP}＝(1-K_CP)×E_{FB_CP}+K_CP×E_{FBH_CP}…(55)

E_{FBC_CN}＝(1-K_CN)×E_{FB_CN}+K_CN×E_{FBH_CN}…(56)

E_{FBC_IP}＝(1-K_IP)×E_{FB_IP}+K_IP×E_{FBH_IP}…(57)

E_{FBC_IN}＝(1-K_IN)×E_{FB_IN}+K_IN×E_{FBH_IN}…(58)

Here, K_CP、K_CN、K_IP、K_INThe estimated values of the dc voltage detectors 25, 26, 35, and 36 are used in proportions, and these values are, for example, 0 or 1.

For example, at K_CP、K_CN、K_IP、K_INWhen 0 is obtained, the equations (55) to (58) are equations (59) to (62), and the correction values are the detection values.

E_{FBC_CP}＝E_{FB_CP}…(59)

E_{FBC_CN}＝E_{FB_CN}…(60)

E_{FBC_IP}＝E_{FB_IP}…(61)

E_{FBC_IN}＝E_{FB_IN}…(62)

For example, at K_CP、K_CN、K_IP、K_INIn the case of 1, the equations (55) to (58) are equations (63) to (66), and the correction values are the estimated values.

E_{FBC_CP}＝E_{FBH_CP}…(63)

E_{FBC_CN}＝E_{FBH_CN}…(64)

E_{FBC_IP}＝E_{FBH_IP}…(65)

E_{FBC_IN}＝E_{FBH_IN}…(66)

Fig. 18 and 19 are flowcharts of the abnormal portion diagnosis process performed by the abnormality determiner 72. In the flowcharts of fig. 18 and 19, the first dc voltage detector is 25, the second dc voltage detector is 26, the third dc voltage detector is 35, and the fourth dc voltage detector is 36. Further, the order may be arbitrary.

Fig. 20 to 24F show an operation example in the case where the dc voltage detector 26 is abnormal, as a first example of the operation of the flowcharts of fig. 18 and 19. Fig. 20 shows the state of the dc voltage detector in the case where the dc voltage detector 26 is abnormal in each time range in fig. 21A to 21D, the number of the corresponding flowchart, and the input of the correction unit.

Fig. 21A to 21D are diagrams showing examples of temporal changes in the respective indices and the comprehensive diagnosis index of the abnormality determiner 72. Fig. 21A is a diagram showing an example of temporal change in the index 201, fig. 21B is a diagram showing an example of temporal change in the index 203 (converter-side index), fig. 21C is a diagram showing an example of temporal change in the index 206 (inverter-side index), and fig. 21D is a diagram showing an example of temporal change in the comprehensive diagnostic index 250.

Here, a method of calculating the comprehensive diagnostic index 250 will be described. Preferably, the comprehensive diagnostic index includes at least 1 converter-side index and at least 1 inverter-side index. In fig. 21D, as an example of the comprehensive diagnostic index 250, the comprehensive diagnostic index 250 is a sum of an absolute value of the index 203 and an absolute value of the index 206.

Note that the index 201, the index 203, the index 206, and the comprehensive diagnostic index in fig. 21A to 21D and fig. 23A to 23D described later are affected by inductance components and capacitance components of the circuit, filter time constants, and the like, and therefore, a delay time occurs with respect to a step response and the index changes transiently, but for ease of description of the embodiment based on the figures, the index changes stepwise with respect to the step response.

The operation of the abnormal part diagnosis process performed by the abnormality determiner 72 shown in the flowcharts of fig. 18 and 19 will be described.

In step S101, the abnormality determiner 72 outputs the estimated values in which the equations (59) to (62) are satisfied to 72e as initial states, and proceeds to step S102. That is, the correction unit of the dc voltage signal generation unit 72e sets the usage ratio of the signal estimation value to 0 and directly outputs the detection value.

In step S102, the abnormality determiner 72 reads the index 201 from the index creating unit 72c, and proceeds to step S103.

In step S103, the abnormality determiner 72 compares the index 201 with a reference value. For example, in the following, indexes 201 and E_{FB_CP}、E_{FB_CN}、E_{FB_IP}、E_{FB_IN}Gain G obtained by substituting in (16) to (19)_CP、G_CN、G_IP、G_INIf at least 1 of the gain values is out of the predetermined gain range, the reference value may be set so that yes is obtained in step S103.

When the absolute value of the index 201 > the reference value is satisfied (S103: YES), the abnormality determiner 72 determines that the indexes 201 and E are set_{FB_CP}、E_{FB_CN}、E_{FB_IP}、E_{FB_IN}Gain G obtained by substituting in (16) to (19)_CP、G_CN、G_IP、G_INAt least 1 of which is out of the predetermined range, i.e., there is an abnormality detector, proceeds to step S105.

On the other hand, when the absolute value of the index 201 is not larger than the reference value (S103: NO), the abnormality determiner 72 determines that the indexes 201 and E are set to be equal_{FB_CP}、E_{FB_CN}、E_{FB_IP}、E_{FB_IN}Gain G obtained by substituting in (16) to (19)_CP、G_CN、G_IP、G_INAll are within the predetermined range, and the process proceeds to step S104.

In step S104, the abnormality determiner 72 stores the comprehensive diagnostic index 250 as 250-S in association with the value of the index 201, and proceeds to step S102. 250-S is the diagnostic standard for the composite diagnostic index.

When the processing of step S104 is executed a plurality of times, a plurality of diagnostic criteria 250-S or an arbitrary comprehensive diagnostic index may be stored without being overwritten. For example, in the case of the example of fig. 21A to 21D, the diagnosis reference 250-S of the integrated diagnosis index becomes the time t₀～t₁The comprehensive diagnosis index of (1).

In step S105, the variable J associated with the selection of the dc voltage detector is set to 1, and the process proceeds to step S106.

In step S106, the abnormality determiner 72 assumes that the J-th dc voltage detector is abnormal, and outputs 72e to 72e an estimated value ratio obtained by changing the estimated value ratio of the J-th dc voltage detector to 1 in equations (55) to (58), and the process proceeds to step S107. For example, when J is 1 and the first dc voltage detector is the dc voltage detector 25, the correction is performed so that the formula (63), the formula (60), the formula (61), and the formula (62) are satisfied.

In step S107, the abnormality determiner 72 stores the comprehensive diagnostic index 250-J when the signal estimated value of the jth dc voltage detector is used, and proceeds to step S108. For example, in the case of the example shown in fig. 21A to 21D, the comprehensive diagnostic index 250-1 at the time of use of the signal estimation value of the first dc voltage detector is the time t₃～t₄At least 1 time point in the range of (a).

In step S108, the abnormality determiner 72 outputs the estimated value usage ratios of 72e using the formula (59), the formula (60), the formula (61), and the formula (62) to 72e, and proceeds to step S109. That is, the correction unit of the dc voltage signal generation unit 72e sets the ratio of the estimated values in the equations (55) to (58) to 0 (returns to the initial state).

In step S109, the abnormality determiner 72 compares J with the number N of dc voltage sensors.

If J > the number N of dc voltage sensors is satisfied (yes in S109), the abnormality determiner 72 determines that the processes in S106 to S108 have been executed the number of times corresponding to the number of dc voltage detectors, and proceeds to step S111.

On the other hand, if J > the number N of dc voltage sensors is not satisfied (S109: no), the abnormality determiner 72 determines that the number of times of execution of the processes from S106 to S108 is smaller than the number of dc voltage detectors, and proceeds to step S110.

In step S110, J is updated to J +1, and the process proceeds to step S106.

In step S111, the comprehensive diagnosis indexes 250-1, 250-2, …, and 250-N at the time of using the signal estimation values of the first to Nth DC voltage detectors are read.

In step S112, the comprehensive diagnostic index having the smallest absolute value of the difference between the normal comprehensive diagnostic index and the comprehensive diagnostic index among the comprehensive diagnostic indexes when the signal estimated values of the first to nth dc voltage detectors are used is selected, and the detector assumed to be abnormal at this time is used as the abnormality detector, and the process proceeds to step S113. For example, in the example of FIGS. 21A to 21D, the comprehensive diagnostic index 250-2 having the smallest absolute value of the difference from the normal comprehensive diagnostic index 250-S among the comprehensive diagnostic indexes 250-1, 250-2, 250-3, and 250-4 is selected. In this example, the selection result is 250-2, and the dc voltage detector assumed to be abnormal (the second assumed to be abnormal dc voltage) at this time is the dc voltage detector 26. Therefore, in the example of fig. 21A to 21D, it can be diagnosed that the dc voltage detector 26 is abnormal.

In step S113, after a predetermined time has elapsed, the signal of the detector for which abnormality is diagnosed is switched to an estimated value. For example, in the case of the example of fig. 21A to 21D, since the abnormality detector is diagnosed as the dc voltage detector 26, the correction unit of the dc voltage signal generation unit 72e performs correction so that the formula (59), the formula (64), the formula (61), and the formula (62) are satisfied, and switches the signal of the abnormality detector to the estimated value. Note that, without performing the operation of step S113, only the abnormality diagnosis of the dc voltage detector may be performed.

Note that, although the description has been made using the indicators 201, 203, and 206, the determination can be made in the same manner even if at least 1 of the indicators 202, 203, and 204 is selected instead of the indicator 203, and at least 1 of the indicators 205, 206, and 207 is selected instead of the indicator 206 to synthesize the comprehensive diagnosis indicator 250.

As a second example of the operation of the flowcharts of fig. 18 and 19, fig. 22 to 23A to 23D show an operation example in the case where the dc voltage detector 36 is abnormal. Fig. 22 shows the state of the dc voltage detector 36 in the case where the dc voltage detector is abnormal in each time range in fig. 21A to 21D, the number of the corresponding flowchart, and the input of the correction unit.

Fig. 23A to 23D are diagrams showing examples of temporal changes in the respective indices and the comprehensive diagnostic index in the case where the dc voltage detector 36 is abnormal. Fig. 23A is a diagram showing an example of temporal change in the index 201, fig. 23B is a diagram showing an example of temporal change in the index 203 (converter-side index), fig. 23C is a diagram showing an example of temporal change in the index 206 (inverter-side index), and fig. 24D is a diagram showing an example of temporal change in the comprehensive diagnostic index 250.

Even in this case, steps S101 to S111 in the flowchart operate similarly to the case where the dc voltage detector 26 is abnormal. In step S112 in the examples of fig. 22 to 23A to 23D, the comprehensive diagnostic index having the smallest absolute value of the difference from the comprehensive diagnostic index 250-S at the normal time among 250-1, 250-2, 250-3, and 250-4 is 250-4, and therefore, the dc voltage detector in which the fourth dc voltage 36 assumed to be abnormal can be diagnosed as abnormal.

In the present embodiment, in step S112, the comprehensive diagnostic index having the smallest difference from the normal comprehensive diagnostic index among the comprehensive diagnostic indexes when the signal estimation values of the first to nth dc voltage detectors are used is selected, and therefore, diagnosis can be performed without using the reference value. Therefore, diagnosis can be performed even if the circuit constant is unknown.

When it is known in advance that the comprehensive diagnostic index at the normal time is close to 0 or a specific value, the comprehensive diagnostic index 250-S at the normal time may be set to 0 or a specific value in advance instead of storing the comprehensive diagnostic index 250-S at the normal time in step S104.

Further, in the power converter 101 according to the first embodiment, when it is determined that there is an abnormality in the dc voltage detector, the normal detection value of the detection target in the dc voltage detector having an abnormality is estimated from the detection values of the healthy dc voltage detectors other than the dc voltage detector having an abnormality in step S113 and the operation is continued, so that the power converter 101 can be used without replacing the dc voltage detector having an abnormality, and the power converter can be continued to be operated until the next periodic inspection, for example. This eliminates the need to stop the power converter 101 unplanned, and thus the operation rate can be improved and the power converter can be operated efficiently.

In the case where the comprehensive diagnostic index is composed of a plurality of indices, the plurality of indices may be normalized by an arbitrary method. For example, the index 203 may be usedThe index 203 and the index 206 are normalized in such a manner that the amount of change is equal to the amount of change of the index 206. Here, the amount of change in the index 203 is, for example, the maximum value of the index 203 (time t in fig. 21A to 21D)₅～t₆Index 203) and the minimum value of the index 203 (time t in fig. 21A to 21D)₃～t₄Index 203) of the first image. The amount of change in the index 206 is, for example, the maximum value of the index 206 (time t in fig. 21A to 21D)₇～t₈Index 206) and the minimum value of the index 206 (time t in fig. 21A to 21D)₉～t₁₀Index 206) of the first image.

The abnormal portion diagnosis process is a process sequentially executed by the abnormality determiner 72 during the operation of the power conversion apparatus 100. In order to eliminate the influence on the load connected to the motor, it is preferable to perform the abnormal portion diagnosis process when there is no load.

[ Effect ]

As described above, the power conversion apparatus 100 (see fig. 1) includes: a first smoothing capacitor 22 connected between a first potential and a second potential; a second smoothing capacitor 23 connected between the second potential and the third potential; a first direct-current voltage detector 25 that detects a potential difference between potentials to which the first smoothing capacitor 22 is connected; a second dc voltage detector 26 for detecting a potential difference between the potentials to which the second smoothing capacitor 23 is connected; a first index calculation unit (index creation unit 75c) that calculates a first index (indexes 201 and 209) for diagnosing the presence or absence of an abnormality in the dc voltage detector based on an index obtained using a detection value of the dc voltage detector based on a voltage relational expression established in a circuit including a potential difference between potentials connected to the first smoothing capacitor 23 and a potential difference between potentials connected to the second smoothing capacitor 23, when a detection abnormality occurs in which the detection value changes in a predetermined direction in either one of the first dc voltage detector 25 and the second dc voltage detector 26; a second index calculation unit (index creation unit 75c) that calculates a second index (indexes 202 to 207) that shows a change in the index when a detection abnormality occurs in which a detection value changes in a predetermined direction in either one of the first direct-current voltage detector 25 and the second direct-current voltage detector 26; and a comprehensive diagnosis index calculation unit (index creation unit 75c) for calculating a comprehensive diagnosis index (one of indexes 202 to 207; comprehensive diagnosis index) obtained by scalar synthesis or vector synthesis of 1 or 2 or more second indexes. Further, the power conversion apparatus 100 includes: and an abnormality determiner 72 that assumes 1 dc voltage detector having an abnormality from among the first dc voltage detector 25 and the second dc voltage detector 26, performs an operation of switching a detection value of the dc voltage detector assumed to have an abnormality to an output estimation value estimated from a detection value of another dc voltage detector for 1 or 2 or more dc voltage detectors, and determines which of the first dc voltage detector 25 and the second dc voltage detector 26 has an abnormality based on a change in the comprehensive diagnosis index after the operation of switching to the output estimation value.

Thus, 1 of the plurality of dc voltage sensors is assumed to be abnormal, and abnormality diagnosis is performed based on a response when an operation is performed using an estimated value instead of a sensor signal assumed to be abnormal. Thus, even if the circuit constant of the circuit connected to the outside of the power conversion device is unknown, it is possible to appropriately detect an abnormality of the dc voltage detector in the power conversion device. Further, even when an abnormality diagnosis device is mounted on an existing motor drive device for which it is difficult to obtain or estimate a circuit constant, it is possible to perform abnormality diagnosis.

Further, the power conversion apparatus 100 includes: neutral point resistors 24 and 34 (see fig. 1) connected between the second potential on the inverter side and the second potential on the converter side for suppressing dc resonance, and when the neutral point resistors 24 and 34 are present (that is, when there are circuits of 4 sensors), 4 kinds of calculations are performed using the first index (index 201) and the second indexes (indexes 202 to 207), and the sensor assumed to be abnormal when the index is minimum is diagnosed as abnormal. In this case, the threshold for abnormality diagnosis is not used.

The power conversion device is also applicable to a case where no neutral point resistance exists (a circuit in which 2 sensors exist), and 4 kinds of calculations are performed using the first index (index 209) and the second indexes (indexes 202 to 207), and a sensor assumed to be abnormal when the index is minimum is diagnosed as abnormal. In this case, the threshold for abnormality diagnosis is not used.

An example in which the ninth index and the tenth index are added will be described as a modification of the first embodiment.

A modification of the first embodiment is a modification in which the ninth index is added as a candidate for the converter-side index and the tenth index is added as a candidate for the inverter-side index in the first embodiment. The abnormality of the dc voltage detector is determined by the same operation as that of the first embodiment.

Fig. 48 is a configuration diagram of an index creation unit of the power conversion device according to the modification of the first embodiment. The same components as those in fig. 39 (described later) are denoted by the same reference numerals.

In the power conversion device according to the modification of the first embodiment, the index creating unit 72c shown in fig. 3 further includes a ninth index creating unit 729 shown in fig. 49 and a tenth index creating unit 730 shown in fig. 51.

< ninth indicator creation section >

The ninth index creating unit 729 will be described.

Fig. 49 is a diagram showing an example of the configuration of the ninth index creating unit 729.

As shown in fig. 49, the ninth index creating unit 729 includes: a Q-axis current calculation unit 7291, a sine wave calculation unit 7292, a cosine wave calculation unit 7293, product calculation units 7294 and 7295, filters 7296 and 7297, and a square root calculation unit 7298.

The Q-axis current calculation unit 7291 calculates a Q-axis current for the fundamental current wave with respect to the current detection value input from the ac current detector 7 (see fig. 1).

The sine wave calculator 7292 calculates a sine wave corresponding to the carrier frequency input from the converter control device 5 (see fig. 1).

The cosine wave calculator 7293 calculates a cosine wave corresponding to the carrier frequency input from the converter control device 5. The phase difference between the output of the sine wave calculation unit 7292 and the output of the cosine wave calculation unit 7293 is 90 degrees.

The product calculation unit 7294 calculates a product of the Q-axis current and a sine wave having a carrier frequency. The product calculation unit 7294 calculates a product of the Q-axis current and a cosine wave having the carrier frequency.

The filter 7296 and the filter 7297 are filters for removing a fluctuation component included in the input.

The square and square root calculation unit 7298 calculates the square and square root of the output of the filter 7296 and the output of the filter 7297.

In the above configuration, the ninth index creating unit 729 calculates the index 209(═ DI 9). The index 209 is a value obtained by using the ac current detection value I on the converter 2 (see fig. 1) side when the dc voltage detector 25 or 26 (see fig. 1) is abnormal_{FB_C}The carrier frequency component is superimposed on the Q-axis current of (a) to detect an index of abnormality of the dc voltage detector. Index 209 is carrier frequency f based on Q-axis current_CCIndices of components (converter side Q-axis current index, converter side index).

Fig. 50A to 50B are schematic diagrams showing analysis results of the Q-axis current in the ninth index creating unit 729. Fig. 50A is a diagram showing an analysis result of the Q-axis current in the normal state of the dc voltage detector, and fig. 50B is a diagram showing an analysis result of the Q-axis current in the abnormal state.

When the dc voltage detector is normal, as shown in fig. 50A, the Q-axis current hardly includes the carrier frequency f_CCAnd (3) components. On the other hand, when the dc voltage detector is normal, as shown in fig. 50B, the carrier frequency f of the Q-axis current_CCThe composition increases.

In addition, the structure diagram shown in fig. 49 is to detect the carrier frequency f in the Q-axis current_CCAs an example of the method of the component, the carrier frequency f of the Q-axis current may be detected by another method such as fourier transform_CCThe structure of the components.

< tenth index creation section >

The tenth index creating unit 730 will be described.

Fig. 51 is a diagram showing an example of the configuration of the tenth index creating unit 730.

As shown in fig. 51, the tenth index creating unit 730 includes: a Q-axis current calculation unit 7301, a sine wave calculation unit 7302, a cosine wave calculation unit 7303, product calculation units 7304 and 7305, filters 7306 and 7307, and a square and square root calculation unit 7308.

The Q-axis current calculation unit 7301 calculates a Q-axis current for the current fundamental wave with respect to the current detection value input from the ac current detector 9.

The sine wave calculation unit 7302 calculates a sine wave corresponding to the carrier frequency input from the inverter control device 6.

Cosine wave calculator 7303 calculates a cosine wave corresponding to the carrier frequency input from inverter control device 6. The phase difference between the output of sine wave calculator 7302 and the output of cosine wave calculator 7303 is 90 degrees.

The product calculation unit 7304 calculates the product of the Q-axis current and a sine wave having a carrier frequency. The product calculation unit 7304 calculates the product of the Q-axis current and a cosine wave having a carrier frequency.

The filters 7306 and 7307 are filters for removing a variable component included in the input.

Square and square root calculation section 7308 calculates the square and square root of the output of filter 7306 and the output of filter 7307.

In the above configuration, the tenth index creating unit 730 calculates the index 210(═ DI 10). The index 210 is a value obtained by using an ac current detection value I on the inverter 3 (see fig. 1) side when the dc voltage detector 35 or 36 (see fig. 1) is abnormal_{FB_I}Q-axis current superimposed carrier frequency f_CIThe abnormality detection unit detects an index of abnormality of the DC voltage detector. Index 210 is an index (inverter-side Q-axis current index, inverter-side index) based on the carrier frequency component of the Q-axis current.

Fig. 52A to 52B are schematic diagrams showing analysis results of the Q-axis current of the tenth index creating unit 730. Fig. 52A is a diagram showing an analysis result of the Q-axis current in the normal state of the dc voltage detector, and fig. 52B is a diagram showing an analysis result of the Q-axis current in the abnormal state.

When the dc voltage detector is normal, as shown in fig. 52A, the Q-axis current hardly includes the carrier frequency f_CIAnd (3) components. On the other hand, when the dc voltage detector is abnormal, as shown in fig. 52B, the carrier frequency f of the Q-axis current_CIThe composition increases.

In addition, the structure diagram shown in fig. 51 is to detect the carrier frequency f in the Q-axis current_CIAs an example of the method of the component, the carrier frequency f of the Q-axis current may be detected by another method such as fourier transform_CIThe structure of the components.

< abnormality determination based on ninth and tenth indicators >

Fig. 53A to 53B are diagrams showing the abnormality detector and the gain and index change of the abnormality detector as tables. Fig. 53A shows the change in the gain of the abnormality detector and the index 209 as a table, and fig. 53B shows the change in the gain of the abnormality detector and the index 210 as a table.

As shown in fig. 53A, the index 209 increases when the detector 25 or the detector 26 is abnormal, and the index 209 does not change when the detector 35 or the detector 36 is abnormal. Therefore, the index 209 can be used as a converter-side index.

On the other hand, as shown in fig. 53B, the index 210 does not change when the detector 25 or the detector 26 is abnormal, and the index 210 increases when the detector 35 or the detector 36 is abnormal. Therefore, the index 210 can be used as an inverter-side index.

As described above, in the power conversion device according to the modification of the first embodiment, the index creating unit 72c includes: a ninth index creating unit 729 configured to calculate, as a second index, an index of a carrier frequency component included in a fundamental wave Q-axis current based on a current at a power supply side position; and a tenth index creating unit 730 that calculates, as the second index, an index of a carrier frequency component included in the fundamental Q-axis current based on the current at the load side position. By using the ninth index and the tenth index, it is possible to diagnose an abnormality of the dc voltage sensor not only in the unipolar modulation but also in the bipolar modulation (e.g., when the motor having a small modulation rate is rotating at a low speed). Therefore, when the abnormality sensor is specified during the standby operation, the diagnosis can be performed regardless of whether the abnormality sensor is bipolar modulation or unipolar modulation, and the abnormality diagnosis can be reliably performed.

In addition, although the present modification is an example in which the ninth index creating unit 729 and the tenth index creating unit 730 are applied to the index creating unit 72c shown in fig. 3, the second index calculating unit may include the ninth index creating unit 729 and the tenth index creating unit 730. Therefore, the second index calculation unit may omit or adaptively use the indexes other than the ninth index generation unit 729 and the tenth index generation unit 730.

(second embodiment)

Next, a power conversion device according to a second embodiment will be described with reference to fig. 24A to 25F.

The power conversion device 100 of the power conversion system 1000 of the second embodiment has a configuration similar to that of the power conversion device 100 of the first embodiment.

The second embodiment is different from the first embodiment in that the comprehensive diagnosis index is a vector composed of a plurality of indices in the second embodiment. Fig. 24A to 24F show an example in which the comprehensive diagnostic index is used as a vector under the same conditions as in fig. 21A to 21D. The comprehensive diagnostic index in fig. 24A to 24F is a vector composed of 2 elements of the value of the index 203 and the value of the index 206.

Fig. 24A to 24F are diagrams showing an example of a case where the comprehensive diagnosis index 250 in the specific time range in fig. 21A to 21D is set as a vector in the case where the dc voltage detector 26 is abnormal. FIG. 24A shows a normal state (t)₀～t₁) Fig. 24B is a diagram showing a vector of the comprehensive diagnosis index 250, and shows a case where the estimated value is not used (t) in the abnormal state₂～t₃) FIG. 24C is a view showing a vector of the comprehensive diagnosis index 250, and E is used in the case of abnormality_{FBH_CP}When (t)₃～t₄) FIG. 24D is a view showing a vector of the comprehensive diagnosis index 250, and E is used in the case of abnormality_{FBH_CN}When (t)₅～t₆) FIG. 24E is a view showing a vector of the comprehensive diagnosis index 250, and E is used in the case of an abnormality_{FBH_IP}When (t)₇～t₈) Comprehensive diagnosis ofA vector of the section index 250, and E is used as a reference in the case of abnormality in FIG. 24F_{FBH_IN}When (t)₉～t₁₀) A map of a vector of the integrated diagnostic index 250.

In the example of fig. 24A to 24F, fig. 24D shows the smallest difference between the comprehensive diagnostic index of fig. 24C to 24F and the comprehensive diagnostic index of fig. 24A at the normal time, and therefore, it is possible to diagnose that the dc voltage detector 26 is abnormal.

Fig. 25A to 25F are diagrams showing an example of a case where the comprehensive diagnostic index 250 in the specific time range in fig. 23A to D is used as a vector in the case where the dc voltage detector 36 is abnormal. FIG. 25A shows a normal state (t)₀～t₁) Fig. 25B is a diagram showing a vector of the comprehensive diagnosis index 250, and shows a normal state and a state where the estimated value is not used (t)₂～t₃) FIG. 25C is a view showing a vector of the comprehensive diagnosis index 250, and E is used in the case of an abnormality_{FBH_CP}When (t)₃～t₄) FIG. 25D is a view showing a vector of the comprehensive diagnosis index 250, and E is used in the case of abnormality_{FBH_CN}When (t)₅～t₆) FIG. 25E is a view showing a vector of the comprehensive diagnosis index 250, and E is used in the case of an abnormality_{FBH_IP}When (t)₇～t₈) FIG. 25F is a view showing a vector of the comprehensive diagnosis index 250, and E is used in the case of an abnormality_{FBH_IN}When (t)₉～t₁₀) A map of a vector of the integrated diagnostic index 250.

In the example of fig. 25A to 25F, the one having the smallest difference from the comprehensive diagnostic index of fig. 25A at the normal time among the comprehensive diagnostic indexes of fig. 25C to 25F is fig. 25F, and therefore, it is possible to diagnose that the dc voltage detector 36 is abnormal.

When it is known in advance that the comprehensive diagnostic index at the normal time is close to the zero vector or the specific vector, the comprehensive diagnostic index 250-S at the normal time may be set in advance as the zero vector or the specific vector instead of storing the comprehensive diagnostic index 250-S at the normal time in step S104.

Further, a plurality of indices, which are components of the comprehensive diagnostic index represented by a vector, may be normalized by an arbitrary method. For example, the index 203 and the index 206 may be normalized so that the amount of change in the index 203 is equal to the amount of change in the index 206. Alternatively, normalization using an average or variance, such as an arithmetic operation based on mahalanobis distance, may be performed based on a plurality of index values in normal times stored in step S104 described later.

(third embodiment)

Next, a power conversion device according to a third embodiment will be described with reference to fig. 26 to 29D.

The power conversion device 100 of the power conversion system 1000 of the third embodiment has a configuration similar to that of the power conversion device 100 of the first embodiment.

Fig. 26 to 27 show flowcharts, and differences from the flowcharts of fig. 18 to 19 will be described.

Steps S201 to S205 and S207 to S213 in fig. 26 to 27 are the same as steps S101 to S105 and steps S107 to S113 in fig. 18 to 19.

Step S206 in fig. 26 is different from step S106 in fig. 18.

The difference from step S106 of the first embodiment is that, in the first embodiment, K is input as input to the correction units 7201, 7202, 7203, and 7204_CP、K_CN、K_IP、K_INIs 0 or 1, in contrast to which, in a third embodiment, K_CP、K_CN、K_IP、K_INTake any value. Preferably, the arbitrary value is set to a value greater than 0 and less than 1.

Fig. 28 and fig. 29A to 29D show an example of operation in the third embodiment.

Fig. 28 is a diagram illustrating an example of the operation of the power converter according to the third embodiment. Fig. 29A to 29D are diagrams showing examples of temporal changes in the respective indices and the comprehensive diagnosis index relating to the abnormality determiner of the power conversion apparatus according to the third embodiment. Fig. 29A is a diagram showing a time variation example of the index 201, fig. 29B is a diagram showing a time variation example of the index 203 (converter-side index), fig. 29C is a diagram showing a time variation example of the index 206 (inverter-side index), and fig. 29D is a diagram showing a time variation example of the comprehensive diagnosis index.

FIGS. 28 and 29A to 29D show K used in S107 of FIGS. 18 to 19_CP、K_CN、K_IP、K_INAn operation example in the third embodiment in the case of 0.5. In fig. 29A to 29D of the third embodiment and fig. 21A to 21D of the first embodiment, the time t will be₃To t₄When the value of the index 203 of (2) is compared, the value of the index 203 in the first embodiment is deviated from 0.

At time t in FIGS. 21A-21D₃To t₄The dc voltage detector that is actually abnormal is the dc voltage detector 26, and the dc voltage detector 25 is operated on the assumption of abnormality. At time t of such condition₃To t₄At time t, the difference between the true voltage value of DC voltage detector 25 and the true voltage value of DC voltage detector 26 is compared with the estimated value₂To t₃Is large. I.e. at time t₃To t₄An overvoltage may be applied to the semiconductor element of the converter power conversion portion 21.

As shown in the third embodiment, by setting the K used in step S107_CP、K_CN、K_IP、K_INIf the value is less than 1, the dc voltage detector that is actually abnormal does not match the dc voltage detector that is assumed to be abnormal in steps S106 to S107, and an effect of suppressing the overvoltage applied to the circuit such as the converter power conversion unit 21 or the inverter power conversion unit 31 is obtained. In addition, the K used in step S107 is changed_CP、K_CN、K_IP、K_INIf the value is less than 1, the voltage imbalance between the P-side and N-side can be suppressed when the dc voltage detector that is actually abnormal does not match the dc voltage detector that is assumed to be abnormal in steps S106 to S107.

(fourth embodiment)

Next, a power conversion device according to a fourth embodiment will be described with reference to fig. 30 to 35.

The power conversion device 100 of the power conversion system 1000 of the fourth embodiment has a configuration similar to that of the power conversion device 100 of the first embodiment.

Fig. 30 to 31 show a flowchart of an abnormal part diagnosis process performed by the abnormality determiner 72 according to the fourth embodiment, and a difference from the flowcharts of fig. 26 to 27 will be described.

Steps S301 to S307 are the same as steps S201 to S207.

In step S308, 250-J stored in step S307 is compared with a reference value 250-S. If yes, the process proceeds to step S312. If no, the process proceeds to step S313.

Steps S309 to S311 are the same as steps S208 to S210.

In step S312, it is diagnosed that the jth dc voltage detector is abnormal, and the process proceeds to step S315.

Steps S313 to S315 are the same processing as steps S211 to S213.

Fig. 32A to 32D to 33 show a first operation example.

Fig. 32A to 32D are diagrams showing examples of temporal changes in the respective indices and the comprehensive diagnosis index relating to the abnormality determiner of the power conversion apparatus according to the fourth embodiment. Fig. 32A is a diagram showing a time variation example of the index 201, fig. 32B is a diagram showing a time variation example of the index 203 (converter-side index), fig. 32C is a diagram showing a time variation example of the index 206 (inverter-side index), and fig. 32D is a diagram showing a time variation example of the comprehensive diagnosis index. Fig. 33 is a diagram showing a first operation example of the power converter according to the fourth embodiment.

As shown in fig. 32A to 32D to 33, at time t₅The overall diagnostic index is lower than the reference value, and therefore, at time t₆Switching to the estimate. The effect of being able to shorten the diagnosis time is obtained by using the reference value.

The reference value is based on the normal comprehensive diagnosis index (time t)₀～t₁The comprehensive diagnostic index of (2), and the comprehensive diagnostic index at the time of abnormality (time t)₃～t₄The comprehensive diagnostic index of (2), the value of the estimated value use ratio in step S306, so that the comprehensive diagnostic index is synthesized when the estimated value use ratio is changedThe target value may be determined to be lower than the reference value. For example, when the estimated value usage ratio is 0.5, it is considered that the value of the comprehensive diagnostic index when the estimated value usage ratio is changed to 0.5 is the normal comprehensive diagnostic index (time t)₀～t₁Integrated diagnostic index of (d) and the integrated diagnostic index at the time of abnormality (time t)₃～t₄Integrated diagnostic index of (d). Therefore, the reference value is set to the time t₃～t₄Is less than the time t₀～t₁Integrated diagnosis index and time t₃～t₄The value of the median of the comprehensive diagnostic index of (1) is not particularly limited.

Fig. 34A to 34D to 35 show a second operation example.

Fig. 34A to 34D are diagrams showing examples of temporal changes in the respective indices and the comprehensive diagnosis index relating to the abnormality determiner of the power conversion apparatus according to the fourth embodiment. Fig. 34A is a diagram showing a time variation example of the index 201, fig. 34B is a diagram showing a time variation example of the index 203 (converter-side index), fig. 34C is a diagram showing a time variation example of the index 206 (inverter-side index), and fig. 34D is a diagram showing a time variation example of the comprehensive diagnosis index. Fig. 35 is a diagram showing a second operation example of the power converter according to the fourth embodiment.

As shown in fig. 34A to 34D to 35, the second operation example is an example in the case where the comprehensive diagnostic index is not lower than the reference value. As shown in fig. 34A to 35, it is understood that the operation is the same as that of the second embodiment even when the comprehensive diagnostic index is not lower than the reference value, and the abnormal dc voltage detector can be diagnosed accurately.

As described above, the power converter according to the fourth embodiment uses the reference value independent of the circuit constant, and thereby has an effect of enabling the abnormal dc voltage detector to be diagnosed in a shorter time as compared with the power converter according to the first embodiment.

(fifth embodiment)

Next, a power conversion device according to a fifth embodiment will be described with reference to fig. 36.

The power conversion device 101 of the power conversion system 1001 according to the fifth embodiment includes a plurality of inverter units 3(3a, 3b, 3c, …) in addition to the power conversion device 100 according to the first embodiment.

In the present embodiment, the abnormality determiner 72 estimates an accurate detection value of the detection target of the abnormal dc voltage detector based on the detection values from the plurality of dc voltage detectors 25, 26, 35(35a, 35b, 35c, …), 36(36a, 36b, 36c, …). In the sixth embodiment, as described below, there are a plurality of methods for estimating accurate detection values of detection targets for the dc voltage detectors in which 1 abnormality occurs.

In the power conversion apparatus 101, the following relationship exists: if the dc voltage detectors are in a normal state, the combined dc voltage value obtained by adding the detection values of the dc voltage detectors 25 and 26 on the converter side and the combined dc voltage value obtained by adding the detection values of the dc voltage detectors 35(35a, 35b, 35c, …) and 36(36a, 36b, 36c, …) on the inverter side all match. This indicates that there are a plurality of candidates of the synthesized dc voltage value required to obtain the estimated detection value. In this way, the number of candidates for obtaining the synthesized dc voltage value increases, and therefore, the possibility that the detection value of the detection target of the abnormal dc voltage detector can be estimated can be improved.

According to the abnormality determiner 72 of the present embodiment, when any one of the 1 dc voltage detectors is abnormal, the detection values of the healthy 1 dc voltage detectors disposed on the same side as the abnormal dc voltage detector are subtracted from the combined dc voltage value obtained by adding the detection values of the healthy 2 dc voltage detectors on the converter side or on the inverter side, whereby the accurate detection value of the measurement target of the abnormal dc voltage detector can be estimated.

Thus, for example, even if 1 dc voltage detector on any one of the inverter sides is abnormal and one dc voltage detector on the converter side is abnormal, if 2 dc voltage detectors on any one of the inverter sides are sound, it is possible to estimate an accurate detection value of a detection target for the 1 abnormal dc voltage detector on the inverter side using a synthesized dc voltage value obtained by adding the detection values of the 2 dc voltage detectors.

Even in the power converter 101, the abnormality of the dc voltage detector can be appropriately determined by the same processing as that of the power converter 100 according to the first embodiment. Further, in the power converter 104, similarly to the power converter 101 of the third embodiment, it is possible to appropriately estimate the detection value of the detection target of the abnormal dc voltage detector from the detection values of the plurality of robust dc voltage detectors.

In the fifth embodiment, the power conversion device 101 is provided with the plurality of inverter units 3, but may be provided with the plurality of converter units 2, for example. In this case, as described above, it is possible to appropriately determine an abnormality of the dc voltage detector, and appropriately estimate a detection value of a detection target of the abnormal dc voltage detector from detection values of a plurality of sound dc voltage detectors.

In addition, the candidates of the synthesized dc voltage value required to obtain the detection value of the detection target of the dc voltage detector for estimating the abnormality can be extended to 2 dc voltage detectors on any one converter side, and the possibility that the detection value of the detection target of the dc voltage detector for estimating the abnormality can be increased.

In this way, in the fifth embodiment, even in the power conversion apparatus having a plurality of inverter unit circuits or a plurality of converter unit circuits, the effect of the dc voltage detector capable of diagnosing an abnormality even if the circuit constant is unknown is obtained.

(sixth embodiment)

Next, a power converter according to a sixth embodiment will be described with reference to fig. 37 to 41C.

Fig. 37 is an overall configuration diagram of a power conversion system according to the sixth embodiment. Note that the same components as those of the power conversion system 1000 according to the first embodiment shown in fig. 1 are denoted by the same reference numerals.

The difference between the main circuit configuration of the power conversion device 102 of the power conversion system 1002 according to the sixth embodiment and the main circuit configuration of the power conversion device 100 according to the first embodiment is that the converter neutral point resistor 24 and the inverter neutral point resistor 34 are removed. In the power conversion device 102, although the main circuit components are reduced, since there is no damping resistor, it is necessary to pay attention to the wiring inductance design based on the selection of the switching frequency and the arrangement of the circuit components so as not to cause resonance in the dc circuit.

The power conversion apparatus 102 includes an abnormality determiner 75 instead of the abnormality determiner 72 in the power conversion apparatus 100. In the power conversion device 102, since the converter-side direct current circuit and the inverter-side direct current circuit are all at the same potential, the power conversion device includes: a dc voltage detector 43 (first dc voltage detector) that detects a voltage between electrodes of the converter-side smoothing capacitor 22 and the inverter-side smoothing capacitor 32; and a dc voltage detector 44 (second dc voltage detector) that detects a voltage between electrodes of the converter-side smoothing capacitor 23 and the inverter-side smoothing capacitor 33.

Further, in order to continue the operation according to redundancy when any one of the dc voltage detector 43 and the dc voltage detector 44 is abnormal, a dc voltage detector 45 (third dc voltage detector) for measuring the total voltage of the dc voltage detector 43 and the dc voltage detector 44 is provided. In normal operation, the detection values of the dc voltage detector 43 and the dc voltage detector 44 are used.

Here, the detection value of the dc voltage detector 43 is denoted as E_{FB_CIP}Setting true value to E_{T_CIP}. The detection value of the DC voltage detector 44 is set to E_{FB_CIN}Setting true value to E_{T_CIN}. Hereinafter, a gain failure is considered as an example of a failure of the voltage detector.

The dc voltage detector 43 generates a gain G_＿CIPIn the event of a fault, the dc voltage detector 44 produces a gain G_＿CINIn the event of a fault, the dc voltage detector 45 produces a gain G_＿CIAThe relational expressions of the failure cases of (2) are expressed as the following expression (67) and a common expression, respectivelyEquation (68) and equation (69).

E_{FB_CIP}＝G_{_CIP}×E_{T_CIP}…(67)

E_{FB_CIN}＝G_{_CIN}×E_{T_CIN}…(68)

E_{FB_CIA}＝G_{_CIA}×E_{T_CIA}…(69)

Further, the following equation (70) is satisfied under the condition that neutral point voltage controller 55 or neutral point voltage controller 65 ideally operates.

E_{FB_CIP}＝E_{FB_CIN}…(70)

Further, under the condition that the dc voltage controller 52 ideally operates, the following formula (71) is established.

E_{FB_CIP}+E_{FB_CIN}＝V_{DC_REF}…(71)

Here, V_{DC_REF}Is the instruction value.

In addition, the following formula (72) holds depending on the circuit.

E_{T_CIP}+E_{T_CIN}＝E_{T_CIA}…(72)

Next, the abnormality determiner 75 will be described.

Fig. 38 is a block diagram of an abnormality determiner according to the sixth embodiment.

The abnormality determiner 75 has: the signal storage unit 75a, the setting storage unit 75b, an index creation unit 75c (first-type index calculation unit, second-type index calculation unit) as an example of the first-type index calculation unit and the second-type index calculation unit, an abnormal portion identification unit 75d, and a dc voltage signal generation unit 75 e. These configurations are substantially the same as the configurations of the abnormality determiner 72 of the first embodiment with the same name.

Next, the index creating unit 75c will be described.

Fig. 39 is a configuration diagram of an index creating unit according to the sixth embodiment. Note that the same components as those of the index creating unit 72c according to the first embodiment are denoted by the same reference numerals.

Since the power conversion device 102 according to the fourth embodiment described above detects the converter-side potential and the inverter-side potential by the common dc voltage detectors 43 and 44, the index 201 using the difference between the converter-side P-N dc voltage detection value and the inverter-side P-N dc voltage detection value cannot be used. Therefore, in order to use a new index 209 instead of the index 201, the index generating unit 75c has a ninth index generating unit 759 for generating the index 251 instead of the first index generating unit 721 in the index generating unit 72 c.

The index creating unit 75c is the same as the second index creating unit 722 for creating the index 202, the third index creating unit 723 for creating the index 203, the fourth index creating unit 724 for creating the index 204, the fifth index creating unit 725 for creating the index 205, the sixth index creating unit 726 for creating the index 206, the seventh index creating unit 727 for creating the index 207, and the index creating unit 72 c.

In the present embodiment, when a failure occurs in either one of the dc voltage detectors 43 and 44, the relationship between the direction of the abnormal dc voltage detector or the abnormal gain and the direction of the change from the index 202 to the index 207 is as shown in fig. 15A to 15B and fig. 16.

Next, the eighth index generating unit will be described.

Fig. 40 is a configuration diagram of an eighth index creating unit according to the sixth embodiment.

The eighth index creating unit 758 calculates the index 209(═ DI)₉). The index 209 is an index for detecting an abnormality of the dc voltage detectors (43, 44, 45) by using a difference between the sum of the detection values of the dc voltage detectors 43 and 44 and the detection value of the dc voltage detector 45 when the dc voltage detector is abnormal.

The ninth index creating unit 758 includes an index calculating unit 7581 and a filter 7582.

The index calculation unit 7581 performs the calculation shown in equation (11).

DI₉＝E_{FB_CIP}+E_{FB_CIN}-E_{FB_CIA}…(73)

When the formula (67), the formula (68), the formula (69) are substituted into the formula (73), and the same operation as the formula (12) is performed using the relationship of the formula (72), under the condition of the formula (74), the formula (75), or the formula (76),index 209(═ DI)₉) Positive, index 209(═ DI) under the condition of formula (77), formula (78), or formula (79)₉) Is negative.

G_CIP＞1…(74)

G_CIN＞1…(75)

G_CIA＜1…(76)

G_CIP＜1…(77)

G_CIN＜1…(78)

G_CIA＞1…(79)

Therefore, when any one of the dc voltage detectors fails, the dc voltage detector having an abnormality, and the relationship between the direction of the gain abnormality and the direction of the change in the index 209 are as shown in fig. 42B.

Specifically, in the dc voltage detector 43, a gain G is generated_CIPIf the abnormality is less than 1, the index 209 is negative (decreased), and the gain G is generated_CIPIf the abnormality is greater than 1, the index 209 is positive (increased). In addition, in the dc voltage detector 44, a gain G is generated_CINIf the abnormality is less than 1, the index 209 is negative (decreased), and the gain G is generated_CINIf the abnormality is greater than 1, the index 209 is positive (increased). In addition, in the dc voltage detector 45, a gain G is generated_CIAIf the abnormality is less than 1, the index 209 is positive (increased), and the gain G is generated_CIAIf the abnormality is greater than 1, the index 209 is negative (decreased).

The filter 7582 removes noise in the index 209 calculated by the index calculation unit 7581. The function of filter 7582 is the same as filter 7212 shown in fig. 4.

Fig. 41A to 41C are first diagrams for explaining a change in the index associated with a detector abnormality according to the sixth embodiment. Fig. 41A is a diagram showing the direction of an abnormal dc voltage detector or gain abnormality and the direction of change of the index 202 when a failure occurs in either of the dc voltage detectors 43 and 44, fig. 41B is a diagram showing the direction of an abnormal dc voltage detector or gain abnormality and the direction of change of the indices 203 and 204 when a failure occurs in either of the dc voltage detectors 43 and 44, and fig. 41C is a diagram showing the direction of an abnormal dc voltage detector or gain abnormality and the direction of change of the index 205 when a failure occurs in either of the dc voltage detectors 43 and 44.

Fig. 42A to 42B are second diagrams for explaining a change in the index associated with the detector abnormality according to the sixth embodiment. Fig. 42A is a diagram showing the direction of an abnormal dc voltage detector or gain abnormality and the direction of change of the indicators 206 and 207 when a failure occurs in either of the dc voltage detectors 43 and 44, and fig. 42B is a diagram showing the direction of an abnormal dc voltage detector or gain abnormality and the direction of change of the indicator 208 when a failure occurs in either of the dc voltage detectors 43 and 44.

Next, the abnormality determination table 750 stored in the setting storage unit 75b and used by the abnormality determiner 75 will be described. The abnormality determination table 750 may be input or changed through a user interface.

Fig. 43 is a configuration diagram of the estimating unit 7500.

In the estimating unit 7500, the estimated values of the detection values of the dc voltage detectors 43, 44, and 45 are calculated using equations (80) to (81). For example, at E_{FB_CIN}、E_{FB_CIA}Under normal conditions, E_{FB_CIP}Estimated value of E_{FBH_CIP}Represented by equation (80). Likewise, in E_{FB_CIP}、E_{FB_CIA}Under normal conditions, E_{FB_CIN}Estimated value of E_{FBH_CN}Represented by equation (81).

E_{FBH_CIP}＝E_{FB_CIA}-E_{FB_CIN}…(80)

E_{FBH_CIN}＝E_{FB_CIA}-E_{FB_CIP}…(81)

In the correction units 7501 and 7502, correction values are calculated using equations (82) to (83).

E_{FBC_CIP}＝(1-K_CIP)×E_{FB_CIP}+K_CIP×E_{FBH_CIP}…(82)

E_{FBC_CIN}＝(1-K_CIN)×E_{FB_CIN}+K_CIN×E_{FBH_CIN}…(83)

Here, K_CIP、K_CINThe estimated values in the dc voltage detectors 43 and 44 are used in proportion, and these values may be any values including 0 or 1, for example.

For example, at K_CIP、K_CINWhen 0 is obtained, the equations (82) to (83) are equations (84) to (85), and the correction values are detected values.

E_{FBC_CIP}＝E_{FB_CIP}…(84)

E_{FBC_CIN}＝E_{FB_CIN}…(85)

For example, at K_CP、K_CN、K_IP、K_INIn the case of 1, the equations (82) to (83) are equations (84) to (85), and the correction values are estimated values.

E_{FBC_CIP}＝E_{FBH_CIP}…(86)

E_{FBC_CIN}＝E_{FBH_CIN}…(87)

Fig. 44 and 45 are flowcharts of the abnormal portion diagnosis process performed by the abnormality determiner 72. In the flowcharts in fig. 44 and 45, the first dc voltage detector is set to 43, and the second dc voltage detector is set to 44. Further, the order may be arbitrary.

In the flowcharts in fig. 44 and 45, the comprehensive diagnostic index is set as the index 203. Further, the comprehensive diagnostic index may be constituted by at least 1 of the indexes 202 to 207.

Further, when the equations (84) to (85) in the initial state of step S401 are used, the detection value E of the dc voltage detector 45 is not used_{FB_CIA}Therefore, it means that the dc voltage detector 45 is assumed to be abnormal.

Fig. 46A to 46D show an operation example in the case where the dc voltage detector 44 is abnormal, as a first example of the operation of the flowcharts of fig. 44 and 45.

Fig. 46A to 46D are diagrams showing an operation example in the case where the dc voltage detector of the sixth embodiment is abnormal. FIG. 46A is a view showing a straight lineEstimated value use ratio K in the case of abnormality of flow voltage detector_CIPFIG. 46B is a graph showing the estimated value use ratio K in the case where the DC voltage detector is abnormal_CINFig. 46C is a diagram showing the index 209 in the case where the dc voltage detector is abnormal, and fig. 46D is a diagram showing the comprehensive diagnostic index in the case where the dc voltage detector is abnormal.

In the example of fig. 46A to 46D, the absolute value of the difference between the integrated diagnostic index 250-S in normal times in 250-0, 250-1, 250-2 is 250-2, which is the smallest in step S413. Therefore, it can be diagnosed that the dc voltage detector 44 is abnormal.

Fig. 47A to 47D show an operation example in the case where the dc voltage detector 45 is abnormal, as a second example of the operation of the flowcharts of fig. 44 and 45.

Fig. 47A to 47D are diagrams showing an operation example in the case where the dc voltage detector of the sixth embodiment is abnormal. FIG. 47A is a graph showing the estimated value use ratio K in the case where the DC voltage detector is abnormal_CIPFIG. 47B is a graph showing the estimated value use ratio K in the case where the DC voltage detector is abnormal_CINFig. 47C is a diagram showing the index 209 in the case where the dc voltage detector is abnormal, and fig. 47D is a diagram showing the comprehensive diagnosis index in the case where the dc voltage detector is abnormal.

In the example of fig. 47A to 47D, in step S413, the absolute value of the difference between the integrated diagnostic index 250-S at normal time and the integrated diagnostic index 250-0 at 250-0, 250-1, 250-2 is 250-0, which is the smallest. In this case, it can be diagnosed that the dc voltage detector 45 is abnormal.

In the present embodiment, in step S413, the comprehensive diagnostic index closest to the comprehensive diagnostic index in the normal state among the comprehensive diagnostic indexes in the abnormality presumption of 1 dc voltage detector is selected, and therefore, diagnosis can be performed without using the reference value.

In the present embodiment, the reference value may be used as in the third embodiment.

In the present embodiment, the dc voltage detector is characterized in that abnormality can be diagnosed even if the circuit constant is unknown.

In addition, in the power conversion device 102 according to the sixth embodiment, when it is determined that there is an abnormality in the dc voltage detector, the normal detection value of the detection target in the dc voltage detector having the abnormality is estimated from the detection values of the healthy dc voltage detectors other than the dc voltage detector having the abnormality in step S414, and the operation is continued. This enables the power converter 102 to be used without replacing the dc voltage detector having an abnormality, and for example, the power converter can be continuously operated until the next periodic inspection. Therefore, it is not necessary to stop the power converter 102 unplanned, and the operation rate can be increased, and the power converter can be operated efficiently.

[ modified examples ]

(1)

In the power conversion device, the abnormality determination unit may change the order of the dc voltage detectors assumed to be abnormal to an arbitrary order in the operation of switching the detection value of the dc voltage detector assumed to be abnormal to the output estimation value estimated from the detection values of the other dc voltage detectors.

(2)

In the power conversion device, the abnormality determination unit may switch the detection value of the dc voltage detector assumed to be abnormal to an output correction value obtained by combining the detection value of the dc voltage detector assumed to be abnormal and the output estimation value estimated from the detection values of the other dc voltage detectors using a ratio, instead of switching the detection value of the dc voltage detector assumed to be abnormal to the output estimation value estimated from the detection values of the other dc voltage detectors.

(3)

In the power converter, the abnormality determination unit may arbitrarily change the ratio in accordance with the magnitude or ratio of the abnormality of the dc voltage detector calculated from the first index.

(4)

In the power conversion device, the abnormality determination unit may detect that the load at a position on the load side of the inverter is no load, and when it is determined that the load is no load, may perform an operation of switching a detection value of the dc voltage detector assumed to be abnormal to the output estimation value or the output correction value.

(5)

In the power conversion apparatus, the abnormality determination unit (abnormality determiner 72) may cause the display device to display information related to the abnormality when it is determined that the abnormality has occurred.

(6) Constant speed detection of rotational speed

In the power converter, the abnormality determination unit may detect that the rotation speed of the motor 4 (see fig. 1) at a position on the load side of the inverter is a constant speed, and when it is determined that the rotation speed of the motor 4 is the constant speed, may perform an operation of switching the detection value of the dc voltage detector assumed to be abnormal to the output estimation value or the output correction value.

(7) Segmentation diagnosis

In the power converter, the abnormality determination unit may set a load at a position on a load side of the inverter to be a load or may change a speed of the motor between after an operation in which an estimated value usage ratio of a J-th (J is an arbitrary natural number) dc voltage detector is changed is ended and before an operation in which an estimated value usage ratio of a J + 1-th dc voltage detector is changed is started.

For example, when a trigger condition for changing from the condition (condition 1) to the condition (condition 2) is satisfied, an operation is performed in which the estimated value usage ratio of the jth dc voltage detector is changed (for example, when J is 1, t in fig. 21A to 21D is t in fig. 21D)₃～t₄) The condition (condition 1) satisfies that the load at the position on the load side of the inverter is at least 1 of the loaded state or the variable speed of the motor, and the condition (condition 2) satisfies that the load at the position on the load side of the inverter is the unloaded state and the speed of the motor is constant. After the operation in which the estimated value use ratio of the jth dc voltage detector is changed is completed (for example, when J is 1, t in fig. 21A to 21D is₄) Changing from the condition 2 to the condition 1, the condition fromWhen the condition 1 changes to the trigger condition of the condition 2, an operation is performed in which the estimated value use ratio of the J +1 th dc voltage detector is changed (for example, when J is 1, t in fig. 21A to 21D is changed₅～t₆)。

By performing such a division diagnosis, for example, even under a continuous short-time operating condition satisfying the above-described condition 2, it is possible to reduce the possibility of a change from the condition 2 to the condition 1 in the operation in which the estimated value usage ratio is changed.

The present invention is not limited to the above-described embodiments, and can be implemented by being appropriately modified within a range not departing from the gist of the present invention.

For example, a part or all of the processing performed by each unit in the above embodiments may be performed by a hardware circuit.

Claims (18)

1. A power conversion device is provided with: a converter that converts alternating current into a first potential, a second potential lower than the first potential, and a third potential lower than the second potential; and an inverter that converts voltages of the first potential, the second potential, and the third potential into alternating current,

the power conversion device includes:

a first smoothing capacitor connected between the first potential and the second potential;

a second smoothing capacitor connected between the second potential and the third potential;

a first direct current voltage detector that detects a potential difference between potentials to which the first smoothing capacitor is connected;

a second dc voltage detector that detects a potential difference between potentials to which the second smoothing capacitor is connected;

a first index calculation unit that calculates a first index for diagnosing whether or not there is an abnormality in the dc voltage detector, based on an index using a detection value of the dc voltage detector, when a detection abnormality occurs in either one of the first dc voltage detector and the second dc voltage detector, the detection abnormality changing in a predetermined direction, the detection value of the dc voltage detector being based on a voltage relational expression established in a circuit including a potential difference between potentials connected to the first smoothing capacitor and a potential difference between potentials connected to the second smoothing capacitor;

a second index calculation unit that calculates a second index showing a change in an index when a detection abnormality occurs in which a detection value changes in a predetermined direction in one of the first direct-current voltage detector and the second direct-current voltage detector;

a comprehensive diagnosis index calculation unit that calculates a comprehensive diagnosis index obtained by scalar synthesis or vector synthesis of 1 or 2 or more second-type indices; and

and an abnormality determination unit that performs an operation of switching a detection value of the dc voltage detector assumed to be abnormal to an output estimation value estimated from a detection value of another dc voltage detector for 1 or 2 or more dc voltage detectors, from among the first dc voltage detector and the second dc voltage detector, assuming that 1 dc voltage detector is abnormal, and determines which of the first dc voltage detector and the second dc voltage detector is abnormal, based on a change in a comprehensive diagnosis index after the operation of switching to the output estimation value.

2. The power conversion apparatus according to claim 1,

the power conversion device further includes: a neutral point resistor connected between a second potential on the inverter side and a second potential on the converter side for suppressing direct-current resonance,

the first smoothing capacitor includes: a converter-side first smoothing capacitor connected to the converter side of the neutral point resistor; and an inverter-side first smoothing capacitor connected to the inverter-side position of the neutral point resistor,

the second smoothing capacitor includes: a converter-side second smoothing capacitor connected to the converter-side position of the neutral point resistor; and an inverter-side second smoothing capacitor connected to the inverter-side neutral point resistor,

the first direct current voltage detector includes: a converter-side first direct-current voltage detector that detects a potential difference between potentials to which the converter-side first smoothing capacitor is connected; and an inverter-side first direct-current voltage detector that detects a potential difference between potentials to which the inverter-side first smoothing capacitor is connected,

the second direct current voltage detector includes: a converter-side second dc voltage detector that detects a potential difference between potentials to which the converter-side second smoothing capacitor is connected; and an inverter-side second direct-current voltage detector that detects a potential difference between potentials to which the inverter-side second smoothing capacitor is connected,

the first index is an index using a detection value of a DC voltage detector based on a voltage relational expression established in a circuit including a potential difference between potentials connected to the converter-side first smoothing capacitor, a potential difference between potentials connected to the converter-side second smoothing capacitor, a potential difference between potentials connected to the inverter-side first smoothing capacitor, and a potential difference between potentials connected to the inverter-side second smoothing capacitor,

the second index includes at least one of the following: the controller may be configured to cause the converter-side index to show a change in the index when a detection abnormality occurs in which a detected value changes in a predetermined direction in either one of the converter-side first direct-current voltage detector and the converter-side second direct-current voltage detector, or to show an inverter-side index to show a change in the index when a detection abnormality occurs in which a detected value changes in a predetermined direction in either one of the inverter-side first direct-current voltage detector and the inverter-side second direct-current voltage detector.

3. The power conversion apparatus according to claim 1,

a neutral point resistor for suppressing direct current resonance is not connected between the second potential on the inverter side and the second potential on the converter side,

the first smoothing capacitor includes a converter-side first smoothing capacitor connected to the converter side and an inverter-side first smoothing capacitor connected to the inverter side,

the second smoothing capacitor includes a converter-side second smoothing capacitor connected to the converter side and an inverter-side second smoothing capacitor connected to the inverter side,

the power conversion device further includes: a third direct-current voltage detector that detects a potential difference between potentials at which the first smoothing capacitor and the second smoothing capacitor are connected,

the first type of index is an index using a detection value of a dc voltage detector based on a voltage relational expression established at a location including a potential difference between potentials connected to the first smoothing capacitor, a potential difference between potentials connected to the second smoothing capacitor, and a potential difference between potentials connected to the first smoothing capacitor and the second smoothing capacitor.

4. The power conversion apparatus according to claim 2,

the first-type index calculation unit calculates, as the first-type index, an inter-inverter and converter voltage detection value difference index based on a difference between a sum of voltage values detected by the converter-side first direct-current voltage detector and the converter-side second direct-current voltage detector and a sum of voltage values detected by the inverter-side first direct-current voltage detector and the inverter-side second direct-current voltage detector.

5. The power conversion apparatus according to claim 2,

the first index calculation unit includes: and a third dc voltage detector that measures a total voltage of the first dc voltage detector and the second dc voltage detector and calculates, as the first indicator, a first and second smoothing capacitor voltage detection value difference indicators that are based on a difference between a sum of a voltage value of the first dc voltage detector and a voltage value detected by the second dc voltage detector and a voltage value of the third dc voltage detector.

6. The power conversion apparatus according to claim 2 or 3,

the power conversion device further includes: a converter neutral point control device that generates a command value for adjusting the potential of the second potential of the converter to zero, based on a difference between the voltage values detected by the first and second direct-current voltage detectors,

the second index calculation portion calculates a converter neutral point voltage control signal index based on the command value as the second index.

7. The power conversion apparatus according to claim 2 or 3,

the power conversion device further includes: an alternating current detector that detects a current at a position on a power supply side of the converter,

the second-type index calculation unit calculates a reference even-order harmonic waveform of the current at the power supply side and calculates a converter-side even-order harmonic current index as the second-type index, the converter-side even-order harmonic current index being an index based on a product of the reference even-order harmonic waveform and a current value detected by the alternating current detector.

8. The power conversion apparatus according to claim 2 or 3,

the power conversion device further includes: an alternating voltage detector that detects a voltage at a position on a power supply side of the converter,

the second-type index calculation unit calculates a reference even-order harmonic waveform for the voltage at the power supply side position, and calculates a converter-side even-order harmonic voltage index as the second-type index, the converter-side even-order harmonic voltage index being an index based on a product of the reference even-order harmonic waveform and a voltage value detected at the power supply side position.

9. The power conversion apparatus according to claim 2 or 3,

the power conversion device further includes: an inverter neutral point control device that generates a command value for adjusting the potential of the second potential of the inverter to zero, based on a difference between the voltage values detected by the first and second direct-current voltage detectors,

the second index calculation portion calculates an inverter neutral point voltage control signal index based on the command value as the second index.

10. The power conversion apparatus according to claim 2 or 3,

the power conversion device further includes: a current detector that detects a current at a position on a load side of the inverter,

the second-type index calculation unit calculates a reference even-order harmonic waveform for the current at the load side position, and calculates an inverter-side even-order harmonic current index as the second-type index, the inverter-side even-order harmonic current index being an index based on a product of the reference even-order harmonic waveform and a current value detected by the current detector.

11. The power conversion apparatus according to claim 2 or 3,

the inverter-side alternating current is a three-phase alternating current including a U-phase, a V-phase, and a W-phase,

the power conversion device further includes: an alternating voltage detector that detects a voltage of each phase of the inverter,

the second-type index calculation unit calculates, as the second-type index, an ac line-to-line voltage index based on a difference between a first line-to-line voltage, which is a voltage between U and V phases, and a second line-to-line voltage, which is a voltage between V and W phases, when both the first line-to-line voltage and the second line-to-line voltage are positive or negative, the first line-to-line voltage being detected by the ac voltage detector.

12. The power conversion apparatus according to any one of claims 2 or 4, 6 to 11,

the abnormality determination unit stores a normal-time comprehensive diagnosis index in a case where all the direct-current transformers are determined to be normal based on the first index,

when it is determined that any of the dc voltage detectors is abnormal based on the first index, the following operations are performed for all the dc voltage detectors: assuming that 1 of the converter-side first direct-current voltage detector, the converter-side second direct-current voltage detector, the inverter-side first direct-current voltage detector, and the inverter-side second direct-current voltage detector is abnormal, switching a detection value of the direct-current voltage detector assumed to be abnormal to an output estimation value estimated based on detection values of other direct-current voltage detectors, and storing an estimated value switching-time comprehensive diagnostic index as a comprehensive diagnostic index at that time,

a difference between the comprehensive diagnosis index at the time of switching the estimated values and the comprehensive diagnosis index at the time of normal is calculated, and when the magnitude of the difference is the minimum, it is determined that the DC voltage detector assumed to be abnormal is an abnormal DC voltage detector.

13. The power conversion apparatus according to any one of claims 3 and 5 to 11,

the abnormality determination unit stores a normal-time comprehensive diagnosis index in a case where all the direct-current transformers are determined to be normal based on the first index,

when it is determined that any of the dc voltage detectors is abnormal based on the first index, the following operations are performed for all the dc voltage detectors: assuming that 1 of the first and second DC voltage detectors is abnormal, switching the detection value of the DC voltage detector assumed to be abnormal to an output estimation value estimated from the detection values of the other DC voltage detectors, storing the comprehensive diagnostic index at the time of switching the estimation value, which is the comprehensive diagnostic index at the time of switching,

a difference between the comprehensive diagnosis index at the time of switching the estimated values and the comprehensive diagnosis index at the time of normal is calculated, and when the magnitude of the difference is the minimum, it is determined that the DC voltage detector assumed to be abnormal is an abnormal DC voltage detector.

14. The power conversion apparatus according to claim 12 or 13,

the abnormality determination unit further stores an abnormality-time comprehensive diagnosis index in a case where it is determined that any of the direct-current transformers is abnormal from the first index,

further, a reference value is set based on the normal-time comprehensive diagnostic index and the abnormal-time comprehensive diagnostic index,

when it is determined that any of the direct-current transformers is abnormal based on the first index, the direct-current voltage detector is determined to be an abnormal direct-current voltage detector when the detection value of the direct-current voltage detector assumed to be abnormal is switched to the output estimation value estimated based on the detection values of the other direct-current voltage detectors, and the comprehensive diagnosis index at the time of operation of the comprehensive diagnosis index at this time is stored as a value closer to the comprehensive diagnosis index at the time of normal than the reference value.

15. The power conversion apparatus according to claim 2 or 3,

the power conversion device further includes: an alternating current detector that detects a current at a position on a power supply side of the converter,

the second index calculation unit calculates, as the second index, an index of a carrier frequency component included in a fundamental wave Q-axis current based on a current at a position on the power supply side.

16. The power conversion apparatus according to claim 2 or 3,

the power conversion device further includes: a current detector that detects a current at a position on a load side of the inverter,

the second index calculation unit calculates, as the second index, an index of a carrier frequency component included in a fundamental wave Q-axis current based on the current at the load side.

17. The power conversion apparatus according to claim 2 or 3,

the abnormality determination section detects whether or not a load at a position on a load side of the inverter is no load,

when it is determined that the load is no load or when it is determined that the load changes from a load to no load,

an operation is performed to switch the detection value of the DC voltage detector assumed to be abnormal to an output estimation value or an output correction value.

18. An abnormality detection method for a power conversion device, the power conversion device having: a converter that converts alternating current into a first potential, a second potential lower than the first potential, and a third potential lower than the second potential; and an inverter that converts voltages of the first potential, the second potential, and the third potential into alternating current,

the power conversion device includes:

a first smoothing capacitor connected between the first potential and the second potential;

a second smoothing capacitor connected between the second potential and the third potential;

a first direct current voltage detector that detects a potential difference between potentials to which the first smoothing capacitor is connected;

a second dc voltage detector that detects a potential difference between potentials to which the second smoothing capacitor is connected;

a first index calculation unit that calculates a first index for diagnosing whether or not there is an abnormality in the dc voltage detector, based on an index using a detection value of the dc voltage detector, when a detection abnormality occurs in either one of the first dc voltage detector and the second dc voltage detector, the detection abnormality changing in a predetermined direction, the detection value of the dc voltage detector being based on a voltage relational expression established in a circuit including a potential difference between potentials connected to the first smoothing capacitor and a potential difference between potentials connected to the second smoothing capacitor;

a second index calculation unit that calculates a second index showing a change in an index when a detection abnormality occurs in which a detection value changes in a predetermined direction in one of the first direct-current voltage detector and the second direct-current voltage detector; and

a comprehensive diagnostic index calculation unit for calculating a comprehensive diagnostic index obtained by scalar synthesis or vector synthesis of 1 or 2 or more second-type indices,

in the abnormality detection method, assuming that 1 of the first and second direct-current voltage detectors has an abnormality, an operation of switching a detection value of the direct-current voltage detector assumed to have an abnormality to an output estimation value estimated from a detection value of another direct-current voltage detector is performed for 1 or 2 or more direct-current voltage detectors,

and determining which of the first and second dc voltage detectors is abnormal, based on a change in the comprehensive diagnosis index after the operation of switching to the output estimation value is performed.

Images