JP2009268303A - Inverter apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of canceling out unstable control upon an instantaneous power interruption and instantaneous voltage drop and avoiding a motor suspension due to out of synchronization or overcurrent. <P>SOLUTION: The inverter apparatus is equipped with a converter unit (110) for converting an alternating current (AC) from a commercial power source (100) into a direct current (DC), an inverter unit (120) for converting DC from the converter unit (110) into AC to supply to a motor (130) by turning on/off a switching element, a controller (200) for controlling on/off of the switching element of the inverter unit (120) and a voltage detection unit (140) for detecting a direct voltage (Vdc) to be input from the converter unit (110) to the inverter unit (120). The controller (200) is provided with first modes (ST207 and ST208) for performing excess modulation PWM control according to the calculation result of a modulation rate calculating unit (210) and switches between execution (ST207 and ST208) and non-execution (ST209 and ST210) of the first modes according to the detection result of the voltage detection unit (140). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for controlling an inverter device that drives a motor.

  In recent years, as one of energy saving technologies, an inverter device that operates a brushless DC motor at a variable speed has been used in a wide range of fields such as industrial use, consumer use, and automobile use. Further, as a technique for increasing the output and the maximum rotation speed with a relatively small motor, overmodulation PWM control and field weakening control as shown in [Patent Documents 1 and 2] and [Non-Patent Document 1] are generally used. .

  FIG. 8 shows a block diagram of a conventional inverter device that performs overmodulation PWM control and field weakening control. FIG. 8 is a block diagram in which overmodulation PWM control and field weakening control are added to vector control of the PM motor (130) by the dq axis. FIG. 9 is an operation flow after the modulation rate calculation in the control performed in FIG. The operation of overmodulation PWM control and field weakening control will be described with reference to FIGS.

The maximum voltage that can be output from the inverter is determined by the intermediate voltage (DC input voltage Vin) of the inverter. The voltage command (Vu ^* , Vv ^* , Vw ^* ) to be output is obtained from the current control unit (207, 208) and the coordinate conversion unit (209), and the voltage command (Vu ^* , Vv ^* , Vw ^* ) and the DC input voltage ( The modulation factor (Vout) is determined from Vin) (ST205). Here, the maximum modulation rate capable of sinusoidal PWM (see Non-Patent Document 1) is assumed to be 100%. Since the voltage utilization rate can be increased by bringing the voltage waveform closer to a rectangular wave, when the modulation rate exceeds 100% (Yes in ST207), the overmodulation PWM control unit (212) performs overmodulation PWM calculation (ST208 ), 100% or less (No in ST207), overmodulation PWM calculation is not performed. Further, when the rotation speed is further increased at the maximum inverter output voltage, the current phase is advanced by the field weakening control unit (211) so as to weaken the motor field. Therefore, if the modulation rate is equal to or greater than the maximum voltage utilization rate (example is 127%, but the value varies depending on the implementation method of the PWM converter (213)) (Yes in ST211), field weakening control is performed (ST212). .
Japanese Patent No. 3788685 JP 2005-348551 A Japanese Patent Laid-Open No. 2001-119978 “Hybrid Motor Control and Boost Converter Control” TOYOTA Technical Review Vol.54 No.1 Aug. 2005 P42-51 "Sensorless Control of IPM Motor" Motor Technology Symposium B-5 (1999-Mar) "Sensorless salient pole type brushless DC motor control based on speed electromotive force estimation" D-117_98 (9-1) "Rotor position sensorless vector control method for reluctance motor" National Institute of Electrical Engineers of Japan, No.16

  [Non-Patent Document 1] assumes that the inverter input is a DC voltage source (battery) as shown in FIG. 6 on page 44, and considers instantaneous power failure (instant blackout) and instantaneous voltage drop in commercial power. Not.

  In [Patent Document 1], there is a description of voltage fluctuations (eg, rated input voltage ± 10%) that guarantees steady operation, but an intermediate voltage (DC) of the inverter due to a power failure such as a power failure or instantaneous voltage drop. No consideration is given to the response when the input voltage changes rapidly.

  [Patent Document 2] describes control at the time of a power failure or instantaneous voltage drop, but it is intended to prevent a decrease in the number of revolutions at the time of a momentary power failure by performing field weakening control at the time of a voltage drop.

  If you perform overmodulation PWM and field-weakening control during momentary power loss or instantaneous voltage drop, there is a merit that the motor output can be maintained to some extent, but the disadvantage is that operation with high response is required when the inverter output voltage is saturated There is a problem that the control becomes unstable, and in some cases, the motor stops due to step-out or overcurrent.

  The operation at the momentary power interruption and instantaneous voltage drop of the conventional method will be described with reference to the timing chart of FIG. FIG. 10 (a) shows a case where the control response is slow with respect to the change of the input voltage (Vin). In particular, the voltage modulation rate is in spite of the sudden increase of the input voltage (Vin) during power recovery. Since it is delayed to reduce (Vout), it is easy to stop overcurrent. FIG. 10B shows a case where a control response equivalent to the change of the input voltage (Vin) can be obtained. However, if the control response is increased, the control becomes unstable due to overshoot, and the step-out stop or overcurrent is caused. It may be stopped. In position sensorless control that estimates the rotor position from the motor voltage, current, etc., the amount of change in the voltage and current detection values when the power supply is abnormal is large and the error in the position estimation value is large. Tend to be more prominent.

  An object of the present invention is to provide a technique for solving control instability at the time of an instantaneous power failure or instantaneous voltage drop in an inverter device for driving a motor, and avoiding motor stop due to step-out or overcurrent.

  An inverter device according to the present invention includes a converter unit (110) that converts alternating current from a commercial power source (100) into direct current, and converts direct current from the converter unit (110) into alternating current by turning on and off a switching element. An inverter unit (120) to be supplied to the motor (130), a control unit (200) for controlling on / off of a switching element of the inverter unit (120), the converter unit (110) or the inverter unit (120 ) And a voltage detection unit (140) that detects a voltage (Vin) input to the control unit (200), and the control unit (200) performs overmodulation PWM control according to the calculation result of the modulation factor calculation unit (210) The first mode (ST207, ST208) is provided, and execution (ST207, ST208) / non-execution (ST209, ST210) of the first mode is switched according to the detection result of the voltage detection unit (140). It is characterized by that.

  Further, in the inverter device, the control unit (200), when the input voltage (Vin) detected by the voltage detection unit (140) is larger than a predetermined threshold (Vin_low) (No in ST202), The first mode is executed (ST207, ST208), and when the input voltage (Vin) is smaller than the threshold (Vin_low) (Yes in ST202), the first mode is not executed (ST209, ST210), It is characterized by that.

  In the inverter device, the control unit (200) detects a change amount (Vc) of the input voltage (Vin) detected by the voltage detection unit (140) (ST401), and the change amount (Vc) Is smaller than a predetermined threshold value (Vin_qc) (No in ST402), the first mode is executed (ST207, ST208), and when the amount of change is larger than the threshold value (Vin_qc) (Yes in ST402) ) Does not execute the first mode (ST209, ST210).

  In the inverter device, the control unit (200) further includes a second mode (ST211, ST212) for performing field-weakening control according to a calculation result of the modulation factor calculation unit (210), and the voltage The execution (ST207, ST208, ST211, ST212) / non-execution (ST209, ST210) of the first and second modes is switched according to the detection result of the detection unit (140).

  Further, in the inverter device, the control unit (200), when the input voltage (Vin) detected by the voltage detection unit (140) is larger than a predetermined threshold (Vin_low) (No in ST202), When the first and second modes are executed (ST207, ST208, ST211, ST212) and the input voltage (Vin) is smaller than the threshold (Vin_low) (Yes in ST202), the first and second modes are executed. The mode is not executed (ST209, ST210).

  In the inverter device, the control unit (200) detects a change amount (Vc) of the input voltage (Vin) detected by the voltage detection unit (140) (ST401), and the change amount (Vc) Is smaller than a predetermined threshold value (Vin_qc) (No in ST402), the first and second modes are executed (ST207, ST208, ST211, ST212), and the amount of change (Vc) is the threshold value When larger than (Vin_qc) (Yes in ST402), the first and second modes are not executed (ST209, ST210).

  The inverter device is a position sensorless control type inverter.

  Moreover, the said inverter apparatus is an inverter for compressor drive for air conditioners, It is characterized by the above-mentioned.

  In the inverter device according to the present invention, a power supply abnormality in which the power supply voltage becomes extremely small or rapidly fluctuates due to a momentary power failure or instantaneous voltage drop is detected based on the detection result of the voltage detection unit (140), and the power supply abnormality is The motor current increase by overmodulation PWM control and field weakening control is prohibited by prohibiting the execution of processing (ST207, ST208) of overmodulation PWM control unit (212) and processing (ST211, ST212) of field weakening control unit (211). And a margin for current overshoot during power recovery can be secured.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, substantially the same components are denoted by the same reference numerals. Further, the following description of the preferred embodiments is merely illustrative in nature and is not intended to limit the present invention, its application, or its use.

  FIG. 1 shows the configuration of an inverter device according to an embodiment of the present invention. This inverter device rectifies alternating current from a commercial power supply (100) by a converter circuit (110), converts the direct current to alternating current by an inverter circuit (120), and supplies the alternating current to the motor (130).

The inverter circuit (120) converts the direct current from the converter circuit (110) into a three-phase alternating current by turning on / off the switching element, and supplies the three-phase alternating current to the motor (130). On / off of the switching element of the inverter circuit (120) is controlled by the PWM control unit (200). The PWM control unit (200) turns on / off the switching elements of the inverter circuit (120) based on the detection values (Vin, Iv, Iw, θe) of the various sensors (140, 150, 160) and the various command values (β ^* , ωe ^* ). PWM control for turning off.

  The voltage sensor (140) detects a DC voltage (Vin) input from the converter circuit (110) to the inverter circuit (120). The current sensor (150) detects three-phase AC V-phase and W-phase currents (Iv, Iw) supplied from the inverter circuit (120) to the motor (130). The position sensor (160) outputs a signal (θe) corresponding to the electrical angle of the rotor of the motor (130).

The coordinate conversion unit (203) of the PWM control unit (200) converts the AC current (Iu, Iv, Iw) for three phases from the AC current (Iv, Iw) for two phases detected by the current sensor (150). Then, based on the detected value (θe) of the position sensor (160), the AC current is obtained and the d-axis current (Id) in the main magnetic flux direction of the motor (130) and the q-axis current in the direction orthogonal to the d-axis current are obtained. Convert to (Iq). The speed calculation unit (204) calculates the rotational speed (ωe) of the motor (130) based on the detection value (θe) of the position sensor (160). The speed control unit (205) calculates a current amplitude command (Ia ^* ) based on the difference between the speed command (ωe ^* ) and the rotation speed (ωe) from the speed calculation unit (204).

The current command generator (206) calculates a d-axis current command (Id ^* ) and a q-axis current command (Iq ^* ) based on the current phase command (β ^* ) and the current amplitude command (Ia ^* ). When field weakening control is performed, the d-axis current is based on the current phase command (β ^* ) advanced by the current phase advance angle (ζ) from the field weakening control unit (211) and the current amplitude command (Ia ^* ). The command (Id ^* ) and the q-axis current command (Iq ^* ) are calculated.

The current control unit (207) generates a d-axis voltage command based on the difference between the d-axis current command (Id ^* ) from the current command generation unit (206) and the d-axis current (Id) from the coordinate conversion unit (203). Calculate (Vd ^* ). The current control unit (208) generates a q-axis voltage command based on the difference between the q-axis current command (Iq ^* ) from the current command generation unit (206) and the q-axis current (Iq) from the coordinate conversion unit (203). Calculate (Vq ^* ).

The coordinate conversion unit (209) detects the d-axis voltage command (Vd ^* ) from the current control unit (207) and the q-axis voltage command (Vq ^* ) from the current control unit (208) by the position sensor (160). Based on the value (θe), it is converted into a U-phase voltage command (Vu ^* ), a V-phase voltage command (Vv ^* ), and a W-phase voltage command (Vw ^* ).

The modulation factor calculation unit (210) is based on the three-phase voltage command (Vu ^* , Vv ^* , Vw ^* ) from the coordinate conversion unit (209) and the detection value (Vin) of the voltage sensor (140). Vout) and voltage phase (δ) are calculated.

  The PWM conversion unit (213) performs PWM control on / off of the switching element of the inverter circuit (120) based on the modulation rate (Vout) and the voltage phase (δ) from the modulation rate calculation unit (210). Generate and output control signals. When execution of overmodulation PWM control is permitted, overmodulation PWM calculation is performed by the overmodulation PWM control unit (212), and based on the calculation result, the PWM conversion unit (213) A control signal for overmodulation PWM control of on / off of the switching element is generated and output.

  The PWM control unit (200) of the inverter device (FIG. 1) of the present embodiment is different from the PWM control unit (800) of the conventional inverter device (FIG. 8) in that a power supply abnormality detection unit (201) and a determination unit (202), a field weakening control permission switch (213) and an overmodulation PWM control permission switch (214). The power supply abnormality detection unit (201) detects a power supply abnormality from the absolute value or change amount of the detection value (Vin) of the voltage sensor (140). The determination unit (202) determines permission / prohibition of execution of overmodulation PWM control and field weakening control based on the detection result of the power supply abnormality detection unit (201). Based on the determination result, the determination unit (202) turns on / off the field weakening control permission switch (213) and the overmodulation PWM control permission switch (214).

  Next, the characteristic operation of the PWM control unit (200) of the present embodiment will be described in detail with reference to the flow of FIG.

  In step (ST201), the input voltage (Vin) to the inverter circuit (120) is detected by the voltage sensor (140). The power supply abnormality detection unit (201) compares the detection value (Vin) of the voltage sensor (140) with a threshold value (Vin_low) (ST202).

  When Vin <Vin_low (Yes in ST202), the power failure detection unit (201) sets “1” to the failure flag (f_err) (ST203). On the other hand, when Vin ≧ Vin_low (No in ST202), the power supply abnormality detection unit (201) clears the abnormality flag (f_err) to “0” (ST204).

  Thus, the power supply abnormality detection unit (201) sets “1” to the abnormality flag (f_err) when the detection value (Vin) of the voltage sensor (140) is smaller than the predetermined threshold value (Vin_low). By detecting power supply abnormality.

  In step (ST205), the modulation factor (Vout) is calculated by the modulation factor calculator (210). The flow of this calculation is as described above.

  Next, in step (ST206), the determination unit (202) checks the value of the abnormality flag (f_err).

  When f_err = 0 (Yes in ST206), the determination unit (202) determines “no power supply abnormality” and permits the overmodulation PWM control unit (212) and the field weakening control unit (211) to be executed. Then, the determination unit (202) turns on the overmodulation PWM control permission switch (214) so that the processing (ST207, ST208) of the overmodulation PWM control unit (212) is executed, and the processing of the field weakening control unit (211) The field weakening control permission switch (213) is turned on so that (ST211, ST212) is executed. As a result, when f_err = 0 (Yes in ST206), the processing of steps (ST207, ST208, ST211, ST212) is performed.

  In step (ST207), the overmodulation PWM control unit (212) determines whether or not the modulation rate (Vout) exceeds 100% (the maximum modulation rate capable of sine wave PWM). When the modulation rate (Vout) exceeds 100% (Yes in ST207), the overmodulation PWM control unit (212) executes overmodulation PWM calculation (ST208). On the other hand, when the modulation rate (Vout) does not exceed 100% (No in ST207), the overmodulation PWM control unit (212) does not execute the overmodulation PWM calculation.

  In step (ST211), the field weakening control unit (211) determines whether the modulation rate (Vout) exceeds 127% (the maximum value of the voltage utilization rate: this value depends on how the PWM conversion unit (213) is implemented). Determine whether. When the modulation rate (Vout) exceeds 127% (Yes in ST211), the field weakening control unit (211) executes field weakening control calculation (ST212). On the other hand, when the modulation rate (Vout) does not exceed 127% (No in ST211), the field weakening control unit (211) does not execute the field weakening control calculation.

  The PWM converter (213) controls on / off of the switching element of the inverter circuit (120) according to the result of the processing in the above steps (ST207, ST208, ST211, ST212).

  On the other hand, when f_err = 1 (No in ST206), the determination unit (202) determines that “the power supply is abnormal” and prohibits the execution of overmodulation PWM control and field weakening control. Then, the determination unit (202) turns off the overmodulation PWM control permission switch (213) so that the processing (ST207, ST208) of the overmodulation PWM control unit (212) is not executed, and the processing of the field weakening control unit (211) ( The field weakening control permission switch (213) is turned off so that ST211, ST212) are not executed. As a result, when f_err = 1 (No in ST206), the processing of step (ST209, ST210) is performed. That is, the process (ST207, ST208) of the overmodulation PWM control unit (212) and the process (ST211, ST212) of the field weakening control unit (211) are not executed.

  In step (ST209), the PWM converter (213) determines whether the modulation rate (Vout) exceeds 100%. When the modulation factor (Vout) exceeds 100% (Yes in ST209), the PWM converter (213) replaces the modulation factor (Vout) with 100% (ST210).

  The PWM converter (213) controls on / off of the switching element of the inverter circuit (120) according to the result of the processing in the above steps (ST209, ST210).

  FIG. 3 shows a timing chart when processing is performed according to the flow described above (FIG. 2). As can be seen from a comparison between FIG. 3 and FIG. 10, in the inverter device of this embodiment, when the input voltage (Vin) to the inverter circuit (120) is smaller than a predetermined threshold value (Vin_low), an abnormality flag is set. By setting “f_err” to “1”, a power supply abnormality in which the power supply voltage becomes extremely small due to a momentary power failure or a momentary voltage drop is detected, and the process of the overmodulation PWM control unit (212) is performed during the power supply abnormality ( By prohibiting the execution of processing (ST211, ST212) of ST207, ST208) and field weakening control unit (211), increase in motor current due to overmodulation PWM control and field weakening control can be suppressed, and current overshoot during power recovery A margin can be secured.

  In the above example, the power supply abnormality detection unit (201) detects a power supply abnormality by comparing the detection value (Vin) of the voltage sensor (140) with a predetermined threshold value (Vin_low). Alternatively, a change amount of the detection value (Vin) of the voltage sensor (140) may be detected, and a power supply abnormality may be detected based on the change amount. The operation flow in this case is shown in FIG. In the following, the description will focus on the parts of the flow of FIG. 4 that are different from those of FIG.

  In step (ST201), the input voltage (Vin) to the inverter circuit (120) is detected by the voltage sensor (140). The power supply abnormality detection unit (201) calculates the absolute value (Vc) of the difference between the current detection value (Vin) of the voltage sensor (140) and the previous detection value (Vin_old) (ST401). Next, the power supply abnormality detecting unit (201) compares the value (Vc) calculated in step (ST401) with a predetermined threshold value (Vin_qc) (ST402).

  When Vc> Vin_qc (Yes in ST402), the power supply abnormality detection unit (201) sets “1” in the abnormality flag (f_err) (ST203). On the other hand, when Vc ≦ Vin_qc (No in ST402), the power supply abnormality detection unit (201) clears the abnormality flag (f_err) to “0” (ST204).

  Thus, the power supply abnormality detection unit (201) sets the abnormality flag (f_err) when the change amount (Vc) of the detection value (Vin) of the voltage sensor (140) is larger than the predetermined threshold value (Vin_qc). A power supply abnormality is detected by setting “1”.

  In step (ST205 to ST212), the same processing as in FIG. 2 is performed, and then in step (ST403), the power supply abnormality detection unit (201) sets the previous detection value (Vin_old) of the voltage sensor (140) Update to detection value (Vin).

  FIG. 5 shows a timing chart when processing is performed according to the flow of FIG. As can be seen from a comparison between FIG. 5 and FIG. 10 or FIG. By setting “1” to the error flag (f_err) when it is smaller than that, it detects power supply abnormality where the power supply voltage fluctuates suddenly due to momentary power failure or instantaneous voltage drop, and overmodulation PWM control during power supply abnormality By prohibiting the execution of the processing (ST207, ST208) of the unit (212) and the processing (ST211, ST212) of the field weakening control unit (211), it is possible to suppress an increase in motor current due to overmodulation PWM control and field weakening control, A margin for current overshoot during power recovery can be secured. Further, except when the DC voltage (Vin) input to the inverter circuit (120) suddenly changes (even when the Vin level is low), the processing (ST206, SY207) and weakening of the overmodulation PWM control unit (212) The field control unit (211) process (ST211, ST212) can be used to prevent control instability and overcurrent during momentary power failure and instantaneous voltage drop, and in addition to the maximum operating range of the reduced DC input voltage (Vin). The motor (130) can be driven.

  In the inverter device (FIG. 1) of the present embodiment, the power supply abnormality is detected by the input voltage (DC voltage) of the inverter unit (120). However, as shown in FIG. (AC voltage) can also be used to detect power supply abnormality, and the input voltage of the power supply abnormality detection unit (201) may be the input voltage of either the inverter unit (120) or the converter unit (110). However, when the input voltage (Vin) of the converter unit (110) is used for the input of the power supply abnormality detection unit (201), a DC value conversion unit (for converting the instantaneous value of the AC voltage into a voltage peak value or a voltage effective value) 215) is required.

  In the above description, the case where the present invention is applied to an inverter device capable of performing both overmodulation PWM control and field weakening control has been described. However, the present invention is also applied to an inverter device capable of performing only one of them. Can do.

  When the present invention is applied to an inverter device that can perform only overmodulation PWM control, the entire configuration of the inverter device is the one in which the field weakening control unit (211) is deleted in FIG. ST211, ST212) are deleted. On the other hand, when the present invention is applied to an inverter device that can perform only field weakening control, the entire configuration of the inverter device is the one in which the overmodulation PWM control unit (212) is deleted in FIG. 1, and the processing flow is shown in FIG. Steps (ST207, ST208) are deleted.

  These inverter devices can be selected depending on the application. For example, the inverter device of the present embodiment can be applied to an air conditioner, and field-weakening control is unnecessary for a load having a square torque characteristic such as a fan. Therefore, an inverter device that can perform only overmodulation PWM control is effective. Become. In addition, an inverter device that can perform only field-weakening control is effective in applications where sound and vibration are a concern when the voltage waveform approaches a rectangular wave by overmodulation PWM. Furthermore, an inverter device capable of executing both overmodulation PWM control and field weakening control is effective for a load such as a compressor. However, in order to drive the magnet synchronous motor used in the compressor, it is indispensable to detect the position of the rotor. Usually, however, the compressor cannot be equipped with a position detection sensor because of high temperature and high pressure. Therefore, conventionally, a position sensorless control method has been generally used. Therefore, when the inverter device of the present invention is applied to a compressor, it is desirable to use a position sensorless control type inverter device.

  In position sensorless control, the amount of change in the detected voltage and current when the power supply is abnormal is large, and the error of the position estimation value is large, and the control tends to become unstable. However, if control tracking is stopped in the voltage saturation region and the control operating point is fixed (the current phase is not changed), the voltage and current detection values do not change abruptly and the position estimation value error does not increase. As a result, control instability due to position detection errors is eliminated, and as a result, step-out and motor stop due to overcurrent can be avoided.

  An example in which the present invention is applied to a position sensorless control type inverter device is shown in FIGS. These are merely examples, and the present invention can be applied to other position sensorless control type inverter devices.

FIG. 6 is an example of a position sensorless system that performs position estimation based on a rotational coordinate (dq axis) model. The inverter device of FIG. 6 is obtained by replacing the position sensor (160) of FIG. 1 with a position estimation unit (601). The position estimation unit (601) includes a d-axis current (Id) and a q-axis current (Iq) from the coordinate conversion unit (203), a d-axis voltage command (Vd ^* ) from the current control unit (207), and a current. Based on the q-axis voltage command (Vq ^* ) from the control unit (208), the position estimated value (^ θe) is calculated. The calculation of the position estimated value (^ θe) in the position estimating unit (601) is performed in, for example, [FIG. 8] [paragraphs 0099, 0124] and [non-patent document 2] [non-patent document 3] Based on.

FIG. 7 is an example of a position sensorless system that performs position estimation based on a fixed coordinate (αβ axis) model. The inverter device of FIG. 7 is obtained by replacing the position sensor (160) of FIG. 1 with a position estimation unit (701) and a three-phase / two-phase conversion unit (702, 703). The three-phase / two-phase converter (702) converts the U-phase and V-phase currents (Iv, Iw) detected by the current sensor (150) into α-axis and β-axis currents in αβ coordinates (two-phase orthogonal stator coordinates). Convert to (Iα, Iβ). The three-phase / two-phase conversion unit (703) converts the voltage command (Vv ^* , Vw ^* ) from the coordinate conversion unit (209) into the α-axis and β-axis voltage (Vα, Vβ). The position estimation unit (701) includes an α axis and β axis current (Iα, Iβ) from the three phase / two phase conversion unit (702), and an α axis and β axis from the three phase / two phase conversion unit (703). Based on the voltages (Vα, Vβ), a position estimated value (^ θe) is calculated. The calculation of the position estimation value (^ θe) in the position estimation unit (701) is performed based on [FIG. 10] [paragraph 0111,0112] and [non-patent document 4] of [Patent Document 3], for example.

  In the PWM control section (700, 800) of the inverter device of FIGS. 6 and 7, the processing of FIG. 2 or FIG. 4 is similarly performed.

  The inverter device according to the present invention is applicable to, for example, an air conditioner.

It is a figure which shows the structure of the inverter apparatus by embodiment of this invention. It is a flowchart of the characteristic operation | movement in the PWM control part (200) of FIG. 3 is a timing chart when processing is performed according to the flow of FIG. 2. It is a modification of the flowchart of FIG. 6 is a timing chart when processing is performed according to the flow of FIG. 4. It is a figure which shows the example which applied this invention to the position sensorless type inverter apparatus. It is a figure which shows the example which applied this invention to the position sensorless type inverter apparatus. It is a figure which shows the structure of the conventional inverter apparatus. It is an operation | movement flow of the conventional inverter apparatus. It is a timing diagram in case the conventional inverter apparatus becomes control unstable. It is a figure which shows the modification of the input of the power supply abnormality detection part (201) of FIG.

Explanation of symbols

100 ... Commercial power
110 ... Converter circuit
120… Inverter circuit
130 ... Motor
140… Voltage sensor
150 ... Current sensor
160 ... Position sensor
200,600,700,800 ... PWM controller

Claims (8)

A converter section (110) for converting alternating current from a commercial power supply (100) into direct current
An inverter unit (120) for converting the direct current from the converter unit (110) into an alternating current by turning on / off the switching element and supplying the alternating current to the motor (130);
A control unit (200) for controlling on / off of a switching element of the inverter unit (120);
A voltage detection unit (140) for detecting a voltage (Vin) input to the converter unit (110) or the inverter unit (120);
With
The control unit (200)
A first mode (ST207, ST208) that performs overmodulation PWM control according to the calculation result of the modulation factor calculation unit (210);
Switching execution (ST207, ST208) / non-execution (ST209, ST210) of the first mode according to the detection result of the voltage detector (140),
An inverter device characterized by that. In claim 1,
The control unit (200)
When the input voltage (Vin) detected by the voltage detector (140) is larger than a predetermined threshold (Vin_low) (No in ST202), the first mode is executed (ST207, ST208), and the input When the voltage (Vin) is smaller than the threshold (Vin_low) (Yes in ST202), the first mode is not executed (ST209, ST210),
An inverter device characterized by that. In claim 1,
The control unit (200)
A change amount (Vc) of the input voltage (Vin) detected by the voltage detector (140) is detected (ST401),
When the change amount (Vc) is smaller than a predetermined threshold value (Vin_qc) (No in ST402), the first mode is executed (ST207, ST208), and the change amount is greater than the threshold value (Vin_qc). When larger (Yes in ST402), the first mode is not executed (ST209, ST210).
An inverter device characterized by that. In claim 1,
The control unit (200)
A second mode (ST211, ST212) for performing field-weakening control according to the calculation result of the modulation factor calculation unit (210);
Switching execution (ST207, ST208, ST211, ST212) / non-execution (ST209, ST210) of the first and second modes according to the detection result of the voltage detection unit (140),
An inverter device characterized by that. In claim 4,
The control unit (200)
When the input voltage (Vin) detected by the voltage detector (140) is larger than a predetermined threshold (Vin_low) (No in ST202), the first and second modes are executed (ST207, ST208, ST211, ST212), when the input voltage (Vin) is smaller than the threshold (Vin_low) (Yes in ST202), the first and second modes are not executed (ST209, ST210),
An inverter device characterized by that. In claim 4,
The control unit (200)
A change amount (Vc) of the input voltage (Vin) detected by the voltage detector (140) is detected (ST401),
When the change amount (Vc) is smaller than a predetermined threshold value (Vin_qc) (No in ST402), the first and second modes are executed (ST207, ST208, ST211, ST212), and the change amount (Vc ) Is larger than the threshold (Vin_qc) (Yes in ST402), the first and second modes are not executed (ST209, ST210),
An inverter device characterized by that. In any one of Claims 1-6,
The inverter device is a position sensorless control type inverter,
It is characterized by that. In any one of Claims 1-7,
The inverter device is an inverter for driving a compressor for an air conditioner,
It is characterized by that.

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