WO2023067723A1 - Power conversion device, electric motor drive device, and refrigeration cycle-applicable apparatus - Google Patents

Abstract

In the present invention, a power conversion device (2) comprises a converter (10), a capacitor (20), an inverter (30), and a controller (100) for controlling an operation of the inverter (30). The converter (10) rectifies a power supply voltage applied from an AC power supply (1). The capacitor (20) is connected to an output terminal of the converter (10), and the inverter (30) is connected to both ends of the capacitor (20). The controller (100) is provided with a vibration suppression control unit (800) and a vibration suppression control restricting unit (506). The vibration suppression control unit (800) performs vibration suppression control to suppress a vibration of a load. The vibration suppression control restricting unit (506) restricts the compensation value for the vibration suppression control such that a harmonic component included in the power supply electric current flowing between the AC power supply (1) and the converter (10) is reduced.

Description

Power conversion device, motor drive device and refrigeration cycle application equipment

The present disclosure relates to a power conversion device that supplies AC power to a motor that drives a load, a motor drive device, and a refrigeration cycle application device.

A power conversion device consists of a converter that rectifies the power supply voltage applied from an AC power supply, a capacitor that is connected to the output end of the converter, and an inverter that converts the DC voltage output from the capacitor into an AC voltage and applies it to the electric motor. Prepare.

Patent Document 1 below discloses a technique for suppressing an increase in vibration by appropriately compensating for torque pulsation, which is a pulsating component of the load torque, according to the state of the electric motor that drives the compressor.

JP 2016-082637 A

In air conditioners, which are one of the applied products of refrigeration cycle equipment, regulations on harmonics of the power supply current are stipulated in order to suppress damage caused by harmonic components contained in the power supply current. For example, in Japan, the Japanese Industrial Standards (JIS) stipulate standard values, which are limiting values for harmonics of power supply current.

However, the technique described in Patent Document 1 does not consider harmonics of the power supply current. For this reason, if the technique of Patent Document 1 is used to generate a compensating component for the torque ripple of the electric motor at a frequency that is asynchronous with the power supply frequency, the power supply current will be in an unbalanced state between the positive and negative polarities of the power supply current. There is a problem that the harmonic component of the power supply current increases.

The present disclosure has been made in view of the above, and an object thereof is to obtain a power conversion device capable of suppressing an increase in harmonic components of a power supply current while compensating for torque pulsation of an electric motor.

In order to solve the above-described problems and achieve the purpose, the power conversion device according to the present disclosure is a power conversion device that supplies AC power to a motor that drives a load. A power converter includes a converter, a capacitor, an inverter, and a controller that controls the operation of the inverter. The converter rectifies a power supply voltage applied from an AC power supply. A capacitor is connected to the output of the converter and an inverter is connected across the capacitor. The control device includes a vibration suppression controller and a vibration suppression control limiter. The vibration suppression control unit performs vibration suppression control to suppress vibration of the load. The vibration suppression control limiter limits a compensation value for vibration suppression control so as to reduce harmonic components contained in power supply current flowing between the AC power supply and the converter.

According to the power converter according to the present disclosure, it is possible to suppress an increase in harmonic components of the power supply current while compensating for torque pulsation of the electric motor.

1 is a diagram showing a configuration example of a power converter according to Embodiment 1; FIG. FIG. 2 is a diagram showing a configuration example of an inverter included in the power converter according to Embodiment 1; FIG. 4 is a diagram showing an operation state of the electric motor drive device according to Embodiment 1 when vibration suppression control is not performed; FIG. 5 is a diagram showing an operation state when vibration suppression control is performed in the electric motor drive device according to Embodiment 1; FIG. 2 is a block diagram showing a configuration example of a control device included in the power conversion device according to Embodiment 1; The first diagram for explaining the problem of the present application A second diagram for explaining the problem of the present application FIG. 3 is a block diagram showing a configuration example of a voltage command value calculation unit included in the control device according to Embodiment 1; FIG. 2 is a block diagram showing a configuration example of a compensation value calculation section included in the voltage command value calculation section according to Embodiment 1; 3 is a block diagram showing a first configuration example of a vibration suppression control limiter included in a voltage command value calculator according to Embodiment 1; FIG. 4 is a flowchart for explaining the operation of the limit value calculation unit according to the first embodiment; FIG. 4 is a block diagram showing a second configuration example of the vibration suppression control limiter included in the voltage command value calculator according to the first embodiment; FIG. 2 is a block diagram showing a configuration example of a power supply harmonic standard value calculation unit included in the vibration suppression control limiter according to the first embodiment; FIG. 4 is a diagram for explaining calculation processing of a current harmonic limit value calculation unit included in the power supply harmonic standard value calculation unit according to the first embodiment; FIG. 4 is a block diagram showing a configuration example of an order component calculation unit included in the vibration suppression control limiter according to Embodiment 1; FIG. 4 is a block diagram showing a configuration example of a speed control unit and a δ-axis current command value generation unit included in the voltage command value calculation unit according to the first embodiment; FIG. Flowchart for explaining operations of a speed control unit and a limit unit according to the first embodiment FIG. 4 is a diagram for explaining the operation of the vibration suppression control limiter included in the voltage command value calculator according to the first embodiment; FIG. 4 is a block diagram showing a configuration example of a vibration suppression control limiter according to a modification of Embodiment 1; FIG. FIG. 4 is a block diagram showing a configuration example of a mechanical angle frequency component extraction unit included in a vibration suppression control limiter according to a modification of the first embodiment; FIG. 4 is a diagram for explaining the influence of the inductance value of the reactor and the capacitance value of the capacitor included in the power converter according to the first embodiment on the power supply harmonics; FIG. 2 is a diagram showing an example of a hardware configuration that implements a control device included in the power conversion device according to Embodiment 1; FIG. A diagram showing a configuration example of a refrigeration cycle application device according to Embodiment 2

A power conversion device, a motor drive device, and a refrigeration cycle application device according to an embodiment of the present disclosure will be described below in detail with reference to the accompanying drawings. In the following description, the term “connection” includes both direct connection between constituent elements and indirect connection between constituent elements via other constituent elements. I'm in.

Embodiment 1.
FIG. 1 is a diagram showing a configuration example of a power conversion device 2 according to Embodiment 1. As shown in FIG. FIG. 2 is a diagram showing a configuration example of the inverter 30 included in the power conversion device 2 according to Embodiment 1. As shown in FIG. The power converter 2 is connected to the AC power supply 1 and the compressor 8 . The compressor 8 is an example of a load that has a characteristic that the load torque periodically fluctuates when it is driven. The compressor 8 has an electric motor 7 . An example of the motor 7 is a three-phase permanent magnet synchronous motor. The power converter 2 converts the power supply voltage applied from the AC power supply 1 into an AC voltage having a desired amplitude and phase, and applies the AC voltage to the electric motor 7 . Power converter 2 includes reactor 4 , converter 10 , capacitor 20 , inverter 30 , voltage detector 82 , current detectors 83 and 84 , and controller 100 . An electric motor driving device 50 is configured by the power conversion device 2 and the electric motor 7 included in the compressor 8 .

The converter 10 has four diodes D1, D2, D3 and D4. Four diodes D1 to D4 are bridge-connected to form a rectifier circuit. Converter 10 rectifies the power supply voltage applied from AC power supply 1 by means of a rectifier circuit composed of four diodes D1 to D4. In converter 10 , one end on the input side is connected to AC power supply 1 via reactor 4 , and the other end on the input side is connected to AC power supply 1 . Also, in the converter 10 , the output side is connected to the capacitor 20 . Note that the reactor 4 may be connected between the converter 10 and the capacitor 20 , that is, connected to the output side of the converter 10 .

The converter 10 may have a rectifying function as well as a boosting function for boosting the rectified voltage. A converter having a boosting function can be configured with one or more transistor elements or one or more switching elements in which a transistor element and a diode are connected in anti-parallel in addition to or instead of a diode. Note that the arrangement and connection of transistor elements or switching elements in a converter having a boosting function are well known, and description thereof will be omitted here.

The capacitor 20 is connected to the output end of the converter 10 via DC buses 22a and 22b. The DC bus 22a is a positive side DC bus, and the DC bus 22b is a negative side DC bus. Capacitor 20 smoothes the rectified voltage applied from converter 10 . Examples of the capacitor 20 include an electrolytic capacitor, a film capacitor, and the like.

The inverter 30 is connected to the output end of the converter 10 via DC buses 22a and 22b, and is connected to both ends of the capacitor 20. The inverter 30 converts the DC voltage smoothed by the capacitor 20 into AC voltage for the compressor 8 and applies it to the electric motor 7 of the compressor 8 . The voltage applied to the electric motor 7 is a three-phase AC voltage with variable frequency and voltage value.

The inverter 30 includes an inverter main circuit 310 and a drive circuit 350, as shown in FIG. The inverter main circuit 310 includes switching elements 311-316. Freewheeling rectifying elements 321 to 326 are connected in anti-parallel to the switching elements 311 to 316, respectively.

In the inverter main circuit 310, the switching elements 311 to 316 are assumed to be IGBTs (Insulated Gate Bipolar Transistors), MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), etc., but elements capable of switching If so, you can use whatever you want. When the switching elements 311 to 316 are MOSFETs, the MOSFETs have parasitic diodes due to their structure, so that the same effect can be obtained without connecting the freewheeling rectifying elements 321 to 326 in anti-parallel.

Also, as materials for forming the switching elements 311 to 316, not only silicon (Si) but also wide bandgap semiconductors such as silicon carbide (SiC), gallium nitride (GaN), and diamond may be used. By forming switching elements 311 to 316 using a wide bandgap semiconductor, loss can be further reduced.

The drive circuit 350 generates drive signals Sr1-Sr6 based on PWM (Pulse Width Modulation) signals Sm1-Sm6 output from the control device 100. FIG. The drive circuit 350 controls on/off of the switching elements 311-316 by the drive signals Sr1-Sr6. As a result, the inverter 30 can apply the frequency-variable and voltage-variable three-phase AC voltage to the electric motor 7 via the output lines 331 to 333 .

The PWM signals Sm1 to Sm6 are signals having a signal level of a logic circuit, for example, a magnitude of 0V to 5V. The PWM signals Sm1 to Sm6 are signals having the ground potential of the control device 100 as a reference potential. On the other hand, the driving signals Sr1 to Sr6 are signals having voltage levels necessary to control the switching elements 311 to 316, eg, -15V to +15V. The drive signals Sr1 to Sr6 are signals having the potential of the negative terminal, that is, the emitter terminal of the corresponding switching element as a reference potential.

The voltage detection unit 82 detects the voltage across the capacitor 20 to detect the bus voltage Vdc. The bus voltage Vdc is the voltage between the DC buses 22a and 22b. The voltage detection unit 82 includes, for example, a voltage dividing circuit that divides the voltage with series-connected resistors. The voltage detection unit 82 converts the detected bus voltage Vdc into a voltage suitable for processing in the control device 100 using a voltage dividing circuit, for example, a voltage of 5 V or less, and outputs it to the control device 100 as a voltage detection signal that is an analog signal. output to The voltage detection signal output from the voltage detection unit 82 to the control device 100 is converted from an analog signal to a digital signal by an AD (Analog to Digital) conversion unit (not shown) in the control device 100, and is subjected to internal processing in the control device 100. Used.

The current detection unit 83 detects the power supply current Iin, which is the current flowing between the AC power supply 1 and the converter 10 . Current detection unit 83 outputs the detected power supply current Iin to control device 100 as a current detection signal, which is an analog signal. A current detection signal output from the current detection unit 83 to the control device 100 is converted from an analog signal to a digital signal by an AD conversion unit (not shown) in the control device 100 and used for internal processing in the control device 100 .

The current detector 84 has a shunt resistor inserted in the DC bus 22b. A current detector 84 detects the capacitor output current idc using a shunt resistor. A capacitor output current idc is an input current to the inverter 30 , that is, a current output from the capacitor 20 to the inverter 30 . The current detection unit 84 outputs the detected capacitor output current idc to the control device 100 as a current detection signal, which is an analog signal. A current detection signal output from the current detection unit 84 to the control device 100 is converted from an analog signal to a digital signal by an AD conversion unit (not shown) in the control device 100 and used for internal processing in the control device 100 .

The control device 100 controls the operation of the inverter 30 by generating the PWM signals Sm1 to Sm6 described above. Specifically, the control device 100 changes the angular frequency ωe and the voltage value of the output voltage of the inverter 30 based on the PWM signals Sm1 to Sm6.

The angular frequency ωe of the output voltage of the inverter 30 determines the rotational angular velocity of the electric motor 7 in electrical angle. In this paper, this rotational angular velocity is also represented by the same symbol ωe. The rotational angular velocity ωm of the electric motor 7 in the mechanical angle is equal to the rotational angular velocity ωe of the electric motor 7 in the electrical angle divided by the pole logarithm P. Therefore, there is a relationship represented by the following equation (1) between the rotational angular velocity ωm of the electric motor 7 in mechanical angle and the angular frequency ωe of the output voltage of the inverter 30 . In this paper, the rotational angular velocity is sometimes simply referred to as "rotational velocity", and the angular frequency is simply referred to as "frequency".

ωm = ωe/P … (1)

Next, the vibration suppression control in the electric motor drive device 50 and its necessity will be described with reference to FIGS. 3 and 4. FIG. FIG. 3 is a diagram showing an operation state of the electric motor drive device 50 according to Embodiment 1 when vibration suppression control is not performed. FIG. 4 is a diagram showing a state of operation when vibration suppression control is performed in electric motor drive device 50 according to the first embodiment.

When the application example of the electric motor drive device 50 is, for example, an air conditioner, control is performed so that the rotation speed fluctuation of the electric motor 7 is reduced in order to reduce the vibration of the compressor 8 . When the rotation speed fluctuation of the electric motor 7 becomes smaller, the vibration of the compressor 8 becomes smaller. For this reason, control for reducing rotation speed fluctuations is generally called "vibration suppression control."

3 and 4 show the load torque of the compressor 8, the output torque of the electric motor 7, the rotation speed of the electric motor 7, and the control device in one rotation of the mechanical angle of the electric motor 7 when the compressor 8 is a single rotary compressor. A relationship of torque current compensation values at 100 is shown. FIG. 3 shows a state in which the control device 100 controls the output torque of the electric motor 7 to be constant. On the other hand, FIG. 4 shows a state in which the control device 100 controls the torque current compensation value so that the output torque of the electric motor 7 matches the load torque of the compressor 8, thereby controlling the rotational speed to be constant.

As can be seen from FIG. 3 , when the control device 100 controls the output torque of the electric motor 7 to be constant, the rotational speed fluctuates due to the difference between the output torque of the electric motor 7 and the load torque of the compressor 8 . When the rotation speed fluctuates, the compressor 8 generates vibration, noise, and the like. If the variation in rotational speed becomes extremely large, the electric motor 7 may step out and stop.

Therefore, the control device 100 according to the first embodiment has a function of vibration suppression control for controlling the output torque of the electric motor 7 to match the load torque of the compressor 8 . Details of the vibration suppression control will be described later.

Next, the configuration of the control device 100 will be described. FIG. 5 is a block diagram showing a configuration example of the control device 100 included in the power conversion device 2 according to Embodiment 1. As shown in FIG. The control device 100 includes an operation control section 102 and an inverter control section 110 .

The operation control unit 102 receives command information Qe from the outside and generates a frequency command value ωe* based on this command information Qe. The frequency command value ωe* can be obtained by multiplying the rotational speed command value ωm*, which is the command value of the rotational speed of the electric motor 7, by the number of pole pairs P, as shown in the following equation (2).

ωe*=ωm*×P……(2)

When controlling an air conditioner as a refrigeration cycle-applied device, the control device 100 controls the operation of each part of the air conditioner based on the command information Qe. The command information Qe is, for example, a temperature detected by a temperature sensor (not shown), information indicating a set temperature instructed from a remote controller (not shown), operation mode selection information, operation start/end instruction information, and the like. be. The operation modes are, for example, heating, cooling, and dehumidification. Note that the operation control unit 102 may be outside the control device 100 . That is, the control device 100 may be configured to acquire the frequency command value ωe* from the outside.

Inverter control unit 110 includes current restoration unit 111, 3-phase 2-phase conversion unit 112, γ-axis current command value generation unit 113, voltage command value calculation unit 115, electrical phase calculation unit 116, 2-phase 3-phase A conversion unit 117 and a PWM signal generation unit 118 are provided.

The current restoration unit 111 restores the phase currents iu, iv, and iw flowing through the electric motor 7 based on the capacitor output current idc detected by the current detection unit 84 . The current restoration unit 111 samples the detected value of the capacitor output current idc detected by the current detection unit 84 at timing determined based on the PWM signals Sm1 to Sm6 generated by the PWM signal generation unit 118. The currents iu, iv, iw can be restored. Note that current detectors may be provided on the output lines 331 to 333 to directly detect the phase currents iu, iv, and iw and input them to the three-to-two-phase converter 112 . In this configuration, the current restoration section 111 is unnecessary.

The three-phase to two-phase conversion unit 112 converts the phase currents iu, iv, and iw restored by the current restoration unit 111 into the γ axis, which is the excitation current, using the electric phase θe generated by the electric phase calculation unit 116, which will be described later. The current iγ and the δ-axis current iδ, which is the torque current, are converted into γ-δ axis current values.

A γ-axis current command value generation unit 113 generates a γ-axis current command value iγ*, which is an exciting current command value, based on the δ-axis current iδ. More specifically, the γ-axis current command value generation unit 113 obtains the current phase angle at which the output torque of the electric motor 7 is equal to or higher than the set value or the maximum value based on the δ-axis current iδ, and the calculated current phase angle is Based on this, the γ-axis current command value iγ* is calculated. Note that the motor current flowing through the electric motor 7 may be used instead of the output torque of the electric motor 7 . In this case, the γ-axis current command value iγ* is calculated based on the current phase angle at which the motor current flowing through the motor 7 is the set value or less or the minimum value.

In addition, although FIG. 5 shows a configuration in which the γ-axis current command value iγ* is obtained based on the δ-axis current iδ, it is not limited to this configuration. The γ-axis current command value iγ* may be obtained based on the γ-axis current iγ instead of the δ-axis current iδ. Further, the γ-axis current command value generator 113 may determine the γ-axis current command value iγ* by flux-weakening control.

The voltage command value calculation unit 115 calculates the frequency command value ωe* obtained from the operation control unit 102, the power supply current Iin obtained from the current detection unit 83, and the γ-axis currents iγ and δ obtained from the three-to-two phase conversion unit 112. A γ-axis voltage command value Vγ* and a δ-axis voltage command value Vδ* are generated based on the axis current iδ and the γ-axis current command value iγ* acquired from the γ-axis current command value generation unit 113 . Furthermore, the voltage command value calculator 115 estimates the frequency estimation value ωest based on the γ-axis voltage command value Vγ*, the δ-axis voltage command value Vδ*, the γ-axis current iγ, and the δ-axis current iδ. .

The electrical phase calculator 116 calculates the electrical phase θe by integrating the frequency estimation value ωest acquired from the voltage command value calculator 115 .

The two-to-three phase conversion unit 117 converts the γ-axis voltage command value Vγ* and the δ-axis voltage command value Vδ* acquired from the voltage command value calculation unit 115, that is, the voltage command values in the two-phase coordinate system, to the electric phase calculation unit 116. are converted into three-phase voltage command values Vu*, Vv*, Vw*, which are output voltage command values in a three-phase coordinate system, using the electric phase θe obtained from .

The PWM signal generator 118 compares the three-phase voltage command values Vu*, Vv*, Vw* acquired from the two-to-three-phase converter 117 with the bus voltage Vdc detected by the voltage detector 82. PWM signals Sm1 to Sm6 are generated. The PWM signal generator 118 can also stop the electric motor 7 by not outputting the PWM signals Sm1 to Sm6.

Next, I will explain why the problem of the present application arises. 6 and 7 are first and second diagrams, respectively, for explaining the problem of the present application. The problem of the present application was briefly described in the section [Problems to be Solved by the Invention], but a more detailed description will be added here.

First, when the load is a load with torque pulsation, such as a single rotary compressor, a scroll compressor, or a twin rotary compressor, the aforementioned vibration suppression control is performed. In general vibration suppression control, the inverter 30 is controlled by generating a torque current compensation value so that the output torque of the electric motor 7 follows the torque pulsation of the compressor 8 . However, if this control is simply performed, as explained in the section [Problems to be Solved by the Invention], the power supply current Iin becomes unbalanced between the positive and negative polarities of the power supply current Iin. A problem arises in that the harmonic components of are increased.

6 and 7 show the waveforms of the power supply voltage Vin, the power supply current Iin, and the capacitor output current idc in order from the top. The horizontal axes in FIGS. 6 and 7 represent time.

In the middle part of FIG. 6, the peak value of the positive side waveform and the peak value of the negative side waveform of the power supply current Iin are different, that is, the peak value is unbalanced between the positive and negative polarities of the power supply current Iin. It is shown. When such imbalance occurs, pulsation occurs in the capacitor output current idc as shown in the lower part. As a result, the power supply current Iin contains many harmonic components.

The inventors of the present application have found that the pulsation of the capacitor output current idc increases as the load torque increases and the inertia of the load decreases. It is Also, the inventors of the present application have found that the pulsation of the capacitor output current idc is greater in the single rotary compressor than in the twin rotary compressor and the scroll compressor.

Also, the lower part of FIG. 7 shows an ideal state in which the capacitor output current idc is constant. In such an ideal state, as shown in the middle part of FIG. 7, the peak value of the positive waveform of the power supply current Iin and the peak value of the negative waveform of the power supply current Iin are equal. imbalance does not occur. Therefore, the harmonic components that can be included in the power supply current Iin are much smaller than in the case of FIG.

As described above, the harmonic components that can be included in the power supply current Iin are related to the pulsation of the capacitor output current idc. Therefore, voltage command value calculation unit 115 included in control device 100 according to the first embodiment performs control to reduce harmonic components that may be included in power supply current Iin when vibration suppression control is performed.

FIG. 8 is a block diagram showing a configuration example of voltage command value calculation section 115 included in control device 100 according to the first embodiment. As shown in FIG. 8, voltage command value calculation unit 115 includes frequency estimation unit 501, subtraction units 502, 509, and 510, speed control unit 503, vibration suppression control unit 800, and vibration suppression control limiting unit 506. , a γ-axis current control unit 511 and a δ-axis current control unit 512 .

Frequency estimator 501 estimates the frequency of the voltage applied to electric motor 7 based on γ-axis current iγ, δ-axis current iδ, γ-axis voltage command value Vγ*, and δ-axis voltage command value Vδ*. and outputs the estimated frequency as the frequency estimation value ωest.

The subtraction unit 502 calculates the difference (ωe*−ωest) between the frequency command value ωe* and the frequency estimation value ωest estimated by the frequency estimation unit 501 .

A speed control unit 503 generates a δ-axis current command value iδ*, which is a torque current command value in a rotating coordinate system. More specifically, the speed control unit 503 performs proportional integral calculation, that is, PI (Proportional Integral) control, on the difference (ωe*−ωest) calculated by the subtraction unit 502 to obtain the difference (ωe*− .omega.est) close to zero is calculated.

The vibration suppression control unit 800 suppresses the vibration of the compressor 8 as a load based on the δ-axis current command value iδ* obtained from the speed control unit 503 and the frequency estimated value ωest obtained from the frequency estimation unit 501. Vibration suppression control is performed. To realize this function, the vibration suppression control section 800 includes a δ-axis current command value generation section 504 and a compensation value calculation section 505 .

A compensation value calculation unit 505 generates a δ-axis current compensation value iδ_trq*, which is a compensation value for vibration suppression control, based on the estimated frequency value ωest. Specifically, the compensation value calculation unit 505 generates the δ-axis current compensation value iδ_trq* so that the output torque of the electric motor 7 follows the periodic variation of the load torque of the compressor 8 . The δ-axis current compensation value iδ_trq* is a control amount component for suppressing the pulsation component of the frequency estimation value ωest, particularly the pulsation component with the frequency ωmn. Here, "the pulsating component of the estimated frequency value ωest, particularly the pulsating component having a frequency of ωmn" means the pulsating component of the DC quantity, which is a value representing the estimated frequency value ωest, particularly the pulsating component having a pulsating frequency of ωmn. do. Note that m is a parameter related to the amount of direct current, and n is a parameter that indicates the compressor 8 that is the load driven by the electric motor 7 . For example, n is 1 when the compressor 8 is a single rotary compressor, and 2 when it is a twin rotary compressor. This n may be 3 or more. In addition, in this paper, the δ-axis current compensation value iδ_trq* may be called a “torque current compensation value” or simply a “compensation value”.

Vibration suppression control limiter 506 limits the δ-axis current based on γ-axis current iγ, δ-axis current iδ, γ-axis voltage command value Vγ*, δ-axis voltage command value Vδ*, and power supply current Iin. Generate the value iδ_trq*_lim. The δ-axis current limit value iδ_trq*_lim is a control amount component for limiting the δ-axis current compensation value iδ_trq*, and is generated so as to reduce harmonic components contained in the power supply current Iin. That is, the vibration suppression control limiting unit 506 performs control to limit the δ-axis current compensation value iδ_trq* so as to reduce the harmonic components contained in the power supply current Iin. In this paper, the δ-axis current limit value iδ_trq*_lim is sometimes called a "torque current limit value" or simply a "limit value".

A δ-axis current command value generation unit 504 generates a δ-axis current command value iδ** based on the δ-axis current command value iδ*, the δ-axis current compensation value iδ_trq*, and the δ-axis current limit value iδ_trq*_lim. Generate. The δ-axis current command value iδ** is a torque current command value obtained by limiting the δ-axis current command value iδ* compensated by the δ-axis current compensation value iδ_trq* using iδ_trq*_lim. In this paper, when distinguishing between the δ-axis current command value iδ* and the δ-axis current command value iδ** without a sign, the δ-axis current command value iδ* is referred to as the “first δ-axis current command value”. , and the .delta.-axis current command value i.delta.** is called a "second .delta.-axis current command value."

A subtraction unit 509 calculates the difference (iγ*-iγ) of the γ-axis current iγ with respect to the γ-axis current command value iγ*. Subtraction unit 510 calculates a difference (iδ**-iδ) between δ-axis current command value iδ** and δ-axis current iδ.

The γ-axis current control unit 511 performs a proportional integral operation on the difference (iγ*−iγ) calculated by the subtraction unit 509 to bring the difference (iγ*−iγ) closer to zero. to generate The γ-axis current control unit 511 generates such a γ-axis voltage command value Vγ* to perform control so that the γ-axis current iγ matches the γ-axis current command value iγ*.

A δ-axis current control unit 512 performs a proportional integral operation on the difference (iδ**-iδ) calculated by the subtraction unit 510 to obtain a δ-axis voltage command value that brings the difference (iδ**-iδ) closer to zero. Generate Vδ*. The δ-axis current control unit 512 generates such a δ-axis voltage command value Vδ* to perform control so that the δ-axis current iδ matches the δ-axis current command value iδ**. As described above, the δ-axis current command value iδ** input to the δ-axis current control unit 512 includes the δ-axis current compensation value iδ_trq* acquired from the compensation value calculation unit 505 . Therefore, the δ-axis current control unit 512 controls the inverter 30 based on the δ-axis voltage command value Vδ* generated based on the δ-axis current compensation value iδ_trq*, thereby suppressing the pulsation of the capacitor output current idc. can be done.

Next, the configuration of compensation value calculation section 505 will be described. FIG. 9 is a block diagram showing a configuration example of compensation value calculation section 505 included in voltage command value calculation section 115 according to the first embodiment. The compensation value calculator 505 includes a calculator 550, a cosine calculator 551, a sine calculator 552, multipliers 553 and 554, low- pass filters 555 and 556, subtractors 557 and 558, a frequency controller 559, 560 , multipliers 561 and 562 , and an adder 563 .

The calculation unit 550 integrates the estimated frequency value ωest and divides it by the pole logarithm P to calculate the mechanical angle phase θmn indicating the rotational position of the electric motor 7 . A cosine calculator 551 calculates a cosine value cos θmn based on the mechanical angle phase θmn. The sine calculator 552 calculates a sine value sin θmn based on the mechanical angle phase θmn.

The multiplier 553 multiplies the frequency estimation value ωest by the cosine value cos θmn to calculate the cosine component ωest·cos θmn of the frequency estimation value ωest. The multiplier 554 multiplies the frequency estimation value ωest by the sine value sinθmn to calculate the sine component ωest·sinθmn of the frequency estimation value ωest. The cosine component ωest·cos θmn and the sine component ωest·sin θmn calculated by the multipliers 553 and 554 include a pulsation component with a frequency of ωmn and a pulsation component with a frequency higher than ωmn, that is, a harmonic component. ing.

The low- pass filters 555 and 556 are first-order lag filters whose transfer function is represented by 1/(1+s·Tf). where s is the Laplacian operator. Tf is a time constant, and is determined to remove pulsation components with frequencies higher than the frequency ωmn. Note that "removal" includes the case where part of the pulsation component is attenuated, that is, reduced. The time constant Tf is set by the operation control unit 102 based on the speed command value, and may be notified to the low- pass filters 555 and 556 by the operation control unit 102, or may be held by the low- pass filters 555 and 556. . As for the low- pass filters 555 and 556, a first-order lag filter is an example, and a moving average filter or the like may be used, and the type of filter is not limited as long as the pulsation component on the high frequency side can be removed.

A low-pass filter 555 performs low-pass filtering on the cosine component ωest·cos θmn, removes pulsation components with a frequency higher than the frequency ωmn, and outputs a low-frequency component ωest_c. The low-frequency component ωest_c is a DC quantity representing a cosine component with a frequency of ωmn among the pulsating components of the estimated frequency value ωest.

A low-pass filter 556 performs low-pass filtering on the sine component ωest·sin θmn, removes pulsation components with a frequency higher than the frequency ωmn, and outputs a low-frequency component ωest_s. The low-frequency component ωest_s is a DC quantity representing a sinusoidal component with a frequency ωmn among the pulsating components of the frequency estimation value ωest.

The subtraction unit 557 calculates the difference (ωest_c−0) between the low frequency component ωest_c output from the low-pass filter 555 and zero. The subtraction unit 558 calculates the difference (ωest_s−0) between the low frequency component ωest_s output from the low-pass filter 556 and zero.

The frequency control unit 559 performs proportional integral calculation on the difference (ωest_c−0) calculated by the subtraction unit 557 to calculate the cosine component iδ_trq_c of the current command value that brings the difference (ωest_c−0) close to zero. By generating the cosine component iδ_trq_c in this manner, the frequency control unit 559 performs control to match the low frequency component ωest_c to zero.

The frequency control unit 560 performs proportional integral calculation on the difference (ωest_s−0) calculated by the subtraction unit 558 to calculate the sine component iδ_trq_s of the current command value that brings the difference (ωest_s−0) close to zero. The frequency control unit 560 generates the sine component iδ_trq_s in this way, thereby performing control to match the low frequency component ωest_s to zero.

The multiplier 561 multiplies the cosine component iδ_trq_c output from the frequency control unit 559 by the cosine value cos θmn to generate iδ_trq_c·cos θmn. iδ_trq_c·cos θmn is an AC component with frequency n·ωest.

The multiplier 562 multiplies the sine component iδ_trq_s output from the frequency control unit 560 by the sine value sinθmn to generate iδ_trq_s·sinθmn. iδ_trq_s·sin θmn is an AC component with frequency n·ωest.

The addition unit 563 obtains the sum of iδ_trq_c·cos θmn output from the multiplication unit 561 and iδ_trq_s·sin θmn output from the multiplication unit 562 . Compensation value calculator 505 outputs the value obtained by adder 563 as δ-axis current compensation value iδ_trq*.

Next, the configuration of the vibration suppression control limiter 506 will be described. FIG. 10 is a block diagram showing a first configuration example of vibration suppression control limiter 506 included in voltage command value calculator 115 according to the first embodiment. Vibration suppression control limiter 506 includes power harmonic standard value calculator 701 , order component calculator 702 , subtractor 703 , integrator 704 , and limit value calculator 705 .

Power supply harmonic standard value calculation unit 701 calculates power supply harmonic standard value Iin_lim_n based on γ-axis current iγ, δ-axis current iδ, γ-axis voltage command value Vγ*, and δ-axis voltage command value Vδ*. Calculate. The power harmonic standard value Iin_lim_n is a threshold for determining whether a specific frequency component satisfies the power harmonic standard.

Based on the power supply current Iin acquired from the current detection unit 83, the order component calculation unit 702 calculates the order component Iin_n, which is a harmonic component of a specific order included in the power supply current Iin. The order component Iin_n calculated by the order component calculation unit 702 is for comparison with the power harmonic standard value Iin_lim_n calculated by the power harmonic standard value calculation unit 701, and the order of each harmonic component is the same. .

The subtraction unit 703 calculates the difference (Iin_lim_n−Iin_n) between the power harmonic standard value Iin_lim_n output from the power harmonic standard value calculation unit 701 and the order component Iin_n output from the order component calculation unit 702.

The integrator 704 is a calculator whose transfer function is represented by K/s. s is the Laplacian operator and K is the multiplication factor. The integration unit 704 performs an integration operation on the difference (Iin_lim_n−Iin_n) output from the subtraction unit 703 . Note that the integral calculation here is an example, and a proportional integral calculation may be performed instead of the integral calculation. The integrated value Iin_k output from the integration section 704 is input to the limit value calculation section 705 .

FIG. 11 is a flowchart for explaining the operation of the limit value calculator 705 according to the first embodiment. The limit value calculator 705 receives the integrated value Iin_k from the integrator 704 (step S11). The limit value calculator 705 compares the integrated value Iin_k with 0 (step S12). If the integrated value Iin_k is less than 0 (step S12, Yes), the limit value calculator 705 sets the δ-axis current limit value iδ_trq*_lim as the integrated value Iin_k (step S13), and calculates the calculated δ-axis current limit value iδ_trq*. _lim is output (step S15). On the other hand, if the integrated value Iin_k is equal to or greater than 0 (step S12, No), the limit value calculator 705 sets the δ-axis current limit value iδ_trq*_lim to 0 (step S14), and the set δ-axis current limit value iδ_trq*_lim is output (step S15).

As described above, the vibration suppression control limiting unit 506 calculates the power harmonic standard value Iin_lim_n and the order component Iin_n, and determines the δ-axis current limit value iδ_trq by the amount that the power harmonic standard value Iin_lim_n exceeds the power harmonic standard value Iin_lim_n. Calculate *_lim. The vibration suppression control unit 800 uses the δ-axis current limit value iδ_trq*_lim to limit the δ-axis current compensation value iδ_trq* by the amount by which a specific order component Iin_n in the power source current Iin exceeds the power source harmonic standard value Iin_lim_n. . The vibration suppression control unit 800 performs vibration suppression control so that the δ-axis current compensation value iδ_trq*, which is the compensation value for the vibration suppression control, is limited by the calculated δ-axis current limit value iδ_trq*_lim. As a result, the vibration suppression control is performed so that the specific order component Iin_n in the power source current Iin conforms to the power source harmonic standard.

FIG. 10 shows a configuration example of the vibration suppression control limiter 506 in the case where the number of harmonic components to be reduced is one. be able to. FIG. 12 is a block diagram showing a second configuration example of vibration suppression control limiter 506 included in voltage command value calculator 115 according to the first embodiment. In FIG. 12, the same or equivalent components as those in FIG. 10 are denoted by the same reference numerals.

In FIG. 12, the first-stage power supply harmonic standard value calculation unit 701 calculates the , the power supply harmonic standard value Iin_lim_2 is calculated. The power supply harmonic standard value Iin_lim_2 is a power supply harmonic standard value for which the harmonic order is "2", that is, the secondary power harmonic standard value. Similarly, the second-stage power supply harmonic standard value calculation unit 701, based on the γ-axis current iγ, the δ-axis current iδ, the γ-axis voltage command value Vγ*, and the δ-axis voltage command value Vδ*, A power harmonic standard value Iin_lim_3 is calculated. The power harmonic standard value Iin_lim_3 is a power harmonic standard value for which the harmonic order is "3", ie, the third order.

Also, the first-stage order component calculation unit 702 calculates the order component Iin_2 based on the power supply current Iin. The order component Iin_2 is a secondary harmonic component contained in the power supply current Iin. Similarly, second-stage order component calculation section 702 calculates order component Iin_3 based on power supply current Iin. The order component Iin_3 is the third harmonic component contained in the power supply current Iin.

The subtraction unit 703 of the first stage calculates the difference (Iin_lim_2-Iin_2) between the power harmonic standard value Iin_lim_2 and the order component Iin_2. The difference (Iin_lim_2-Iin_2) is subjected to integration processing by the corresponding integration unit 704, and an integrated value Iin_k2 is output. The subtraction unit 703 in the second stage calculates the difference (Iin_lim_3−Iin_3) between the power harmonic standard value Iin_lim_3 and the order component Iin_3. The difference (Iin_lim_3-Iin_3) is subjected to integration processing by the corresponding integration unit 704, and an integrated value Iin_k3 is output. These integrated values Iin_k2 and Iin_k3 are added by the addition section 706 and output to the limit value calculation section 705 . The limit value calculator 705 performs processing according to the flowchart of FIG. 11 to generate and output the δ-axis current limit value iδ_trq*_lim described above.

Note that FIG. 12 exemplifies a case where the number of harmonic components to be reduced is two (secondary and tertiary). It is only necessary to increase the number and perform addition in the addition section 706 . Also, the number of adders 706 does not need to be the same as the number of stages, and any configuration may be used as long as the outputs of the respective integration sections 704 are added and input to the limit value calculator 705 . Moreover, the configurations of FIGS. 10 and 12 are examples, and the present invention is not limited to these examples. Any control system may be used as long as it operates such that the compensation value of the vibration suppression control is limited.

Next, the power supply harmonic standard value calculation unit 701 will be described. FIG. 13 is a block diagram showing a configuration example of power supply harmonic standard value calculation section 701 included in vibration suppression control limit section 506 according to the first embodiment. The power harmonic standard value calculator 701 includes a motor power calculator 751 , a current harmonic limit value calculator 752 , and a coefficient multiplier 753 .

First, the motor power calculator 751 calculates the motor power W using the following equation (3).

　W=Vγ*・iγ+Vδ*・iδ　...(3)

A current harmonic limit value calculation unit 752 calculates a current harmonic limit value based on the motor power W. The coefficient multiplier 753 multiplies the current harmonic limit value calculated by the current harmonic limit value calculation unit 752 by a coefficient K1 that determines how much margin is taken into account. The calculation result by the coefficient multiplier 753 is output as the above-described power supply harmonic standard value Iin_lim_n.

Next, a specific calculation example by the current harmonic limit value calculator 752 will be described. FIG. 14 is a diagram for explaining calculation processing of current harmonic limit value calculation section 752 included in power supply harmonic standard value calculation section 701 according to the first embodiment. FIG. 14 shows a table showing the procedure for calculating limit values applied to air conditioners exceeding 600 W specified in JIS_C_61000-3-2. Specifically, the left side of FIG. 14 shows the calculation formula for the maximum permissible harmonic current of odd-order harmonics from the 3rd to the 39th, and the maximum permissible harmonic current of the even-order harmonics from the 2nd to 40th. is shown. For example, the fifth-order maximum allowable harmonic current is obtained by substituting the motor power W calculated using the above formula (3) into the formula "1.14 + 0.00070 (W-600)" and calculating the current harmonic limit value. calculate. The numerical value "1.14" in the formula is converted using the conversion formula shown in the right frame based on the rated voltage of the equipment. As shown in the calculation example, "2.62" is used instead of "1.14" when the rated voltage is 100V, and "1.14" is used when the rated voltage is 200V. Use "1.31" instead of Also, when the rated voltage is 220V, 230V, and 240V, "1.14" is used as it is.

Note that FIG. 14 is an example, and the calculation of the current harmonic limit value is not limited to this example. Instead of the γ-axis voltage command value Vγ* and the δ-axis voltage command value Vδ*, the d-axis voltage command value Vd*, the q-axis voltage command value Vq*, the d-axis current id and the q-axis current iq are used for calculation. good too. In addition, an LPF (Low Pass Filter) is inserted between the motor power calculation unit 751 and the current harmonic limit value calculation unit 752 to remove harmonics contained in the calculated value of the motor power W, and then the above calculation is performed. you can go Further, in FIG. 14, harmonic components of the 2nd to 40th orders are calculated, but in addition to these harmonic components, harmonic components exceeding the 40th order may also be calculated.

Next, the order component calculation unit 702 will be described. FIG. 15 is a block diagram showing a configuration example of the order component calculator 702 provided in the vibration suppression control limiter 506 according to the first embodiment. The order component calculation section 702 includes a first calculation block 702-1 and a second calculation block 702-2.

The first computation block 702-1 computes an effective value Iin_x of order (n-1).5 to n.5 (where n is an integer equal to or greater than 2) based on the power supply current Iin. For example, when n=3, that is, the harmonic component of the third order, the harmonic components of the (n−1).5th to n.5th order are the 2.5th, 2.6th, . , . . . , 3.4th and 3.5th harmonic components. In the first operation block 702-1, the detected value of the power supply current Iin is multiplied by the cosine value cos θx and the sine value sin θx of the phase angle θx synchronized with the frequency of the harmonic component, and passed through a low-pass filter to obtain the quadrature component Iin_c, Iin_s is computed. Furthermore, the square root of the orthogonal components Iin_c and Iin_s is calculated, and by multiplying by 1/√2, the effective value Iin_x of the order (n−1).5 to n.5 is calculated.

In the second operation block 702-2, each effective value Iin_x of the (n-1).5th to n.5th order is squared, and the square root of the sum of the squared values is calculated. , the order component Iin_n is calculated. In the addition process, the (n-1).5 order and n.5 order components located at both ends of the 11 harmonic components are multiplied by 1/2 because they overlap between adjacent orders. is added from

Note that the calculation example in FIG. 15 is just an example, and the calculation of the order component Iin_n is not limited to this example. The calculation may be performed by further dividing the harmonic components of each order. Further, similar to the calculation of the current harmonic limit value, calculation of harmonic components exceeding the 40th order may be performed.

Next, the speed control unit 503 and the δ-axis current command value generation unit 504 will be explained. FIG. 16 is a block diagram showing a configuration example of speed control section 503 and δ-axis current command value generation section 504 included in voltage command value calculation section 115 according to the first embodiment. Note that FIG. 16 also includes the preceding subtraction unit 502 .

The speed control unit 503 generates the δ-axis current command value iδ* in the rotating coordinate system described above. Specifically, speed control section 503 includes proportional control section 611 , integral control section 612 , and addition section 613 . The proportional control unit 611 performs proportional control on the difference (ωe*−ωest) between the frequency command value ωe* and the frequency estimated value ωest obtained from the subtraction unit 502, and outputs a proportional term iδ_p*. The integral control unit 612 performs integral control on the difference (ωe*−ωest) between the frequency command value ωe* and the frequency estimated value ωest obtained from the subtraction unit 502, and outputs an integral term iδ_i*. The addition unit 613 adds the proportional term iδ_p* obtained from the proportional control unit 611 and the integral term iδ_i* obtained from the integral control unit 612 to generate the δ-axis current command value iδ*.

In addition, the δ-axis current command value generating section 504 includes a limiting section 504a and a vibration suppressing section 504b.

The restriction unit 504a includes a storage unit 631, a selection unit 632, and a limiter 633. The storage unit 631 stores limiter values iδ_lim1 and iδ_lim2. That is, the limiter 504a has limiter values iδ_lim1 and iδ_lim2. The selection unit 632 selects one of the limiter values iδ_lim1 and iδ_lim2 stored in the storage unit 631 and sets it as the limiter value iδ_lim. The limiter 633 limits the δ-axis current command value iδ* generated by the speed control unit 503 with the limiter value iδ_lim and outputs the δ-axis current command value iδ_lim*.

The limiter value iδ_lim1 is based on the assumption that the current value of the electric motor 7 is limited when the rotation speed of the electric motor 7 is in the low speed range. This limiter value iδ_lim1 can be defined based on the current limit value for the phase current of the electric motor 7 and the γ-axis current iγ. Also, the limiter value iδ_lim2 is based on the assumption that the limit is applied based on the voltage value of the electric motor 7 when the rotation speed of the electric motor 7 is in the middle to high speed range. The limiter value iδ_lim2 can be defined based on the limit value of the γδ-axis voltage, the γ-axis and δ-axis inductances of the rotating coordinate system, the γ-axis current iγ, the γδ-axis magnetic flux linkage of the motor 7, and the angular frequency ωe.

The calculation formulas for the limiter values iδ_lim1 and iδ_lim2 are well known, and further explanation is omitted here. Further, the limiting unit 504a may store the limiter values iδ_lim1 and iδ_lim2 calculated by itself in the storage unit 631, or acquire them from the outside, for example, the operation control unit 102, and store them in the storage unit 631. may be stored.

The vibration suppression unit 504b uses the δ-axis current command value iδ_lim*, the limiter value iδ_lim, the δ-axis current limit value iδ_trq*_lim, and the δ-axis current compensation value iδ_trq* to generate the δ-axis current command value iδ**. Specifically, the vibration suppressing section 504 b includes a subtracting section 641 , adding sections 642 and 644 and a limiter 643 .

The subtracting unit 641 calculates the difference between the limiter value iδ_lim obtained from the limiting unit 504a and the δ-axis current command value iδ_lim*, and calculates the first limiter value iδ_trq_lim1 for the δ-axis current compensation value iδ_trq*. The adder 642 adds the first limiter value iδ_trq_lim1 and the δ-axis current limit value iδ_trq*_lim to generate a second limiter value iδ_trq_lim2.

The limiter 643 limits the δ-axis current compensation value iδ_trq* with the second limiter value iδ_trq_lim2 and outputs it as the δ-axis current compensation value iδ_trq*_lim* after the limiter. The adder 644 adds the δ-axis current command value iδ_lim* and the δ-axis current compensation value iδ_trq*_lim* after the limiter to generate the δ-axis current command value Iδ**.

In the example shown in FIG. 16, the δ-axis current command value generating section 504 has a limiting section 504a at the front end and a vibration suppressing section 504b at the rear stage. As a result, the δ-axis current command value generator 504 can secure a δ-axis current command that can follow the speed command, and can use the surplus as a δ-axis current command for vibration suppression control. Further, while limiting the δ-axis current command so as to comply with the power supply harmonic standard, the surplus can be used as the δ-axis current command for vibration suppression control.

FIG. 17 is a flow chart for explaining the operations of the speed control unit 503 and the limiting unit 504a according to the first embodiment. The speed control unit 503 generates a δ-axis current command value iδ* from the difference (ωe*−ωest) between the frequency command value ωe* and the frequency estimated value ωest (step S21). If the limiter value iδ_lim is smaller than the δ-axis current command value iδ* (step S22, No), the limiting unit 504a reduces the integral term iδ_i* of the integral control unit 612 (step S23). Specifically, the limiter 633 of the limiting unit 504a instructs the integral control unit 612 of the speed control unit 503 to set "iδ_i*=iδ_lim−iδ_p*", that is, set the value of the integral term iδ_i* to iδ_lim−iδ_p*. . On the other hand, when the limiter value iδ_lim is equal to or greater than the δ-axis current command value iδ* (step S22: Yes), the limiter 633 of the limiter 504a does not instruct the integral control unit 612, and the speed control unit 503 outputs The δ-axis current command value iδ* is output as the δ-axis current command value iδ_lim* after the limiter (step S24).

FIG. 18 is a diagram for explaining the action of vibration suppression control limiter 506 included in voltage command value calculator 115 according to the first embodiment. Specifically, FIG. 18 shows, from the top, the rotation speed ωm of the electric motor 7, the power supply current Iin, the secondary frequency Iin_2f and the quaternary frequency Iin_4f of the power supply current Iin, the integral term iδ_i* of the integral control unit 612, and the waveform of the δ-axis current command value iδ**. The horizontal axis of FIG. 18 represents time. In the middle part of FIG. 18, the level of the 4th order standard value of power source harmonics is set to the reference value, that is, "1", and the 2nd order value of power source harmonics is indicated by multiples of the 4th order standard value. Also, the secondary frequency Iin_2f and the quaternary frequency Iin_4f of the power supply current Iin are indicated by a solid line and a dashed line, respectively.

In the waveform of FIG. 18, regarding the vibration suppression control by the vibration suppression control unit 800, only the compensation value calculation unit 505 is activated immediately after activation, and both the compensation value calculation unit 505 and the vibration suppression control limit unit 506 are activated about seven seconds after activation. I am working. Regarding the control of the vibration suppression control limiter 506, in the waveform of FIG. 18, the control target is the second harmonic component.

The torque pulsation of the electric motor 7 is suppressed as shown in the upper part of FIG. 18 from immediately after startup until the vibration suppression control is limited. On the other hand, the secondary frequency Iin_2f and the quaternary frequency Iin_4f of the power supply current Iin no longer satisfy the secondary standard value and the quaternary standard value, respectively, during the period immediately before the vibration suppression control is limited.

On the other hand, when the vibration suppression control limitation is started, both the secondary and the quaternary integral control work at first. The following integral control is suppressed, and the integral control works only for the fourth order. As a result, the secondary frequency Iin_2f falls below the secondary standard value.

Note that in the example of FIG. 18, the fourth order frequency Iin_4f slightly exceeds the fourth order standard value. In such a case, the control target of the vibration suppression control limiter 506 may include the fourth harmonic component. The configuration of the vibration suppression control limiter 506 targeting a plurality of harmonic components is as shown in FIG.

Next, a modification of the vibration suppression control limiter 506 according to Embodiment 1 will be described. FIG. 19 is a block diagram showing a configuration example of the vibration suppression control limiter 506A according to the modification of the first embodiment. The vibration suppression control limiter 506A includes a power harmonic standard value calculator 701A, a subtractor 703, an integrator 704, a limit value calculator 705, and a mechanical angle frequency component extractor 708. The same reference numerals are assigned to the same or equivalent components as the vibration suppression control limiter 506 shown in FIG. 10 .

The mechanical angular frequency component extraction unit 708 extracts the mechanical 1f component idc_m1f included in the capacitor output current idc based on the capacitor output current idc acquired from the current detection unit 84 and outputs it to the subtraction unit 703 . The "machine 1f component" is one times the mechanical angular frequency of the electric motor 7, that is, a mechanical angular frequency component. When the load of the electric motor 7 is, for example, a single rotary compressor, the mechanical 1f component is the most dominant frequency component among the pulsation components contained in the capacitor output current idc.

The power harmonic standard value calculation unit 701 A calculates the power harmonic standard value idc_m1f_lim and outputs it to the subtraction unit 703 . The power harmonic standard value idc_m1f_lim calculated by the power harmonic standard value calculator 701A is a threshold for comparison with the machine 1f component idc_m1f calculated by the mechanical angular frequency component extractor 708 .

Based on the γ-axis current iγ, the δ-axis current iδ, the γ-axis voltage command value Vγ*, and the δ-axis voltage command value Vδ*, the power supply harmonic standard value calculation unit 701 shown in FIGS. The power supply harmonic standard value Iin_lim_n was calculated. On the other hand, the power harmonic standard value calculation unit 701A illustrated in FIG. 19 generates the power harmonic standard value idc_m1f_lim without using a specific input signal. Any method may be used to generate the power harmonic standard value idc_m1f_lim. As an example, for various loads of the electric motor 7, data of the capacitor output current idc when driving the load is experimentally obtained, and the values obtained by analyzing the data are stored in a table. It is possible to keep Data held in the table may be stored in the memory 202, which will be described later.

FIG. 20 is a block diagram showing a configuration example of the mechanical angular frequency component extraction section 708 included in the vibration suppression control limiting section 506A according to the modification of the first embodiment. As described above, the mechanical angular frequency component extraction unit 708 extracts the mechanical 1f component idc_m1f included in the capacitor output current idc based on the capacitor output current idc. In the mechanical angular frequency component extraction unit 708 shown in FIG. 20, the detected value of the capacitor output current idc is multiplied by the cosine value cos θm1f and the sine value sin θm1f of the phase angle θm1f synchronized with the frequency of the mechanical 1f component, and passed through a low-pass filter. Orthogonal components idc_c and idc_s are calculated. Further, the machine 1f component idc_m1f is calculated by doubling the square root of the orthogonal components idc_c and idc_s.

The processing of the mechanical angular frequency component extraction unit 708 in FIG. 20 will be supplemented. Since the capacitor output current idc is a DC current, the method of extracting by multiplying the cosine value cos θm1f and the sine value sin θm1f results in a value half the actual value. Therefore, this value is doubled with respect to the square root of the orthogonal components idc_c and idc_s. In this way, the intended machine 1f component idc_m1f is extracted.

Although the mechanical angular frequency component extraction unit 708 in FIGS. 19 and 20 extracts the mechanical 1f component idc_m1f included in the capacitor output current idc, it is not limited to this. The mechanical angular frequency component extracting unit 708 may extract a mechanical 2f component that is twice the mechanical angular frequency of the electric motor 7 in addition to the mechanical 1f component idc_m1f. By extracting the mechanical 2f component, there is a margin for suppressing harmonic components contained in the power supply current Iin, and the margin can be used for the δ-axis current command for vibration suppression control.

Next, the influence of the inductance value of the reactor 4 and the capacitance value of the capacitor 20 on power source harmonics will be described. FIG. 21 is a diagram for explaining the influence of the inductance value of the reactor 4 and the capacitance value of the capacitor 20 included in the power converter 2 according to Embodiment 1 on power source harmonics. The upper part of FIG. 21 shows a waveform example of the power supply current Iin when the inductance value L=L ₀ and the capacitance value C=C ₀ . When the values of L ₀ and C ₀ are used as references, L=2L ₀ and C=C ₀ are shown in the middle part of FIG. An example waveform is shown. The lower part of FIG. 21 shows an example of the waveform of the power supply current Iin when L=L ₀ and C=3C ₀ , that is, when the capacitance value C is three times the reference value.

In the waveform in the middle part of FIG. 21, the part indicated by the ellipse has a smaller amplitude than the same part in the waveform in the upper part. Therefore, it can be seen that increasing the inductance value L of the reactor 4 reduces the harmonics contained in the power supply current Iin. Similarly, in the lower waveform of FIG. 21, the elliptical portion has a smaller amplitude than the same portion of the upper waveform. Therefore, it can be seen that increasing the capacitance value C of the capacitor 20 reduces the harmonics contained in the power supply current Iin.

As described above, the magnitude of harmonic components contained in the power supply current Iin is related to the inductance value L of the reactor 4 and the capacitance value C of the capacitor 20 . As described above, the power harmonic standard value calculation unit 701A generates the power harmonic standard value idc_m1f_lim without using a specific input signal. Therefore, when generating the power supply harmonic standard value idc_m1f_lim, it is preferable to consider the effects of these inductance value L and capacitance value C.

Further, the relationship between the harmonic component, the inductance value L, and the capacitance value C can be used to confirm whether or not the δ-axis current limit value iδ_trq*_lim generated by the vibration suppression control limiting unit 506 contributes to vibration suppression control. can be done. For example, when at least one of the inductance value L and the capacitance value C is increased, the δ-axis current limit value iδ_trq*_lim is lower than before at least one of the L and C values is increased. If it is smaller, it can be seen that the vibration suppression control limiter 506 is effectively acting on the vibration suppression control. Similarly, when at least one of the inductance value L and the capacitance value C is decreased, the δ-axis current limit value iδ_trq*_lim is large, it can be seen that the vibration suppression control limiter 506 is effectively acting on the vibration suppression control.

As described above, according to the power converter according to Embodiment 1, the vibration suppression control unit included in the control device performs vibration suppression control to suppress vibration of the load. Further, the vibration suppression control limiter included in the control device limits the compensation value of the vibration suppression control so that the harmonic component contained in the power supply current flowing between the AC power supply and the converter is reduced. This makes it possible to suppress an increase in harmonic components of the power supply current while compensating for torque ripple of the electric motor.

Further, according to the power converter according to Embodiment 1, the pulsation of the machine 1f component contained in the capacitor output current is reduced by limiting the compensation value of the vibration suppression control. This suppresses the unbalanced state between the positive and negative sides of the power supply current, thereby facilitating compliance with the power supply harmonic standard.

In addition, according to the power converter according to the first embodiment, the conformity to the power supply harmonic standard is automatically controlled by the control device. It is possible to obtain a motor drive device that is inexpensive, highly reliable, and has a small development load.

Furthermore, according to the power converter according to Embodiment 1, the reduction of power source harmonics also increases the power factor of the power source, so there is no need to flow wasteful current. As a result, the efficiency of the converter can be increased, and the current flowing through the inverter and the motor can be reduced, so that a highly efficient motor driving device can be obtained.

In addition, in the above control, the vibration suppression control limiter can generate a limit value for limiting the compensation value based on the harmonic component of the power supply current. Alternatively, the vibration suppression control limiter can generate a limit value for limiting the compensation value based on the mechanical angular frequency component of the capacitor output current.

In addition, the limit value in the above control is the power harmonic standard value, which is a threshold value for determining whether a specific frequency component satisfies the power harmonic standard, and the harmonic component calculated based on the power current. can be calculated based on the order components. Based on this limit value, the vibration suppression control section operates to limit the compensation value by the amount by which the order component exceeds the power supply harmonic standard value. As a result, the vibration suppression control section can limit the torque current command so as to comply with the power supply harmonic standard, and distribute the surplus torque current command to the torque current command for vibration suppression control.

The limit value in the above control is the power harmonic standard value, which is a threshold value for determining whether a specific frequency component satisfies the power harmonic standard, and the mechanical angle frequency extracted based on the capacitor output current. can be calculated based on the components Based on this limit value, the vibration suppression control section operates to limit the compensation value by the amount by which the mechanical angular frequency component exceeds the power supply harmonic standard value. As a result, the vibration suppression control section can limit the torque current command so as to comply with the power supply harmonic standard, and distribute the surplus torque current command to the torque current command for vibration suppression control.

Next, the hardware configuration of the control device 100 included in the power electronics device 2 will be described. FIG. 22 is a diagram showing an example of a hardware configuration that implements the control device 100 included in the power conversion device 2 according to Embodiment 1. As shown in FIG. The control device 100 is implemented by a processor 201 and memory 202 .

The processor 201 is a CPU (Central Processing Unit, central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, DSP (Digital Signal Processor)), or a system LSI (Large Scale Integration). The memory 202 may be RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM (registered trademark) (Electrically Erasable Programmable Read Only Memory), non-volatile or non-volatile memory such as can be exemplified. Also, the memory 202 is not limited to these, and may be a magnetic disk, an optical disk, a compact disk, a mini disk, or a DVD (Digital Versatile Disc).

Embodiment 2.
FIG. 23 is a diagram showing a configuration example of a refrigeration cycle equipment 900 according to Embodiment 2. As shown in FIG. A refrigerating cycle applied equipment 900 according to the second embodiment includes the power converter 2 described in the first embodiment. The refrigerating cycle applied equipment 900 according to Embodiment 2 can be applied to products equipped with a refrigerating cycle, such as air conditioners, refrigerators, freezers, and heat pump water heaters. In FIG. 23, constituent elements having functions similar to those of the first embodiment are denoted by the same reference numerals as those of the first embodiment.

A refrigerating cycle application device 900 includes a compressor 901 incorporating the electric motor 7 according to Embodiment 1, a four-way valve 902, an indoor heat exchanger 906, an expansion valve 908, and an outdoor heat exchanger 910 with a refrigerant pipe 912. attached through

A compression mechanism 904 for compressing refrigerant and an electric motor 7 for operating the compression mechanism 904 are provided inside the compressor 901 .

The refrigeration cycle applied equipment 900 can perform heating operation or cooling operation by switching operation of the four-way valve 902 . Compression mechanism 904 is driven by electric motor 7 whose speed is controlled.

During heating operation, as indicated by solid line arrows, the refrigerant is pressurized by the compression mechanism 904 and sent out through the four-way valve 902, the indoor heat exchanger 906, the expansion valve 908, the outdoor heat exchanger 910, and the four-way valve 902. Return to compression mechanism 904 .

During cooling operation, as indicated by dashed arrows, the refrigerant is pressurized by the compression mechanism 904 and sent through the four-way valve 902, the outdoor heat exchanger 910, the expansion valve 908, the indoor heat exchanger 906, and the four-way valve 902. Return to compression mechanism 904 .

During heating operation, the indoor heat exchanger 906 acts as a condenser to release heat, and the outdoor heat exchanger 910 acts as an evaporator to absorb heat. During cooling operation, the outdoor heat exchanger 910 acts as a condenser to release heat, and the indoor heat exchanger 906 acts as an evaporator to absorb heat. The expansion valve 908 reduces the pressure of the refrigerant to expand it.

The configuration shown in the above embodiment is an example, and can be combined with another known technique, and part of the configuration can be omitted or changed without departing from the scope of the invention. It is possible.

1 AC power supply, 2 power converter, 4 reactor, 7 electric motor, 8 compressor, 10 converter, 20 capacitor, 22a, 22b DC bus, 30 inverter, 50 motor drive device, 82 voltage detector, 83, 84 current detector , 100 control device, 102 operation control unit, 110 inverter control unit, 111 current restoration unit, 112 three-phase to two-phase conversion unit, 113 γ-axis current command value generation unit, 115 voltage command value calculation unit, 116 electrical phase calculation unit, 117 2-phase 3-phase converter, 118 PWM signal generator, 201 processor, 202 memory, 310 inverter main circuit, 311 to 316 switching elements, 321 to 326 rectifying elements, 331 to 333 output lines, 350 drive circuit, 501 frequency estimation 502, 509, 510, 557, 558, 641, 703 Subtraction section 503 Speed control section 504 δ-axis current command value generation section 504a Limitation section 504b Vibration suppression section 505 Compensation value calculation section 506, 506A Vibration suppression control limit unit, 511 γ-axis current control unit, 512 δ-axis current control unit, 550 operation unit, 551 cosine operation unit, 552 sine operation unit, 553, 554, 561, 562 multiplication unit, 555, 556 low-pass filter, 559, 560 frequency control unit, 563, 613, 642, 644, 706 addition unit, 611 proportional control unit, 612 integral control unit, 631 storage unit, 632 selection unit, 633, 643 limiter, 701, 701A power supply harmonic standard value Operation unit 702 Order component operation unit 702-1 First operation block 702-2 Second operation block 704 Integration unit 705 Limit value operation unit 708 Mechanical angular frequency component extraction unit 751 Electric motor power operation unit , 752 current harmonic limit value calculation unit, 753 coefficient multiplication unit, 800 vibration suppression control unit, 900 refrigeration cycle application equipment, 901 compressor, 902 four-way valve, 904 compression mechanism, 906 indoor heat exchanger, 908 expansion valve, 910 Outdoor heat exchanger, 912 refrigerant pipes, D1, D2, D3, D4 diodes.

Claims (8)

1. A power conversion device that supplies AC power to a motor that drives a load,
   a converter that rectifies a power supply voltage applied from an AC power supply;
   a capacitor connected to the output terminal of the converter;
   an inverter connected across the capacitor;
   a control device that controls the operation of the inverter;
   with
   The control device is
   a vibration suppression control unit that performs vibration suppression control to suppress vibration of the load;
   a vibration suppression control limiter that limits a compensation value of the vibration suppression control so as to reduce harmonic components contained in a power supply current flowing between the AC power supply and the converter;
   A power conversion device comprising:
2. The power converter according to claim 1, wherein the vibration suppression control limiter generates a limit value for limiting the compensation value based on harmonic components of the power supply current.
3. The limit value is a power harmonic standard value that is a threshold value for determining whether a specific frequency component satisfies the power harmonic standard, and an order component of the harmonic component calculated based on the power current. is calculated based on
   The power converter according to claim 2, wherein the vibration suppression control section limits the compensation value by the amount by which the order component exceeds the power supply harmonic standard value using the limit value.
4. The power converter according to claim 1, wherein the vibration suppression control limiter generates a limit value for limiting the compensation value based on a mechanical angular frequency component of a capacitor output current output from the capacitor to the inverter. .
5. The limit value is a power harmonic standard value that is a threshold value for determining whether a specific frequency component satisfies the power harmonic standard, and the mechanical angle frequency component extracted based on the capacitor output current. calculated based on
   The power converter according to claim 4, wherein the vibration suppression control section limits the compensation value by the amount by which the mechanical angular frequency component exceeds the power supply harmonic standard value using the limit value.
6. A reactor is connected to the input side or the output side of the converter,
   When at least one of the inductance value of the reactor and the capacitance value of the capacitor is increased, the limit value becomes smaller than before increasing at least one of the inductance value and the capacitance value. 6. The power converter according to any one of items 2 to 5.
7. An electric motor drive device comprising the power conversion device according to any one of claims 1 to 6.
8. A refrigerating cycle application device comprising the power converter according to any one of claims 1 to 6.

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