CN113691152B

CN113691152B - Power conversion device and abnormality detection method

Info

Publication number: CN113691152B
Application number: CN202110532150.7A
Authority: CN
Inventors: 田中秀明; 秋田佳稔; 景山宽; 伊藤智道
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2020-05-19
Filing date: 2021-05-17
Publication date: 2023-08-22
Anticipated expiration: 2041-05-17
Also published as: CN113691152A

Abstract

The invention provides a power conversion device and an abnormality detection method. The power conversion device (100) is provided with: a first index calculation unit that calculates a first index for diagnosing the presence or absence of an abnormality in the dc voltage detector based on an index using the detection value of the dc voltage detector; a second index calculation unit that calculates a second index that shows an index change when either one of the first direct-current voltage detector (25) and the second direct-current voltage detector (26) has a detection abnormality in which the detection value changes in a predetermined direction; a comprehensive diagnosis index calculation unit that calculates a comprehensive diagnosis index from the second index; and an abnormality determiner (72) that performs an operation of switching the detection value of the DC voltage detector that is supposed 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 integrated diagnostic index.

Description

Power conversion device and abnormality detection method

Technical Field

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

Background

A power conversion device that converts power from an ac power source into power of a variable voltage and variable frequency is known. In a power conversion device, a direct current circuit includes a smoothing capacitor and a direct current voltage detector for measuring a voltage across the smoothing capacitor, and the direct current voltage is controlled to be constant by power transfer from and to an alternating current system interconnected with the power converter.

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

Patent document 1 discloses a technique of creating a plurality of diagnostic indicators based on the behavior of the dc voltage during operation to confirm the soundness of the dc voltage detector, and comparing the plurality of diagnostic indicators with a reference value to determine an abnormality, but does not disclose a technique of setting the reference value when the circuit constant of a motor or a transformer connected to the outside of the power conversion device of the application target is 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 conversion device to be applied are known, the index change amount with respect to the abnormality of the dc voltage detector is different depending on the circuit constants, and therefore, it is necessary to set the reference value for each application target. The dc voltage detector is necessary for controlling the dc voltage of the power conversion device, and an abnormality of the dc voltage detector may cause unstable operation of the system, and in the worst case, the system may be stopped unplanned, resulting in serious 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 problems, 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 having: 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 connected to the first smoothing capacitor; a second dc voltage detector that detects a potential difference between potentials of the second smoothing capacitor connected thereto; a first index calculation unit that calculates a first index for diagnosing the presence or absence of an abnormality of a dc voltage detector based on 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 first smoothing capacitor and a potential difference between potentials connected to the second smoothing capacitor, when a detection abnormality in which a detection value of either one of the first dc voltage detector and the second dc voltage detector changes in a predetermined direction occurs; a second index calculation unit that calculates a second index that shows a change in index when either one of the first direct-current voltage detector and the second direct-current voltage detector has a detection abnormality in which a detection value changes in a predetermined direction; 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 indexes; and an abnormality determination unit that determines, from among the first dc voltage detector and the second dc voltage detector, which one of the first dc voltage detector and the second dc voltage detector has an abnormality, based on a change in the integrated diagnostic index after the switching to the output estimated value, by performing an operation of switching the detected value of the dc voltage detector that is assumed to be abnormal to the output estimated value estimated from the detected value of the other dc voltage detector with respect to 1 or 2 or more dc voltage detectors.

According to the present invention, even if the circuit constant of the circuit connected to the outside of the power conversion device is unknown, the abnormality of the dc voltage detector in the power conversion device can be appropriately detected.

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 block diagram of the abnormality determiner of the first embodiment.

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

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

Fig. 5 is a block diagram of the second index creating unit according to the first embodiment.

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

Fig. 7A is a first diagram (1) illustrating the 2 nd harmonic of the first embodiment.

Fig. 7B is a first diagram (2) illustrating the 2 nd harmonic of the first embodiment.

Fig. 8A is a second diagram (1) illustrating the 2 nd harmonic of the first embodiment.

Fig. 8B is a second diagram (2) illustrating the 2 nd harmonic of the first embodiment.

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

Fig. 10 is a block diagram of the fifth index creating unit according to the first embodiment.

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

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

Fig. 13 is a diagram illustrating extraction of a determination section according to the first embodiment.

Fig. 14A is a diagram showing the gains of the anomaly detector and the anomaly detector according to the first embodiment and the changes in the index 201 as tables.

Fig. 14B is a diagram showing the gains of the anomaly detector and the anomaly detector according to the first embodiment and the changes in the index 202 as tables.

Fig. 14C is a diagram showing the gains of the anomaly detector and the anomaly detector according to the first embodiment and the changes in the indices 203 and 204 as tables.

Fig. 15A is a diagram showing the gains of the anomaly detector and the anomaly detector according to the first embodiment and the change in the index 205 as a table.

Fig. 15B is a diagram showing the gains of the anomaly detector and the anomaly detector according to the first embodiment and the changes in the indices 206 and 207 as tables.

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 block diagram of the dc voltage signal generating unit according to the first embodiment.

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

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

Fig. 20 is a diagram showing the state of the dc voltage detector, the number of the corresponding flowchart, and the input of the correction unit when the dc voltage detector is abnormal in each time range of the abnormality determiner according to the first embodiment.

Fig. 21A is a diagram showing an example of time variation of the index 201 related to the abnormality determiner of the first embodiment.

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

Fig. 21C is a diagram showing a time-varying example of the index 206 (inverter-side index) related to the abnormality determiner of the first embodiment.

Fig. 21D is a diagram showing an example of the time change of the integrated diagnostic index 250 according to the abnormality determiner of the first embodiment.

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

Fig. 23A is a diagram showing a time-varying example 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 a time change of the index 203 (converter-side index) in the case of abnormality of the dc voltage detector according to the first embodiment.

Fig. 23C is a diagram showing an example of a time 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 a time-varying example of the integrated diagnostic index in the case where the dc voltage detector according to the first embodiment is abnormal.

Fig. 24A shows a dc voltage detector according to the second embodiment of the present invention when the dc voltage detector is normal (t ₀ ～t ₁ ) A graph of vectors of integrated diagnostic criteria.

Fig. 24B shows a case where the dc voltage detector according to the second embodiment is abnormal and the estimated value is not used (t ₂ ～t ₃ ) A graph of vectors of integrated diagnostic criteria.

Fig. 24C shows the use of E when the dc voltage detector of the second embodiment is abnormal _{FBH_CP} Time (t) ₃ ～t ₄ ) A graph of vectors of integrated diagnostic criteria.

Fig. 24D shows the use of E when the dc voltage detector of the second embodiment is abnormal _{FBH_CN} Time (t) ₅ ～t ₆ ) A graph of vectors of integrated diagnostic criteria.

Fig. 24E shows the use of E when the dc voltage detector of the second embodiment is abnormal _{FBH_IP} Time (t) ₇ ～t ₈ ) A graph of vectors of integrated diagnostic criteria.

Fig. 24F shows the use of E when the dc voltage detector of the second embodiment is abnormal _{FBH_IN} Time (t) ₉ ～t ₁₀ ) A graph of vectors of integrated diagnostic criteria.

Fig. 25A shows a dc voltage detector according to the second embodiment of the present invention when the dc voltage detector is normal (t ₀ ～t ₁ ) A graph of vectors of integrated diagnostic criteria.

Fig. 25B shows an unused estimation of the dc voltage detector according to the second embodiment when the dc voltage detector is abnormalWhen the value is (t) ₂ ～t ₃ ) A graph of vectors of integrated diagnostic criteria.

Fig. 25C shows the use of E when the dc voltage detector of the second embodiment is abnormal _{FBH_CP} Time (t) ₃ ～t ₄ ) A graph of vectors of integrated diagnostic criteria.

Fig. 25D shows the use of E when the dc voltage detector according to the second embodiment is abnormal _{FBH_CN} Time (t) ₅ ～t ₆ ) A graph of vectors of integrated diagnostic criteria.

Fig. 25E shows the use of E when the dc voltage detector of the second embodiment is abnormal _{FBH_IP} Time (t) ₇ ～t ₈ ) A graph of vectors of integrated diagnostic criteria.

Fig. 25F shows the use of E when the dc voltage detector according to the second embodiment is abnormal _{FBH_IN} Time (t) ₉ ～t ₁₀ ) A graph of vectors of integrated diagnostic criteria.

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

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

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

Fig. 29A is a diagram showing a time-varying example of the index 201 related to the abnormality determiner of the power conversion device according to the third embodiment.

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

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

Fig. 29D is a diagram showing a time-varying example of the integrated diagnostic index of the power conversion device according to the third embodiment.

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

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

Fig. 32A is a diagram showing a time-varying example of the index 201 related to the abnormality determiner of the power conversion device according to the fourth embodiment.

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

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

Fig. 32D is a diagram showing a time-varying example of the integrated diagnostic index of the power conversion device according to the fourth embodiment.

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

Fig. 34A is a diagram showing a time-varying example of the index 201 related to the abnormality determiner of the power conversion device according to the fourth embodiment.

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

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

Fig. 34D is a diagram showing a time-varying example of the integrated diagnostic index of the power conversion device according to the fourth embodiment.

Fig. 35 is a diagram showing a second operation example of the power conversion device 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 block diagram of the abnormality determiner of the sixth embodiment.

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

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

Fig. 41A is a first diagram illustrating a change in the index accompanied by the detector abnormality in the sixth embodiment, and is a diagram showing a dc voltage detector having an abnormality when any one of the dc voltage detectors has failed, a direction of the gain abnormality, and a direction of change in the index 202.

Fig. 41B is a first diagram illustrating a change in the index accompanied by the detector abnormality in the sixth embodiment, and is a diagram showing the direction of the gain abnormality and the direction of change of the indexes 203 and 204, in the case where any one of the dc voltage detectors has failed.

Fig. 41C is a first diagram illustrating a change in the index accompanied by the detector abnormality in the sixth embodiment, and is a diagram showing a dc voltage detector having an abnormality when any one of the dc voltage detectors has failed, a direction of the gain abnormality, and a direction of change in the index 205.

Fig. 42A is a second diagram illustrating a change in the index accompanied by the detector abnormality in the sixth embodiment, and is a diagram showing the direction of the gain abnormality and the direction of change of the indexes 206 and 207, in the case where a fault occurs in either the dc voltage detector 43 or 44.

Fig. 42B is a second diagram illustrating a change in the index accompanied by the detector abnormality in the sixth embodiment, and is a diagram showing a dc voltage detector having an abnormality when either one of the dc voltage detectors 43 and 44 fails, a direction of the gain abnormality, and a direction of change in the index 208.

Fig. 43 is a block diagram of an estimating unit according to the sixth embodiment.

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

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

Fig. 46A shows an estimated value use ratio K in the case of abnormality of the dc voltage detector according to the sixth embodiment _CIP Is a diagram of (a).

Fig. 46B shows an estimated value use ratio K in the case of abnormality of the dc voltage detector according to the sixth embodiment _CIN Is a diagram of (a).

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

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

Fig. 47A shows an estimated value use ratio K in the case of abnormality of the dc voltage detector according to the sixth embodiment _CIP Is a diagram of (a).

Fig. 47B shows an estimated value use ratio K in the case of abnormality of the dc voltage detector according to the sixth embodiment _CIN Is a diagram of (a).

Fig. 47C is a diagram showing an index 209 in the case where the dc voltage detector of 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 block diagram of an index creating unit of the power conversion device according to the modification of the first embodiment.

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

Fig. 50A is a diagram showing a result of analysis of the Q-axis current when the dc voltage detector according to the ninth index creating unit of the power conversion device according to the modification of the first embodiment is normal.

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

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

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

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

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

Symbol description

2. A converter unit (converter),

3. An inverter unit (inverter),

4. A motor,

5. A converter control device,

6. An inverter control device,

7. A current detector,

8. A speed detector,

9. A current detector,

11. A voltage detector,

12. A transformer (transformer),

21. A converter power conversion part,

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

23 A smoothing capacitor on the N side (second smoothing capacitor, second smoothing capacitor on the converter side),

24. 34 neutral point resistance,

25. A DC voltage detector (first DC voltage detector, converter side first DC voltage detector),

26. A DC voltage detector (second DC voltage detector, converter side second DC voltage detector),

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

31. An inverter power conversion unit,

32. 33 smoothing capacitor,

51. A DC voltage command generator,

52. A DC voltage controller,

53. A current controller,

54. A pulse generator,

55. A neutral point voltage controller,

61. A speed command generator,

62. A speed controller,

63. A current controller,

64. A pulse generator,

65. A neutral point voltage controller,

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

75c index producing section (first index calculating section, second index calculating section, comprehensive diagnosis index calculating section),

73. A display unit,

74. An output estimator,

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

250. Comprehensive diagnostic index,

201. 209 (first index),

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

729. A ninth index producing part,

730. A tenth index producing part,

1000. 1001 a power conversion system.

Detailed Description

Several embodiments are described with reference to the accompanying drawings. The embodiments described below do not limit the invention related to the scope of patent protection, and all of the elements and combinations thereof described in the embodiments are not necessarily essential to the solution 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 the ac power supply 1 into desired ac power and outputs the same; and a motor 4 that operates using ac power output from the power conversion device 100. The power conversion device 100 is connected to the motor 4 via, for example, an ac cable.

The power conversion device 100 includes: a transformer 12 that transforms ac power; a converter unit (also referred to as a converter) 2 that is 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 desired 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 that converts an ac voltage into a dc voltage of positive potential (first potential) level, neutral point (zero potential) level, 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) level, and a negative potential (third potential) level into an alternating-current voltage for the motor 4. The positive potential level of the converter unit 2 and the inverter unit 3 is connected via the P wiring 40, the neutral point potential level is connected via the C wiring 41, and the negative potential level is connected via the N wiring 42.

The converter unit 2 has: the converter power conversion unit 21, a smoothing capacitor 22 on the P-side of the converter 2 (first smoothing capacitor: converter-side first smoothing capacitor) for suppressing fluctuation of the dc voltage, a smoothing capacitor 23 on the N-side of the converter 2 (second smoothing capacitor, converter-side second smoothing capacitor), a dc voltage detector 25 (first dc voltage detector, converter-side first dc voltage detector) for measuring the inter-terminal voltage of the smoothing capacitor 22, a dc voltage detector 26 (second dc voltage detector, converter-side second dc voltage detector) for measuring the inter-terminal voltage of the smoothing capacitor 23, and a converter neutral point resistor 24 for suppressing dc resonance. The converter neutral resistor 24 is connected to the C-wiring 41. In fig. 1, 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 configuration is similar for other phases.

The inverter unit 3 has: the inverter power conversion unit 31, the smoothing capacitor 32 on the P-side of the inverter 3 (first smoothing capacitor, inverter-side first smoothing capacitor), the smoothing capacitor 33 on the N-side of the inverter 3 (second smoothing capacitor, inverter-side second smoothing capacitor), the dc voltage detector 35 for measuring the inter-terminal voltage of the smoothing capacitor 32 (first dc voltage detector, inverter-side first dc voltage detector), the dc voltage detector 36 for measuring the inter-terminal voltage of the smoothing capacitor 33 on the N-side of the inverter 3 (second dc voltage detector, inverter-side second dc voltage detector), and the inverter neutral point resistor 34 for suppressing dc resonance. The inverter neutral point resistor 34 is connected to the C wiring 41. In fig. 1, only the configuration for the 1-phase 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 shown for other phases.

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

The power conversion device 100 further includes: a current detector 7 as an example of an ac current detector that detects and outputs a current flowing between the converter unit 2 and the ac power supply 1; a voltage detector 11 as 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 the 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 an abnormality determining section; and a display 73.

Signals (output signals) of the 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 processing based on the input detection value, and outputs a signal for controlling the converter power conversion unit 21.

Signals (output signals) of the 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 processing 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.

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, 26, and the dc voltage detectors 35, 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 P-N voltage outputted from the converter 2 as a fixed value.

The dc voltage controller 52 calculates an effective current command value output from the converter 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 effective current command 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 matches the dc voltage command value.

The neutral point voltage controller 55 calculates an ac output voltage correction value AVzR such that the neutral point voltage is zero from the difference between the detected values of the dc voltages input from the 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 will input the ac output voltage correction value AVzR from the midpoint voltage controller 55 _{OUT_C} And adding the output of the predetermined current control operation, that is, the AC output voltage command value, to calculate a converter AC voltage command value.

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 performing pulse width modulation on the triangular wave as a 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 a speed command value input from the speed command generator 61, and outputs the inverter output current command value to the current controller 63.

The neutral point voltage controller 65 calculates an ac output voltage correction value AVzR such that the neutral point voltage is zero from the difference between the detected values of the dc voltages input from the 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 inverter ac voltage command value to the pulse generator 64. At this time, the current controller 63 outputs the ac output voltage correction value AVzR inputted from the neutral point voltage controller 65 _{OUT_I} And adding the output of the predetermined current control operation, that is, the AC output voltage command value, to calculate an inverter AC voltage command value.

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 performing pulse width modulation on a triangular wave as a 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 inputted 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, 36 based on the detection values detected by the various detectors, the input values from the operators 52, 53, 54, 55 of the inverter control device 5, and the input values from the operators 62, 63, 64, 65 of the inverter control device 6, and sends the determination result to the display 73. The various detectors include, for example, dc voltage detectors 25, 26, 35, 36, current detector 7, speed detector 8, current detector 9, voltage detector 10, and voltage detector 11.

When an abnormality of the dc voltage detector is detected, the abnormality determiner 72 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.

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

The signal storage unit 72a stores, as time-series data, signals of detection values inputted from the various detectors 25, 26, 35, 36, 7, 8, 9, 10, 11, input values from the operators 52, 53, 54, 55 of the converter control device 5, and input values from the operators 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 abnormalities in the voltage detectors 25, 26, 35, and 36. Specifically, the index creating unit 72c reads a signal for calculating the index from the signal storage unit 72a, and performs a filter operation or the like having the filter constant read from the setting storage unit 72b on the read value, thereby calculating a plurality of indexes.

The index creating unit 72c has a function as a comprehensive diagnosis index calculating unit that calculates a comprehensive diagnosis index obtained by scalar synthesis or vector synthesis of 1 or 2 or more second indexes.

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

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

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

The index creating unit 72c receives the filter constants stored in the setting storage unit 72b, and creates each index from various signals read from the signal storage unit 72a by performing an operation including a low-pass filter operation using the filter constants. The index creating unit 72c includes: a first pointer producing section 721 of the production pointer 201, a second pointer producing section 722 of the production pointer 202, a third pointer producing section 723 of the production pointer 203, a fourth pointer producing section 724 of the production pointer 204, a fifth pointer producing section 725 of the production pointer 205, a sixth pointer producing section 726 of the production pointer 206, and a seventh pointer producing section 727 of the production pointer 207. Details of the indices 201, 202, 203, 204, 205, 206, 207 and the index creation units 721, 722, 723, 724, 725, 726, 727 will be described later.

In addition, it is not necessary to use all of the indices 201, 202, 203, 204, 205, 206, 207 in abnormality diagnosis. That is, abnormality diagnosis is performed using at least 1 of the index 201, the converter-side index (index 202, index 203, index 204), and at least 1 of the inverter-side index (index 205, index 206, index 207). In the embodiment described later with reference to fig. 17, 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 the respective indices, the detection values of the dc voltage detectors 25, 26, 35, 36 are described, and the correlation of the detection values is described.

The relationship between the detection values and the true values of the dc voltage detectors 25, 26, 35, and 36 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_**} A detection value of the direct current voltage detector indicating a position corresponding to the subscript, G _** Indicating the gain of the DC voltage detector corresponding to subscript, E _{T_**} The true value of the dc voltage detection value corresponding to the subscript is indicated. C in the subscript indicates a converter side, I indicates an inverter side, P indicates a P side, and N indicates an N side. Thus, CP denotes the dc voltage detectors on the converter side and the P side, i.e., dc voltage detector 25, cn denotes the dc voltage detectors on the converter side and the N side, i.e., dc voltage detector 26, ip denotes the dc voltage detectors on the inverter side and the P side, i.e., dc voltage detector 35, and in denotes the dc voltage detectors on the inverter side and the N side, i.e., dc voltage detector 36.

In the case where all of the dc voltage detectors 25, 26, 35, 36 are normal, the detection value E of each dc voltage detector _FB And true value E _T Equal, therefore, the value of gain G is 1. On the other hand, in the case where the dc voltage detectors 25, 26, 35, 36 are abnormal (for example, in the case where gain abnormality is generated), the detection value E _FB And true value E _T The gain G is not uniform, but has a value other than 1 (e.g., 0.9 or 1.1).

The detection value (E _{FB_CP} 、E _{FB_CN} 、E _{FB_IP} 、E _{FB_IN} ) The interrelationship of (c) is shown below.

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

E _{FB_CP} ＝E _{FB_CN} …(5)

E _{FB_IP} ＝E _{FB_IN} …(6)

In this case, the value E is detected by the dc voltage controller 52 of the converter 2 _{FB_CP} And a detection value E _{FB_CN} And the dc voltage command value V output from the dc voltage command generator 51 _{DC_REF} The converter power conversion unit 21 is controlled in a uniform manner, and therefore, the relationship shown in the following equation (7) holds.

E _{FB_CP} +E _{FB_CN} ＝V _{DC_REF} …(7)

In addition, the formulas (5), (7), (8) and (9) are satisfied.

E _{FB_CP} ＝V _{DC_REF} /2…(8)

E _{FB_CN} ＝V _{DC_REF} /2…(9)

Further, as shown in fig. 1, the smoothing capacitor 22 and the smoothing capacitor 32 are connected via the P wiring 40, and the smoothing capacitor 23 and the smoothing capacitor 33 are connected via the N wiring 42, so that the following equation (10) holds.

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

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

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

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).

DI ₁ ＝(E _{FB_IP} +E _{FB_IN} )-(E _{FB_CP} +E _{FB_CN} )…(11)

Here, the index 201 (DI) in the case where a fault (abnormality) occurs in the dc voltage detector 25 _{1_25} ) An explanation is given. The gain G of the abnormal dc voltage detector 25 _CP The gain G of the DC voltage detectors 26, 35, 36 is set to a value other than 1 (e.g., 0.9 or 1.1) _CN 、G _IP 、G _IN Let 1 be the value.

When the formula (1) to the formula (4) are substituted into the formula (11) and the relationship of the formula (10) is used, the following formula (12) is obtained.

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)

If E is according to formula (12) _{FB_CP} 、G _CP If it is positive, the gain G _CP When the direction is changed to less than 1 (e.g., 0.9), the index 201 (DI _{1_25} ) Positive, at G _CP When the direction is changed to be greater than 1 (e.g., 1.1), the index 201 (DI _{1_25} ) Is negative.

The index 201 in the case where any one of the dc voltage detectors 26, 35, 36 has failed can be obtained in the same manner as in the equation (12). That is, the index 201 when the dc voltage detector 26 fails is expressed by the formula (13), the index 201 when the dc voltage detector 35 fails is expressed by the formula (14), and the index 201 when the dc voltage detector 36 fails is expressed by the 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 formulas (12), (13), (14) and (15) can be modified to gain on the left as shown in the formulas (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 converting the index 201 (DI ₁ ) The sum of values of E _{FB_CP} 、E _{FB_CN} 、E _{FB_IP} 、E _{FB_IN} The value of (c) is substituted into the equation (16), the equation (17), the equation (18), and the equation (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 an abnormality, the direction of the gain abnormality (greater than 1 or less than 1), and the direction of the change in the index 201 is shown in fig. 14A.

Specifically, in the dc voltage detector 25, the gain G is generated _CP If the anomaly is less than 1, the index 201 is positive (increases), and the gain G is generated _CP In the case of an abnormality greater than 1, the index 201 is negative (decreases). In addition, in the dc voltage detector 26, a gain G is generated _CN If the anomaly is less than 1, the index 201 is positive (increases), and the gain G is generated _CN In the case of an abnormality greater than 1, the index 201 is negative (decreases). In addition, in the dc voltage detector 35, a gain G is generated _IP If the anomaly is less than 1, the index 201 is negative (decreasing), and the gain G is generated _IP In the case of an abnormality greater than 1, the index 201 is positive (increases). In addition, in the dc voltage detector 36, a gain G is generated _IN If the anomaly is less than 1, the index 201 is negative (decreasing), and the gain G is generated _IN In the case of an abnormality greater than 1, the index 201 is positive (increases).

Even if any one of the dc voltage detector 25 and the dc voltage detector 26 is abnormal, if the direction of the gain abnormality is the same, the index 201 shows a change in the same direction. In addition, even if any one of the dc voltage detector 35 and the dc voltage detector 36 is abnormal, 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, the dc voltage detector 35 and the dc voltage detector 36, if the directions of the gain anomalies are 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 ripple and noise, and the influence of these fluctuation components affects the value output from the index calculation unit 7211. Therefore, the filter 7212 performs a filtering process 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 a time constant which is a filter constant input from the setting storage unit 72 b. The filter 7212 is not limited to the first-order lag filter, and may be, for example, an averaging filter or a low-pass filter.

Next, the second specification producing section 722 will be described.

The second index creating unit 722 calculates the index 202 (=di ₂ ). Index 202 is a DC voltage detectorAC output voltage correction value AVzR of abnormal neutral point voltage controller 55 _{OUT_C} The index for detecting abnormality of the dc voltage detectors 25 and 26 when the change occurs will be used to make the difference Δe between the detected values of the dc voltage detectors _{FB_C} (＝E _{FB_CN} -E _{FB_CP} ) AC output voltage correction value AVzR of zero _{OUT_C} The index (the index of the neutral point voltage control signal of the converter, the index of the second type, the index of the converter side) is set. Calculating an ac output voltage correction value AVzR _{OUT_C} So that the difference DeltaE between the detection values of the DC voltage detector _{FB_C} (＝E _{FB_CN} -E _{FB_CP} ) The method of zero can be, for example, a technique disclosed in japanese patent application laid-open No. 2008-01606.

The second index producing unit 722 includes 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 variable 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 is described.

When the dc voltage detectors 25 and 26 are normal, the detection value and the true value are substantially identical (E _{FB_CP} ＝E _{T_CP} 、E _{FB_CN} ＝E _{T_CN} ) Thus, the neutral point voltage ((E) _{T_CN} -E _{T_CP} ) And/2) is substantially zero. On the other hand, in the case of abnormality of the dc voltage detector, the detected value does not coincide with 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) biasing to either positive or negative in a steady state.

By the formulas (1), (2) and (5), only the neutral point voltage V in the case where the direct voltage detector 25 fails _{T_CZ} As shown in the following equation (20), only the neutral point voltage V in the case where the direct voltage detector 26 fails _{T_CZ} As shown in the following formula (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)

In the case where the gain abnormality of the direct-current voltage detector 25 is in the state shown by the formula (22), the neutral point voltage V is calculated according to the formula (20) _{T_CZ} Is negative. In addition, 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 calculated according to the formula (20) _{T_CZ} Is positive.

On the other hand, in the case where the gain abnormality of the direct-current voltage detector 26 is in the state shown by the formula (23), the neutral point voltage V is calculated according to the formula (21) _{T_CZ} Is negative. In addition, when the gain abnormality of the dc voltage detector 26 is in the state shown in the formula (25), the neutral point voltage V is calculated according to the formula (21) _{T_CZ} Is positive.

G _CP ＜1…(22)

G _CN ＞1…(23)

G _CP ＞1…(24)

G _CN ＜1…(25)

In the case where the voltage of the capacitor is made to be true (E) due to the abnormality shown in any one of the formulas (22) to (25) _{T_CP} 、E _{T_CN} ) In the case of asymmetry, a true value of the balance capacitor voltage flows slightly from the system. 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 _{FB_CP} 、E _{FB_CN} ). For example, at neutral point voltage V _{T_CZ} In the case of abnormality represented by the negative equation (22) or the negative equation (23), the true value V of the negative neutral point voltage is maintained _{T_CZ} The neutral point voltage controller 55 continuously outputs a negative ac output voltage correction value AVzR _{OUT_C} 。

When either one of the dc voltage detectors 25 and 26 fails, the relationship among the dc voltage detector having an abnormality, the direction of the gain abnormality, and the direction of the change of the index 202 is shown in fig. 14B.

Specifically, in the dc voltage detector 25, the gain G is generated _CP If the anomaly is less than 1, the index 202 is negative (decreasing), and the gain G is generated _CP In the case of an abnormality greater than 1, the index 202 is positive (increases). In addition, in the dc voltage detector 26, a gain G is generated _CN If the anomaly is less than 1, the index 202 is positive (increases), and the gain G is generated _CN In the case of an abnormality greater than 1, the index 202 is negative (decreasing). The index 202 is unchanged from the abnormality of the dc voltage detectors 35 and 36.

When any one of the dc voltage detector 25 and the dc voltage detector 26 is abnormal, if the direction of change of the gain is the same, the index 202 shows a change in a different direction (reverse direction).

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

The third index creating unit 723 calculates an index 203 (=di ₃ ). The index 203 is a value obtained by using an ac current detection value I for the converter 2 side when the dc voltage detector is abnormal _{FB_C} The index for detecting an abnormality of the dc voltage detector by superimposing the 2 nd harmonic components is an index (even harmonic current index on the converter side, second index, and converter side index) obtained by calculating a reference even harmonic waveform for the current at the ac side connection point 13 and by integrating the reference even harmonic waveform with 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 ac current detection value I _{FB_C} Principle of (2) and 2 nd harmonic current I _{FB_C2} Is described.

Fig. 7A to 7B are first diagrams for explaining the 2 nd harmonic of the first embodiment. FIG. 7A shows a true value E of the DC voltage on the P-side due to a failure of the DC voltage detector 25 or 26 with the horizontal axis as time _{T_CP} A true value E of DC voltage greater than N side _{T_CN} (E _{T_CP} ＞E _{T_CN} ) Ac output of ac side connection point 13 in the state of (2)Voltage V _{PWM_C} Fig. 7B shows an ac output voltage V of the ac side connection point 13 _{PWM_C} Fundamental wave V of (2) _{PWM_C1} With 2 nd harmonic V _{PWM_C2} Is a composite wave V of (2) _{PWM_C12} As an example of (a) is described.

Fig. 8A to 8B are second diagrams for explaining the 2 nd harmonic of the first embodiment. FIG. 8A shows a fault occurring in the DC voltage detector 25 or 26 with time on the horizontal axis, the true value E of the DC voltage on the P side _{T_CP} A true value E of DC voltage smaller than N side _{T_CN} Ac output voltage V of ac side connection point 13 in the state of (2) _{PWM_C} Fig. 8B shows an ac output voltage V of the ac side connection point 13 in the case shown in fig. 8A _{PWM_C} Fundamental wave V of (2) _{PWM_C1} With 2 nd harmonic V _{PWM_C2} Is a composite wave V of (2) _{PWM_C12} As an example of (a) is described.

A true value E of the DC voltage on the P side due to abnormality of the DC voltage detector 25 or 26 _{T_CP} A true value E of DC voltage greater than N side _{T_CN} State (E) _{T_CP} ＞E _{T_CN} ) At the bottom, AC output voltage V _{PWM_C} The time waveform of (a) is shown in fig. 7A. The ac voltage command value of the power conversion unit 21 is obtained by the product of the dc capacitor voltage and the switching signal obtained by pulse width modulation of the ac output voltage. True value E of DC voltage on P side _{T_CP} True value E of DC voltage on N side _{T_CN} In different cases (E _{T_CP} ≠E _{T_CN} In the case of (a), the ac output voltage V outputted from the power conversion unit 21 is an ac output voltage command value having a waveform that is symmetrical in both positive and negative directions _{PWM_C} Also has a waveform with asymmetric positive and negative. Thus, the ac voltage 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 (2) _{PWM_C1} With 2 nd harmonic V _{PWM_C2} Is a composite wave V of (2) _{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 _C1 cos(ωt)+V _C2 cos(2ωt)…(26)

Here, V _C1 Is a synthetic wave V _{PWM_C12} V of the voltage fundamental component of (2) _C2 Is a synthetic wave V _{PWM_C12} The voltage 2 nd harmonic component of (a).

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

On the other hand, the ac output voltage V is due to 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 (2) _{PWM_C1} With 2 nd harmonic V _{PWM_C2} Is a composite wave V of (2) _{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 _C1 cos(ωt)+V _C2 cos(2ωt+π)

＝V _C1 cos(ωt)-V _C2 cos(2ωt)…(27)

As can be seen from fig. 7A-7B and fig. 8A-8B, equation (26) and equation (27): synthetic wave V _{PWM_C12} The phase of the 2 nd harmonic component contained is the true value E of the direct current voltage at the P side _{T_CP} A true value E of DC voltage greater than 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} A true value E of DC voltage smaller than N side _{T_CN} State (E) _{T_CP} ＜E _{T_CN} ) The lower 180 degrees apart.

At E _{T_CP} ＞E _{T_CN} In (a state shown by formula (26)), an ac current detection value I _{FB_C} As shown in the following formula (28), at E _{T_CP} ＜E _{T_CN} In (a state shown by formula (27)), an ac current detection value I _{FB_C} As shown in the following formula (29).

I _{FB_C} ＝I _C1 cos(ωt-φ ₁ )+I _C2 cos(2ωt-φ ₂ )…(28)

I _{FB_C} ＝I _C1 cos(ωt-φ ₁ )-I _C2 cos(2ωt-φ ₂ )…(29)

Here, I _C1 Is the AC current detection value I _{FB_C} Current fundamental component, I _C2 Is the AC current detection value I _{FB_C} Is a current 2 nd harmonic component phi ₁ Is the phase difference phi between the fundamental voltage phase of the AC side connection point 13 and the fundamental current phase of the current detector 7 ₂ Is the phase difference between the fundamental voltage phase of the ac side connection point 13 and the 2 nd harmonic current phase of the current detector 7.

Phase difference phi ₂ When the magnitude of the 2 nd harmonic of the voltage waveform included in the ac power supply 1 is so small that it can be disregarded, 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 inductance component, thus φ ₂ Pi/2. In addition, I is obtained from the amplitude of the fundamental voltage of the AC side connection point 13 and the impedance of the transformer 12 _C1 . Further, phi is obtained from the phase of the fundamental voltage of the ac side connection point 13 and the impedance of the transformer 12 ₁ . 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 。

From the formulas (28) and (29), it can be seen that: at E _{T_CP} ＞E _{T_CN} And E _{T_CP} ＜E _{T_CN} The 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 is connected with _{T_CN} And can be according to I _C2 Is estimated by the size of E _{T_CP} And E is connected with _{T_CN} Is a deviation of (2).

In the above example, the description was given taking the 2 nd harmonic as an example, but the low-order even harmonic currents of 4 th and 6 th orders other than 2 th order are as in the above E _{T_CP} And E is _{T_CN} With different values, the phases of the 2 nd harmonic currents are 180 degrees out of phase. Therefore, even if an even number of harmonics other than 2 are used, E can be performed in the same manner as 2 harmonics _{T_CP} And E is connected with _{T_CN} And (3) estimating the magnitude relation and voltage deviation of the voltage.

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 nd 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 obtained 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 conversion value by d-q converting the detection value of the current detector 7 using the fundamental wave phase, and vector-synthesizes a voltage d-q conversion value obtained by d-q converting the detection value of the voltage detector 11 from the current d-q conversion value and the inductance Xc, thereby calculating a voltage vector of the ac side connection point 13.

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

Here, when the inductance Xc of the transformer 12 is small, the detection value V of the voltage detection value 11 _{AC_C} Is set to be the fundamental wave voltage V of _{AC_C1} Ac output voltage V of ac side connection point 13 _{PWM_C} Is set to be the fundamental wave voltage V of _{PWM_C1} Substantially uniform, therefore, it is also possible to use the detected value V of the voltage detected value 11 alone _{AC_C} The phase of the fundamental voltage of the ac side connection point 13 is approximately obtained. The phase of the fundamental voltage of the ac side connection point 13 may be obtained from the converter ac voltage command value output from the current controller 53 of the converter control device 5.

Reference 2 nd harmonic cosine wave operation unit 7232 calculates reference 2 nd harmonic cosine wave α _{BASE_C} . For example, when the 2 nd harmonic cos (2ωt) in phase with the fundamental wave cos (ωt) of the ac side connection point 13 is set as a reference, the 2 nd harmonic of the current detected by the current detector 7Is delayed by phi from the phase of the ac side connection point 13 ₂ . Therefore, the reference 2 nd harmonic cosine wave α is obtained by the following formula (30) _{BASE_C} 。

α _{BASE_C} ＝cos(2ωt-φ ₂ )…(30)

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

The product operation unit 7233 outputs the ac current detection value I to the current detector 7 _{FB_C} Multiplying the reference 2 nd harmonic cosine wave alpha _{BASE_C} . Here, alternating current I _{FB_C} At E _{T_CP} ＞E _{T_CN} In (7A-7B) as shown in equation (28), at E _{T_CP} ＜E _{T_CN} Is shown in the formula (29). Therefore, the product operation unit 7233 calculates the result (α _{BASE_C} ×I _{FB_C} ) At E _{T_CP} ＞E _{T_CN} At E as shown in the following equation (31) _{T_CP} ＜E _{T_CN} As shown in the following equation (32).

α _{BASE_C} ×I _{FB_C} ＝I _C1 cos(2ωt-φ ₂ )cos(ωt-φ ₁ )

+I _C2 cos(2ωt-φ ₂ )cos(2ωt-φ ₂ )…(31)

α _{BASE_C} ×I _{FB_C} ＝I _C1 cos(2ωt-φ ₂ )cos(ωt-φ ₁ )

-I _C2 cos(2ωt-φ ₂ )cos(2ωt-φ ₂ )…(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 1-cycle quantity moving average (index 203) of equation (31) or equation (32). Here, when a moving average of 1-cycle amounts is calculated for the formulas (31) and (32), the first terms of the formulas (31) and (32) are zero according to the orthogonality of the trigonometric functions. Therefore, the moving average of equation (32) is negative for the moving average of equation (31) is positive.

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

When either one of the dc voltage detectors 25 and 26 fails, the relationship between the direction of the gain abnormality and the direction of the change in the index 203, and the dc voltage detector having the abnormality, is shown in fig. 14C.

Specifically, in the dc voltage detector 25, the gain G is generated _CP If the anomaly is less than 1, the index 203 is positive (increases), and the gain G is generated _CP In the case of an abnormality greater than 1, the index 203 is negative (decreasing). In addition, in the dc voltage detector 26, a gain G is generated _CN If the anomaly is smaller than 1, the index 203 is negative (decreasing), and the gain G is generated _CN In the case of an abnormality greater than 1, the index 203 is positive (increases). The index 203 does not change with respect to the abnormality of the dc voltage detectors 35 and 36.

When any one of the dc voltage detector 25 and the dc voltage detector 26 is abnormal, 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.

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

The fourth index creating unit 724 includes: a waveform operation unit 7241, a fundamental waveform detection unit 7242, a reference 2 nd harmonic cosine wave operation unit 7243, a product operation unit 7244, a moving average 7245, and a filter 7246. The fourth index creating unit 724 performs a process partially different from that of the third index creating unit 723.

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

The waveform operation unit 7241 calculates the ac output voltage V of the ac side connection point 13 by obtaining 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} Is a waveform of (a). Alternatively, the ac output voltage may be calculated instead of the calculation performed by the waveform calculation unit 7241 _{PWM_C} And a voltage detector for detecting the voltage of the ac side connection point 13 is provided to directly measure the voltage of the ac side connection point 13.

The fundamental wave phase detection unit 7242 outputs the ac output voltage V calculated by the waveform calculation unit 7241 _{PWM_C} The fundamental wave phase of the voltage waveform of the ac side connection point 13 is detected. Specifically, the fundamental wave phase detection unit 7242 outputs the voltage V to the ac side connection point 13 _{PWM_C} By performing PLL operation on the values of (a) and (b), the phase of the fundamental voltage of the ac side connection point 13 is calculated.

In addition, in the case where the inductance of the transformer 12 is small, the detection value V of the voltage detector 11 _{AC_C} Is set to be the fundamental wave voltage V of _{AC_C1} Ac output voltage V of ac side connection point 13 _{PWM_C} Is set to be the fundamental wave voltage V of _{PWM_C1} Substantially uniform, therefore, it is also possible to use only the voltage detector 11The voltage waveform approximately obtains the fundamental phase of the ac side connection point 13. The fundamental wave phase of the voltage waveform of the ac side connection point 13 may be obtained from the converter voltage command value output from the current controller 53 of the converter control device 5.

When either one of the dc voltage detectors 25 and 26 fails, the relationship among the dc voltage detector having an abnormality, the direction of the gain abnormality, and the direction of the change in the index 204 is shown in fig. 14C.

Specifically, in the dc voltage detector 25, the gain G is generated _CP If the anomaly is less than 1, the index 204 is positive (increases), and the gain G is generated _CP In the case of an abnormality greater than 1, the index 204 is negative (decreasing). In addition, in the dc voltage detector 26, a gain G is generated _CN If the anomaly is less than 1, the index 204 is negative (decreasing), and the gain G is generated _CN If the abnormality is greater than 1, the index 204 is positive (increases). The index 204 does not change with respect to the abnormality of the dc voltage detectors 35 and 36.

In the case where 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 204 shows a change in a different direction (opposite direction). The magnitude of the index 204 is proportional to the magnitude of the 2 nd harmonic of the voltage at the ac-side connection point 13.

Next, the fifth index creating unit 725 will be described.

Fig. 10 is a block diagram of the fifth index producing unit according to the first embodiment.

The fifth index creating unit 725 calculates the index 205 (=di) ₅ ). Index 205 is an ac output voltage correction value AVzR using neutral point voltage controller 65 at the time of abnormality of dc voltage detector _{OUT_I} An index for detecting abnormality of the DC voltage detectors (35, 36) when a change occurs is used to make the difference delta E between the detected values of the DC voltage detectors _{FB_I} (＝E _{FB_IN} -E _{FB_IP} ) AC output voltage correction value AVzR of zero _{OUT_I} Is set as an index (inverter neutral point voltage control signal index: second)The index is as follows: inverter side index).

The fifth index creating unit 725 has a filter 7251. The fifth index creating unit 725 and the second index creating unit 722 are different in the output destination of the input ac output voltage correction value, but the processing itself is the same. The filter 7251 performs a function for removing the ac output voltage correction value AVzR input from the neutral point voltage controller 65 _{OUT_I} Filtering the variable component of (2). The function of the filter 7251 is the same as that of the filter 7212 shown in fig. 4.

When any one of the dc voltage detectors 35 and 36 fails, the relationship among the dc voltage detector having an abnormality, the direction of the gain abnormality, and the direction of the change in the index 205 is shown in fig. 15A.

Specifically, in the dc voltage detector 35, the gain G is generated _IP If the anomaly is less than 1, the index 205 is negative (decreasing), and the gain G is generated _IP If the abnormality is greater than 1, the index 205 is positive (increases). In addition, in the dc voltage detector 36, a gain G is generated _IN If the anomaly is less than 1, the index 205 is positive (increases), and the gain G is generated _IN In the case of an abnormality greater than 1, the index 205 is negative (decreasing). The index 205 does not change with respect to the abnormality of the dc voltage detectors 25 and 26.

When any one of the dc voltage detector 35 and the dc voltage detector 36 is abnormal, if the direction of change of the gain is the same, the index 205 shows a change in a different direction (opposite direction).

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

The sixth index creating unit 726 calculates the index 206 (=di ₆ ). The index 206 is a value obtained by using an ac current detection value I for 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 a reference even harmonic waveform for calculating a current to a connection point of the subsequent stage of the inverter 3An index based on the product of the reference even harmonic waveform and the current value detected by the current detector 9 (inverter-side even harmonic current index, second index, inverter-side index). 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 nd harmonic cosine wave calculation unit 7262, a product calculation unit 7263, a moving average calculation unit 7264, and a filter 7265. Each of the sixth index creating unit 726 basically has the same function as the same name part of the third index creating unit 723, except for the points shown below. The difference between the position of the sixth index creating unit 726 and the position of the third index creating unit 723 will be described below.

The product operation unit 7263 inputs the detection value (current waveform) of the current detector 9 instead of the detection value of the current detector 7 input by the product operation unit 7233, and performs 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 current may be detected based on the phase of the inverter output current command value output from the speed controller 62, or may be detected based on the phase of the inverter voltage command value output from the current controller 63 and a phase difference caused by the impedance of the motor 4.

When either one of the dc voltage detectors 35 and 36 fails, the relationship among the dc voltage detector having an abnormality, the direction of the gain abnormality, and the direction of the change in the index 206 is shown in fig. 15B.

Specifically, in the dc voltage detector 35, the gain G is generated _IP If the anomaly is less than 1, the index 206 is positive (increases), and the gain G is generated _IP In the case of an abnormality greater than 1, the index 206 is negative (decreasing). In addition, in the dc voltage detector 36, a gain G is generated _IN If the anomaly is less than 1, the index 206 is negative (decreasing), and the gain G is generated _IN In the case of an abnormality greater than 1, the index 206 is positive (increasing). In addition, index 206 is relative toThe abnormality of the dc voltage detectors 25, 26 does not change.

In the case where an abnormality occurs in either the dc voltage detector 35 or the dc voltage detector 36, if the direction of change of the gain is the same, the index 206 shows a change in a different direction (opposite direction).

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

The seventh index creating unit 727 calculates the index 207 (=di ₇ ). The index 207 is a value (V) obtained by detecting the AC line voltage between the U phase and the V phase when the DC voltage detector is abnormal _{FB_IUV} ) A detection value of an alternating-current line-to-line voltage between the V phase and the W phase (V _{FB_IVW} ) The difference between the dc voltage detectors 35 and 36 is detected as an index of abnormality (ac line voltage index, second index, inverter side index) in the case of occurrence of positive and negative deviation.

Index 207 is a detection value (V _{FB_IUV} 、V _{FB_IVW} ) Is represented by formula (33).

DI ₇ ＝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.

Detection value of AC line voltage (V _{FB_IUV} 、V _{FB_IVW} ) From ac phase voltage (U-phase voltage V _{FB_IU} V phase voltage V _{FB_IV} W-phase voltage V _{FB_IW} ) When expressed, the expression (34) and the expression (35) are shown.

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.

DI ₇ ＝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. Thus, the ac phase voltage (V _{FB_IU} 、V _{FB_IV} 、V _{FB_IW} ) At 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) of the electric power source. Each voltage level (V) _{LV1_I} 、V _{LV2_I} 、V _{LV3_I} ) True value E of voltage using smoothing capacitor 32 _{T_IP} True value E of the voltage of smoothing capacitor 33 _{T_IN} Neutral point potential V of inverter-side neutral point 14 _{T_IZ} ＝(E _{T_IN} -E _{T_IP} ) And/2 is expressed as shown in the formulas (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 take V respectively _{LV1_I} 、V _{LV2_I} 、V _{LV3_I} These 3 values, therefore, the combination of ac phase voltages is 27 sets (=3 to the power of 3). In this combination, the detected value of the ac line-to-line voltage (V _{FB_IUV} 、V _{FB_IVW} ) Is of positive sign of alternating phase voltage (V _{FB_IU} 、V _{FB_IV} 、V _{FB_IW} ) Is only the case as shown in equation (40). In addition, the detection value (V _{FB_IUV} 、V _{FB_IVW} ) Is negative in sign of alternating-current phase voltage (V _{FB_IU} 、V _{FB_IV} 、V _{FB_IW} ) Is only the case as shown in formula (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 _{UV_I} 、V _{VW_I} ) As shown in equation (42). When the formula (41) is satisfied, the detection value (V _{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 the formula (42) is established, the index 207 is as shown in the formula (44). When the expression (43) is satisfied, the index 207 is also expressed as the expression (44).

DI ₇ ＝E _{T_IP} -E _{T_IN} …(44)

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

E _{T_IP} ＝E _{FB_IP} /G _IP …(45)

E _{T_IN} ＝E _{FB_IN} /G _IN …(46)

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

DI ₇ ＝(E _{FB_IP} /G _IP )-(E _{FB_IN} /G _IN )…(47)

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

DI ₇ ＝E _{FB_IP} (1/G _IP -1/G _IN )…(48)

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

Specifically, in the dc voltage detector 35, the gain G is generated _IP If the anomaly is less than 1, the index 207 is positive (increases), and the gain G is generated _IP In the case of an abnormality greater than 1, the index 207 is negative (decreases). In addition, in the dc voltage detector 36, a gain G is generated _IN If the anomaly is less than 1, the index 207 is negative (decreases), and the gain G is generated _IN In the case of an abnormality greater than 1, the index 207 is positive (increases). The index 207 does not change with respect to the abnormality of the dc voltage detectors 25 and 26.

When any one of the dc voltage detector 35 and the dc voltage detector 36 is abnormal, if the direction of change of the gain is the same, the index 207 shows a change in a different direction (reverse direction).

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

The determination section extracting unit 7271 extracts a time section (determination section) in which the equation (40) or the equation (41) is satisfied.

Fig. 13 is a diagram illustrating extraction of a determination section according to the first embodiment. Fig. 13 shows temporal changes in pulse signals output from the pulse generator 64 for each phase for on and off control of each switching element of the inverter power conversion section 31.

The determination section extracting unit 7271 extracts a time section in which the equation (40) or the equation (41) holds from the time variation of the pulse signal output from the pulse generator 64 for each phase for on and off control of each switching element of the inverter power converting unit 31. The time section in which the equation (42) or the equation (43) is established may be extracted based on the detection value of the voltage detector 10. In this case, a true value E _{T_IP} And true value E _{T_IN} And gain G _IP And gain G _IN Accordingly, the detected value V of the AC line voltage varies _{UV_I} And a detection value V of the alternating-current line-to-line voltage _{VW_I} Instead of using the formulas (42) and (43), the formulas (49) and (50) may be used within a predetermined range.

((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 _L Is a constant, G _H ＞1，0＜G _L ＜1。

The index calculation unit 7272 obtains, from the voltage detector 10, a detection value (V) of the ac line-to-line voltage of the time section extracted by the determination section extraction unit 7271 _{FB_IUV} 、V _{FB_IVW} ). The index calculation unit 7272 calculates the value (V _{FB_IUV} 、V _{FB_IVW} ) Substituting the index into the formula (33), the index 207 is calculated. 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 that of the filter 7212 shown in fig. 4.

Fig. 14A to 14C and fig. 15A to 15B show the anomaly detector and the gain and index change of the anomaly detector as tables. Fig. 14A shows the changes in the gain and index 201 of the anomaly detector, fig. 14B shows the changes in the gain and index 202 of the anomaly detector, and fig. 14C shows the changes in the gain and index 203, 204 of the anomaly detector. Fig. 15A shows the anomaly detector, the gain of the anomaly detector, and the change of index 205, and fig. 15B shows the anomaly detector, the gain of the anomaly detector, and the change of indexes 206 and 207.

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

Fig. 16 is a diagram showing the relationship among the abnormality detector, the index 201, the converter-side index, and the inverter-side index, based on 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 in the vicinity of 0.

On the other hand, when the detector 25 or the detector 26 is abnormal, the index 201 and the converter-side index are increased or decreased, and the inverter-side index is not changed.

On the other hand, in the case where the detector 35 or the detector 36 is abnormal, the index 201 and the inverter-side index are increased or decreased, and the converter-side index is not changed.

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

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 block diagram of the dc voltage signal generating unit 72 e.

The estimation unit 7200 calculates an estimated value of the detection values of the dc voltage detectors 25, 26, 35, and 36 using the formulas (51) to (54). For example, at E _{FB_CN} 、E _{FB_IP} 、E _{FB_IN} Under normal conditions E _{FB_CP} The estimated value E of (2) _{FBH_CP} Represented by equation (51). Similarly, at E _{FB_CP} 、E _{FB_IP} 、E _{FB_IN} Under normal conditions E _{FB_CN} The estimated value E of (2) _{FBH_CN} Represented by equation (52). Similarly, at E _{FB_CP} 、E _{FB_CN} 、E _{FB_IN} Under normal conditions E _{FB_IP} The estimated value E of (2) _{FBH_IP} Represented by equation (53). Similarly, at E _{FB_CP} 、E _{FB_CN} 、E _{FB_IP} Under normal conditions E _{FB_IN} The estimated value E of (2) _{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 sections 7201, 7202, 7203, 7204, the correction value is calculated using the formulas (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 is _CP 、K _CN 、K _IP 、K _IN The estimated values in the dc voltage detectors 25, 26, 35, 36 are used in proportion, and for example, these values are 0 or 1.

For example, at K _CP 、K _CN 、K _IP 、K _IN When 0, the formulas (55) to (58) are formulas (59) to (62), and the correction value is a detection value.

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 _IN When 1, the formulas (55) to (58) are formulas (63) to (66), and the correction value is an estimated value.

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.

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

Fig. 21A to 21D are diagrams showing time-varying examples of the respective indices and the integrated diagnostic index of the abnormality determiner 72. Fig. 21A is a diagram showing a time variation example of the index 201, fig. 21B is a diagram showing a time variation example of the index 203 (converter-side index), fig. 21C is a diagram showing a time variation example of the index 206 (inverter-side index), and fig. 21D is a diagram showing a time variation example of the integrated diagnostic index 250.

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

In addition, since the index 201, the index 203, the index 206, and the integrated diagnostic index in fig. 21A to 21D and fig. 23A to 23D described later are affected by the inductance component, the capacitance component, the filter time constant, and the like of the circuit, they are transitionally changed with respect to the step response generation delay time, but for ease of explanation of the embodiment based on the drawings, they are illustrated in a manner of being changed with respect to the step response.

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

In step S101, the abnormality determiner 72 outputs the estimated value, which is established in the formulas (59) to (62), as an initial state to 72e, and the flow advances to step S102. That is, the correction unit of the dc voltage signal generation unit 72e directly outputs the detection value with the use ratio of the signal estimation value set to 0.

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

In step S103, the abnormality determiner 72 compares the index 201 with a reference value. For example, in the case of index 201 and E _{FB_CP} 、E _{FB_CN} 、E _{FB_IP} 、E _{FB_IN} Substituting the gain G obtained by (16) to (19) _CP 、G _CN 、G _IP 、G _IN If at least 1 of the gain ranges is out of the predetermined gain range, the reference value may be set so that yes is set in step S103.

If the absolute value of the index 201 > the reference value is established (yes in S103), the abnormality determiner 72 determines that the indexes 201 and E are to be combined _{FB_CP} 、E _{FB_CN} 、E _{FB_IP} 、E _{FB_IN} The gain G obtained by substituting the gain G into the gain (16) to the gain (19) _CP 、G _CN 、G _IP 、G _IN Is out of the predetermined range, i.e., an abnormality detector is present, and the process proceeds to step S105.

On the other hand, if the absolute value of the index 201 > the reference value is not established (S103: NO), the abnormality determiner 72 determines that the indexes 201 and E are to be combined _{FB_CP} 、E _{FB_CN} 、E _{FB_IP} 、E _{FB_IN} The gain G obtained by substituting the gain G into the gain (16) to the gain (19) _CP 、G _CN 、G _IP 、G _IN All within a predetermined range, and the process proceeds to step S104.

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

In the case where the processing of step S104 is performed a plurality of times, a plurality of or an arbitrary diagnosis criterion 250-S of the integrated diagnosis index may be stored without being covered. For example, in the case of the examples of fig. 21A to 21D, the diagnostic criterion 250-S of the integrated diagnostic index becomes the time t ₀ ～t ₁ Is a comprehensive diagnostic index.

In step S105, the variable J related to 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 determines that the J-th dc voltage detector is abnormal, and outputs the estimated value ratio obtained by changing the estimated value ratio of the J-th dc voltage detector to 1 in equations (55) to (58) to 72e, and the flow advances to step S107. For example, when J is 1 and the first dc voltage detector is the dc voltage detector 25, correction is performed so that the equations (63), (60), (61) and (62) are established.

In step S107, the abnormality determiner 72 stores the integrated diagnostic index 250-J at the time of use of the estimated signal value of the J-th dc voltage detector, and proceeds to step S108. For example, in the case of the example shown in fig. 21A to 21D, the integrated diagnostic index 250-1 at the time of use of the signal estimation value of the first direct current voltage detector is the time t ₃ ～t ₄ Comprehensive diagnostic index for at least 1 point in time in the range of (2).

In step S108, the abnormality determiner 72 outputs the estimated value use ratios of the use formulae (59), (60), (61) and (62) of 72e to 72e, and the flow advances to step S109. That is, the correction unit of the dc voltage signal generation unit 72e sets the estimated value ratio in the formulas (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.

When 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 are executed a number of times corresponding to the number of dc voltage detectors, and the process 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 the processes of S106 to S108 are executed is smaller than the number of dc voltage detectors, and the process proceeds to step S110.

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

In step S111, the integrated diagnostic index 250-1, 250-2, …, 250-N at the time of using the estimated signal values of the first to Nth DC voltage detectors is read.

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

In step S113, after a predetermined time has elapsed, the signal of the detector that diagnosed the abnormality is switched to the estimated value. For example, in the case of the example of fig. 21A to 21D, the abnormality detector is diagnosed as the dc voltage detector 26, and therefore, the correction unit of the dc voltage signal generation unit 72e corrects the signal of the abnormality detector to the estimated value so that the formulas (59), (64), (61) and (62) are established. In addition, in the case where the operation of step S113 is not performed, only the abnormality diagnosis of the dc voltage detector may be performed.

Although the description has been made using the indices 201, 203, and 206, the same determination can be made even if at least 1 of the indices 202, 203, and 204 is selected instead of the index 203, and at least 1 of the indices 205, 206, and 207 is selected instead of the index 206 to synthesize the integrated diagnostic index 250.

As a second example of the operation of the flowcharts of fig. 18 and 19, fig. 22 to 23A to 23D show an example of the operation 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 of abnormality in the dc voltage detector in each time range of fig. 21A to 21D, and the numbers of the corresponding flowcharts and the inputs of the correction unit.

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

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

In the present embodiment, in step S112, the integrated diagnostic index having the smallest difference from the integrated diagnostic index at the normal time among the integrated diagnostic indexes at the time of using the signal estimated values of the first to nth direct current voltage detectors 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.

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

In addition, in the power conversion device 101 according to the first embodiment, when it is determined that there is an abnormality in the dc voltage detector, in step S113, 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, and the operation is continued, so that the power conversion device 101 can be used without replacing the dc voltage detector having an abnormality, and for example, the power conversion device can be continued to be operated until the next periodic inspection. This eliminates the need to stop the power conversion device 101 unplanned, thereby improving the operation rate and enabling the power converter to be operated efficiently.

In addition, when the integrated diagnostic index is composed of a plurality of indices, the plurality of indices may be normalized by any method. For example, the index 203 and the index 206 may be normalized so that the amount of change of the index 203 is equal to the amount of change of the index 206. Here, the change amount of the index 203 is, for example, the maximum value of the index 203 (time t in fig. 21A to 21D ₅ ～t ₆ Index 203 of (a) and the minimum value of the index 203 (time t in fig. 21A-21D) ₃ ～t ₄ 203) of the index(s) 203). The change amount of the index 206 is, for example, the maximum value of the index 206 (time t in fig. 21A to 21D ₇ ～t ₈ Index 206 of (a)) and the minimum value of the index 206 (time t in fig. 21A-21D) ₉ ～t ₁₀ 206) of the index (x.

The abnormal portion diagnosis process is a process that is successively executed by the abnormality determiner 72 during the operation of the power conversion device 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 device 100 (see fig. 1) includes: a first smoothing capacitor 22 connected between the first potential and the 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 connected to the first smoothing capacitor 22; a second dc voltage detector 26 that detects a potential difference between potentials of the second smoothing capacitor 23 connected thereto; a first index calculating unit (index creating unit 75 c) that calculates, when a detection abnormality occurs in either one of the first dc voltage detector 25 and the second dc voltage detector 26 in which the detected value changes in a predetermined direction, a first index (indices 201, 209) for diagnosing the presence or absence of an abnormality in the dc voltage detector based on an index obtained from the detected value of the dc voltage detector using a voltage relation 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; a second index calculation unit (index creation unit 75 c) that calculates a second index (indexes 202 to 207) that shows a change in index when any one of the first direct-current voltage detector 25 and the second direct-current voltage detector 26 generates a detection abnormality in which the detection value changes in a predetermined direction; and a comprehensive diagnosis index calculation unit (index creation unit 75 c) that calculates a comprehensive diagnosis index (index 202-207; one of the comprehensive diagnosis indexes) obtained by scalar synthesis or vector synthesis of 1 or 2 or more second indexes. The power conversion device 100 further includes: an abnormality determiner 72 that determines, from among the first dc voltage detector 25 and the second dc voltage detector 26, which one of the first dc voltage detector 25 and the second dc voltage detector 26 is abnormal, by performing an operation of switching the detection value of the dc voltage detector that is assumed to be abnormal to an output estimation value estimated from the detection values of the other dc voltage detectors, based on a change in the integrated diagnostic index after the operation of switching to the output estimation value.

Accordingly, 1 of the plurality of dc voltage sensors is assumed to be abnormal, and abnormality diagnosis is performed based on a response when the operation is performed using the estimated value instead of the 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, the abnormality of the dc voltage detector in the power conversion device can be appropriately detected. In addition, even when the abnormality diagnosis device is mounted on the motor drive device which is already provided and has a circuit constant which is difficult to obtain or estimate, abnormality diagnosis can be performed.

The power conversion device 100 further includes: the neutral point resistances 24 and 34 (see fig. 1) are connected between the second potential on the inverter side and the second potential on the converter side, and are used to suppress direct-current resonance, and when the neutral point resistances 24 and 34 are present (i.e., a circuit having 4 sensors), 4 kinds of calculations are performed using the first index (index 201) and the second index (indexes 202 to 207), and the sensor whose index is assumed to be abnormal when the index is the smallest is diagnosed as abnormal. In this case, the threshold value for abnormality diagnosis is not used.

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

As a modification of the first embodiment, an example in which the ninth index and the tenth index are added will be described.

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

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

Regarding the power conversion device according to the modification of the first embodiment, the index creating unit 72c of 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 index preparation part >)

The ninth index creating unit 729 will be described.

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

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

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

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

The cosine wave calculation unit 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 computing unit 7292 and the output of the cosine wave computing unit 7293 is 90 degrees.

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

The filters 7296 and 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 an ac current detection value I on the side of the converter 2 (see fig. 1) when the dc voltage detector 25 or 26 (see fig. 1) is abnormal _{FB_C} The Q-axis current of (2) is superimposed on the carrier frequency component to detect an index of abnormality of the DC voltage detector. Index 209 is based on Q-axis electricity Carrier frequency f of stream _CC Index of component (converter-side Q-axis current index, converter-side index).

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

When the DC voltage detector is normal, as shown in FIG. 50A, the carrier frequency f is hardly contained in the Q-axis current _CC The components are as follows. On the other hand, when the direct-current voltage detector is normal, as shown in fig. 50B, the carrier frequency f of the Q-axis current _CC The composition increases.

In addition, the structure shown in fig. 49 is to detect the carrier frequency f in the Q-axis current _CC An example of the method of the component may be a method of detecting the carrier frequency f of the Q-axis current by other methods such as fourier transform _CC The structure of the components.

< tenth index preparation part >)

The tenth index creating unit 730 will be described.

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

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

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

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

The filters 7306 and 7307 are filters for removing a fluctuation component included in an input.

The square and square root calculation unit 7308 calculates the square and square root of the output of the filter 7306 and the output of the 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 for the inverter 3 (see fig. 1) side when the dc voltage detector 35 or 36 (see fig. 1) is abnormal _{FB_I} The Q-axis current superimposed carrier frequency f _CI In this case, an index of abnormality of the dc voltage detector is detected. The index 210 is an index based on the carrier frequency component of the Q-axis current (inverter-side Q-axis current index, inverter-side index).

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

When the dc voltage detector is normal, as shown in fig. 52A, the Q-axis current contains almost no carrier frequency f _CI The components are as follows. 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 _CI The composition increases.

The configuration shown in fig. 51 is to detect the carrier frequency f in the Q-axis current _CI An example of the method of the component may be a method of detecting the carrier frequency f of the Q-axis current by other methods such as fourier transform _CI The structure of the components.

< abnormality determination based on ninth index and tenth index >)

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

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, when the detector 25 or the detector 26 is abnormal, the index 210 does not change, and when the detector 35 or the detector 36 is abnormal, the index 210 increases. 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 for calculating, as a second index, an index of a carrier frequency component included in the fundamental Q-axis current based on the current at the position on the power supply side; and a tenth index creating unit 730 that calculates, as a 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 abnormality of the dc voltage sensor at the time of bipolar modulation (at the time of low-speed rotation of the motor with a small modulation rate, or the like) in addition to the time of unipolar modulation. Therefore, when the abnormality sensor is determined during the standby operation, diagnosis can be performed regardless of bipolar modulation or unipolar modulation, and abnormality diagnosis can be reliably performed.

In this modification, 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, but the second index calculating unit may have the ninth index creating unit 729 and the tenth index creating unit 730. Therefore, the second index calculating unit may omit or adaptively use the index other than the ninth index creating unit 729 and the tenth index creating 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 according to the second embodiment has the same configuration as the power conversion device 100 according to the first embodiment.

The second embodiment differs from the first embodiment in that in the second embodiment, the integrated diagnostic index is a vector composed of a plurality of indices. Fig. 24A to 24F show examples in the case where the integrated diagnostic index is set as a vector under the same conditions as those in fig. 21A to 21D. The integrated diagnostic index in fig. 24A to 24F is a vector composed of 2 elements, i.e., the value of the index 203 and the value of the index 206.

Fig. 24A to 24F are diagrams showing an example of the case where the integrated diagnostic 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 the normal state (t ₀ ～t ₁ ) Fig. 24B is a diagram showing vectors of the integrated diagnostic index 250 of (a) when abnormality is indicated and the estimated value is not used (t ₂ ～t ₃ ) FIG. 24C is a diagram showing vectors of the integrated diagnostic index 250 of (1), and E is used in the case of abnormality _{FBH_CP} Time (t) ₃ ～t ₄ ) FIG. 24D is a diagram of vectors of the integrated diagnostic index 250 of (1), and E is used in the case of an abnormality _{FBH_CN} Time (t) ₅ ～t ₆ ) FIG. 24E is a diagram of vectors of the integrated diagnostic index 250 of (1), which shows the use of E in the case of abnormality _{FBH_IP} Time (t) ₇ ～t ₈ ) FIG. 24F is a diagram of vectors of the integrated diagnostic index 250 of (1), and E is used in the case of an abnormality _{FBH_IN} Time (t) ₉ ～t ₁₀ ) A graph of vectors of the integrated diagnostic index 250.

In the example of fig. 24A to 24F, the difference between the integrated diagnostic index of fig. 24C to 24F and the integrated diagnostic index of fig. 24A at the time of normal is the smallest in fig. 24D, and therefore, abnormality of the dc voltage detector 26 can be diagnosed.

Fig. 25A to 25F are diagrams showing an example of the case where the integrated diagnostic index 250 in the specific time range in fig. 23A to D is set as a vector in the case where the dc voltage detector 36 is abnormal. FIG. 25A shows the normal state (t ₀ ～t ₁ ) Fig. 25B is a diagram showing vectors of the integrated diagnostic index 250 of (t) when the estimated value is not used and normal (t ₂ ～t ₃ ) FIG. 25C is a diagram showing vectors of the integrated diagnostic index 250 of (1) and using E when an abnormality is indicated _{FBH_CP} Time (t) ₃ ～t ₄ ) FIG. 25D is a diagram of vectors of the integrated diagnostic index 250 of (A) and (B) showing an abnormality and using E _{FBH_CN} Time (t) ₅ ～t ₆ ) FIG. 25E is a diagram of vectors of the integrated diagnostic index 250 of (1) and is a graph showing the use of E in the case of abnormality _{FBH_IP} Time (t) ₇ ～t ₈ ) FIG. 25F is a diagram of vectors of the integrated diagnostic index 250 of (1), and E is used in the case of an abnormality _{FBH_IN} Time (t) ₉ ～t ₁₀ ) A graph of vectors of the integrated diagnostic index 250.

Even in the example of fig. 25A to 25F, the difference between the integrated diagnostic index of fig. 25C to 25F and the integrated diagnostic index of fig. 25A at the time of normal is the smallest in fig. 25F, and therefore, it can be diagnosed that the dc voltage detector 36 is abnormal.

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

The plurality of indices, which are components of the integrated diagnostic index represented by the vector, may be normalized by any method. For example, the index 203 and the index 206 may be normalized so that the amount of change of the index 203 is equal to the amount of change of the index 206. Alternatively, the normalization of the calculation using the mean or variance, such as the calculation based on the mahalanobis distance, may be performed based on a plurality of normal index values stored in step S104, which will be 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 according to the third embodiment has the same configuration as the power conversion device 100 according to the first embodiment.

Fig. 26 to 27 show flowcharts, and differences from the flowcharts of fig. 18 to 19 are explained.

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 an input to the correction units 7201, 7202, 7203, 7204 _CP 、K _CN 、K _IP 、K _IN Is 0 or 1, in contrast, in the third embodiment, K _CP 、K _CN 、K _IP 、K _IN Take on arbitrary values. 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 the operation of the third embodiment.

Fig. 28 is a diagram showing an example of the operation of the power conversion device according to the third embodiment. Fig. 29A to 29D are diagrams showing time-varying examples of the respective indices and the integrated diagnostic index related to the abnormality determiner of the power conversion device 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 integrated diagnostic index.

Fig. 28 and fig. 29A to 29D show K used in S107 of fig. 18 to 19 _CP 、K _CN 、K _IP 、K _IN An operation example in the third embodiment when the value is 0.5. In fig. 29A to 29D of the third embodiment and fig. 21A to 21D of the first embodiment, a time t is set to ₃ To t ₄ When the values of the index 203 of (a) are compared, the value of the index 203 deviates from 0 in the first embodiment.

At time t in fig. 21A-21D ₃ To t ₄ In contrast to the dc voltage detector 26, which is a truly abnormal dc voltage detector, the dc voltage detector 25 is assumed to be abnormal and operates. At time t of such condition ₃ To t ₄ When the ratio of the difference between the voltage true value of the DC voltage detector 25 and the voltage true value of the DC voltage detector 26 is not the estimated valueEngraving t ₂ To t ₃ Large. That is, at time t ₃ To t ₄ An overvoltage may be applied to the semiconductor element of the converter power conversion section 21.

As shown in the third embodiment, by using K in step S107 _CP 、K _CN 、K _IP 、K _IN If the value is smaller than 1, if the truly abnormal dc voltage detector does not match the dc voltage detector assumed to be abnormal in steps S106 to S107, the overvoltage applied to the circuits such as the converter power conversion unit 21 and the inverter power conversion unit 31 can be suppressed. In addition, by adding K used in step S107 _CP 、K _CN 、K _IP 、K _IN If the value is smaller than 1, if the truly abnormal dc voltage detector does not match the dc voltage detector assumed to be abnormal in steps S106 to S107, the voltage imbalance between the P side and the N side can be suppressed.

(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 according to the fourth embodiment has the same configuration as the power conversion device 100 according to the first embodiment.

Fig. 30 to 31 are flowcharts showing the abnormal portion 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. In the case of yes, the process proceeds to step S312. In the case of no, the flow advances to step S313.

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

In step S312, it is diagnosed that the J-th direct-current voltage detector is abnormal, and the process proceeds to step S315.

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

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

Fig. 32A to 32D are diagrams showing time-varying examples of the respective indices and the integrated diagnostic index related to the abnormality determiner of the power conversion device 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 integrated diagnostic index. Fig. 33 is a diagram showing a first operation example of the power conversion device according to the fourth embodiment.

As shown in fig. 32A-32D-33, at time t ₅ Since the integrated diagnostic index is lower than the reference value, at time t ₆ Switching to the estimated value. The use of the reference value can reduce the diagnostic time.

The reference value is calculated based on the integrated diagnostic index at the time of normal operation (time t ₀ ～t ₁ Is a comprehensive diagnostic index of (2), a comprehensive diagnostic index at the time of abnormality (time t) ₃ ～t ₄ The integrated diagnostic index of (c), the estimated value use ratio in step S306), and the value of the integrated diagnostic index may be determined so as to be lower than the reference value when the estimated value use ratio is changed. For example, when the estimated value use ratio is 0.5, it is considered that the value of the integrated diagnostic index when the estimated value use ratio is changed to 0.5 is the normal integrated diagnostic index (time t ₀ ～t ₁ Is the integrated diagnostic index of (2)) and the integrated diagnostic index at the time of abnormality (time t) ₃ ～t ₄ Is included) is determined. Therefore, the reference value is set to be equal to time t ₃ ～t ₄ The difference between the integrated diagnostic indices of (2) is less than time t ₀ ～t ₁ Comprehensive diagnostic index of (a) and time t ₃ ～t ₄ The central value of the integrated diagnostic index.

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

Fig. 34A to 34D are diagrams showing time-varying examples of the respective indices and the integrated diagnostic index related to the abnormality determiner of the power conversion device 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 integrated diagnostic index. Fig. 35 is a diagram showing a second operation example of the power conversion device 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 integrated diagnostic index is not lower than the reference value. As shown in fig. 34A to 35, it is known that even when the integrated diagnostic index is not lower than the reference value, the same operation as that of the second embodiment is performed, and the abnormal dc voltage detector can be accurately diagnosed.

In this way, in the power conversion device according to the fourth embodiment, by using the reference value independent of the circuit constant, the effect of being able to diagnose the abnormal dc voltage detector in a shorter time is obtained as compared with the power conversion device 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 of the fifth embodiment includes a plurality of inverter units 3 (3 a, 3b, 3c, …) in addition to the power conversion device 100 of 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 from the detection values from the plurality of dc voltage detectors 25, 26, 35 (35 a, 35b, 35c, …), 36 (36 a, 36b, 36c, …). In the sixth embodiment, there are a plurality of methods of estimating accurate detection values for detection targets of the dc voltage detector in which 1 abnormality occurs, as described below.

In the power conversion device 101, there is a relationship as follows: 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 (35 a, 35b, 35c, …) and 36 (36 a, 36b, 36c, …) on the inverter side are all identical. This means that there are a plurality of candidates of the synthesized dc voltage value required to obtain the estimated detection value. In this way, since the number of candidates for obtaining the synthesized dc voltage value increases, the possibility of the detection value of the detection object of the dc voltage detector that can estimate an abnormality can be increased.

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

Even in this power conversion device 101, abnormality of the dc voltage detector can be appropriately determined by the same processing as that of the power conversion device 100 of the first embodiment. In the power conversion device 104, the detection value of the detection target of the abnormal dc voltage detector can be estimated appropriately from the detection values of the plurality of healthy dc voltage detectors, similarly to the power conversion device 101 of the third embodiment.

In the fifth embodiment, the power conversion device 101 is provided with a plurality of inverter units 3, but may be provided with a plurality of converter units 2, for example. Even in this case, the abnormality of the dc voltage detector can be appropriately determined, and the detection value of the detection target of the abnormal dc voltage detector can be appropriately estimated from the detection values of the plurality of healthy dc voltage detectors, in the same manner as described above.

Further, candidates of the synthesized dc voltage value required to obtain the detection value of the detection object of the dc voltage detector for estimating the abnormality can be expanded to 2 dc voltage detectors on any one of the converter sides, and the possibility of the detection value of the detection object of the dc voltage detector for estimating the abnormality can be increased.

As described above, in the fifth embodiment, even in the power conversion device including the plurality of inverter unit circuits or the plurality of converter unit circuits, the effect of the dc voltage detector capable of diagnosing abnormality even if the circuit constant is unknown is obtained.

(sixth embodiment)

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

Fig. 37 is an overall configuration diagram of the power conversion system of 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 power conversion device 102 of the power conversion system 1002 according to the sixth embodiment is different from the main circuit configuration of the power conversion device 100 according to the first embodiment in 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, attention must be paid to design of wiring inductance based on selection of the switching frequency and arrangement of the circuit components so as not to cause resonance in the dc circuit.

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

In addition, in order to continue operation according to redundancy when any 1 of the dc voltage detectors 43 and 44 is abnormal, a dc voltage detector 45 (third dc voltage detector) for measuring the total voltage of the dc voltage detector 43 and 44 is provided. In the 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 set to E _{FB_CIP} Setting the true value as E _{T_CIP} . The detection value of the DC voltage detector 44 is set to E _{FB_CIN} Setting the true value as 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 _＿CIP The dc voltage detector 44 generates a gain G in case of a failure of (a) _＿CIN In the event of a fault, the dc voltage detector 45 generates a gain G _＿CIA The relational expressions of the failure cases of (a) are expressed as the following formulas (67), (68) and (69), respectively.

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)

In addition, the following equation (70) holds under the condition that the neutral point voltage controller 55 or the neutral point voltage controller 65 operates desirably.

E _{FB_CIP} ＝E _{FB_CIN} …(70)

In addition, the following equation (71) holds under the condition that the dc voltage controller 52 operates desirably.

E _{FB_CIP} +E _{FB_CIN} ＝V _{DC_REF} …(71)

Here, V _{DC_REF} Is an instruction value.

In addition, the following equation (72) holds according to the circuit.

E _{T_CIP} +E _{T_CIN} ＝E _{T_CIA} …(72)

Next, the abnormality determiner 75 will be described.

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

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

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

Fig. 39 is a structural diagram of the index creating unit according to the sixth embodiment. The same reference numerals are given to the same configurations as those of the index creating unit 72c of the first embodiment.

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

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

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

Next, the eighth index creating unit will be described.

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 detector (43, 44, 45) by using the fact that a difference is generated 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 formula (11).

DI ₉ ＝E _{FB_CIP} +E _{FB_CIN} -E _{FB_CIA} …(73)

When formula (67), formula (68), and formula (69) are substituted into formula (73) and the same operation as that of formula (12) is performed using the relationship of formula (72), index 209 (=di) is calculated under the condition of formula (74) or formula (75) or formula (76) ₉ ) Positive, under the condition of formula (77) or formula (78) or formula (79), index 209 (=di) 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 relationship between the direction of the abnormal dc voltage detector and the gain abnormality and the direction of the change in the index 209 is shown in fig. 42B.

Specifically, in the dc voltage detector 43, the gain G is generated _CIP Less than 1In the case of abnormality, the index 209 is negative (decreasing), and the gain G is generated _CIP In the case of an abnormality greater than 1, the index 209 is positive (increases). In addition, in the dc voltage detector 44, a gain G is generated _CIN If the anomaly is less than 1, the index 209 is negative (decreasing), and the gain G is generated _CIN In the case of an abnormality greater than 1, the index 209 is positive (increases). In addition, in the dc voltage detector 45, a gain G is generated _CIA If the anomaly is less than 1, the index 209 is positive (increases), and the gain G is generated _CIA In the case of an abnormality greater than 1, the index 209 is negative (decreasing).

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

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

Fig. 42A to 42B are second diagrams for explaining a change in index associated with a detector abnormality according to the sixth embodiment. Fig. 42A is a diagram showing the direction of the gain abnormality and the direction of the change of the index 206, 207 in the case where a fault occurs in either the dc voltage detector 43 or 44, and fig. 42B is a diagram showing the direction of the gain abnormality and the direction of the change of the index 208 in the case where a fault occurs in either the dc voltage detector 43 or 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 block diagram of the estimating unit 7500.

The estimating unit 7500 calculates an estimated value of the detection values of the dc voltage detectors 43, 44, 45 using the formulas (80) to (81). For example, at E _{FB_CIN} 、E _{FB_CIA} Under normal conditions E _{FB_CIP} The estimated value E of (2) _{FBH_CIP} Represented by equation (80). Similarly, at E _{FB_CIP} 、E _{FB_CIA} Under normal conditions E _{FB_CIN} The estimated value E of (2) _{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 sections 7501, 7502, correction values are calculated using formulas (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 is _CIP 、K _CIN The estimated values in the dc voltage detectors 43 and 44 are used in proportion, and these values include, for example, 0 or 1.

For example, at K _CIP 、K _CIN When 0, the formulas (82) to (83) are formulas (84) to (85), and the correction value is a detection value.

E _{FBC_CIP} ＝E _{FB_CIP} …(84)

E _{FBC_CIN} ＝E _{FB_CIN} …(85)

For example, at K _CP 、K _CN 、K _IP 、K _IN When 1, the formulas (82) to (83) are formulas (84) to (85), and the correction value is an estimated value.

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 43, and the second dc voltage detector is 44. Further, the order may be arbitrary.

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

In addition, when formulas (84) to (85) in the initial state of step S401 are used, the detection value E of the direct-current voltage detector 45 is not used _{FB_CIA} Therefore, it means that the dc voltage detector 45 is assumed to be abnormal.

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

Fig. 46A to 46D are diagrams showing operation examples in the case where the dc voltage detector of the sixth embodiment is abnormal. FIG. 46A is a graph showing the estimated value utilization ratio K in the case of abnormality of the DC voltage detector _CIP FIG. 46B is a graph showing the estimated value use ratio K in the case of abnormality of the DC voltage detector _CIN Fig. 46C is a diagram showing an index 209 in the case of abnormality of the dc voltage detector, and fig. 46D is a diagram showing a comprehensive diagnosis index in the case of abnormality of the dc voltage detector.

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

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

FIGS. 47A to 47D show a sixth embodimentA diagram of an operation example in the case of abnormality of the direct current voltage detector of the formula. FIG. 47A shows the estimated value use ratio K in the case of abnormality of the DC voltage detector _CIP FIG. 47B is a graph showing the estimated value use ratio K in the case of abnormality of the DC voltage detector _CIN Fig. 47C is a diagram showing the index 209 in the case of abnormality of the dc voltage detector, and fig. 47D is a diagram showing the overall diagnostic index in the case of abnormality of the dc voltage detector.

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

In the present embodiment, in step S413, the most approximate integrated diagnostic index to the integrated diagnostic index in the normal state among the integrated diagnostic indexes in the abnormality assumption of the 1 direct current 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 in the same manner as in the third embodiment.

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

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, in step S414, 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 this way, the power conversion device 102 can be used without replacing the dc voltage detector having an abnormality, and for example, the power conversion device can be continued to be operated until the next periodic inspection. Therefore, it is not necessary to stop the power conversion device 102 unplanned, and the operation rate can be improved, so that the power converter can be operated efficiently.

Modification example

(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 an operation of switching the detection values of the dc voltage detectors assumed to be abnormal to output estimation values 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 estimation value estimated from the detection values of the other dc voltage detectors, and 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 at a use ratio.

(3)

In the power conversion device, the abnormality determination unit may arbitrarily change the ratio according to the magnitude or the 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 is no load at a position on the load side of the inverter, and 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 when the load is determined to be no load.

(5)

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

(6) Constant speed detection of rotational speed

In the power conversion device, the abnormality determination unit may detect that the rotational speed of the motor 4 (see fig. 1) at the position on the load side of the inverter is a constant speed, and 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 when it is determined that the rotational speed of the motor 4 is a constant speed.

(7) Segmentation diagnosis

In the power conversion device, the abnormality determination unit may change the load at the position on the load side of the inverter or change the speed of the motor between the end of the operation in which the estimated value use ratio of the J-th (J is an arbitrary natural number) direct-current voltage detector is changed and the start of the operation in which the estimated value use ratio of the j+1th direct-current voltage detector is changed.

For example, when the trigger condition changing from condition (condition 1) to condition (condition 2) is satisfied, an operation is performed in which the estimated value usage ratio of the J-th direct-current voltage detector is changed (for example, when j=1, t of fig. 21A to 21D ₃ ～t ₄ ) The condition (condition 1) satisfies at least 1 of a load or a speed variation of the motor at a position on a load side of the inverter, the condition (condition 2) satisfies no load at a position on a load side of the inverter, and the speed of the motor is constant. After the operation of changing the estimated value use ratio of the J-th direct-current voltage detector is completed (for example, in the case of j=1, t of fig. 21A to 21D ₄ ) When the condition 2 is changed to the condition 1 and the trigger condition for changing from the condition 1 to the condition 2 is satisfied again, an operation is performed in which the estimated value usage ratio of the j+1th direct current voltage detector is changed (for example, when j=1, t of fig. 21A to 21D ₅ ～t ₆ )。

By performing such a division diagnosis, for example, even under the operation condition in which the continuous time period satisfying the above condition 2 is short, the possibility of changing from the condition 2 to the condition 1 in the operation in which the estimated value use ratio is changed can be reduced.

The present invention is not limited to the above-described embodiments, and can be implemented by appropriately modifying the present invention without departing from the scope of the present invention.

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

Claims

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 for converting voltages of the first potential, the second potential, and the third potential into an alternating current, characterized in that,

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 connected to the first smoothing capacitor;

a second dc voltage detector that detects a potential difference between potentials of the second smoothing capacitor connected thereto;

a first index calculation unit that calculates a first index for diagnosing the presence or absence of an abnormality of a dc voltage detector based on 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 first smoothing capacitor and a potential difference between potentials connected to the second smoothing capacitor, when a detection abnormality in which a detection value of either one of the first dc voltage detector and the second dc voltage detector changes in a predetermined direction occurs;

A second index calculation unit that calculates a second index that shows a change in index in a different direction when the direction in which the detection value changes is the same when a detection abnormality in which the detection value changes in a predetermined direction occurs in either the first direct-current voltage detector or 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 indexes; and

and an abnormality determination unit that performs an 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 on 1 dc voltage detector or on 2 dc voltage detectors assuming that 1 dc voltage detector or more of the first dc voltage detector and the second dc voltage detector is abnormal, calculates a difference between the integrated diagnostic index after the operation of switching to the output estimation value and the normal integrated diagnostic index, and determines that the dc voltage detector assumed to be abnormal is abnormal when the difference is minimum.

2. The power conversion device according to claim 1, wherein,

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

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

the second smoothing capacitor includes: a converter-side second smoothing capacitor connected to a position closer to the converter than the neutral point resistor; and an inverter-side second smoothing capacitor connected to a position closer to the inverter than the 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 of a first smoothing capacitor connected to the converter-side first direct-current voltage detector; and an inverter-side first direct-current voltage detector that detects a potential difference between potentials of the inverter-side first smoothing capacitor connected thereto,

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

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

the second index includes at least one of the following indexes: when any one of the converter-side first direct-current voltage detector and the converter-side second direct-current voltage detector generates a detection abnormality in which the detection value changes in a predetermined direction, the converter-side index that appears as a change in index, or when any one of the inverter-side first direct-current voltage detector and the inverter-side second direct-current voltage detector generates a detection abnormality in which the detection value changes in a predetermined direction, the inverter-side index that appears as a change in index.

3. The power conversion device according to claim 1, wherein,

a neutral point resistance 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 DC voltage detector that detects a potential difference between potentials of the first smoothing capacitor and the second smoothing capacitor connected,

the first index is an index using a detection value of a direct current voltage detector based on a voltage relation established at a position 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 device according to claim 2, wherein,

the first index calculating unit calculates an index of a voltage detection value difference between an inverter and a converter, which is an index based on a difference between a sum of voltage values detected by the first dc voltage detector on the converter side and the second dc voltage detector on the converter side and a sum of voltage values detected by the first dc voltage detector on the inverter side and the second dc voltage detector on the inverter side, as the first index.

5. The power conversion device according to claim 2, wherein,

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 a first and second smoothing capacitor voltage detection value difference index as the first index, the first and second smoothing capacitor voltage detection value difference index being an index of a difference between a voltage value of the third dc voltage detector and a voltage value of the first dc voltage detector based on a sum of the voltage value of the first dc voltage detector and the voltage value detected by the second dc voltage detector.

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

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 direct-current voltage detector and the second direct-current voltage detector,

the second index calculation unit calculates, as the second index, an index of the converter neutral point voltage control signal based on the command value.

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

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

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

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

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

the second 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, which is an index based on a product of the reference even-order harmonic waveform and the voltage value detected at the power supply side position, as the second index.

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

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 direct-current voltage detector and the second direct-current voltage detector,

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

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

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 a reference even-numbered harmonic waveform for the current at the load side position, and calculates an inverter side even-numbered harmonic current index, which is an index based on a product of the reference even-numbered harmonic waveform and the current value detected by the current detector, as the second index.

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

The alternating current at the inverter side is three-phase alternating current comprising a U phase, a V phase and a W phase,

the power conversion device further includes: an alternating-current voltage detector that detects voltages of respective phases of the inverter,

the second index calculating unit calculates an ac line voltage index based on a difference between the first line voltage and the second line voltage when the voltage between the U phase and the V phase, i.e., the first line voltage, and the voltage between the V phase and the W phase, i.e., the second line voltage, detected by the ac voltage detector are both positive or negative, as the second index.

12. The power conversion device according to claim 2 or 4, wherein,

the abnormality determination unit stores a normal-time integrated diagnosis index when all DC voltage devices 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 of the dc voltage detectors: assuming that 1 of the converter-side first dc voltage detector, the converter-side second dc voltage detector, the inverter-side first dc voltage detector, and the inverter-side second dc voltage detector is abnormal, switching the detection value of the dc voltage detector assumed to be abnormal to an output estimation value estimated based on the detection values of the other dc voltage detectors, storing an estimation value switching integrated diagnostic index which is an integrated diagnostic index at this time,

The difference between the estimated value switching integrated diagnostic index and the normal integrated diagnostic index is calculated, and when the difference is minimum, the dc voltage detector assumed to be abnormal is determined to be an abnormal dc voltage detector.

13. The power conversion device according to claim 3 or 5, wherein,

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 of the dc voltage detectors: assuming that 1 of the first DC voltage detector and the second DC voltage detector 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 integrated diagnosis index at that time, i.e., the estimation value switching integrated diagnosis index,

14. The power conversion device according to claim 12, wherein,

the abnormality determination unit further stores an abnormality-time integrated diagnosis index when it is determined that any one of the dc voltage devices is abnormal based on the first index,

the reference value is also set based on the normal-time integrated diagnostic index and the abnormal-time integrated diagnostic index,

when it is determined that any dc voltage device is abnormal based on the first index, if the detected value of the dc voltage detector that is supposed to be abnormal is switched to an output estimated value estimated based on the detected values of the other dc voltage detectors, and the integrated diagnostic index at the time of operation of storing the integrated diagnostic index at that time is a value closer to the integrated diagnostic index at normal time than the reference value, it is determined that the dc voltage detector at that time is an abnormal dc voltage detector.

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

the second index calculating unit 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 power supply side position.

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

the second index calculating unit 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.

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

the abnormality determination section detects whether or not the load at the position on the 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 loaded to no load,

an operation of switching the detection value of the dc voltage detector assumed to be abnormal to an output estimated value or an output correction value is performed.

18. An abnormality detection method for a power conversion device, the power conversion device comprising: 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 for converting voltages of the first potential, the second potential, and the third potential into an alternating current, characterized in that,

The power conversion device includes:

a second index calculation unit that calculates a second index that shows a change in index in a different direction when the direction in which the detection value changes is the same when a detection abnormality in which the detection value changes in a predetermined direction occurs in either the first direct-current voltage detector or the second direct-current voltage detector; and

A comprehensive diagnosis index calculation unit for calculating a comprehensive diagnosis index obtained by scalar synthesis or vector synthesis of 1 or 2 or more second indexes,

in the abnormality detection method, 1 DC voltage detector is assumed to generate abnormality from the first DC voltage detector and the second DC voltage detector, 1 or more DC voltage detectors are subjected to operation of switching the detection value of the assumed abnormality DC voltage detector to an output estimation value estimated from the detection values of other DC voltage detectors,

and calculating differences between the integrated diagnostic indicators after the operation of switching to the output estimated value and the normal integrated diagnostic indicators, and determining that an abnormality has occurred in the dc voltage detector assumed to be abnormal when the difference is minimum.