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

Abstract

A power conversion device (200) is provided with: a rectifying unit (3) that rectifies first AC power supplied from a commercial power source (1); a smoothing capacitor (5) connected to the output end of the rectifying unit (3); an inverter (30) that is connected to both ends of the smoothing capacitor (5), generates second AC power, and outputs the second AC power to a motor (7); and a control device (100) that controls the rotation speed of the motor (7) by controlling the operation of the inverter (30). The control device (100) performs a reduction control that reduces a pulsation component that is superimposed on a three-phase current output from the inverter (30) to the motor (7) and that is generated due to the dead time of a switching element provided in the inverter (30) and the induced voltage distortion of the motor (7).

Description

Technical Field

[0001] The present disclosure relates to a power conversion device, a motor drive device, and a refrigeration cycle application device that convert AC power into desired power. Background Art

[0002] Conventionally, in a power conversion device that controls the switching of an inverter and the driving of a motor, higher harmonic components are generated due to the influence of the operation of the inverter, motor, etc. When the measured values ​​such as current values ​​and voltage values, and the estimated motor position, etc. of the power conversion device contain the influence of higher harmonic components, it becomes difficult to perform high-precision control. In order to solve such a problem, Patent Document 1 discloses a technology for reducing six-fold spatial higher harmonics generated during motor operation.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-255314 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] However, according to the above-mentioned prior art, only the 6-fold spatial harmonics generated during the operation of the motor are targeted. In motor control, the pulsating component of 6 times the power supply frequency, that is, the electrical 6f component, is superimposed on the d-axis current and the q-axis current represented by the dq rotating coordinate system that rotates synchronously with the rotor position of the motor, but there are various reasons why the electrical 6f component is superimposed on the d-axis current and the q-axis current. Therefore, there is a problem that the control by only the above-mentioned prior art is not sufficient.

[0008] The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to obtain a power conversion device capable of reducing pulsation components caused by an inverter and a motor.

[0009] Means used to solve problems

[0010] In order to solve the above problems and achieve the purpose, the power conversion device disclosed in the present invention comprises: a rectifier that rectifies a first AC power supplied from a commercial power source; a capacitor connected to an output end of the rectifier; an inverter that is connected to both ends of the capacitor and generates a second AC power and outputs it to a motor; and a control device that controls the operation of the inverter to control the rotation speed of the motor. The control device implements the following reduction control: the pulsation component generated by the dead time of the switching element provided by the inverter and the influence of the induced voltage distortion of the motor and superimposed on the three-phase current output from the inverter to the motor is reduced.

[0011] Effects of the Invention

[0012] The power conversion device of the present disclosure has an effect of being able to reduce pulsation components caused by an inverter and a motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a diagram showing a configuration example of a power conversion device according to Embodiment 1.

[0014] Figure 2 This is a diagram showing a configuration example of an inverter included in the power conversion device according to the first embodiment.

[0015] Figure 3 This is a block diagram showing a configuration example of a control device included in the power conversion device according to the first embodiment.

[0016] Figure 4 This is a block diagram showing a configuration example of a voltage command value calculation unit included in the control device of the power conversion device according to the first embodiment.

[0017] Figure 5 This is a block diagram showing a configuration example of a d-axis current control unit included in a voltage command value calculation unit of a control device in the power conversion device according to the first embodiment.

[0018] Figure 6 This is a block diagram showing a configuration example of a q-axis current control unit included in a voltage command value calculation unit of a control device in the power conversion device according to the first embodiment.

[0019] Figure 7 This is a diagram showing, as a comparative example, an example of the operating state of the power conversion device when the control device of the power conversion device of Embodiment 1 does not perform the reduction control for reducing the pulsation of the electric 6f component included in the current.

[0020] Figure 8 This is a diagram showing an example of the operating state of the power conversion device when the control device of the power conversion device according to the first embodiment performs reduction control for reducing the pulsation of the electric 6f component included in the q-axis current.

[0021] Fig. 9 This is a diagram showing an example of the operating state of the power conversion device when the control device of the power conversion device according to the first embodiment performs reduction control for reducing the pulsation of the electric 6f component included in the d-axis current and the q-axis current.

[0022] Fig.10 This is a flowchart showing the operation of the power conversion device according to the first embodiment.

[0023] Fig.11 This is a diagram showing an example of a hardware configuration for realizing a control device included in the power conversion device according to the first embodiment.

[0024] Fig.12 This is a block diagram showing a configuration example of a voltage command value calculation unit included in the control device of the power conversion device according to the second embodiment.

[0025] Fig.13 This is a block diagram showing a configuration example of a d-axis current control unit included in a voltage command value calculation unit of a control device in the power conversion device according to the second embodiment.

[0026] Fig.14 This is a block diagram showing a configuration example of a q-axis current control unit included in a voltage command value calculation unit of a control device in the power conversion device according to the second embodiment.

[0027] Fig.15 This is a diagram showing a configuration example of a refrigeration cycle application device according to the third embodiment. DETAILED DESCRIPTION

[0028] Hereinafter, 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 in detail based on the drawings.

[0029] Implementation method 1.

[0030] Figure 1 This is a diagram showing a configuration example of a power conversion device 200 according to the first embodiment. Figure 2 1 is a diagram showing a configuration example of the inverter 30 included in the power conversion device 200 of the first embodiment. The power conversion device 200 is connected to the commercial power supply 1 and the motor 7. The power conversion device 200 converts the first AC power of the power supply voltage Vs supplied from the commercial power supply 1 into the second AC power having a desired amplitude and phase, and supplies the second AC power to the motor 7. The power conversion device 200 includes a reactor 2, a rectifier 3, a smoothing capacitor 5, an inverter 30, a bus voltage detection unit 10, a load current detection unit 40, and a control device 100. In addition, the motor drive device 400 is constituted by the power conversion device 200 and the motor 7.

[0031] Reactor 2 is connected between commercial power source 1 and rectifier 3. Rectifier 3 includes a bridge circuit including rectifier elements 131 to 134, and rectifies and outputs first AC power of power source voltage Vs supplied from commercial power source 1. Rectifier 3 performs full-wave rectification.

[0032] The smoothing capacitor 5 is a smoothing element connected to the output end of the rectifier 3 and smoothing the power rectified by the rectifier 3. The smoothing capacitor 5 is, for example, a capacitor such as an electrolytic capacitor or a film capacitor. The smoothing capacitor 5 has a capacitance that smoothes the power rectified by the rectifier 3. The voltage generated in the smoothing capacitor 5 by smoothing is not a full-wave rectified waveform of the commercial power supply 1, but a waveform obtained by superimposing a voltage ripple corresponding to the frequency of the commercial power supply 1 on a DC component, and does not pulsate greatly. The frequency of this voltage ripple becomes a component twice the frequency of the power supply voltage Vs when the commercial power supply 1 is single-phase, and a component six times the frequency becomes the main component when the commercial power supply 1 is three-phase.

[0033] The bus voltage detection unit 10 detects the voltage across the smoothing capacitor 5, that is, the voltage between the DC buses 12a and 12b as the bus voltage Vdc, and outputs the detected voltage value to the control device 100. The load current detection unit 40 detects the load current Idc, which is the DC current flowing from the smoothing capacitor 5 to the inverter 30, and outputs the detected current value to the control device 100.

[0034] The inverter 30 is connected to both ends of the smoothing capacitor 5, and converts the power output from the rectifier 3 and the smoothing capacitor 5 into a second AC power having a desired amplitude and phase, that is, generates the second AC power, and outputs it to the motor 7. Specifically, the inverter 30 receives the bus voltage Vdc, generates a three-phase AC voltage with a variable frequency and voltage value, and supplies it to the motor 7 via the output lines 331 to 333. Figure 2 As shown, the inverter 30 includes an inverter main circuit 310 and a drive circuit 350. The input terminal of the inverter main circuit 310 is connected to the DC bus 12a, 12b. The inverter main circuit 310 includes switching elements 311 to 316. Rectifying elements 321 to 326 for return are connected in anti-parallel to the switching elements 311 to 316, respectively.

[0035] The drive circuit 350 generates drive signals Sr1 to Sr6 based on PWM (Pulse Width Modulation) signals Sm1 to Sm6 output from the control device 100. The drive circuit 350 controls the on and off of the switching elements 311 to 316 by the drive signals Sr1 to Sr6. Thus, the inverter 30 can supply a three-phase AC voltage with a variable frequency and a variable voltage to the motor 7 via the output lines 331 to 333.

[0036] The PWM signals Sm1 to Sm6 are signals having a signal level of a logic circuit, that is, a magnitude of 0V to 5V. The PWM signals Sm1 to Sm6 are signals with a ground potential of the control device 100 as a reference potential. On the other hand, the drive signals Sr1 to Sr6 are signals having a voltage level required for controlling the switching elements 311 to 316, for example, a magnitude of -15V to +15V. The drive signals Sr1 to Sr6 are signals with a potential of the negative terminal, that is, the emitter terminal, of the corresponding switching elements 311 to 316 as a reference potential.

[0037] The motor 7 rotates according to the amplitude and phase of the second AC power supplied from the inverter 30. The motor 7 is used, for example, for a compression operation in a compressor, a rotation operation in a fan, and the like. Figure 1 The motor winding of the motor 7 may be a Δ connection, or may be a specification that allows switching between the Y connection and the Δ connection.

[0038] In addition, in the power conversion device 200, Figure 1 The configuration of each structure shown is an example, and the configuration of each structure is not limited to Figure 1 The example shown. For example, the reactor 2 may also be arranged at the rear stage of the rectifier 3. In addition, the power conversion device 200 may also include a boost unit, and the rectifier 3 may also have the function of a boost unit. In the following description, the bus voltage detection unit 10 and the load current detection unit 40 are sometimes collectively referred to as detection units. In addition, the voltage value detected by the bus voltage detection unit 10 and the current value detected by the load current detection unit 40 are sometimes referred to as detection values.

[0039] The control device 100 obtains the bus voltage Vdc from the bus voltage detection unit 10 and obtains the load current Idc from the load current detection unit 40. The control device 100 uses the detection values ​​detected by each detection unit to control the operation of the inverter main circuit 310, specifically, the on-off of the switching elements 311 to 316 of the inverter main circuit 310. The control device 100 controls the rotation speed of the motor 7 by controlling the on-off of the switching elements 311 to 316 of the inverter main circuit 310. In addition, the control device 100 calculates the load torque of the motor 7. In addition, the control device 100 may not use all the detection values ​​obtained from each detection unit, but may use a part of the detection values ​​for control. In the present embodiment, the control device 100 performs control in a rotating coordinate system having a d-axis and a q-axis.

[0040] The detailed structure and operation of the control device 100 will be described. Figure 3This is a block diagram showing a configuration example of the control device 100 included in the power conversion device 200 according to Embodiment 1. The control device 100 includes an operation control unit 102 and an inverter control unit 110 .

[0041] The operation control unit 102 obtains the command information Qe from the outside. For example, when the power conversion device 200 is mounted on an air conditioner as a refrigeration cycle application device, the command information Qe is based on information indicating the temperature detected by a temperature sensor (not shown), information indicating the set temperature indicated by a remote controller (not shown) as an operating unit, information on the selection of the operation mode, and information indicating the start and end of the operation. Examples of the operation mode are heating, cooling, dehumidification, etc. Based on the command information Qe, the operation control unit 102 generates a frequency command value ωe, which is a command value for generating a voltage to be applied to the motor 7, i.e., a voltage command value. * The operation control unit 102 controls the frequency command value ωe * The command value of the rotation speed of the motor 7, that is, the rotation angular velocity command value ωm * The frequency command value ωe is multiplied by the number of pole pairs Pm of the motor 7. In addition, the operation control unit 102 generates a stop signal St, which is a signal for stopping the operation of the inverter 30, based on the command information Qe. The operation control unit 102 generates a stop signal St, which is a signal for stopping the operation of the inverter 30. * The voltage command value calculation unit 115 outputs the stop signal St to the PWM signal generation unit 118 of the inverter control unit 110 .

[0042] The inverter control unit 110 includes a current recovery unit 111 , a 3-phase to 2-phase conversion unit 112 , a d-axis current command value generation unit 113 , a voltage command value calculation unit 115 , an electric phase calculation unit 116 , a 2-phase to 3-phase conversion unit 117 , and a PWM signal generation unit 118 .

[0043] The current recovery unit 111 recovers the phase currents iu, iv, and iw flowing through the motor 7 based on the load current Idc detected by the load current detection unit 40. The current recovery unit 111 samples the load current Idc detected by the load current detection unit 40 at a timing determined based on the PWM signals Sm1 to Sm6 generated by the PWM signal generation unit 118, thereby recovering the phase currents iu, iv, and iw.

[0044] The 3-phase to 2-phase conversion unit 112 uses the electric phase θe generated by the electric phase calculation unit 116 described later to convert the phase currents iu, iv, iw recovered by the current recovery unit 111 into a d-axis current id as an excitation current and a q-axis current iq as a torque current, that is, current values ​​of the dq axes.

[0045] The d-axis current command value generating unit 113 generates the d-axis current command value Id in the aforementioned rotating coordinate system.* Specifically, the d-axis current command value generating unit 113 generates a d-axis current command value based on the q-axis current iq, the bus voltage Vdc, and the d-axis voltage command value Vd * And the q-axis voltage command value Vq * , find the most appropriate d-axis current command value Id with the best efficiency * , to drive the motor 7. The d-axis current command value generating unit 113 generates a d-axis current command value based on the q-axis current iq, the bus voltage Vdc, and the d-axis voltage command value Vd * And the q-axis voltage command value Vq * The output becomes the d-axis current command value Id with the current phase βm as follows * At this current phase βm, the output torque of the motor 7 becomes greater than or equal to a predetermined value or is at a maximum, that is, the current value becomes less than or equal to a predetermined value or is at a minimum. In addition, here, the d-axis current command value generating unit 113 obtains the d-axis current command value Id based on the q-axis current iq, etc. * , but this is an example and is not limited to this. The d-axis current command value generating unit 113 can generate the d-axis current command value based on the d-axis current id and the frequency command value ωe * The d-axis current command value Id is obtained * , the same effect can be obtained. In addition, the d-axis current command value generating unit 113 can also determine the d-axis current command value Id by using a weak magnetic flux control or the like. * .

[0046] The voltage command value calculation unit 115 calculates the frequency command value ωe obtained from the operation control unit 102 based on the frequency command value ωe. * , the d-axis current id and the q-axis current iq obtained from the 3-phase to 2-phase conversion unit 112, and the d-axis current command value Id obtained from the d-axis current command value generation unit 113 * , generate the d-axis voltage command value Vd * and q-axis voltage command value Vq * Furthermore, the voltage command value calculation unit 115 calculates the voltage command value Vd based on the d-axis voltage command value Vd * , q-axis voltage command value Vq * , d-axis current id, and q-axis current iq, and estimate the frequency estimation value ωest.

[0047] The electric phase calculation unit 116 calculates the electric phase θe by integrating the frequency estimated value ωest obtained from the voltage command value calculation unit 115 .

[0048] The 2-phase to 3-phase converter 117 uses the electric phase θe obtained from the electric phase calculator 116 to convert the d-axis voltage command value Vd obtained from the voltage command value calculator 115 into * and q-axis voltage command value Vq *That is, the voltage command value of the two-phase coordinate system is converted into the output voltage command value of the three-phase coordinate system, that is, the three-phase voltage command value Vu * 、Vv * 、Vw * .

[0049] The PWM signal generation unit 118 generates a 3-phase voltage command value Vu based on the 3-phase voltage command value Vu obtained from the 2-phase to 3-phase conversion unit 117. * 、Vv * 、Vw * The PWM signals Sm1 to Sm6 are generated by the PWM signal generating unit 118 and the stop signal St obtained from the operation control unit 102. The PWM signal generating unit 118 stops outputting the PWM signals Sm1 to Sm6 based on the stop signal St, thereby also being able to stop the motor 7.

[0050] The configuration and operation of the voltage command value calculation unit 115 will be described in detail. Figure 4 1 is a block diagram showing a configuration example of a voltage command value calculation unit 115 included in the control device 100 of the power conversion device 200 according to Embodiment 1. The voltage command value calculation unit 115 includes a frequency estimation unit 501, addition and subtraction units 502, 504, 505, 509, and 513, a speed control unit 503, a d-axis current control unit 506, a q-axis current control unit 507, multiplication units 508, 510, and 512, and an addition unit 511.

[0051] The frequency estimation unit 501 calculates the frequency of the d-axis current id, the q-axis current iq, and the d-axis voltage command value Vd. * And the q-axis voltage command value Vq * , to estimate the frequency of the voltage supplied to the motor 7 and output it as the frequency estimated value ωest. Figure 4 The frequency estimation value ωest output from the frequency estimation unit 501 to the voltage command value calculation unit 115 is Figure 3 The frequency estimated value ωest output from the voltage command value calculation unit 115 to the electric phase calculation unit 116. The adder and subtractor 502 calculates the frequency estimated value ωest from the frequency command value ωe * Subtract the frequency estimate ωest and output the frequency command value ωe * The frequency deviation del_ω from the frequency estimate ωest.

[0052] The speed control unit 503 calculates and outputs the q-axis current command value Iq based on the frequency deviation del_ω. * q-axis current command value Iq * is the command value of the q-axis current iq that makes the frequency deviation del_ω zero, that is, the frequency command value ωe *The command value of the q-axis current iq is consistent with the frequency estimation value ωest. The speed control unit 503 is, for example, a proportional-integral (PI) controller, but is not limited thereto.

[0053] The adding and subtracting unit 504 calculates the d-axis current command value Id from * Subtract the d-axis current id and output the d-axis current command value Id * The d-axis current control unit 506 performs PI control and, in parallel, performs control to reduce the pulsation component caused by the dead time of the switching elements 311 to 316 of the inverter 30 and the induced voltage distortion of the motor 7, so that the d-axis current command value Id * The d-axis current control unit 506 operates so that the deviation from the d-axis current id converges to zero. The d-axis current control unit 506 outputs the first d-axis voltage command value Vdfb * The detailed structure and operation of the d-axis current control unit 506 will be described later.

[0054] The addition and subtraction unit 505 uses the q-axis current command value Iq * Subtract the q-axis current iq and output the q-axis current command value Iq * The q-axis current control unit 507 performs PI control and, in parallel, performs control to reduce the pulsation component caused by the dead time of the switching elements 311 to 316 of the inverter 30 and the induced voltage distortion of the motor 7, so that the q-axis current command value Iq * The q-axis current control unit 507 operates so that the deviation from the q-axis current iq converges to zero. The q-axis current control unit 507 outputs the first q-axis voltage command value Vqfb * The detailed structure and operation of the q-axis current control unit 507 will be described later.

[0055] The multiplication unit 508 performs a multiplication on the q-axis current command value Iq. * The q-axis inductance Lq of the motor 7 and the frequency estimation value ωest are multiplied to calculate and output the first d-axis voltage command value Vdfb * Compensation value Vdff * The addition and subtraction unit 509 calculates the first d-axis voltage command value Vdfb from * Subtract the compensation value Vdff * , the 1d-axis voltage command value Vdfb * and compensation value Vdff * Deviation (Vdfb * -Vdff * ) That is, the second d-axis voltage command value is the d-axis voltage command value Vd from the voltage command value calculation unit 115. * And output.

[0056] The multiplication unit 510 performs the calculation on the d-axis current command value Id. * The output from the multiplication unit 510 is multiplied by the d-axis inductance Ld of the motor 7 and outputted. The adding unit 511 adds the output from the multiplication unit 510 to the magnetic flux linkage vector Ld of the motor 7. The multiplication unit 512 multiplies the output from the addition unit 511 by the frequency estimation value ωest, and calculates and outputs the first q-axis voltage command value Vqfb * Compensation value Vqff * The adder and subtractor 513 calculates the first q-axis voltage command value Vqfb from * Subtract the compensation value Vqff * , the 1q-axis voltage command value Vqfb * and compensation value Vqff * Deviation (Vqfb * -Vqff * ) That is, the second q-axis voltage command value is the q-axis voltage command value Vq from the voltage command value calculation unit 115. * And output.

[0057] Next, the control of the control device 100 in the power conversion device 200 to reduce the harmonic components of six times the power supply frequency of the first AC power supplied from the commercial power supply 1, which are included in the d-axis current id and the q-axis current iq, will be described. In the following description, in order to simplify the description, the harmonic components of six times the power supply frequency of the first AC power supplied from the commercial power supply 1 will be described as electrical 6f components. Specifically, in the voltage command value calculation unit 115 of the control device 100, the d-axis current control unit 506 performs a reduction control to reduce the electrical 6f component included in the d-axis current id, and the q-axis current control unit 507 performs a reduction control to reduce the electrical 6f component included in the q-axis current iq. The detailed structure and operation of the d-axis current control unit 506 and the q-axis current control unit 507 will be described below.

[0058] Figure 5 1 is a block diagram showing a configuration example of a d-axis current control unit 506 included in the voltage command value calculation unit 115 of the control device 100 in the power conversion device 200 according to the first embodiment. The d-axis current control unit 506 includes a d-axis current PI control unit 601, multiplication units 602, 603, 610, 611, low-pass filters 604, 605, addition and subtraction units 606, 607, PI control units 608, 609, and addition units 612, 613. Figure 5 As shown, in the d-axis current control unit 506 , the d-axis current PI control unit 601 performs control in parallel with the configurations from the multiplication unit 602 to the addition unit 612 .

[0059] In the normal voltage command value calculation unit 115, the d-axis current PI control unit 601 is a d-axis current command value Id output from the addition and subtraction unit 504. * The d-axis current PI control unit 601 outputs a d-axis voltage command value V * d_PI.

[0060] The multiplication unit 602 first multiplies the deviation Id_err by cos(ωe6f) in order to extract the cos component of the electrical 6f component included in the deviation Id_err output from the addition and subtraction unit 504. ωe6f is obtained by multiplying the electrical phase θe calculated by the electrical phase calculation unit 116 by six. The d-axis current control unit 506 may calculate ωe6f internally or calculate ωe6f using the electrical phase θe calculated by the electrical phase calculation unit 116. The value calculated by the multiplication unit 602 includes, in addition to the pulsation component having a frequency of ωe6f, a pulsation component having a frequency higher than ωe6f, i.e., a higher harmonic component.

[0061] The multiplication unit 603 first multiplies the deviation Id_err by sin(ωe6f) in order to extract the sin component from the electrical 6f component included in the deviation Id_err output from the addition and subtraction unit 504. ωe6f is the same as the ωe6f used by the multiplication unit 602. The value calculated by the multiplication unit 603 includes, in addition to the pulsation component having a frequency of ωe6f, a pulsation component having a frequency higher than ωe6f, that is, a higher harmonic component.

[0062] The low-pass filters 604 and 605 are first-order lag filters whose transfer function is represented by 2 / (1+Tf·s). Here, s is the Laplace operator. Tf is a time constant, which is determined to remove the pulsating component of a frequency higher than the frequency ωe6f. In addition, "removal" includes the situation where a part of the pulsating component is attenuated, that is, reduced. Regarding the time constant Tf, it can be set by the operation control unit 102 based on the speed instruction and notified to the low-pass filters 604 and 605 by the operation control unit 102, or the time constant Tf can be maintained by the low-pass filters 604 and 605. Regarding the low-pass filters 604 and 605, a first-order lag filter is an example, and a moving average filter or the like can also be used. As long as the pulsating component on the high-frequency side can be removed, the type of filter is not limited. In addition, the amplitude of the low-pass filters 604 and 605 becomes 1 / 2 in the filter processing, and therefore, it is set to 2 times by the denominator "2" of the transfer function.

[0063] The low-pass filter 604 performs low-pass filtering on the output from the multiplication unit 602, removes the pulsation component with a frequency higher than the frequency ωe6f, and outputs the low-frequency component Ide_6f_cos. The low-frequency component Ide_6f_cos is a DC value representing the cosine component with a frequency of ωe6f in the pulsation component of the deviation Id_err.

[0064] The low-pass filter 605 performs low-pass filtering on the output from the multiplication unit 603, removes the pulsation component with a frequency higher than the frequency ωe6f, and outputs the low-frequency component Ide_6f_sin. The low-frequency component Ide_6f_sin is a DC value representing the sin component with a frequency of ωe6f in the pulsation component of the deviation Id_err.

[0065] The addition and subtraction unit 606 calculates the difference (Ide_6f_cos-0) between the low-frequency component Ide_6f_cos output from the low-pass filter 604 and the command value 0. Here, since the low-frequency component Ide_6f_cos is to be reduced, that is, ideally, to be 0, the command value is set to 0. The control device 100 may also set the command value to a value other than 0 as long as the level can satisfy control stability, noise, etc.

[0066] The addition and subtraction unit 607 calculates the difference (Ide_6f_sin-0) between the low-frequency component Ide_6f_sin output from the low-pass filter 605 and the command value 0. Here, since the low-frequency component Ide_6f_sin is to be reduced, that is, ideally to be 0, the command value is set to 0. The control device 100 may also set the command value to a value other than 0 as long as the level can satisfy control stability, noise, etc.

[0067] PI control unit 608 performs proportional integral operation on the difference (Ide_6f_cos-0) calculated by addition and subtraction unit 606, and calculates the cos component of the current command value that makes the difference (Ide_6f_cos-0) close to 0. PI control unit 608 performs control for making the low-frequency component Ide_6f_cos coincide with 0 by generating the cos component of the current command value in this way.

[0068] PI control unit 609 performs proportional integral operation on the difference (Ide_6f_sin-0) calculated by addition and subtraction unit 607, and calculates the sin component of the current command value that makes the difference (Ide_6f_sin-0) close to 0. PI control unit 609 performs control for making the low-frequency component Ide_6f_sin coincide with 0 by generating the sin component of the current command value in this way.

[0069] The multiplication unit 610 multiplies the cosine component of the current command value output from the PI control unit 608 by cos(ωe6f). As described above, the output from the low-pass filter 604 is a DC quantity, and therefore, the calculations of the addition and subtraction unit 606 and the PI control unit 608 are based on the DC quantity. Therefore, the multiplication unit 610 generates a command value having an AC component of ωe6f by multiplying the cosine component of the current command value output from the PI control unit 608 by cos(ωe6f).

[0070] The multiplication unit 611 multiplies the sin component of the current command value output from the PI control unit 609 by sin(ωe6f). As described above, the output from the low-pass filter 605 is a DC quantity, and therefore, the calculations of the addition and subtraction unit 607 and the PI control unit 609 are based on the DC quantity. Therefore, the multiplication unit 611 generates a command value having an AC component of ωe6f by multiplying the sin component of the current command value output from the PI control unit 609 by sin(ωe6f).

[0071] The adding unit 612 adds the command value having the AC component ωe6f calculated by the multiplying unit 610 and the command value having the AC component ωe6f calculated by the multiplying unit 611, and generates and outputs a d-axis voltage command value V for compensating the d-axis current PI control unit 601. * Compensation value V of the AC value of d_PI * d_ωe_6f.

[0072] The adding unit 613 adds the d-axis voltage command value V calculated by the d-axis current PI control unit 601 to * d_PI and the compensation value V calculated by the adding unit 612 * d_ωe_6f is added to generate and output the 1d-axis voltage command value Vdfb * .

[0073] Figure 6 1 is a block diagram showing a configuration example of a q-axis current control unit 507 included in the voltage command value calculation unit 115 of the control device 100 in the power conversion device 200 according to the first embodiment. The q-axis current control unit 507 includes a q-axis current PI control unit 621, multiplication units 622, 623, 630, 631, low-pass filters 624, 625, addition and subtraction units 626, 627, PI control units 628, 629, and addition units 632, 633. Figure 6 As shown, in the q-axis current control unit 507, the q-axis current PI control unit 621 and the configuration from the multiplication unit 622 to the addition unit 632 are controlled in parallel.

[0074] In the normal voltage command value calculation unit 115, the q-axis current PI control unit 621 controls the q-axis current command value Iq output from the addition and subtraction unit 505. * The q-axis current PI control unit 621 outputs a q-axis voltage command value V * q_PI.

[0075] The multiplication unit 622 first multiplies the deviation Iq_err by cos(ωe6f) in order to extract the cos component of the electrical 6f component included in the deviation Iq_err output from the addition and subtraction unit 505. ωe6f is obtained by multiplying the electrical phase θe calculated by the electrical phase calculation unit 116 by six. The q-axis current control unit 507 may calculate ωe6f internally or calculate ωe6f using the electrical phase θe calculated by the electrical phase calculation unit 116. The value calculated by the multiplication unit 622 includes, in addition to the pulsating component having a frequency of ωe6f, a pulsating component having a frequency higher than ωe6f, i.e., a higher harmonic component.

[0076] The multiplication unit 623 first multiplies the deviation Iq_err by sin(ωe6f) in order to extract the sin component from the electrical 6f component included in the deviation Iq_err output from the addition and subtraction unit 505. ωe6f is the same as the ωe6f used by the multiplication unit 622. The value calculated by the multiplication unit 623 includes, in addition to the pulsation component having a frequency of ωe6f, a pulsation component having a frequency higher than ωe6f, that is, a higher harmonic component.

[0077] The low-pass filters 624 and 625 are first-order lag filters whose transfer function is represented by 2 / (1+Tf·s). Here, s is the Laplace operator. Tf is a time constant, which is determined to remove the pulsating component of a frequency higher than the frequency ωe6f. In addition, "removal" includes the situation where a part of the pulsating component is attenuated, that is, reduced. Regarding the time constant Tf, it can be set by the operation control unit 102 based on the speed instruction and notified to the low-pass filters 624 and 625 by the operation control unit 102, or it can be maintained by the low-pass filters 624 and 625. Regarding the low-pass filters 624 and 625, a first-order lag filter is an example, and a moving average filter or the like can also be used. As long as the pulsating component on the high-frequency side can be removed, the type of filter is not limited. In addition, the amplitude of the low-pass filters 624 and 625 becomes 1 / 2 in the filter processing, and therefore is set to 2 times by the denominator "2" of the transfer function.

[0078] The low-pass filter 624 performs low-pass filtering on the output from the multiplication unit 622, removes the pulsation component with a frequency higher than the frequency ωe6f, and outputs the low-frequency component Iqe_6f_cos. The low-frequency component Iqe_6f_cos is a DC value representing the cosine component with a frequency of ωe6f in the pulsation component of the deviation Iq_err.

[0079] The low-pass filter 625 performs low-pass filtering on the output from the multiplication unit 623, removes the pulsation component with a frequency higher than the frequency ωe6f, and outputs the low-frequency component Iqe_6f_sin. The low-frequency component Iqe_6f_sin is a DC value representing the sin component with a frequency of ωe6f in the pulsation component of the deviation Iq_err.

[0080] The addition and subtraction unit 626 calculates the difference (Iqe_6f_cos-0) between the low-frequency component Iqe_6f_cos output from the low-pass filter 624 and the command value 0. Here, since the low-frequency component Iqe_6f_cos is to be reduced, that is, ideally, to be 0, the command value is set to 0. The control device 100 may also set the command value to a value other than 0 as long as the level can satisfy control stability, noise, etc.

[0081] The addition and subtraction unit 627 calculates the difference (Iqe_6f_sin-0) between the low-frequency component Iqe_6f_sin output from the low-pass filter 625 and the command value 0. Here, since the low-frequency component Iqe_6f_sin is to be reduced, that is, ideally to be 0, the command value is set to 0. The control device 100 may also set the command value to a value other than 0 as long as the level can satisfy control stability, noise, etc.

[0082] The PI control unit 628 performs a proportional integral operation on the difference (Iqe_6f_cos-0) calculated by the addition and subtraction unit 626, and calculates the cos component of the current command value that makes the difference (Iqe_6f_cos-0) close to 0. The PI control unit 628 performs control for making the low-frequency component Iqe_6f_cos coincide with 0 by generating the cos component of the current command value in this way.

[0083] The PI control unit 629 performs a proportional integral operation on the difference (Iqe_6f_sin-0) calculated by the addition and subtraction unit 627, and calculates the sin component of the current command value that makes the difference (Iqe_6f_sin-0) close to 0. The PI control unit 629 performs control for making the low-frequency component Iqe_6f_sin consistent with 0 by generating the sin component of the current command value in this way.

[0084] The multiplication unit 630 multiplies the cosine component of the current command value output from the PI control unit 628 by cos(ωe6f). As described above, the output from the low-pass filter 624 is a DC quantity, and therefore, the calculations of the addition and subtraction unit 626 and the PI control unit 628 are based on the DC quantity. Therefore, the multiplication unit 630 generates a command value having an AC component of ωe6f by multiplying the cosine component of the current command value output from the PI control unit 628 by cos(ωe6f).

[0085] The multiplication unit 631 multiplies the sin component of the current command value output from the PI control unit 629 by sin(ωe6f). As described above, the output from the low-pass filter 625 is a DC quantity, and therefore, the calculations of the addition and subtraction unit 627 and the PI control unit 629 are based on the DC quantity. Therefore, the multiplication unit 631 generates a command value having an AC component of ωe6f by multiplying the sin component of the current command value output from the PI control unit 629 by sin(ωe6f).

[0086] The adding unit 632 adds the command value having the AC component ωe6f calculated by the multiplying unit 630 and the command value having the AC component ωe6f calculated by the multiplying unit 631, and generates and outputs a q-axis voltage command value V for compensating the q-axis current PI control unit 621. * Compensation value V of the AC value of q_PI * q_ωe_6f.

[0087] The adding unit 633 calculates the q-axis voltage command value V calculated by the q-axis current PI control unit 621. * q_PI and the compensation value V calculated by the adding unit 632 * q_ωe_6f is added to generate and output the first q-axis voltage command value Vqfb * .

[0088] In this way, the control device 100 implements a reduction control to reduce the pulsating component superimposed on the three-phase current output from the inverter 30 to the motor 7, and the pulsating component is generated due to the dead time of the switching elements 311 to 316 provided in the inverter 30 and the influence of the induced voltage distortion of the motor 7. The three-phase current refers to the phase currents iu, iv, and iw restored by the current recovery unit 111. Specifically, the control device 100 converts the three-phase current into a d-axis current id and a q-axis current iq represented by a dq rotating coordinate system, and in parallel with the current control, performs a control to extract a pulsating component of a frequency six times the power supply frequency of the commercial power supply 1 contained in the d-axis current id and the q-axis current iq and reduce the extracted pulsating component, generates a voltage command value, and controls the operation of the switching elements 311 to 316 of the inverter 30. In fact, in the voltage command value calculation unit 115 of the control device 100, the d-axis current control unit 506 performs a reduction control to reduce the electric 6f component included in the d-axis current id, and the q-axis current control unit 507 performs a reduction control to reduce the electric 6f component included in the q-axis current iq. Thus, the control device 100 can reduce the pulsation component of the electric 6f component generated by the dead time of the switching elements 311 to 316 provided in the inverter 30 and the influence of the induced voltage distortion of the motor 7.

[0089] In addition, the electrical 6f component is a pulsating component when the three-phase current flowing from the inverter 30 of the power conversion device 200 to the motor 7 is converted into a d-axis current id and a q-axis current iq of a dq coordinate system having a d-axis and a q-axis. The pulsating component of the electrical 6f component superimposed on the d-axis current id and the q-axis current iq is expressed as a pulsating component of the electrical 5f component or a pulsating component of the electrical 7f component in the state of the three-phase current flowing from the inverter 30 of the power conversion device 200 to the motor 7. Figure 3 In FIG. 1 , the different methods of expressing the pulsation components are shown by “6f” and “5f, 7f” before and after the control of the 3-phase 2-phase conversion unit 112 and before and after the control of the 2-phase 3-phase conversion unit 117. In this way, the control device 100 can be said to control so as to reduce the pulsation components of 5 times and 7 times the power supply frequency of the commercial power supply 1 generated in the three-phase current, and can also be said to control so as to reduce the pulsation components of 6 times the power supply frequency of the commercial power supply 1 generated in the d-axis current id and the q-axis current iq represented in the dq rotating coordinate system after the three-phase current is converted.

[0090] Effects obtained by the reduction control performed by the control device 100 of the present embodiment will be described. Figure 7 As a comparative example, this diagram shows an example of the operating state of the power conversion device 200 when the control device 100 of the power conversion device 200 according to the first embodiment does not perform the reduction control for reducing the pulsation of the electric 6f component included in the current. Figure 8 1 is a diagram showing an example of the operating state of the power conversion device 200 when the control device 100 of the power conversion device 200 according to the first embodiment performs a reduction control for reducing the pulsation of the electric 6f component included in the q-axis current iq.

[0091] Fig. 9 1 is a diagram showing an example of the operating state of the power conversion device 200 when the control device 100 of the power conversion device 200 according to the first embodiment performs a reduction control for reducing the pulsation of the electric 6f component included in the d-axis current id and the q-axis current iq. Figures 7 to 9 In the first graph from the top, the actual rotation speed of the motor 7 is indicated by a solid line, the estimated rotation speed of the motor 7 is indicated by a dotted line, and the rotation speed command value for the motor 7 is indicated by a dashed line. In the second graph from the top, the load torque of the motor 7 is indicated by a solid line, and the output torque of the inverter 30 for the motor 7 is indicated by a dotted line. In the third graph from the top, the d-axis current id is indicated by a solid line, and the d-axis current command value id is indicated by a dotted line. * In the fourth graph from the top, the q-axis current command value iq is indicated by a solid line. * , and the q-axis current iq is indicated by a dotted line. The graph in the fifth section from the top shows the three-phase current. The graph in the sixth section from the top shows the three-phase induced voltage with the most distortion caused by the pulsating component of the electric current 5f. In addition, in all graphs, the horizontal axis represents time.

[0092] When compared Figure 7 and Figure 8 , it can be seen that the control device 100 reduces the pulsation component of the electric 6f by taking the q-axis current iq as the object, and thus greatly improves the output torque of the inverter 30 for the motor 7 and the q-axis current iq, that is, the pulsation component is greatly reduced. It can also be seen that the pulsation component is reduced for the d-axis current id and the three-phase current. Since the output torque of the inverter 30 is mainly determined by the q-axis current iq, the q-axis voltage, etc., the control device 100 can obtain the above effect even if it only takes the q-axis current iq as the object. In addition, when comparing Figure 8 and Fig. 9 It can be seen that the control device 100 also controls the d-axis current id as a target to reduce the pulsation component of the electric current 6f, and thus the d-axis current id and the three-phase current are greatly improved, that is, the pulsation component is greatly reduced. Figures 7 to 9In the embodiment, although it is not described that the control device 100 performs control to reduce the pulsation component of the electric current 6f by taking the d-axis current id as the object, the control device 100 can also perform control to reduce the pulsation component of the electric current 6f by taking only the d-axis current id as the object without taking the q-axis current iq as the object. For example, when the control device 100 generates noise that does not contribute to the torque in the power conversion device 200 or the motor 7 due to the pulsation of the d-axis current id, there is a possibility that the noise can be improved by performing control to reduce the pulsation component of the electric current 6f by taking only the d-axis current id as the object.

[0093] The operation of the control device 100 of the power conversion device 200 which is characteristic of the first embodiment will be described using a flowchart. Fig.10 2 is a flowchart showing the operation of the power conversion device 200 according to the first embodiment. In the power conversion device 200, the control device 100 controls the d-axis current command value Id * The control device 100 performs current control based on the deviation Id_err from the d-axis current id (step S1). * The pulsating component of the electrical 6f component of the d-axis current id is extracted from the deviation Id_err from the d-axis current id (step S2). The control device 100 actually separates the pulsating component of the electrical 6f component into the cosine component and the sinine component as described above, and extracts the pulsating component of the electrical 6f component from the deviation Id_err. The control device 100 generates a compensation value V such that the pulsating component of the extracted electrical 6f component becomes 0. * d_ωe_6f (step S3). The control device 100 uses the compensation value V * d_ωe_6f is used to compensate the d-axis current command value Id * The d-axis voltage command value V is the value obtained by implementing current control based on the deviation Id_err from the d-axis current id. * d_PI (step S4), thereby generating and outputting the first d-axis voltage command value Vdfb * Then, the control device 100 further uses the compensation value Vdff calculated using the q-axis inductance Lq of the motor 7 and the like. * To compensate the 1d-axis voltage command value Vdfb * , thereby generating the d-axis voltage command value Vd * .

[0094] Similarly, the control device 100 controls the q-axis current command value Iq * The control device 100 performs current control based on the deviation Iq_err from the q-axis current iq (step S5). *The pulsating component of the electrical 6f component of the q-axis current iq is extracted from the deviation Iq_err from the q-axis current iq (step S6). In practice, as described above, the control device 100 extracts the pulsating component of the electrical 6f component from the deviation Iq_err by separating it into a cos component and a sin component. The control device 100 generates a compensation value V such that the pulsating component of the extracted electrical 6f component becomes zero. * q_ωe_6f (step S7). The control device 100 uses the compensation value V * q_ωe_6f is used to compensate for the q-axis current command value Iq * The q-axis voltage command value V is the value obtained by implementing current control based on the deviation Iq_err from the q-axis current iq. * q_PI (step S8), thereby generating and outputting the first q-axis voltage command value Vqfb * Then, the control device 100 further uses the compensation value Vqff calculated using the d-axis inductance Ld of the motor 7 and the like. * To compensate the 1st q-axis voltage command value Vqfb * , thereby generating the q-axis voltage command value Vq * .

[0095] In addition, the control device 100 may perform the operations of step S1 to step S4 and the operations of step S5 to step S8 in parallel, or may perform the operations of step S5 to step S8 first.

[0096] Next, the hardware configuration of the control device 100 included in the power conversion device 200 will be described. Fig.11 1 is a diagram showing an example of a hardware configuration for realizing the control device 100 included in the power conversion device 200 according to Embodiment 1. The control device 100 is realized by a processor 91 and a memory 92 .

[0097] The processor 91 is a CPU (also called a Central Processing Unit, a central processing device, a processing device, an arithmetic device, a microprocessor, a microcomputer, a processor, a DSP (Digital Signal Processor), or a system LSI (Large Scale Integration). The memory 92 can be exemplified by a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable ROM), or an EEPROM (registered trademark) (Electrically EPROM). In addition, the memory 92 is not limited thereto, and may be a magnetic disk, an optical disk, a high-density disk, a mini disk, or a DVD (Digital Versatile Disc).

[0098] As described above, according to the present embodiment, in the power conversion device 200, the control device 100 performs the reduction control for reducing the pulsation component superimposed on the electrical 6f component of the d-axis current id in the d-axis current control unit 506, and performs the reduction control for reducing the pulsation component superimposed on the electrical 6f component of the q-axis current iq in the q-axis current control unit 507. As a result, the control device 100 can reduce the pulsation component generated by the influence of the dead time of the switching elements 311 to 316 provided in the inverter 30 and the induced voltage distortion of the motor 7. Even when the inverter 30 is replaced and the motor 7 connected to the power conversion device 200 is replaced, the control device 100 can reduce the pulsation component generated by the influence of the dead time of the switching elements 311 to 316 provided in the inverter 30 and the induced voltage distortion of the motor 7 by performing the above reduction control. As a result, the control device 100 can suppress the decline of control stability and suppress the generation of noise.

[0099] Implementation method 2.

[0100] In the first embodiment, the case where the control device 100 of the power conversion device 200 performs a reduction control to reduce the pulsation of the electrical 6f component caused by the dead time of the switching elements 311 to 316 provided in the inverter 30 and the induced voltage distortion of the motor 7 is described. Here, the following case is also considered: when the pulsation of the electrical 6f component is of a small size, since the control device 100 of the power conversion device 200 performs the above-mentioned reduction control, control interference occurs in the control device 100 between the reduction control and the normal control of controlling the operation of the inverter 30 and the motor 7. When the control interference occurs, the control device 100 may not converge at the desired control response speed or may diverge. In the second embodiment, the case where the generation of control interference in the control device 100 of the power conversion device 200 is reduced is described.

[0101] In the second embodiment, the structure of the power conversion device 200 is the same as that of the Figure 1 The structure of the power conversion device 200 of the embodiment 1 shown in FIG. Figure 3 In the second embodiment, the control device 100 has the same structure as the control device 100 of the first embodiment. Figure 4 The configuration of the voltage command value calculation unit 115 in the first embodiment shown is different.

[0102] Fig.12 1 is a block diagram showing a configuration example of a voltage command value calculation unit 115 provided in the control device 100 of the power conversion device 200 according to the second embodiment. The voltage command value calculation unit 115 according to the second embodiment is Figure 4 The voltage command value calculation unit 115 of the illustrated first embodiment is obtained by adding a band elimination filter 521 .

[0103] The band elimination filter 521 performs a calculation based on the frequency command value ωe calculated by the addition and subtraction unit 502. * The filter process is performed to remove the pulsation of the electrical 6f component from the frequency deviation del_ω from the frequency estimated value ωest. As a result, in the control device 100, the speed control unit 503 does not adjust the frequency command value ωe calculated by the addition and subtraction unit 502. * Since the speed control is performed based on the pulsation of the electric 6f component included in the frequency deviation del_ω of the frequency estimated value ωest, it is possible to reduce the occurrence of control interference between the reduction control described in Embodiment 1 and the speed control of the speed control unit 503. In this way, the control device 100 includes the band removal filter 521 for reducing the interference between the reduction control and the speed control when generating the voltage command value for the q-axis.

[0104] Furthermore, the voltage command value calculation unit 115 may include a band-removing filter inside the d-axis current control unit 506 and the q-axis current control unit 507 .

[0105] Fig.13 2 is a block diagram showing a configuration example of a d-axis current control unit 506 included in the voltage command value calculation unit 115 of the control device 100 in the power conversion device 200 according to the second embodiment. The d-axis current control unit 506 of the second embodiment is Figure 5 The d-axis current control unit 506 of the first embodiment shown is obtained by adding a band elimination filter 614 .

[0106] The band elimination filter 614 performs a filter operation on the d-axis current command value Id calculated by the adder and subtracter 504. * The filter processing is performed to remove the pulsation of the electric 6f component from the deviation Id_err from the d-axis current id. As a result, the d-axis current PI control unit 601 does not adjust the d-axis current command value Id calculated by the addition and subtraction unit 504. * The ripple of the electric current component included in the deviation Id_err from the d-axis current id is subjected to current control processing. Therefore, the d-axis voltage command value V outputted from the d-axis current PI control unit 601 is * The pulsation of the electrical 6f component is not included in d_PI. As a result, the d-axis current control unit 506 can reduce the generation of control interference between the reduction control and the current control described in Embodiment 1. In this way, the control device 100 includes a band removal filter 614 for reducing the interference between the reduction control and the current control when generating the voltage command value for the d-axis.

[0107] Fig.14 1 is a block diagram showing a configuration example of a q-axis current control unit 507 provided in the voltage command value calculation unit 115 of the control device 100 in the power conversion device 200 according to the second embodiment. The q-axis current control unit 507 of the second embodiment is Figure 6 The q-axis current control unit 507 of the first embodiment shown is obtained by adding a band elimination filter 634 .

[0108] The band elimination filter 634 performs a calculation on the q-axis current command value Iq calculated by the addition and subtraction unit 505. * The q-axis current PI control unit 621 performs a filter process to remove the pulsation of the electric 6f component from the deviation Iq_err from the q-axis current iq. * The pulsation of the electrical 6f component included in the deviation Iq_err of the q-axis current iq is subjected to current control processing. Therefore, the q-axis voltage command value V outputted from the q-axis current PI control unit 621 is *The pulsation of the electrical 6f component is not included in q_PI. As a result, the q-axis current control unit 507 can reduce the generation of control interference between the reduction control and the current control described in Embodiment 1. In this way, the control device 100 includes a band removal filter 634 for reducing the interference between the reduction control and the current control when generating the voltage command value for the q-axis.

[0109] In addition, in Embodiment 2, Fig.12 The band removal filter 521 described in Fig.13 The band removal filter 614 described in Fig.14 The control device 100 of the power conversion device 200 may include the three band-removing filters 634 described above, or may include any one or two of them.

[0110] In addition, the control device 100 controls the control response of the step-down control so that the speed of the control response of the current control becomes a predetermined multiple or more of the speed of the control response of the step-down control, thereby reducing the occurrence of control interference between the step-down control and the current control described in the first embodiment. In the control device 100, the d-axis current control unit 506 makes the speed of the control response of the d-axis current PI control unit 601 that performs the current control become five times or more of the speed of the control response of the multiplication unit 602 to the addition unit 612 that performs the step-down control. The d-axis current control unit 506 can reduce the occurrence of control interference by separating the speed of the control response of the d-axis current PI control unit 601 that performs the current control from the speed of the control response of the multiplication unit 602 to the addition unit 612 that performs the step-down control. Similarly, in the control device 100, the q-axis current control unit 507 makes the speed of the control response of the q-axis current PI control unit 621 that performs the current control become five times or more of the speed of the control response of the multiplication unit 622 to the addition unit 632 that performs the step-down control. The q-axis current control unit 507 can reduce the occurrence of control interference by separating the control response speed of the q-axis current PI control unit 621 that performs current control from the control response speed of the multiplication unit 622 to the addition unit 632 that perform reduction control.

[0111] As described above, according to the present embodiment, in the power conversion device 200, the control device 100 includes a band elimination filter at at least one of the input stage of the speed control unit 503, the input stage of the d-axis current PI control unit 601, and the input stage of the q-axis current PI control unit 621 of the voltage command value calculation unit 115. Thus, the control device 100 can reduce the occurrence of control interference between the normal control for controlling the operation of the inverter 30 and the motor 7 and the reduction control for reducing the pulsation component generated due to the influence of the dead time of the switching elements 311 to 316 included in the inverter 30 and the induced voltage distortion of the motor 7 described in the first embodiment.

[0112] Implementation method 3.

[0113] Fig.15 Refrigeration cycle application device 900 of Embodiment 3 is a diagram showing a configuration example. Refrigeration cycle application device 900 of Embodiment 3 includes power conversion device 200 described in Embodiment 1 or Embodiment 2. Refrigeration cycle application device 900 of Embodiment 3 can be applied to products including refrigeration cycles such as air conditioners, refrigerators, freezers, and heat pump water heaters. Fig.15 In the present invention, components having the same functions as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment.

[0114] In the refrigeration cycle application equipment 900 , the compressor 8 with the motor 7 built therein, the four-way valve 902 , the indoor heat exchanger 906 , the expansion valve 908 , and the outdoor heat exchanger 910 in the first embodiment are installed via the refrigerant pipe 912 .

[0115] A compression mechanism 904 for compressing the refrigerant and a motor 7 for operating the compression mechanism 904 are provided inside the compressor 8 .

[0116] The refrigeration cycle application device 900 can perform heating operation or cooling operation by switching the four-way valve 902. The compression mechanism 904 is driven by the motor 7 which is controlled by a variable speed.

[0117] During heating operation, as shown by the solid arrow, the refrigerant is pressurized and sent out by the compression mechanism 904, and returns to the compression mechanism 904 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.

[0118] During cooling operation, as shown by the dotted arrow, the refrigerant is pressurized and sent out by the compression mechanism 904, and returns to the compression mechanism 904 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.

[0119] During heating operation, the indoor heat exchanger 906 functions as a condenser to release heat, and the outdoor heat exchanger 910 functions as an evaporator to absorb heat. During cooling operation, the outdoor heat exchanger 910 functions as a condenser to release heat, and the indoor heat exchanger 906 functions as an evaporator to absorb heat. The expansion valve 908 decompresses the refrigerant to expand it.

[0120] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, the embodiments may be combined with each other, and some configurations may be omitted or changed without departing from the spirit and scope of the invention.

[0121] Description of Reference Numerals

[0122] 1 Commercial power supply, 2 Reactor, 3 Rectification unit, 5 Smoothing capacitor, 7 Motor, 8 Compressor, 10 Bus voltage detection unit, 12a, 12b DC bus, 30 Inverter, 40 Load current detection unit, 91 Processor, 92 Memory, 100 Control device, 102 Operation control unit, 110 Inverter control unit, 111 Current recovery unit, 112 3-phase 2-phase conversion unit, 113 D-axis current command value generation unit, 115 Voltage command value calculation unit, 116 Electric phase calculation unit, 117 2-phase to 3-phase conversion unit, 118 PWM signal generation unit, 131-134, 321-326 rectification elements, 200 power conversion device, 310 inverter main circuit, 311-316 switching elements, 331-333 output lines, 350 drive circuit, 400 motor drive device, 501 frequency estimation unit, 502, 504, 505, 509, 513, 606, 607, 626, 627 addition and subtraction unit, 503 speed control unit, 506 d-axis current control unit, 507 q-axis current control unit, 508, 510, 512, 602, 603 , 610, 611, 622, 623, 630, 631 multiplication units, 511, 612, 613, 632, 633 addition units, 521, 614, 634 band removal filters, 601d-axis current PI control unit, 604, 605, 624, 625 low-pass filters, 608, 609, 628, 629 PI control units, 621q-axis current PI control unit, 900 refrigeration cycle application equipment, 902 four-way valve, 904 compression mechanism, 906 indoor heat exchanger, 908 expansion valve, 910 outdoor heat exchanger, 912 refrigerant piping.

Claims

1. A power conversion device, wherein: The power conversion device comprises: a rectifier that rectifies the first AC power supplied from the commercial power source; A capacitor connected to the output end of the rectifying unit; an inverter connected to both ends of the capacitor, generating a second AC power and outputting the second AC power to the motor; and a control device that controls the operation of the inverter to control the rotation speed of the motor, The control device performs a reduction control for reducing a pulsation component superimposed on a three-phase current output from the inverter to the motor, which is caused by the influence of a dead time of a switching element provided in the inverter and an induced voltage distortion of the motor.

2. The power conversion device according to claim 1, wherein: The control device performs control so as to reduce pulsation components at frequencies five times and seven times the power supply frequency of the commercial power supply generated in the three-phase current.

3. The power conversion device according to claim 1, wherein: The control device performs control to reduce a pulsation component having a frequency six times the power supply frequency of the commercial power supply generated in a d-axis current and a q-axis current represented in a dq rotating coordinate system after conversion of the three-phase current.

4. The power conversion device according to any one of claims 1 to 3, wherein: The control device converts the three-phase current into a d-axis current and a q-axis current represented by a dq rotating coordinate system, and in parallel with the current control, performs control to extract the pulsating component with a frequency six times the power supply frequency of the commercial power supply contained in the d-axis current and the q-axis current and reduce the extracted pulsating component, generates a voltage command value, and controls the operation of the switching element.

5. The power conversion device according to claim 4, wherein: The control device includes a band-removal filter for reducing interference between the reduction control and speed control when generating the voltage command value for the q-axis.

6. The power conversion device according to claim 4 or 5, wherein: The control device includes a band removal filter for reducing interference between the reduction control and current control when generating the voltage command value for the d-axis, and a band removal filter for reducing interference between the reduction control and current control when generating the voltage command value for the q-axis.

7. The power conversion device according to any one of claims 4 to 6, wherein: The control device controls the control response of the reduction control so that the control response speed of the current control becomes equal to or greater than a predetermined multiple of the control response speed of the reduction control.

8. A motor drive device, wherein: The motor drive device includes the power conversion device according to any one of claims 1 to 7.

9. A refrigeration cycle application device, wherein: The refrigeration cycle application equipment includes the power conversion device according to any one of claims 1 to 7.

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