WO2022149210A1 - Power conversion device, motor driving device, and refrigeration-cycle application device - Google Patents

Abstract

This power conversion device (1) comprises: a rectifying unit (130) for rectifying a first AC power supplied from a commercial power supply (110); a capacitor (210) connected to the output ends of the rectifying unit (130); an inverter (310) connected to both ends of the capacitor (210) and generating a second AC power which is output to a motor (314); a detection unit for detecting the power state of the capacitor (210); and a control unit (400) for controlling the operation of the inverter (310) so that a ripple corresponding to a detection value of the detection unit is superimposed on a drive pattern of the motor (314) and suppressing the charge/discharge current of the capacitor (210).

Description

Power converters, motor drives and refrigeration cycle applicable equipment

The present disclosure relates to a power conversion device, a motor drive device, and a refrigeration cycle applicable device for converting AC power into desired power.

Conventionally, there is a power conversion device that converts AC power supplied from an AC power source into desired AC power and supplies it to a load such as an air conditioner. For example, in Patent Document 1, a power conversion device, which is a control device for an air conditioner, rectifies AC power supplied from an AC power supply by a diode stack, which is a rectifying unit, and further smoothes a plurality of powers by a smoothing capacitor. There is disclosed a technique of converting the AC power into desired AC power by an inverter including a switching element of the above and outputting it to a compressor motor which is a load.

Japanese Unexamined Patent Publication No. 7-71805

However, according to the above-mentioned conventional technique, there is a problem that aged deterioration of the smoothing capacitor is accelerated because a large current flows through the smoothing capacitor. To solve this problem, it is conceivable to suppress the ripple change of the capacitor voltage by increasing the capacity of the smoothing capacitor, or to use a smoothing capacitor with a large deterioration tolerance due to ripple, but the cost of capacitor parts is high. In addition, the size of the device becomes large.

The present disclosure has been made in view of the above, and an object of the present disclosure is to obtain a power conversion device capable of suppressing the increase in size of the device while suppressing the deterioration of the smoothing capacitor.

In order to solve the above-mentioned problems and achieve the object, the power conversion device according to the present disclosure is connected to a rectifying unit that rectifies a first AC power supplied from a commercial power source and an output end of the rectifying unit. A capacitor, an inverter connected to both ends of the capacitor to generate a second AC power and output it to the motor, a detector that detects the power state of the capacitor, and a pulsation according to the detection value of the detector drives the motor. It is provided with a control unit that controls the operation of the inverter so as to be superimposed on the pattern and suppresses the charge / discharge current of the capacitor.

The power conversion device according to the present disclosure has the effect of suppressing the deterioration of the smoothing capacitor and suppressing the increase in size of the device.

The figure which shows the structural example of the power conversion apparatus which concerns on Embodiment 1. A block diagram showing a configuration example of a control unit included in the power conversion device according to the first embodiment. The figure which shows the structural example of the q-axis current pulsation calculation part of the control part provided in the power conversion apparatus which concerns on Embodiment 1. As a comparative example, a diagram showing an example of a drive waveform in a power conversion device having the same circuit configuration as the power conversion device of the first embodiment. The figure which shows the example of the drive waveform in the power conversion apparatus which concerns on Embodiment 1. A flowchart showing the operation of the control unit included in the power conversion device according to the first embodiment. The figure which shows an example of the hardware configuration which realizes the control part provided in the power conversion apparatus which concerns on Embodiment 1. The figure which shows the structural example of the power conversion apparatus which concerns on Embodiment 2. A block diagram showing a configuration example of a control unit included in the power conversion device according to the second embodiment. The figure which shows the structural example of the q-axis current pulsation calculation part of the control part provided in the power conversion apparatus which concerns on Embodiment 2. A flowchart showing the operation of the control unit included in the power conversion device according to the second embodiment. The figure which shows the structural example of the power conversion apparatus which concerns on Embodiment 3. A block diagram showing a configuration example of a control unit included in the power conversion device according to the third embodiment. The figure which shows the structural example of the q-axis current pulsation calculation part of the control part provided in the power conversion apparatus which concerns on Embodiment 3. A flowchart showing the operation of the control unit included in the power conversion device according to the third embodiment. A block diagram showing a configuration example of a control unit included in the power conversion device according to the fourth embodiment. A flowchart showing the operation of the control unit included in the power conversion device according to the fourth embodiment. The figure which shows the structural example of the refrigerating cycle application apparatus which concerns on Embodiment 5.

Hereinafter, the power conversion device, the motor drive device, and the refrigeration cycle applicable device according to the embodiment of the present disclosure will be described in detail with reference to the drawings.

Embodiment 1.
FIG. 1 is a diagram showing a configuration example of the power conversion device 1 according to the first embodiment. The power converter 1 is connected to the commercial power supply 110 and the compressor 315. The power conversion device 1 converts the first AC power of the power supply voltage Vs supplied from the commercial power supply 110 into the second AC power having a desired amplitude and phase, and supplies the first AC power to the compressor 315. The power conversion device 1 includes a reactor 120, a rectifying unit 130, a current detecting unit 501, a smoothing unit 200, an inverter 310, current detecting units 313a and 313b, and a control unit 400. The motor drive device 2 is composed of the power converter 1 and the motor 314 included in the compressor 315.

The reactor 120 is connected between the commercial power supply 110 and the rectifying unit 130. The rectifying unit 130 has a bridge circuit composed of rectifying elements 131 to 134, and rectifies and outputs the first AC power of the power supply voltage Vs supplied from the commercial power supply 110. The rectifying unit 130 performs full-wave rectification. The current detection unit 501 detects the current rectified by the rectifying unit 130 and flows into the smoothing unit 200 from the rectifying unit 130, that is, the input current to the smoothing unit 200, and outputs the detected current value to the control unit 400. The current detection unit 501 is a detection unit that detects the power state of the capacitor 210.

The smoothing unit 200 is connected to the output end of the rectifying unit 130. The smoothing unit 200 has a capacitor 210 as a smoothing element, and smoothes the electric power rectified by the rectifying unit 130. The capacitor 210 is, for example, an electrolytic capacitor, a film capacitor, or the like. The capacitor 210 is connected to the output end of the rectifying unit 130 and has a capacity for smoothing the power rectified by the rectifying unit 130, and the voltage generated in the capacitor 210 by the smoothing is full-wave rectification of the commercial power supply 110. It is not a waveform shape, but a waveform shape in which a voltage ripple corresponding to the frequency of the commercial power supply 110 is superimposed on a DC component, and does not pulsate significantly. The frequency of this voltage ripple is twice the frequency of the power supply voltage Vs when the commercial power supply 110 is single-phase, and is mainly composed of six times the frequency when the commercial power supply 110 is three-phase. When the power input from the commercial power supply 110 and the power output from the inverter 310 do not change, the amplitude of this voltage ripple is determined by the capacity of the capacitor 210. For example, the voltage ripple generated in the capacitor 210 is pulsating in a range where the maximum value is less than twice the minimum value.

The inverter 310 is connected to the smoothing portion 200, that is, both ends of the capacitor 210. The inverter 310 has switching elements 311a to 311f and freewheeling diodes 312a to 312f. The inverter 310 turns on and off the switching elements 311a to 311f under the control of the control unit 400, and converts the power output from the rectifying unit 130 and the smoothing unit 200 into a second AC power having a desired amplitude and phase, that is, a second AC power. AC power is generated and output to the compressor 315. The current detection units 313a and 313b each detect the current value of one of the three-phase currents output from the inverter 310, and output the detected current value to the control unit 400. The control unit 400 can calculate the current value of the remaining one phase output from the inverter 310 by acquiring the current value of two phases out of the current values of the three phases output from the inverter 310. .. The compressor 315 is a load having a motor 314 for driving the compressor. The motor 314 rotates according to the amplitude and phase of the second AC power supplied from the inverter 310, and performs a compression operation. For example, when the compressor 315 is a closed type compressor used in an air conditioner or the like, the load torque of the compressor 315 can often be regarded as a constant torque load. Regarding the motor 314, FIG. 1 shows a case where the motor winding is Y-connected, but this is an example and is not limited thereto. The motor winding of the motor 314 may have a Δ connection or a specification in which the Y connection and the Δ connection can be switched.

In the power conversion device 1, the arrangement of each configuration shown in FIG. 1 is an example, and the arrangement of each configuration is not limited to the example shown in FIG. For example, the reactor 120 may be arranged after the rectifying unit 130. Further, the power conversion device 1 may be provided with a boosting unit, or the rectifying unit 130 may be provided with the function of a boosting unit. In the following description, the current detection unit 501 and the current detection units 313a and 313b may be collectively referred to as a detection unit. Further, the current value detected by the current detection unit 501 and the current value detected by the current detection units 313a and 313b may be referred to as a detection value.

The control unit 400 acquires the current value of the input current of the smoothing unit 200 from the current detection unit 501, and the current of the second AC power having a desired amplitude and phase converted from the current detection units 313a and 313b by the inverter 310. Get the value. The control unit 400 controls the operation of the inverter 310, specifically, the on / off of the switching elements 311a to 311f of the inverter 310 by using the detection value detected by each detection unit. In the present embodiment, the control unit 400 outputs a second AC power including a pulsation corresponding to the pulsation of the electric power flowing from the rectifying unit 130 to the capacitor 210 of the smoothing unit 200 from the inverter 310 to the compressor 315 which is a load. The operation of the inverter 310 is controlled so as to be performed. The pulsation according to the pulsation of the electric power flowing into the capacitor 210 of the smoothing portion 200 is, for example, a pulsation that fluctuates depending on the frequency of the pulsation of the electric power flowing into the capacitor 210 of the smoothing portion 200. As a result, the control unit 400 suppresses the current flowing through the capacitor 210 of the smoothing unit 200. The control unit 400 does not have to use all the detected values acquired from each detection unit, and may perform control using some of the detected values.

The control unit 400 controls so that any one of the speed, voltage, and current of the motor 314 is in a desired state. Here, when the motor 314 is used for driving the compressor 315 and the compressor 315 is a closed type compressor, it is structurally and cost-wise to attach a position sensor for detecting the rotor position to the motor 314. Since it is difficult, the control unit 400 controls the motor 314 without a position sensor. There are two types of position sensorless control methods for the motor 314: primary magnetic flux constant control and sensorless vector control. In this embodiment, as an example, a sensorless vector control will be described as a base. The control method described below can also be applied to the constant primary magnetic flux control with minor changes.

Next, the characteristic operation of the control unit 400 in the present embodiment will be described. As shown in FIG. 1, in the power conversion device 1, the input current from the rectifying unit 130 to the capacitor 210 of the smoothing unit 200 is the input current I1, and the output current from the capacitor 210 of the smoothing unit 200 to the inverter 310 is the output current I2. Let the charge / discharge current of the capacitor 210 of the smoothing portion 200 be the charge / discharge current I3. Although the input current I1 is affected by the power supply phase of the commercial power supply 110, the characteristics of the elements installed before and after the rectifying unit 130, and the like, it basically has a characteristic of including a component 2n times the power supply frequency. Note that n is an integer of 1 or more.

When an electrolytic capacitor is used as the capacitor 210 of the smoothing portion 200, if the charge / discharge current I3 is large, the aging deterioration of the capacitor 210 accelerates. In order to reduce the charge / discharge current I3 and suppress the deterioration of the capacitor 210, the control unit 400 may control the inverter 310 so that the input current I1 to the capacitor 210 = the output current I2 from the capacitor 210. .. However, since the ripple component caused by PWM (Pulse Width Modulation) is superimposed on the output current I2, the control unit 400 needs to control the inverter 310 in consideration of the ripple component. In order to suppress the deterioration of the capacitor 210, the control unit 400 monitors the power state of the smoothing unit 200, that is, the capacitor 210, and gives an appropriate pulsation to the motor 314 so that the charge / discharge current I3 decreases. good. Here, the power state of the capacitor 210 is an input current I1 to the capacitor 210, an output current I2 from the capacitor 210, a charge / discharge current I3 of the capacitor 210, a DC bus voltage _Vdc of the capacitor 210, and the like. The control unit 400 needs information on at least one of the power states of these capacitors 210 for deterioration suppression control.

In the present embodiment, the control unit 400 uses the input current I1 to the capacitor 210 detected by the current detection unit 501 so that the value obtained by removing the PWM ripple from the output current I2 matches the input current I1. Add pulsation to 314. That is, the control unit 400 controls the operation of the inverter 310 so that the pulsation according to the detection value of the current detection unit 501 is superimposed on the drive pattern of the motor 314, and suppresses the charge / discharge current I3 of the capacitor 210. The control unit 400 controls the q-axis current command i _q ^* of the motor 314 from the relationship between the input / output power of the motor 314 so that the difference between the input current I1 and the output current I2 becomes small. In this control method, the control unit 400 calculates an ideal q-axis current for reducing the charge / discharge current I3 by utilizing the relationship between the input power to the inverter 310 and the mechanical output of the motor 314. This control method requires a sensor that detects the input current I1, that is, a current detection unit 501, but since the pulsating waveform of the q-axis current is directly determined using a theoretical formula, it is responsive to changes in the input current I1. There is a merit that deterioration of the capacitor 210 can be easily suppressed when used in combination with pulsating load compensation. As described above, in the present embodiment, the control unit 400 controls in the rotating coordinate system having the d-axis and the q-axis.

In the power conversion device 1, the current detection unit 501 detects the current value of the input current I1 to the capacitor 210 and outputs the current value to the control unit 400. The control unit 400 controls the inverter 310 so that the value obtained by removing the PWM ripple from the output current I2 from the capacitor 210 to the inverter 310 matches the input current I1, and adds pulsation to the power output to the motor 314. The control unit 400 can reduce the charge / discharge current I3 of the capacitor 210 by appropriately pulsating the output current I2. As described above, since the input current I1 to the capacitor 210 contains a component 2n times the power supply frequency, the output current I2 and the q-axis current of the motor 314 also contain a component 2n times the power supply frequency. .. As a specific method for calculating the q-axis current of the motor 314 for appropriately pulsating the output current I2, for example, there are the following methods.

The AC power supply voltage from the commercial power supply 110, which is the input to the power conversion device 1, is represented by the equation (1).

In equation (1), V _s indicates the amplitude of the AC power supply voltage, ω _in indicates the angular frequency of the AC power supply voltage, and t indicates the time. The angular frequency ω _in depends on the power supply environment, but in most cases, it is 50 Hz × 2π = 314 rad / s or 60 Hz × 2π = 377 rad / s. In the case of a circuit configuration in which the power converter 1 includes a booster in the front or rear of the rectifier 130, the input current I1 to the capacitor 210 includes a PWM ripple, but it should not be averaged and considered. And. Assuming that the input current I1 is a periodic function, if the input current I1 is approximated by a Fourier series, the input current I1 can be expressed by the equation (2). The input current I1 has a waveform that includes many components that are integral multiples of the power supply frequency 2f due to the rectifying unit 130. The fundamental wave of the input current I1 is a component of the power supply frequency 2f. In the mathematical formula, the "1" part of the input current I1 is subscripted in order to match the notation with the others. The same shall apply thereafter.

In equation (2), I _DC indicates the direct current component of the current, I _2f , I _4f , I _6f , ... Indicates the fundamental and harmonic amplitudes of the current, and θ _2f , θ _4f , θ _6f , ... Shows the fundamental phase and harmonic phase. The input current I1 may be used as it is for the control of the control unit 400, or the input current I1 may be filtered and then used for the control of the control unit 400. For example, assuming that the input current I1 ′ is obtained by extracting the DC component, the fundamental wave component, and the low-order harmonic component of the input current I1 by a low-pass filter and a band-pass filter, the input current I1 ′ is expressed by, for example, the equation (3). It can be expressed as. In the formula (3), the input current I1'is obtained by extracting the DC component, the power supply frequency 2f component, and the power supply frequency 4f component, but a component having a power supply frequency of 6f or more may be added. The bandpass filter may be configured by an FIR (Fiinite Impulse Response) filter or an IIR (Infinite Impulse Response) filter. Further, the input current I1'may be calculated from the coefficient calculation formula of the Fourier series expansion.

The reason why only a specific frequency component is extracted by the above-mentioned filters is to prevent an unintended frequency component from being included in the pulsation given to the motor 314. On the other hand, when the above-mentioned filters are used, the responsiveness to the change of the input current I1 is lowered, so whether or not to use the filters may be decided depending on the situation. In the following description, it is assumed that the above-mentioned filters are used. The output current command I ₂ ^* of the output current I 2 from the capacitor 210 is given as in the equation (4).

To add pulsation to the motor 314 so that the output current command I ₂ ^* flows according to the command value, for example, the following may be performed. When the output current command I ₂ ^* flows according to the command value, the active power input from the capacitor 210 to the motor 314 is expressed by the equation (5).

In equation (5), V _dc represents the DC bus voltage. On the other hand, the active power P _mot consumed by the motor 314 is expressed by the dq-axis voltage and the dq-axis current as shown in the equation (6).

Here, the voltage equation in the steady state of the permanent magnet synchronous motor is considered and substituted into the equation (6) to obtain the equation (7).

In equation (7), Ra indicates the armature resistance, L _d and L _q indicate the _dq axis inductance, Φ _a indicates the number of dq axis interlinkage magnetic fluxes, and ω _e indicates the electric angular velocity. In the case where the voltage drop due to the armature resistance R _a can be ignored and the _d -axis current id can be regarded as almost zero, the equation (8) holds.

If a pulsation is applied to the motor ₃₁₄ so that P _mot = _Pin , the current flowing through the smoothing portion 200, that is, the charge / discharge current ^I3 can be reduced. Just give it.

If the q-axis current pulsation command i _qrip ^* is given as in the equation (9), it is possible to suppress the deterioration of the capacitor 210 of the smoothing portion 200. When the _d -axis current id is non-zero, the calculation may be performed as in the equation (10) in consideration of the reluctance torque.

Here, id ^* is a _d -axis current command. _In equations (9) and (10), P _mot = Pin is assumed, but the motor 314 is accompanied by losses such as copper loss, iron loss, and mechanical loss. Therefore, the calculation may be performed in consideration of such a loss.

The configuration of the control unit 400 that performs the above calculation will be described. FIG. 2 is a block diagram showing a configuration example of the control unit 400 included in the power conversion device 1 according to the first embodiment. The control unit 400 includes a rotor position estimation unit 401, a speed control unit 402, a weakening magnetic flux control unit 403, a current control unit 404, a coordinate conversion unit 405, 406, a PWM signal generation unit 407, and a q-axis current. A pulsation calculation unit 408 and an addition unit 409 are provided.

The rotor position estimation unit 401 is the direction of the rotor magnetic pole on the dq axis with respect to the rotor (not shown) of the motor 314 from the dq axis voltage command vector V _dq ^* and the dq axis current vector i _dq applied to the motor 314. The estimated phase angle θ _est and the estimated speed ω _est , which is the rotor speed, are estimated.

The speed control unit 402 automatically adjusts the q-axis current command i _q ^* so that the speed command ω ^* and the estimated speed ω _est match. The speed command ω ^* is set when the power conversion device 1 is used as an air conditioner or the like as a refrigeration cycle application device, for example, the temperature detected by a temperature sensor (not shown) or a setting instructed by a remote controller which is an operation unit (not shown). It is based on information indicating the temperature, operation mode selection information, operation start and operation end instruction information, and the like. The operation mode is, for example, heating, cooling, dehumidification, and the like.

The weakening magnetic flux control unit 403 automatically adjusts the _d -axis current command id ^* so that the absolute value of the dq-axis voltage command vector V _dq ^* falls within the limit value of the voltage limit value V _lim ^* . Further, in the present embodiment, the weakening magnetic flux control unit 403 performs the weakening magnetic flux control in consideration of the q-axis current pulsation command i _qrip ^* calculated by the q-axis current pulsation calculation unit 408. Weak magnetic flux control is roughly divided into a method of calculating the _d -axis current command id ^* from the equation of the voltage limiting ellipse, and the deviation of the absolute value between the voltage limit value V _lim ^* and the dq-axis voltage command vector V _dq ^* is zero. There are two methods for calculating the _d -axis current command id ^* so that, but either method may be used.

The current control unit 404 automatically adjusts the dq-axis voltage command vector V _dq ^* so that the dq-axis current vector i _dq follows the _d -axis current command id ^* and the q-axis current command i _q ^* .

The coordinate conversion unit 405 converts the dq axis voltage command vector V _dq ^* from the dq coordinates to the voltage command V _uvw ^* of the AC amount according to the estimated phase angle θ _est .

The coordinate conversion unit 406 converts the current I _uvw flowing through the motor 314 from the alternating current amount into the dq-axis current vector i _dq of the dq coordinates according to the estimated phase angle θ _est . As described above, the control unit 400 has the current values of the two phases detected by the current detection units 313a and 313b among the three-phase current values output from the inverter 310 with respect to the current _Ivw flowing through the motor 314. It can be obtained by calculating the current value of the remaining one phase using the current value of the two phases.

The PWM signal generation unit 407 generates a PWM signal based on the voltage command V _uvw ^* coordinate-converted by the coordinate conversion unit 405. The control unit 400 applies a voltage to the motor 314 by outputting the PWM signal generated by the PWM signal generation unit 407 to the switching elements 311a to 311f of the inverter 310.

The q-axis current pulsation calculation unit 408 uses the above-mentioned q-axis current pulsation command i _qrip ^* based on the input current I1, the DC bus voltage V _dc , and the estimated speed ω _est , which are the current values detected by the current detection unit 501. Is calculated. Although omitted in FIG. 1, the power conversion device 1 generally includes a detection unit that detects the DC bus voltage _Vdc of the capacitor 210 for circuit protection, control reasons, and the like.

The addition unit 409 adds and adds the q-axis current command i _q ^* output from the speed control unit 402 and the q-axis current pulsation command i _qrip ^* calculated by the q-axis current pulsation calculation unit 408. It is output as a q-axis current command i _q ^* to the current control unit 404.

The control unit 400 calculates the q-axis current pulsation command i _qrip ^* based on the equation (9) or the equation (10) as compared with the power conversion device that performs the same control as the conventional one, and the q-axis current pulsation command i. The difference is that the q-axis current command i _q ^* is calculated using _qrip ^* and the weakening magnetic flux control is performed by adding the q-axis current pulsation command i _qrip ^* . Applications such as compressor motors for air conditioning actively utilize weakened magnetic flux control, inverter overmodulation, etc., but in the voltage saturation range where these controls are used, even if pulsation is applied only to the q-axis current, the voltage is insufficient. Does not follow the value. Therefore, it is necessary to pulsate the _d -axis current id in accordance with the q-axis current pulsation command i _qrip ^* . A method of weakening magnetic flux control in which the _d -axis current id is also pulsated at the same time so that the voltage amplitude becomes constant is known. The weakening magnetic flux control unit 403 pulsates the _d -axis current id at the same time as the q-axis current pulsation command i _qrip ^* at the time of voltage saturation to prevent the voltage from becoming insufficient.

FIG. 3 is a diagram showing a configuration example of the q-axis current pulsation calculation unit 408 of the control unit 400 included in the power conversion device 1 according to the first embodiment. The q-axis current pulsation calculation unit 408 includes a filter 381 and an amplitude conversion unit 382. The filter 381 passes the input current I1 to the capacitor 210 and calculates the output current command I ₂ ^* from the capacitor 210. In the present embodiment, the filter 381 has been described as a combination of a low-pass filter and a band-pass filter, but this configuration is an example, and another type of filter may be used. Further, when the q-axis current pulsation calculation unit 408 places more importance on responsiveness, the filter 381 may be omitted. The amplitude conversion unit 382 performs the calculation of equation (9) or equation (10) using the output current command I ₂ ^* from the capacitor 210, the DC bus voltage V _dc , and the estimated speed ω _est of the motor 314. Calculate the shaft current pulsation command i _qrip ^* . Since the pulsating amplitude of the q-axis current changes depending on the driving conditions of the motor 314, the amplitude conversion unit 382 determines the amplitude in consideration of the driving conditions appropriately.

The control unit 400 appropriately applies pulsation to the motor 314 by the q-axis current pulsation calculation unit 408, and controls the current flowing through the capacitor 210 to be close to zero or to a small value, so that the current flows into and out of the capacitor 210. That is, the charge / discharge current I3 of the capacitor 210 can be reduced.

FIG. 4 is a diagram showing an example of a drive waveform in a power conversion device having the same circuit configuration as the power conversion device 1 of the first embodiment as a comparative example. It is assumed that the power conversion device of the comparative example, which is the object of FIG. 4, is not controlled like the power conversion device 1 of the present embodiment. FIG. 5 is a diagram showing an example of a drive waveform in the power conversion device 1 according to the first embodiment. In FIGS. 4 and 5, the upper figure shows the input current I1 from the rectifying unit 130 to the capacitor 210, the output current I2 from the capacitor 210, and the charge / discharge current I3 of the capacitor 210, and the lower figure shows the DC bus voltage _Vdc . ing. Note that FIGS. 4 and 5 are drawn on the same scale. Further, for convenience of explanation, PWM ripple is not considered in FIGS. 4 and 5.

When the capacity of the capacitor 210 of the smoothing portion 200 is large to some extent, the input current I1 flowing into the capacitor 210 has a shape like a “rabbit ear”. In the power conversion device of the comparative example, since the output current I2 from the capacitor is almost constant, the charge / discharge current I3 of the capacitor also has the shape of a “rabbit ear”. Along with this, a large ripple occurs in the DC bus voltage _Vdc . Since these waveforms have a large periodic pulsation, the deterioration of the capacitor 210 over time is accelerated.

On the other hand, in the power conversion device 1 of the present embodiment, the control unit 400 controls the operation of the inverter 310 so that the output current I2 from the capacitor 210 is in the shape of a “rabbit ear”, so that the capacitor 210 The peak value of the charge / discharge current I3 becomes smaller. At the same time that the peak value of the charge / discharge current I3 of the capacitor 210 becomes small, the ripple of the DC bus voltage _Vdc also becomes small. By reducing the outflow and inflow of the current of the capacitor 210, the deterioration of the element can be suppressed and the aging deterioration of the component can be suppressed. In the power conversion device 1, the capacity of the element can be reduced by the amount of suppression of the control unit 400 as described above, and the ripple withstand capacity is relaxed. Therefore, an inexpensive smoothing element, that is, a capacitor 210 can be utilized, and the system cost can be suppressed. In FIG. 5, only the DC component, the power supply frequency 2f component, and the power supply frequency 4f component are extracted to perform deterioration suppression control, but when it is desired to make the charge / discharge current I3 of the capacitor 210 smaller, the order is higher. Ingredients may be added. However, in practice, it is considered necessary and sufficient if the power frequency up to the 6f component is taken into consideration. Further, when it is desired to reduce the amount of calculation, only the DC component and the power supply frequency 2f component may be considered.

Since the control method of the control unit 400 according to the present embodiment is based on the theoretical formula of the input / output power of the motor 314, the q-axis current pulsation of the motor 314 can be directly determined with respect to the change of the input current I1. Highly responsive to changes in the input current I1. Therefore, there is an advantage that deterioration of the capacitor 210 of the smoothing portion 200 can be easily suppressed when used in combination with pulsation load compensation. However, the control method of the first embodiment has a difficulty in robustness as compared with the control method based on the automatic search of the second embodiment and the third embodiment described later. It is clear from Eqs. (9), Eq. (10), etc. that the desired control becomes difficult when the constant fluctuation occurs. For example, if there is an error in Φ _a , the magnitude of the q-axis current pulsation will be excessive or insufficient. Further, it is considered that the deterioration suppressing effect of the capacitor 210 is reduced under the operating conditions in which the assumptions used in the derivation of the equations (9) and (10) do not hold. Further, a sensor for detecting the input current I1, that is, a current detection unit 501 is required. A control method for solving these problems will be described in the second and third embodiments described later. Further, the control methods of the respective embodiments may be freely combined and used, including the control method of the fourth embodiment described later.

As shown in FIG. 1, when the motor 314 drives the compressor 315, which is a load having periodic load torque pulsation, the control unit 400, in addition to the above-mentioned control, speed pulsation caused by the load torque pulsation. It may be controlled so as to suppress.

The operation of the control unit 400 will be described using a flowchart. FIG. 6 is a flowchart showing the operation of the control unit 400 included in the power conversion device 1 according to the first embodiment. The control unit 400 acquires the input current I1 of the capacitor 210, which is a detected value, from the current detection unit 501 (step S1). The control unit 400 controls the operation of the inverter 310 based on the acquired detection value so that the difference between the input current I1 to the capacitor 210 and the output current I2 from the capacitor 210 becomes small (step S2).

Next, the hardware configuration of the control unit 400 included in the power conversion device 1 will be described. FIG. 7 is a diagram showing an example of a hardware configuration that realizes the control unit 400 included in the power conversion device 1 according to the first embodiment. The control unit 400 is realized by the processor 91 and the memory 92.

The processor 91 is a CPU (Central Processing Unit, central processing unit, processing unit, arithmetic unit, microprocessor, microprocessor, processor, DSP (Digital Signal Processor)), or system LSI (Large Scale Integration). The memory 92 is a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), an EPROM (registered trademark) (Electrically Memory) A semiconductor memory can be exemplified. Further, the memory 92 is not limited to these, and may be a magnetic disk, an optical disk, a compact disk, a mini disk, or a DVD (Digital Versaille Disc).

As described above, according to the present embodiment, in the power conversion device 1, the control unit 400 uses the input current I1 to the capacitor 210 detected by the current detection unit 501 to generate the q-axis current pulsation command i. It was decided to calculate _qrip ^* and generate _d -axis current command id ^* using the q-axis current pulsation command i _qrip ^* to control the operation of the inverter 310 and suppress the charge / discharge current I3 of the capacitor 210. As a result, the power conversion device 1 can suppress the deterioration of the smoothing capacitor 210 while suppressing the increase in size of the power conversion device 1.

Embodiment 2.
In the second embodiment, in the power conversion device, the motor 314 that detects the charge / discharge current I3 flowing through the capacitor 210 and reduces the peak value of the charge / discharge current I3 or a specific frequency component contained in the charge / discharge current I3. The drive pattern including the pulsation of the electric current is automatically searched.

The famous automatic search method is, for example, the mountain climbing method, but any method may be used as long as it is an automatic search method. For example, in a broad sense, feedback control is also considered to be a kind of automatic search method, so the feedback control technique may be used. The control method of the second embodiment requires a sensor for detecting the charge / discharge current I3, which is difficult in terms of cost. However, in order to automatically search for an appropriate operating point, it is robust even when the constant fluctuation of the motor 314 occurs. It is possible to suppress deterioration.

Specifically, the control that minimizes the charge / discharge current I3 by utilizing the feedback control will be described. The control method described here automatically searches for a drive pattern including the pulsation of the motor 314 that minimizes the charge / discharge current I3.

FIG. 8 is a diagram showing a configuration example of the power conversion device 1a according to the second embodiment. The power conversion device 1a is the power conversion device 1 of the first embodiment shown in FIG. 1, in which the control unit 400 and the current detection unit 501 are deleted, and the control unit 400a and the current detection unit 502 are added. be. The motor drive device 2a is composed of the power conversion device 1a and the motor 314 included in the compressor 315. The current detection unit 502 detects the charge / discharge current I3 of the capacitor 210 and outputs the detected current value to the control unit 400a. The current detection unit 502 is a detection unit that detects the power state of the capacitor 210. FIG. 9 is a block diagram showing a configuration example of the control unit 400a included in the power conversion device 1a according to the second embodiment. The control unit 400a is obtained by deleting the q-axis current pulsation calculation unit 408 and adding the q-axis current pulsation calculation unit 408a to the control unit 400 of the first embodiment shown in FIG.

FIG. 10 is a diagram showing a configuration example of the q-axis current pulsation calculation unit 408a of the control unit 400a included in the power conversion device 1a according to the second embodiment. The q-axis current pulsation calculation unit 408a is configured as a feedback controller with the command value set to zero. Normally, the feedback controller has a lower control response than the feedforward controller and is not suitable for suppressing high frequency pulsation, but various high frequency pulsation suppressing means have been proposed in the past. As a well-known method, there is a method using a Fourier coefficient calculation and a PID (Proportional Integral Differential) controller. The q-axis current pulsation calculation unit 408a includes a subtraction unit 383, a Fourier coefficient calculation unit 384 to 387, a PID control unit 388 to 391, and an AC restoration unit 392.

The subtraction unit 383 calculates the deviation between the command value = 0 and the charge / discharge current I3 of the capacitor 210. Using the theory of Fourier series expansion, it is possible to extract the amplitudes of the sin signal component and cos signal component of a specific frequency included in the deviation. The Fourier coefficient calculation units 384 to 387 calculate the amplitudes of the sin2f component, the cos2f component, the sin4f component, and the cos4f component included in the deviation, assuming that the power frequency is the 1f component. The detection signals multiplied by the Fourier coefficient calculation units 384 to 387 are sin2ω _int , cos2ω _int , sin4ω _int , and cos4ω _int , respectively, and the deviation includes twice the average value of the product of the input signal and the detection signal, respectively. It is the amplitude of the sin2f component, the cos2f component, the sin4f component, and the cos4f component. That is, the Fourier coefficient calculation units 384 to 387 calculate the amplitude of the component corresponding to the power supply frequency of the commercial power supply 110 included in the deviation between the detected value and the command value. If the charge / discharge current I3 of the capacitor 210 is a periodic waveform, the output signals of the Fourier coefficient calculation units 384 to 387 are substantially constant.

The PID control units 388 to 391 carry out proportional-integral-differential control, that is, PID control so that the specific frequency components of these deviations become zero. The proportional gain and derivative gain can be zero, but the integrated gain value must be non-zero in order for the deviation to converge to zero. Therefore, in the PID control units 388 to 391, the integration operation is the main operation. Normally, since the output of the integral control changes slowly, the output of the PID control units 388 to 391 can also be regarded as being substantially constant. The AC restoration unit 392 multiplies the outputs of the PID control units 388 to 391 with sin2ω _int , cos2ω _int , sin4ω _int , and cos4ω _int , respectively, and then adds them up to restore the q-axis current pulsation command i _qrip. ^* Determine. That is, the AC restoration unit 392 generates the q-axis current pulsation command i _qrip ^* , which is a command for the pulsation for suppressing the charge / discharge current I3 of the capacitor 210.

In the second embodiment, by using such a control method, the problem of robustness, which is a drawback of the control method of the first embodiment, is improved. On the other hand, the control response cannot be increased because the PID control is mainly used for the integral operation. Further, since a sensor for detecting the charge / discharge current I3, that is, a current detection unit 502 is required, there is a problem in terms of cost. As described above, in order to compensate for the weaknesses of the control methods of each embodiment, the control methods of each embodiment may be freely combined and used, including the control method of the third embodiment described later.

In the second embodiment, the case where the sensorless vector control method is used has been illustrated, but it can also be applied to the constant primary magnetic flux control by adding a pulsation to the speed command, the voltage command, etc. by adding some deformation. .. Specifically, in the AC restoration unit 392, an appropriate phase offset may be given to the trigonometric function for AC restoration to be multiplied. For example, when the motor 314 is a permanent magnet synchronous motor, the current vector and the voltage vector in the steady state have a phase difference of about several tens of degrees. If it is added to the command, the same control is possible even with constant primary magnetic flux control.

The operation of the control unit 400a will be described using a flowchart. FIG. 11 is a flowchart showing the operation of the control unit 400a included in the power conversion device 1a according to the second embodiment. The control unit 400a acquires the charge / discharge current I3 of the capacitor 210, which is a detected value, from the current detection unit 502 (step S11). The control unit 400a controls the operation of the inverter 310 so that the specific frequency component included in the charge / discharge current I3 of the capacitor 210 is reduced based on the acquired detected value (step S12).

As described above, according to the present embodiment, in the power conversion device 1a, the control unit 400a determines the drive pattern of the motor 314 in which the pulsation component of a specific frequency included in the charge / discharge current I3 of the capacitor 210 is reduced. It was decided to suppress the charge / discharge current I3 of the capacitor 210 by automatically searching and controlling the operation of the inverter 310. As a result, the power conversion device 1a can suppress the deterioration of the smoothing capacitor 210 and the increase in size of the power conversion device 1a.

Embodiment 3.
In the third embodiment, in the power conversion device, the DC bus voltage V _dc , which is the voltage across the capacitor 210, is detected, and the drive pattern including the pulsation of the motor 314 such that the pulsation width of the DC bus voltage V _dc is reduced is automatically performed. Explore.

For reasons of circuit protection, control, etc., the power conversion device generally detects the DC bus voltage Vdc of the capacitor 210 by the voltage detection unit. Therefore, the control method of the third embodiment is the embodiment. Unlike the control method of 1 and 2, it is not necessary to add a current detection unit. The control method of the third embodiment is superior in terms of cost as compared with the control method of the first embodiment and the second embodiment.

As in the case of the second embodiment, any method may be used as long as it is an automatic search method. For example, in a broad sense, feedback control is also considered to be a kind of automatic search method, so the feedback control technique may be used. The control method based on the automatic search can robustly suppress deterioration even when the constant fluctuation of the motor 314 occurs.

Specifically, the control for reducing the pulsation width of the DC bus voltage _Vdc using the feedback control will be described. The control method described here automatically searches for a drive pattern including the pulsation of the motor 314 in which the pulsation width of the DC bus voltage _Vdc decreases.

FIG. 12 is a diagram showing a configuration example of the power conversion device 1b according to the third embodiment. The power conversion device 1b is the power conversion device 1 of the first embodiment shown in FIG. 1, in which the control unit 400 and the current detection unit 501 are deleted, and the control unit 400b and the voltage detection unit 503 are added. be. The motor drive device 2b is composed of the power conversion device 1b and the motor 314 included in the compressor 315. The voltage detection unit 503 detects the DC bus voltage _Vdc , which is the voltage across the capacitor 210, and outputs the detected voltage value to the control unit 400b. The voltage detection unit 503 is a detection unit that detects the power state of the capacitor 210. Although not shown in FIGS. 1 and 8, as described above, the power conversion device generally detects the DC bus voltage V _dc of the capacitor 210 for reasons of circuit protection, control, and the like. It has a configuration, that is, a detection unit corresponding to the voltage detection unit 503 of the present embodiment. FIG. 13 is a block diagram showing a configuration example of the control unit 400b included in the power conversion device 1b according to the third embodiment. The control unit 400b deletes the q-axis current pulsation calculation unit 408 and adds the q-axis current pulsation calculation unit 408b to the control unit 400 of the first embodiment shown in FIG. In the q-axis current pulsation calculation unit 408a of the second embodiment shown in FIG. 9, the charge / discharge current I3 of the capacitor 210 was input, but in the q-axis current pulsation calculation unit 408b of the third embodiment shown in FIG. 13, the charge / discharge current I3 was input. The point that the DC bus voltage V _dc of the capacitor 210 is input is different from the second embodiment.

FIG. 14 is a diagram showing a configuration example of the q-axis current pulsation calculation unit 408b of the control unit 400b included in the power conversion device 1b according to the third embodiment. The q-axis current pulsation calculation unit 408b is configured as a feedback controller with a target value of zero. The q-axis current pulsation calculation unit 408b includes a subtraction unit 383, a Fourier coefficient calculation unit 384 to 387, a PID control unit 388 to 391, and an AC restoration unit 392b.

The subtraction unit 383 calculates the deviation between the target value = 0 and the DC bus voltage V _dc of the capacitor 210. The Fourier coefficient calculation units 384 to 387 calculate the amplitudes of the sin2f component, the cos2f component, the sin4f component, and the cos4f component included in the deviation, assuming that the power frequency is the 1f component. That is, the Fourier coefficient calculation units 384 to 387 calculate the amplitude of the component corresponding to the power supply frequency of the commercial power supply 110 included in the deviation between the detected value and the target value. The PID control units 388 to 391 carry out proportional-integral-differential control, that is, PID control so that the specific frequency components of these deviations become zero. The proportional gain and derivative gain can be zero, but the integrated gain value must be non-zero in order for the deviation to converge to zero. Therefore, in the PID control units 388 to 391, the integration operation is the main operation. Normally, since the output of the integral control changes slowly, the output of the PID control units 388 to 391 can also be regarded as being substantially constant. Regarding the Fourier coefficient calculation units 384 to 387 and the PID control units 388 to 391, the calculation contents are almost the same as those in the second embodiment except that the input values are different.

The AC restoration unit 392b integrates the charge / discharge current I3 of the capacitor 210. Here, since the DC bus voltage V _dc is divided by the capacity of the capacitor 210, there is a phase difference of 90 degrees between the charge / discharge current I3 of the capacitor 210 and the DC bus voltage V _dc . The AC restoration unit 392b must determine the q-axis current pulsation command i _qrip ^* in consideration of the phase difference of 90 degrees. When the phase difference of 90 degrees is set to θ _offset (= π / 2 [rad]), the AC restoration unit 392b performs the restoration operation as follows. In this way, the AC restoration unit 392b generates the q-axis current pulsation command i _qrip ^* , which is a command for the pulsation for suppressing the charge / discharge current I3 of the capacitor 210.

When the detection signals multiplied by the Fourier coefficient calculation units 384 to 387 are sin2ω _int , cos2ω _int , sin4ω _int , and cos4ω _int , respectively, the restoration signals in the AC restoration unit 392b are sin2 (ω _int + θ _offset ) and cos2. (Ω _int + θ _offset ), sin4 (ω _int + θ _offset ), and cos4 (ω _int + θ _offset ). The q-axis current pulsation calculation unit 408a of the second embodiment shown in FIG. 10 may use the same detection signal and restoration signal, but the q-axis current pulsation calculation unit 408b of the third embodiment shown in FIG. 14 may use the same detection signal and restoration signal. It is necessary to shift the restoration signal by the amount of θ _offset . The AC restoration unit 392b can determine the q-axis current pulsation command i _qrip ^* by calculating the sum of products of the outputs of the PID control units 388 to 391 and the restoration signal.

In the third embodiment, by using such a control method, it is advantageous in terms of cost as compared with the first embodiment and the second embodiment. Further, in the third embodiment, by using such a control method, the problem of robustness, which is a drawback of the control method of the first embodiment, is improved. On the other hand, the control response cannot be increased because the PID control is mainly used for the integral operation. As described above, in order to compensate for the weaknesses of the control methods of each embodiment, the control methods of each embodiment may be freely combined and used, including the control method of the fourth embodiment described later.

The operation of the control unit 400b will be described with reference to a flowchart. FIG. 15 is a flowchart showing the operation of the control unit 400b included in the power conversion device 1b according to the third embodiment. The control unit 400b acquires the DC bus voltage V _dc , which is the voltage across the capacitor 210, which is the detected value, from the voltage detection unit 503 (step S21). The control unit 400b controls the operation of the inverter 310 so that the specific pulsation width included in the DC bus voltage _Vdc is reduced based on the acquired detected value (step S22).

As described above, according to the present embodiment, in the power conversion device 1b, the control unit 400b automatically searches for the drive pattern of the motor 314 in which the pulsation component of a specific frequency included in the DC bus voltage _Vdc is reduced. By controlling the operation of the inverter 310, the charge / discharge current I3 of the capacitor 210 is suppressed. As a result, the power conversion device 1b can suppress the deterioration of the smoothing capacitor 210 while suppressing the increase in size of the power conversion device 1b.

Embodiment 4.
In the first to third embodiments, a method of determining a drive pattern including a pulsation of the q-axis current in which the charge / discharge current I3 of the capacitor 210 decreases during driving of the motor 314 has been described. However, if the drive pattern including the pulsation of the q-axis current in which the charge / discharge current I3 of the capacitor 210 decreases is known, deterioration suppression control may be performed based on the known data. That is, a method is conceivable in which a pulsation pattern representing the pulsation of the q-axis current in which the charge / discharge current I3 of the capacitor 210 decreases is investigated in advance, and deterioration suppression control is performed based on the pre-learned data. In the fourth embodiment, the pulsation pattern of the motor 314 in which the pulsation of the charge / discharge current I3 or the DC bus voltage _Vdc is reduced is investigated in advance, and the pulsation is given to the motor 314 using the data investigated in advance. The data investigated in advance is stored in a storage unit in the power conversion device, and an appropriate pulsation pattern is selected according to the driving conditions of the motor 314.

FIG. 16 is a block diagram showing a configuration example of the control unit 400c included in the power conversion device according to the fourth embodiment. The power conversion device including the control unit 400c may have the same circuit configuration as the power conversion devices 1 to 1b described in the first to third embodiments, or may be individually provided in each embodiment. The circuit configuration may not include the detection unit. The control unit 400c is obtained by deleting the q-axis current pulsation calculation unit 408 and adding the q-axis current pulsation calculation unit 408c to the control unit 400 of the first embodiment shown in FIG. The q-axis current pulsation calculation unit 408c includes a storage unit (not shown) and a pulsation pattern generation unit. The storage unit stores a pulsation pattern of the motor 314 in which the charge / discharge current I3 of the capacitor 210 is reduced. The pulsation pattern data stored in the storage unit was obtained by a preliminary survey.

Any method of preliminary survey may be used. For example, a certain pulsation pattern may be applied by trial and error to investigate a pattern in which the pulsation of the charge / discharge current I3 or the DC bus voltage _Vdc decreases, or the investigation is performed using the above-mentioned automatic search method. It doesn't matter. Further, the survey may be conducted through an actual machine test or a computer simulation. In recent years, machine learning and AI (Artificial Intelligence) techniques have become common, and such techniques may be used.

Further, in the example of the second embodiment, the control unit 400c automatically searches for a pulsation pattern in which the pulsation component of a specific frequency included in the charge / discharge current I3 detected by the current detection unit 502 decreases, and controls the control. The pulsation pattern obtained in the process may be stored as a pulsation pattern set for each operating condition. Similarly, in the example of the third embodiment, the control unit 400c automatically searches for a pulsation pattern in which the pulsation component of a specific frequency included in the DC bus voltage _Vdc detected by the voltage detection unit 503 decreases. The pulsation pattern obtained in the control process may be stored as a pulsation pattern set for each operating condition.

The pulsation pattern data stored in the storage unit is associated with the operating conditions of the motor 314. For example, in the case of the motor 314, the suction pressure, the discharge pressure, the temperature of the refrigerant, the target value of the room temperature of the air conditioner, and the like of the compressor 315 correspond to the operating conditions. The q-axis current pulsation calculation unit 408c selects an appropriate pulsation pattern from the storage unit for reducing the charge / discharge current I3 of the capacitor 210 according to such operating conditions. The q-axis current pulsation calculation unit 408c uses the pulsation pattern generation unit to generate the q-axis current pulsation command i _qrip ^* based on the pulsation pattern selected from the storage unit. The q-axis current pulsation calculation unit 408c performs deterioration suppression control of the capacitor 210 by such control.

The control method based on the preliminary survey has the disadvantages of having difficulty in robustness and requiring a storage unit having a large capacity, but the calculation process itself is simple. Therefore, when the calculation performance of the computer is poor and the number of operating conditions is very small, the control method as in the fourth embodiment may be an effective means. In order to reduce the complexity of the preliminary survey, the control methods described in the first to fourth embodiments may be freely combined.

The operation of the control unit 400c will be described using a flowchart. FIG. 17 is a flowchart showing the operation of the control unit 400c included in the power conversion device according to the fourth embodiment. The control unit 400c acquires the operating conditions of the compressor 315 (step S31). The control unit 400c selects an appropriate pulsation pattern for reducing the charge / discharge current I3 of the capacitor 210 based on the acquired operating conditions, and controls the operation of the inverter 310 (step S32).

As described above, according to the present embodiment, the control unit 400c stores the pulsation pattern for suppressing the charge / discharge current I3 of the capacitor 210 set for each operating condition of the load including the motor 314. Using the pulsation pattern according to the operating conditions of the compressor 315, which is the load, the q-axis current pulsation command i _qrip ^* , which is the command for the pulsation to suppress the charge / discharge current I3 of the capacitor 210, is generated, and the inverter 310 Control the operation. Also in this case, the same effects as those of the first to third embodiments can be obtained.

Embodiment 5.
FIG. 18 is a diagram showing a configuration example of the refrigeration cycle application device 900 according to the fifth embodiment. The refrigeration cycle application device 900 according to the fifth embodiment includes the power conversion device 1 described in the first embodiment. The refrigeration cycle application device 900 may include the power conversion devices 1a and 1b described in other embodiments, but here, as an example, a case where the power conversion device 1 is provided will be described. The refrigerating cycle applicable device 900 according to the fifth embodiment can be applied to products including a refrigerating cycle such as an air conditioner, a refrigerator, a freezer, and a heat pump water heater. In FIG. 18, the components having the same functions as those of the first embodiment are designated by the same reference numerals as those of the first embodiment.

In the refrigeration cycle application device 900, the compressor 315 having a built-in motor 314, the four-way valve 902, the indoor heat exchanger 906, the expansion valve 908, and the outdoor heat exchanger 910 form the refrigerant pipe 912 according to the first embodiment. It is attached via.

Inside the compressor 315, a compression mechanism 904 for compressing the refrigerant and a motor 314 for operating the compression mechanism 904 are provided.

The refrigeration cycle applicable device 900 can perform heating operation or cooling operation by switching operation of the four-way valve 902. The compression mechanism 904 is driven by a variable speed controlled motor 314.

During the heating operation, as shown by the solid arrow, the refrigerant is pressurized by the compression mechanism 904 and sent out, and passes 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 the compression mechanism 904.

During the cooling operation, as shown by the broken arrow arrow, the refrigerant is pressurized by the compression mechanism 904 and sent out, and passes 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 the compression mechanism 904.

During the 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 the 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 depressurizes the refrigerant and expands it.

The configuration shown in the above embodiments is an example, and can be combined with another known technique, can be combined with each other, and does not deviate from the gist. It is also possible to omit or change a part of the configuration.

1,1a, 1b power converter, 2,2a, 2b motor drive, 110 commercial power supply, 120 reactor, 130 rectifier, 131-134 rectifier, 200 smoother, 210 capacitor, 310 inverter, 311a-311f switching element , 312a to 312f Freewheeling diode, 313a, 313b, 501,502 Current detector, 314 motor, 315 compressor, 381 filter, 382 amplitude conversion unit, 383 subtraction unit, 384 to 387 Fourier coefficient calculation unit, 388 to 391 PID control Unit, 392,392b AC restoration unit, 400,400a, 400b, 400c control unit, 401 rotor position estimation unit, 402 speed control unit, 403 weakening magnetic flux control unit, 404 current control unit, 405, 406 coordinate conversion unit, 407 PWM signal generation unit, 408, 408a, 408b, 408c q-axis current pulsation calculation unit, 409 addition unit, 503 voltage detection unit, 900 refrigeration cycle applicable equipment, 902 four-way valve, 904 compression mechanism, 906 indoor heat exchanger, 908 expansion Valve, 910 outdoor heat exchanger, 912 refrigerant pipe.

Claims (10)

1. A rectifying unit that rectifies the first AC power supplied from a commercial power source,
   The capacitor connected to the output end of the rectifying unit and
   An inverter connected to both ends of the capacitor to generate a second AC power and output it to the motor.
   A detector that detects the power status of the capacitor and
   A control unit that controls the operation of the inverter so that the pulsation according to the detection value of the detection unit is superimposed on the drive pattern of the motor, and suppresses the charge / discharge current of the capacitor.
   A power converter equipped with.
2. The detection unit detects the input current flowing from the rectifying unit to the capacitor, and detects the input current.
   The control unit controls the q-axis current command of the motor from the relationship between the input / output power of the motor so that the difference between the input current and the output current from the capacitor to the inverter becomes small.
   The power conversion device according to claim 1.
3. The detection unit detects the charge / discharge current and
   The control unit automatically searches for the drive pattern in which the pulsating component of a specific frequency included in the charge / discharge current is reduced.
   The power conversion device according to claim 1 or 2.
4. The detection unit detects the DC bus voltage, which is the voltage across the capacitor, and detects it.
   The control unit automatically searches for the drive pattern in which the pulsating component of a specific frequency included in the DC bus voltage is reduced.
   The power conversion device according to any one of claims 1 to 3.
5. The control unit
   A Fourier coefficient calculation unit that calculates the amplitude of the component according to the power frequency of the commercial power supply, which is included in the deviation between the detected value and the command value or the target value.
   A proportional integral differential control unit that converges the deviation, and
   An AC restoration unit that restores the output from the proportional integral differential control unit to an AC component and generates a command for the pulsation to suppress the charge / discharge current of the capacitor.
   The power conversion device according to claim 3 or 4.
6. The control unit stores a pulsation pattern for suppressing the charge / discharge current of the capacitor set for each operating condition of the load including the motor, and uses the pulsating pattern according to the operating condition of the load. Generates a pulsating command to suppress the charge / discharge current of the capacitor and controls the operation of the inverter.
   The power conversion device according to any one of claims 1 to 5.
7. The detection unit detects at least one of the charge / discharge current of the capacitor and the DC bus voltage which is the voltage across the capacitor.
   The control unit automatically searches for the pulsation pattern in which the pulsation component of a specific frequency included in the detection value of the detection unit decreases, and stores it as the pulsation pattern set for each operation condition.
   The power conversion device according to claim 6.
8. When the motor drives a load with periodic load torque pulsations
   The control unit suppresses the speed pulsation caused by the load torque pulsation.
   The power conversion device according to any one of claims 1 to 7.
9. A motor drive device including the power conversion device according to any one of claims 1 to 8.
10. A refrigeration cycle applicable device provided with the power conversion device according to any one of claims 1 to 8.

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