JP2015042010A - Motor drive, motor drive module, compressor and refrigeration unit including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor drive capable of achieving current beatless control effective even during overmodulation, while eliminating a bypass filter, by detecting the low frequency pulsation component of directly from the output voltage or output current from an inverter by cycle integration, and correcting each phase voltage command, and to provide a refrigeration unit.SOLUTION: In a motor drive including a rectifier circuit for converting an AC voltage from an AC power supply into a DC voltage, a smoothing capacitor for smoothing the output from the rectifier circuit, i.e., the DC voltage, and an inverter circuit outputting an AV voltage from the output of the smoothing capacitor, i.e., a DC voltage, and driving a motor with a variable number of revolutions, low frequency pulsation components of the inver circuit are reduced by adjusting each phase voltage command value so that the PWM pulse width of the output voltage from the inverter circuit is widened during a section where the DC voltage has a predetermined value or less, and narrowed during a section where the DC voltage has a predetermined value or more.

Description

  The present invention relates to a motor drive device, a motor drive module, and a refrigeration apparatus including the same. In particular, in a motor drive device that drives a motor using a diode rectifier circuit that obtains a DC voltage by inputting an AC voltage from an AC power supply and an inverter circuit that converts the DC voltage into an AC voltage, the influence of the voltage ripple of the DC voltage It is related with the technique which suppresses the low frequency electric current beat which generate | occur | produces, and reduces the torque ripple and noise of a motor.

  Motor drive devices composed of a rectifier circuit that converts AC voltage from an AC power source into DC voltage and an inverter circuit that converts DC voltage into AC voltage are widely used in the field of refrigeration equipment such as air conditioners and industrial equipment. .

  When a single-phase or three-phase AC voltage is converted to a DC voltage by a diode rectifier circuit, the DC voltage has a frequency component that is twice or six times the frequency (fs) of the AC voltage input to the rectifier circuit. The voltage ripple that you have occurs. This voltage ripple can be reduced by increasing the capacity of the smoothing capacitor connected to the output side of the rectifier circuit, but there is a problem that the cost and volume increase.

  When there is a voltage ripple in the DC voltage, the output voltage and output current of the inverter circuit, in addition to the output frequency (f1) component of the inverter circuit, are affected by the detection delay of the DC voltage and the calculation delay of the inverter controller. Therefore, a “frequency component of difference” (| fr−f1 |) between the DC voltage ripple frequency (fr) component and the output frequency component of the inverter is included.

  Here, when the output frequency of the inverter circuit and the DC voltage ripple frequency approach, if the winding resistance value or impedance of the motor driven by the inverter circuit is small, a large pulsating current is generated due to the above "frequency component of difference". A beat phenomenon occurs in which the motor output torque pulsates.

  Regarding the suppression method of the beat phenomenon, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2004-104898) detects a high-frequency component of a γ-δ axis current in a rotating coordinate system and detects a three-phase phase current beat component. There is disclosed a method of correcting the three-phase voltage command value by calculating and amplifying the calculated value.

  Further, in Patent Document 2 (Japanese Patent Laid-Open No. 2008-167568), the output voltage value of the inverter is corrected by processing such as multiplication of a sine signal and a cosine signal instead of a high-pass filter. Means for suppressing the current beat are disclosed.

JP 2004-104898 A JP 2008-167568 A

  However, the method described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-104898) requires a high-pass filter in order to extract a high-frequency component of the γ-δ axis current of the rotating coordinate system. For this reason, if there is a difference in power supply frequency (50 Hz, 60 Hz), or an error in frequency, fine adjustment of the gain set in the high-pass filter is essential to improve the effect of suppressing the beat phenomenon. .

  In the method described in Patent Document 2 (Japanese Patent Laid-Open No. 2008-167568), the output voltage value of the inverter is corrected by processing such as multiplication of a sine signal and a cosine signal instead of a high-pass filter. Thus, the current beat is suppressed, but there is a disadvantage that the correction effect is lowered because the output voltage of the inverter is saturated at the time of overmodulation. That is, the correction component is added to the output voltage command of the inverter. However, in the case of overmodulation, the output voltage becomes saturated and no more voltage can be output, so that the output voltage with the correction amount added cannot be output.

  Therefore, the present invention detects a low-frequency pulsation component directly from the inverter output voltage or output current by periodic integration processing, and corrects each phase voltage command to eliminate the need for a bypass filter and is also effective during overmodulation. It is an object of the present invention to provide a motor driving device and a refrigeration apparatus that can realize a current beatless control.

In order to solve the above problems, the present invention
"A rectifier circuit that converts AC voltage from an AC power source into DC voltage;
A smoothing capacitor that smoothes the DC voltage that is the output of the rectifier circuit;
In a motor drive apparatus comprising: an inverter circuit that outputs an AC voltage from a DC voltage that is an output of the smoothing capacitor and variably drives the rotation speed of the motor
While expanding the PWM pulse width of the output voltage of the inverter circuit, while the DC voltage is below a predetermined value,
By adjusting each phase voltage command value so that the PWM pulse width of the output voltage of the inverter circuit is narrowed during the period in which the DC voltage is greater than or equal to a predetermined value, the low frequency pulsation component of the output voltage of the inverter circuit is reduced. It is characterized by.

  According to the present invention, a low-frequency current beat generated from a DC voltage voltage ripple caused by a diode rectifier circuit is suppressed, an overmodulation operation area is expanded, a voltage utilization factor is improved, and a motor torque ripple and noise are reduced. can do.

It is a block diagram of the motor drive device of Example 1 of this invention. It is a functional block block diagram of the control part of the motor drive device of Example 1 of this invention. It is the control shaft of the motor drive device of Example 1 of this invention, and a motor rotating shaft. It is a block diagram of the pulsation voltage detection circuit of the motor drive device of Example 1 of this invention. It is a figure which shows the DC voltage waveform and output voltage waveform of the motor drive device of Example 1 of this invention. It is a block diagram of the command voltage regulator of the motor drive device of Example 1 of this invention. It is a voltage waveform of the motor drive device of Example 1 of this invention. It is the electric current and voltage waveform of the motor drive device of Example 1 of this invention. It is the voltage and PWM pulse waveform of the motor drive device of Example 1 of this invention. It is a block diagram of the motor drive device of Example 2 of this invention. It is a block diagram of the motor drive device of Example 3 of this invention. It is a functional block block diagram of the control part of the motor drive device of Example 3 of this invention. It is a block diagram of the pulsation voltage detection of the motor drive device of Example 3 of this invention. It is an external view of the motor drive module of Example 4 of this invention. It is a block diagram of the freezing apparatus of Example 5 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

Hereinafter, Example 1 of the present invention will be described with reference to FIGS.
(overall structure)
FIG. 1 is a diagram illustrating an overall configuration of the motor driving apparatus according to the first embodiment. The motor drive device of this embodiment includes a rectifier circuit 2 that is connected to an AC power source 1 and converts an AC voltage from the AC power source 1 into a DC voltage. The smoothing capacitor 3 is connected to the DC output terminal of the rectifier circuit 2 and smoothes the DC voltage that is the output of the rectifier circuit 2. The inverter circuit 4 outputs an AC voltage from the DC voltage that is the output of the smoothing capacitor 3 and the three-phase AC voltage command values Vu *, Vv *, and Vw *, and variably drives the rotational speed of the motor 5.

The bus current detector 7 detects a DC current (bus current) of the inverter circuit 4 by a shunt resistor provided between the smoothing capacitor 3 and the inverter circuit 4. The motor driving apparatus is configured by a controller 6 that controls the inverter circuit 4, a DC voltage detection circuit 8, and a pulsation voltage detection circuit 9 that detects a pulsation component of the output voltage of the inverter circuit 4. The controller 6 uses a semiconductor arithmetic element such as a microcomputer or a DSP (digital signal processor).
(Controller configuration)
FIG. 2 is a diagram showing the configuration of the controller 6 of the inverter circuit 4, and each function is realized by a CPU (computer) and a storage program. The controller 6 calculates a voltage command signal to be applied to the motor 5 by dq vector control and generates a PWM control signal of the inverter circuit 4. The controller 6 includes a speed controller 10, a d-axis current command generator 11, and the like. , Voltage controller 12, 2-axis / 3-phase converter 13, command voltage regulator 14, speed & phase estimator 15, 3-phase / 2-axis converter 16, current reproduction calculator 17, PWM A controller 18 and a pulsation voltage correction calculator 19 are provided.

  The current reproduction calculator 17 uses the detection signal (Ish) output from the bus current detector 7 and the three-phase voltage command values Vu *, Vv *, Vw * to output currents Iu, Iv, Iw of the inverter circuit 4. To reproduce. Here, in order to reduce the cost, a method of reproducing the three-phase current from the bus current is adopted, but the three-phase output current may be detected using means such as a current sensor.

FIG. 3 is a diagram showing a control axis and a motor rotation axis of the motor drive device of the present embodiment, where a dc-qc axis is an estimation axis of the control system, a dq axis is a motor rotor axis, and a dq axis And the axis error between the dc-qc axes is defined as Δθc. Then, the three-phase / two-axis converter 16 determines the dc-axis current Idc based on the reproduced three-phase output currents Iu, Iv, Iw and the phase information θ _dc estimated by the speed & phase estimator 15. The qc-axis current Iqc is calculated based on the following equation.

  The speed controller 10 creates a q-axis current command value (iqc *) in accordance with an external speed command value (ω *). In order to minimize the motor current, a d-axis current command value (idc *) is generated from the d-axis current command generator.

  In the voltage controller 12, the current command value Idc * given from the d-axis current command generator 11, the current command value Iqc * given from the speed controller 10, the dc-axis current detection value Idc, and the qc-axis current detection value. Using Iqc, speed command value ω1 *, and motor constant, dc-axis voltage command value Vdc * and qc-axis voltage command value Vqc * are calculated.

  Using the calculated dq-axis command voltage (Vdc *, Vqc *) and the phase information (θdc) from the speed & phase estimator 15, the 2-axis / 3-phase converter 13 uses the three-phase command voltage (Vu *, Vv). *, Vw *) is calculated.

  The processing in the speed & phase estimator 15 is the same as that disclosed in Patent Document 2, and a detailed description thereof is omitted here. This control eliminates the need for the rotor position sensor of the motor 5, thereby reducing the cost of the entire drive system. Of course, a rotor position sensor such as an encoder may be employed to always detect rotor position information.

  The command voltage adjuster 14 corrects the three-phase command voltages (Vu *, Vv *, Vw *) using the calculation amounts (ΔVu *, ΔVv *, ΔVw *) from the pulsation voltage correction calculator 19. . Details of the correction calculation method of the pulsation voltage and the adjustment method of the three-phase command voltage will be described later.

  Finally, the PWM signal is calculated by the PWM controller 18 using the voltage signal (Ed) from the DC voltage detection circuit 8 to create a PWM (Pulse width modulation) control signal for the inverter circuit 4. The semiconductor switching element (IGBT, power MOS, etc.) of the inverter circuit 4 is turned on / off according to the PWM control signal, and a pulse voltage (amplitude value is a DC voltage, width is changed by the PWM signal) from each phase output terminal. ) Is output.

  FIG. 4 is a diagram illustrating a detailed configuration of the pulsation voltage detection circuit 9. The pulsation voltage detection circuit 9 detects each phase output voltage (Eun, Evn, Ewn) of the inverter using the voltage dividing resistor 20. Next, half of the detected value of the DC voltage (Edc / 2) is subtracted from the detected value of each phase output voltage and input to each integrator 21. The integral value of the integrator is processed by the sampling and hold 22 and the A / D converter 23 by the controller 6 and then periodically cleared by the integral clear signal from the controller 6. The subtraction and integration operations here are realized using an analog circuit such as an operational amplifier. The period of this period integration process can be calculated from the control phase θdc using the period determination 25 as shown in FIG. In addition to the control phase, the period may be calculated from any information of the motor rotational speed command, the detected motor rotational speed value, the detected rotational position of the motor, and the inverter output frequency.

  When there is no voltage ripple in the DC voltage, the difference between the output voltage of each phase and 1/2 of the DC voltage is periodically positive and negative symmetrical, so that the voltage integral value for one cycle of the output of the inverter is about zero.

  On the other hand, as shown in FIG. 5, when the DC voltage waveform 30 has a periodic voltage ripple, the output voltage of the inverter is large in a section where the DC voltage is high (for example, around 0.595 s on the time axis). On the contrary, the amplitude value of the integrator input voltage waveform 31 in the section where the amplitude value of the input voltage waveform 31 is large and the DC voltage is low (for example, around 0.6 s on the time axis) becomes small.

  Then, positive and negative asymmetrical components appear in the integrator input voltage waveform 31 in the first half cycle and the second half cycle of the inverter output, and the low frequency (the difference frequency between the inverter output frequency (f1) and the voltage ripple component frequency (fr)) from the integrator. A pulsating voltage of (| f1-fr |) is generated. In this embodiment, as described above, the pulsation voltage can be detected by periodically integrating the output voltage of the inverter circuit using the integrator or the integration circuit.

  FIG. 6 shows the configuration of the pulsating voltage correction calculator 19 of the controller 6. The voltage integration signal of each phase from the pulsation voltage detection circuit 9 is processed using the sampling and holding 22 and the A / D converter 23 to calculate a low-frequency pulsation component of each phase. The difference from the command value 0 is obtained so that the low-frequency pulsation component is eliminated, and the correction amount (ΔVu *, ΔVv *, ΔVw *) of each phase voltage is created using the PI controller. Finally, as shown in FIG. 7, the correction amounts (ΔVu *, ΔVv *, ΔVw *) of each phase are added to the three-phase command voltage (Vu *, Vv *, Vw *) to obtain the three-phase command voltage. Corrected and output as corrected three-phase command voltage (Vu * ′, Vv * ′, Vw * ′). Here, the correction amount (ΔVu *, ΔVv *, ΔVw *) of each phase voltage is calculated by proportional integral control using the PI controller, but either proportional control or integral control is used instead of this PI controller. It may be calculated by a controller.

  By correcting the three-phase command voltage, the amount of low-frequency pulsation is superimposed on each phase modulation wave, and the PWM pulse width of each phase output voltage of the inverter circuit 4 changes. FIG. 8 is a waveform showing the effect of the voltage correction described above. The voltage correction control of this embodiment is turned on from 0.4 s of the time axis, the U-phase voltage correction amount 32 (the same applies to the V and W phases) is output from the pulsation voltage correction calculator 19, and the U-phase voltage command In addition, a U-phase voltage command waveform 33 is generated.

  As shown in FIG. 9, since the U-phase voltage command waveform 33 is composed of a U-phase voltage command (substantially sinusoidal component) before correction and a voltage correction amount 32 of low frequency fluctuation, comparison with a triangular carrier wave 35 is performed. When the PWM pulse waveform 36 of the U-phase upper arm is generated by the above, if the voltage correction amount 32 is increased, the voltage command waveform 33 is shifted in the positive direction, and the ON width of the PWM pulse of the U-phase upper arm is widened. Conversely, when the voltage correction amount 32 is reduced, the voltage command waveform 33 is shifted in the negative direction, and the on-width of the PWM pulse of the U-phase upper arm is reduced.

  As a result, the PWM pulse width of the inverter output voltage can be widened while the DC voltage 30 shown in FIG. 5 is low, and the PWM pulse width of the inverter output voltage can be narrowed while the DC voltage is high, thereby reducing the inverter output voltage. The frequency pulsation component is reduced, and the low frequency pulsation of the current can be suppressed. Further, as shown in FIG. 9, the above-described adjustment of the PWM pulse width is established even under overmodulation conditions, and therefore, low-frequency pulsation (beat) of current during overmodulation can be suppressed.

  FIG. 8 is a waveform showing the effect of the voltage correction described above. From the time axis of 0.4 s, it can be confirmed that the current beat of the U-phase current waveform 34 is significantly suppressed by the voltage correction of the present embodiment.

Embodiment 2 of the present invention will be described below with reference to the drawings.
(Overall configuration)
FIG. 10 shows the configuration of the motor drive device of this embodiment. The same reference numerals as those in FIG. 1 of the first embodiment perform the same operations. FIG. 10 is different from FIG. 1 in that an output voltage detection circuit 20 is used instead of the pulsation voltage detection circuit 9. In other words, since the controller 6 includes the subtraction circuit and the integrator in the pulsation voltage detection circuit 9, the analog circuit of the first embodiment can be simplified.

  In order to perform similar subtraction and integration processing in the controller 6 and maintain the calculation accuracy, it is necessary to shorten the period of A / D sampling and calculation processing in the microcomputer. Since other processes are the same as those in the first embodiment, detailed description thereof is omitted.

  By using this embodiment, a high-precision analog circuit is unnecessary, so that cost reduction is advantageous.

  FIG. 11 shows the configuration of the motor drive apparatus according to the third embodiment of the present invention.

  The same reference numerals as those in FIG. 1 of the first embodiment perform the same operations.

  The difference of the configuration of the present embodiment from the first and second embodiments is the deletion of the pulsation voltage detection circuit 9 and the output voltage detection circuit 20. By using this embodiment, a high-precision analog circuit is unnecessary, so that cost reduction is advantageous.

  In addition, as shown in FIG. 12, the control configuration in the inverter controller 6 replaces the pulsating voltage correction calculator 19 shown in FIG. 2 with 27, and changes its input from a three-phase output voltage to a detected value of a three-phase current. As shown in FIG. 5, when the DC voltage waveform 30 has a periodic ripple component, a positive and negative asymmetric component appears in each phase output voltage. As a result, low-frequency pulsations appear in the U-phase current waveform 34 0.4 s before the time axis in FIG.

  FIG. 13 shows a detailed configuration of the pulsating voltage correction calculation processing 27 of this embodiment. Using the integrator 26, the sampling & hold 22 and the period determination process 25, the period average process of each phase current is performed. By calculating the positive and negative asymmetric components of each phase current by the periodic averaging process, the pulsation voltage correction amount is calculated using the PI controller 24 so that the asymmetric components are eliminated.

  Since other processes are the same as those in the first embodiment, detailed description thereof is omitted.

  FIG. 13 is an external view of the motor drive module 100 according to the fourth embodiment of the present invention, and shows one form of the final product.

  The module 100 is a module for a motor driving device in which a semiconductor element 102 is mounted on a control unit substrate 101. The control unit substrate 101 includes a bus current detection circuit 7, a DC voltage detector 8, and a controller illustrated in FIG. 6 and the like are directly mounted, and the inverter 4 is mounted as a semiconductor element 102 formed into one chip. By modularization, downsizing is achieved and costs can be reduced. The module means “standardized structural unit” and is composed of separable hardware / software components. Moreover, although it is preferable to comprise on the same board | substrate on manufacture, it is not limited to the same board | substrate. From this, it may be configured on a plurality of circuit boards built in the same housing.

  According to the present embodiment, by using the motor driving apparatus of the first to third embodiments, even if there is a voltage ripple of DC voltage, low frequency pulsation (beat) of the motor current is suppressed, and high control performance is achieved. It can be secured.

  FIG. 14 shows a configuration diagram of a refrigeration apparatus such as an air conditioner or a refrigerator according to a fifth embodiment of the present invention. The refrigeration apparatus 200 is an apparatus that harmonizes the air temperature, and is configured by connecting an outdoor unit and an indoor unit through a refrigerant pipe 206. Here, the outdoor unit includes an outdoor heat exchanger 202 that performs heat exchange between the refrigerant and air, an outdoor fan 204 that blows air to the outdoor heat exchanger 202, and a compressor 205 that compresses and circulates the refrigerant. The compressor 205 has a compressor motor 208 having a permanent magnet synchronous motor therein, and the compressor is driven by driving the compressor motor 208 by the motor driving device 207. The motor driving device 207 converts the AC voltage of the AC power source into a DC voltage and provides it to the motor driving inverter to drive the motor.

  Although the compressor 205 does not have a detailed illustrated structure, a rotary compressor, a scroll compressor, or the like is adopted, and a compression mechanism unit is provided therein. The compression mechanism unit is driven by a compressor motor 208. If the compression mechanism unit is a scroll compressor, it is composed of a fixed scroll and a turning scroll, and the turning scroll makes a turning motion with respect to the fixed scroll, thereby forming a compression chamber between the scrolls.

  By using the motor driving device according to the first to third embodiments or the motor driving module according to the fourth embodiment as the motor driving device 207, even if there is a DC voltage voltage ripple, the motor current has a low frequency pulsation (beat). Can be suppressed and high control performance can be secured. In addition, since the motor current beat is suppressed, stable driving with a higher modulation rate (overmodulation) can be performed, and the voltage utilization rate of the inverter can be improved. Moreover, if the motor drive device of Examples 1-3 or the motor drive module of Example 4 is used as a refrigeration device, vibration and noise can be reduced.

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Rectifier circuit 3 Smoothing capacitor 4 Inverter 5 Motor 6 Controller 7 Current detection circuit 8 DC voltage detection circuit 9 Pulsation voltage detection circuit 10 Speed controller 11 d-axis current command generator 12 Voltage controller 13 2 axis / 3 Phase converter 14 Command voltage regulator 15 Speed & phase estimator 16 3-phase / 2-axis converter 17 Current reproduction calculator 18 PWM controller 19 Pulsating voltage correction calculator 20 Voltage divider resistor 21 Integrator 22 Sampling & hold 23 A / D converter 24 PI controller 25 period determination processing 26 integrator 27 pulsation voltage correction calculator 30 DC voltage waveform 31 integrator input voltage waveform 32 U phase voltage correction amount waveform 33 U phase voltage command waveform 34 U phase current waveform 35 carrier wave 36 PWM pulse waveform of U-phase upper arm 100 module 101 substrate 102 semiconductor switching element (power module )
200 Refrigeration apparatus 201, 202 Heat exchanger 203, 204 Fan 205 Compressor 206 Pipe 207 Motor drive unit 208 Compressor motor

Claims (9)

A rectifier circuit that converts AC voltage from an AC power source into DC voltage;
A smoothing capacitor that smoothes the DC voltage that is the output of the rectifier circuit;
In a motor drive apparatus comprising: an inverter circuit that outputs an AC voltage from a DC voltage that is an output of the smoothing capacitor and variably drives the rotation speed of the motor
While expanding the PWM pulse width of the output voltage of the inverter circuit, while the DC voltage is below a predetermined value,
By adjusting each phase voltage command value so that the PWM pulse width of the output voltage of the inverter circuit is narrowed during the period in which the DC voltage is greater than or equal to a predetermined value, the low frequency pulsation component of the output voltage of the inverter circuit is reduced. A motor drive device characterized by that. In claim 1,
The method for adjusting each phase voltage command value is a motor drive characterized by calculating a command voltage correction amount by periodically integrating the output voltage of the inverter circuit using an integrator or an integration circuit. apparatus. In claim 1,
The method for adjusting each phase voltage command value is to calculate a command voltage correction amount by periodically integrating the output current of the inverter circuit using an integrator or an integration circuit. apparatus. In the motor drive device according to any one of claims 1 to 3,
The correction amount of each phase voltage command value is calculated by any one of proportional control, integral control, and proportional integral control. In the motor drive device according to any one of claims 1 to 3,
The input of the integrator or the integration circuit calculates a difference between a voltage detection value between each phase output terminal of the inverter circuit and a negative end of the DC voltage and a half of the detection value of the DC voltage. A motor drive device. In the motor drive device according to claim 2 or 3,
The cycle of the period integration process is calculated from any information of a motor rotation speed command, a motor rotation speed detection value, a motor rotation position detection value, and an inverter output frequency. In a motor drive module having a rectifier circuit that converts AC voltage to DC and an inverter that converts DC to AC,
The motor drive module is provided with the motor drive device according to any one of claims 1 to 3.
A compression mechanism for compressing the refrigerant;
A compressor motor that drives the compression mechanism;
In a compressor provided with a motor driving device for driving the compressor motor,
A compressor using the motor driving device according to claim 1 as the motor driving device. A compressor for compressing the refrigerant;
An outdoor heat exchanger that exchanges heat between refrigerant and air;
An outdoor fan that blows air to the outdoor heat exchanger;
The compressor mechanism of the compressor is driven by a compressor motor,
A motor driving device according to any one of claims 1 to 3 is used as a motor driving device for driving the compressor motor.