Motor control device

Abstract

Provided is a motor control device with improved harmonic suppression. A virtual neutral point voltage calculation section calculates first to third virtual voltages based on first to third inter-terminal voltages of a motor, and further calculates a virtual neutral point voltage. A correction voltage calculation section calculates first to third corrected inter-terminal voltages based on the first to third inter-terminal voltages and the virtual neutral point voltage. A three-phase-dq conversion section converts the first to third corrected inter-terminal voltages into a d-axis corrected voltage and a q-axis corrected voltage. A d-axis current control section calculates a d-axis voltage command based on a d-axis command current, a d-axis current, and the d-axis corrected voltage. A q-axis current control section calculates a q-axis voltage command based on a q-axis command current, a q-axis current, and the q-axis corrected voltage.

Description

Technical Field

[0001] This disclosure relates to an electric motor control device, and more particularly to an electric motor control device capable of suppressing harmonics. Background Technology

[0002] As a motor control device, a motor control device is used that supplies sinusoidal AC voltage to each winding of the motor (U-phase winding, V-phase winding, W-phase winding). By supplying sinusoidal AC voltage to each winding of the motor, the efficiency of the motor can be improved, and noise and vibration can be reduced.

[0003] A motor control device that supplies sinusoidal AC voltage to each winding of a motor is disclosed, for example, in Japanese Patent Application Publication No. 2006-223089.

[0004] like Figure 1 As shown, the electric motor control device disclosed in Japanese Patent Application Publication No. 2006-223089 includes: a power supply device 100, which includes an inverter 121; and an inverter control device 200, which controls the inverter 121.

[0005] Inverter 121 supplies the first AC voltage to the third AC voltage (three-phase AC voltage) from the power supply terminals R, S, T to the motor terminals X, Y, Z of motor 10.

[0006] The inverter control device 200 controls the switching elements 121a to 121f constituting the inverter 121 by using known vector control, so as to supply a first AC voltage to a third AC voltage of sinusoidal waves to the motor terminals X, Y, and Z of the motor 10.

[0007] Specifically, the terminal currents Ix, Iy, and Iz flowing at the motor terminals X, Y, and Z are detected by the terminal current detection unit 210.

[0008] Then, the three-phase-dq conversion unit 220 converts the terminal currents Ix, Iy, and Iz into d-axis current Id and q-axis current Iq. The three-phase-dq conversion unit 220 includes: a three-phase-to-two-phase conversion unit that converts the three phases (Ix, Iy, Iz) into two phases (Iα, Iβ) (referred to as "Clark conversion"); and a two-phase-dq conversion unit that converts from fixed coordinates (Iα, Iβ) to rotating coordinates (Id, Iq) (referred to as "Park conversion"). When converting from fixed coordinates to rotating coordinates, the rotor's rotation angle θ is used. As a method for detecting the rotor's rotation angle θ, methods utilizing a rotation angle sensor or methods estimating it through calculation can be used.

[0009] The d-axis current control unit 230 outputs the d-axis voltage command Vd based on the d-axis current Id and the d-axis current command Ids. Similarly, the q-axis current control unit 240 outputs the q-axis voltage command Vq based on the q-axis current Iq and the q-axis current command Iqs.

[0010] The dq-three-phase conversion unit 250 converts the d-axis voltage command Vd and the q-axis voltage command Vq into terminal voltage commands Vxa, Vya, and Vza. The dq-three-phase conversion unit 250 includes: a dq-two-phase conversion unit that converts the rotating coordinates (Vd, Vq) into fixed coordinates (Vα, Vβ) (referred to as the "inverse Park conversion"); and a two-phase to three-phase conversion unit that converts two phases (Vα, Vβ) into three phases (Vxa, Vya, Vza) (referred to as the "inverse Clark conversion"). The rotor's rotation angle θ is also used when converting from rotating coordinates to fixed coordinates.

[0011] The drive unit 260 drives the switching elements 121a to 121f of the inverter 121 based on the terminal voltage commands Vxa, Vya, and Vza.

[0012] Figure 1 The motor control device shown can be applied to motors 10 of various structures. For example, it can be applied to... Figure 2 The first winding 21U, the second winding 21V, and the third winding 21W, as shown, are connected in a delta configuration to the motor terminals X, Y, and Z of a motor 20. Furthermore, it can also be applied to... Figure 3 The motor 30, as shown, has its first winding 31U, second winding 31V, and third winding 31W connected in a star configuration to the motor terminals X, Y, and Z.

[0013] Existing technical documents

[0014] Japanese Patent Application Publication No. 2006-223089

[0015] The problem the invention aims to solve

[0016] Typically, the impedances of each winding of the motor and the parameters of the inverter control circuit are set to supply a sinusoidal AC voltage to each winding. For example, the waveforms of the voltages Vxy, Vyz, and Vzx between the terminals are set as follows: Figure 4 The sine wave shown.

[0017] However, due to load variations, the waveforms of the voltages Vxy, Vyz, and Vzx between terminals may sometimes become waveforms containing harmonics.

[0018] Here, as Figure 5As shown, when the waveforms of the voltages Vxy, Vyz, and Vzx between each terminal become the same trapezoidal waveform (containing the same harmonics), even vector synthesis cannot control the inverter to suppress harmonic components.

[0019] In particular, when the first to third windings are connected in a delta configuration, harmonic currents flow through the closed circuit formed by the first to third windings, thus increasing losses.

[0020] The purpose of this disclosure is to provide a technique that can improve harmonic suppression.

[0021] Solution for solving the problem

[0022] The first disclosure relates to an electric motor control device comprising: an inverter that supplies a first AC voltage to a third AC voltage to a first motor terminal to a third motor terminal connected to a first winding to a third winding; and an inverter control device that controls the inverter to make the first AC voltage to the third AC voltage a sine wave.

[0023] The first disclosed motor control device suppresses harmonics based on voltage.

[0024] The inverter control device disclosed herein has a voltage correction unit, which includes an inter-terminal voltage detection unit, a virtual neutral point voltage calculation unit, and a correction voltage output unit.

[0025] The terminal voltage detection unit detects the first terminal voltage between the first motor terminal and the second motor terminal, the second terminal voltage between the second motor terminal and the third motor terminal, and the third terminal voltage between the third motor terminal and the first motor terminal.

[0026] The virtual neutral point voltage calculation unit calculates a first virtual voltage based on the sum of the voltage between the second and third terminals and the voltage between the first terminals; it calculates a second virtual voltage based on the sum of the voltage between the third and first terminals and the voltage between the second terminals; and it calculates a third virtual voltage based on the sum of the voltage between the first and second terminals and the voltage between the third terminals. Furthermore, the virtual neutral point voltage calculation unit calculates the virtual neutral point voltage based on the first to third virtual voltages.

[0027] The correction voltage output unit outputs the correction voltage based on the virtual neutral point voltage.

[0028] Furthermore, the inverter control device controls the inverter based on the correction voltage, thereby correcting the waveforms of the first AC voltage to the third AC voltage.

[0029] By using the first disclosed motor control device, the harmonic suppression effect can be improved.

[0030] In different embodiments of the first disclosed motor control device, the virtual neutral point voltage calculation unit calculates the voltage by using [first virtual voltage = (second terminal voltage + third terminal voltage - first terminal voltage) / (2 × 3)]. 1 / 2 [Second virtual voltage = (Third terminal voltage + First terminal voltage - Second terminal voltage) / (2 × 3)] 1 / 2 [The third virtual voltage = (voltage between the first terminal + voltage between the second terminal - voltage between the third terminal) / (2 × 3)] 1 / 2 The virtual neutral point voltage calculation unit calculates the first to third virtual voltages using the formula [virtual neutral point voltage = first virtual voltage + second virtual voltage + third virtual voltage].

[0031] In this method, the virtual neutral point voltage can be easily calculated.

[0032] In different embodiments of the first disclosed motor control device, the correction voltage output unit also includes a correction voltage calculation unit.

[0033] The correction voltage calculation unit calculates the correction voltage, which includes the first correction voltage to the third correction voltage corresponding to the difference between each of the inter-terminal voltages from the first to the third inter-terminal voltages and the virtual neutral point voltage.

[0034] Furthermore, the correction voltage output unit outputs the correction voltage calculated by the correction voltage calculation unit.

[0035] In this method, the correction voltage can be easily calculated.

[0036] In different embodiments of the first disclosed motor control device, the correction voltage output unit also includes a correction voltage calculation unit.

[0037] The correction voltage calculation unit calculates the correction voltage, which includes a first correction voltage to a third correction voltage obtained by amplifying the first terminal voltage to the third terminal voltage with an amplification rate corresponding to the virtual neutral point voltage.

[0038] Furthermore, the correction voltage output unit outputs the correction voltage calculated by the correction voltage calculation unit.

[0039] In this method, the correction voltage can be easily calculated.

[0040] In different embodiments of the first disclosed motor control device, the correction voltage calculation unit has a three-phase-dq conversion unit that converts the first to third correction voltages into d-axis correction voltages and q-axis correction voltages.

[0041] Furthermore, the correction voltage output unit outputs a correction voltage that includes the d-axis correction voltage and the q-axis correction voltage.

[0042] In addition, the inverter control unit has a three-phase-dq conversion unit, a d-axis current control unit, a q-axis current control unit, a dq-three-phase conversion unit, and a drive unit, and controls the inverter through vector control.

[0043] The three-phase dq converter transforms the first terminal current flowing from the first motor terminal to the third motor terminal into d-axis current and q-axis current, respectively.

[0044] The d-axis current control unit outputs a corrected d-axis voltage command, which is obtained by correcting the d-axis voltage command calculated based on the d-axis current and the d-axis current command using the d-axis correction voltage.

[0045] The q-axis current control unit outputs a corrected q-axis voltage command, which is obtained by correcting the q-axis voltage command calculated based on the q-axis current and the q-axis current command using a q-axis correction voltage.

[0046] The dq-three-phase converter transforms the d-axis voltage correction command and the q-axis voltage correction command into the first AC voltage command to the third AC voltage command.

[0047] The drive unit drives the inverter based on the first AC voltage command to the third AC voltage command.

[0048] In this method, harmonics can be easily suppressed.

[0049] The second disclosure, like the first disclosure, relates to an electric motor control device comprising: an inverter that supplies a first AC voltage to a third AC voltage to a first motor terminal connected to a third motor terminal having a first winding to a third winding; and an inverter control device that controls the inverter to make the first AC voltage to the third AC voltage a sine wave.

[0050] The second disclosed motor control device suppresses harmonics based on current.

[0051] The inverter control device disclosed herein has a current correction unit, which includes an inter-terminal current detection unit, a virtual neutral point current calculation unit, and a correction current output unit.

[0052] The inter-terminal current detection unit detects the first inter-terminal current flowing between the first motor terminal and the second motor terminal, the second inter-terminal current flowing between the second motor terminal and the third motor terminal, and the third inter-terminal current flowing between the third motor terminal and the first motor terminal.

[0053] The virtual neutral point current calculation unit calculates a first virtual current based on the sum of the current between the second and third terminals and the current between the first terminals; it calculates a second virtual current based on the sum of the current between the third and first terminals and the current between the second terminals; and it calculates a third virtual current based on the sum of the current between the first and second terminals and the current between the third terminals. Furthermore, the virtual neutral point current calculation unit calculates the virtual neutral point current based on the first to third virtual currents.

[0054] The correction current output unit outputs the correction current based on the virtual neutral point current.

[0055] Furthermore, the inverter control device controls the inverter based on the correction current, thereby correcting the waveforms of the first AC voltage to the third AC voltage.

[0056] By using the second disclosed motor control device, the harmonic suppression effect can be improved.

[0057] In different embodiments of the second disclosed motor control device, the virtual neutral point current calculation unit calculates the virtual neutral point current using [first virtual current = (second terminal current + third terminal current - first terminal current) / (2 × 3)]. 1 / 2 [Second virtual current = (current between third terminals + current between first terminals - current between second terminals) / (2 × 3)] 1 / 2 [The third virtual current = (current between the first terminal + current between the second terminal - current between the third terminal) / (2 × 3)] 1 / 2 The virtual neutral point current calculation unit calculates the first to third virtual currents using the formula [virtual neutral point current = first virtual current + second virtual current + third virtual current].

[0058] In this method, the virtual neutral point current can be easily calculated.

[0059] In different embodiments of the second disclosed motor control device, the correction current output unit also includes a correction current calculation unit.

[0060] The correction current calculation unit calculates the correction current, which includes the first correction current to the third correction current corresponding to the difference between the inter-terminal current and the virtual neutral point current in the first to third inter-terminal currents.

[0061] Furthermore, the correction current output unit outputs the correction current calculated by the correction current calculation unit.

[0062] In this method, the correction current can be easily calculated.

[0063] In different embodiments of the second disclosed motor control device, the correction current output unit also includes a correction current calculation unit.

[0064] The correction current calculation unit calculates the correction current, which includes a first correction current to a third correction current obtained by amplifying the first terminal current to the third terminal current with an amplification rate corresponding to the virtual neutral point current.

[0065] Furthermore, the correction current output unit outputs the correction current calculated by the correction current calculation unit.

[0066] In this method, the correction current can be easily calculated.

[0067] In a different embodiment of the second disclosed motor control device, the correction current calculation unit has a three-phase-dq conversion unit that converts the first to third correction currents into d-axis correction currents and q-axis correction currents.

[0068] Furthermore, the correction current output unit outputs a correction current that includes both d-axis correction current and q-axis correction current.

[0069] In addition, the inverter control unit has a three-phase-dq conversion unit, a d-axis current control unit, a q-axis current control unit, a dq-three-phase conversion unit, and a drive unit, and controls the inverter through vector control.

[0070] The three-phase dq converter transforms the first terminal current flowing from the first motor terminal to the third motor terminal into d-axis current and q-axis current, respectively.

[0071] The d-axis current control unit outputs the d-axis voltage command based on the d-axis current, the d-axis current command, and the d-axis correction current.

[0072] The q-axis current control unit outputs the q-axis voltage command based on the q-axis current, the q-axis current command, and the q-axis correction current.

[0073] The dq-three-phase conversion unit converts the d-axis voltage command and the q-axis voltage command into the first AC voltage command to the third AC voltage command.

[0074] The drive unit drives the inverter based on the first AC voltage command to the third AC voltage command.

[0075] In this method, harmonics can be easily suppressed.

[0076] In the different embodiments of the first and second disclosures, the first winding to the third winding are connected to the first motor terminal to the third motor terminal in a delta configuration.

[0077] In this method, losses caused by harmonic currents flowing in the closed circuit formed by the first to third windings can be reduced.

[0078] The effects of the invention

[0079] By using the first disclosed motor control device and the second disclosed motor control device, the harmonic suppression effect can be improved. Attached Figure Description

[0080] Figure 1 This is a schematic diagram of a conventional electric motor control device.

[0081] Figure 2 This is a schematic diagram of a motor in which the first to third windings are connected in a delta configuration.

[0082] Figure 3 This is a schematic diagram of a motor in which the first to third windings are connected in a star configuration.

[0083] Figure 4 This is a diagram showing the state where the voltage between the first and third terminals is a sinusoidal waveform.

[0084] Figure 5 This is a diagram showing the state of the voltage between the first and third terminals, including harmonics.

[0085] Figure 6 This is a schematic diagram of the motor control device according to the first embodiment.

[0086] Figure 7 This is a schematic diagram of the inverter control device constituting the motor control device of the first embodiment.

[0087] Figure 8 This is a schematic diagram of one embodiment of the virtual neutral point voltage calculation unit constituting the motor control device of the first embodiment.

[0088] Figure 9 This is a schematic diagram of one embodiment of the correction voltage calculation unit constituting the motor control device of the first embodiment.

[0089] Figure 10 This is a schematic diagram of another embodiment of the correction voltage calculation unit constituting the motor control device of the first embodiment.

[0090] Figure 11 This is a diagram showing the waveforms of each part when using the motor control device of the first embodiment.

[0091] Figure 12 This is a diagram showing the waveforms of the inter-terminal voltage and the virtual neutral point voltage when using a conventional motor control device.

[0092] Figure 13 This is a diagram showing the waveforms of the inter-terminal voltage and the virtual neutral point voltage when using the motor control device of the first embodiment.

[0093] Figure 14 This is a schematic diagram of the motor control device according to the second embodiment.

[0094] Figure 15 This is a schematic diagram of the inverter control device constituting the motor control device of the second embodiment.

[0095] Figure 16 This is a schematic diagram of one embodiment of the virtual neutral point current calculation unit constituting the motor control device of the second embodiment.

[0096] Figure 17 This is a schematic diagram of one embodiment of the correction current calculation unit constituting the motor control device of the second embodiment.

[0097] Figure 18 This is a schematic diagram of another embodiment of the correction current calculation unit constituting the motor control device of the second embodiment. Detailed Implementation

[0098] Hereinafter, embodiments of the electric motor control device of this disclosure will be described with reference to the accompanying drawings.

[0099] Reference Figure 6 The outline structure of the first embodiment of the electric motor control device of this disclosure will be described below. Figure 6 The electric motor control device shown corresponds to the electric motor control device disclosed in the first disclosure.

[0100] Furthermore, the motor control device disclosed herein can be applied to a motor 20 whose first winding 21U to the third winding 21W are connected in a delta configuration. Figure 2 The first winding 31U to the third winding 31W are connected in a star configuration to the motor 30. Figure 3 The following describes the application of the motor 20 connected in a delta configuration.

[0101] The motor control device of the first embodiment includes a power supply device 100 and an inverter control device 300.

[0102] The power supply device 100 has a DC power supply device 110 and an AC power supply device 120.

[0103] As a DC power supply device 110, it can use a battery 111, a three-phase rectifier 112 for rectifying three-phase AC voltage, and a single-phase rectifier 113 for rectifying single-phase AC voltage. The DC power supply device 110 outputs a DC voltage with a voltage value VD from the output terminals D1 and D2.

[0104] The AC power supply device 120 includes an inverter 121 that converts the DC voltage input to the input terminals E1 and E2 into a first AC voltage to a third AC voltage and outputs it from the first power supply terminals to the third power supply terminals R, S, and T. The inverter 121 has bridging switching elements 121a to 121f.

[0105] The first power supply terminal to the third power supply terminal R, S, T are connected to the first motor terminal to the third motor terminal X, Y, Z of the motor 10.

[0106] Hereinafter, the motor terminals X, Y, and Z of the motor 10 will be referred to as the first motor terminal, the second motor terminal, and the third motor terminal, respectively. The AC voltages supplied to the motor terminals X, Y, and Z of the motor 10 will be referred to as terminal voltages Vx, Vy, and Vz, respectively. The currents flowing through the first motor terminal to the third motor terminal X, Y, and Z will be referred to as terminal currents Ix, Iy, and Iz, respectively. The voltage between motor terminal X and motor terminal Y will be referred to as the inter-terminal voltage Vxy, the voltage between motor terminal Y and motor terminal Z will be referred to as the inter-terminal voltage Vyz, and the voltage between motor terminal Z and motor terminal X will be referred to as the inter-terminal voltage Vzx. The current flowing between motor terminal X and motor terminal Y will be referred to as the inter-terminal current Ixy, the current flowing between motor terminal Y and motor terminal Z will be referred to as the inter-terminal current Iyz, and the current flowing between motor terminal Z and motor terminal X will be referred to as the inter-terminal current Izx.

[0107] The inverter control device 300 includes a main control unit 400 and a voltage correction unit 500.

[0108] The main control unit 400 controls the inverter 121 via vector control. The main control unit 400 uses a known vector control unit.

[0109] The main control unit 400 includes a terminal current detection unit 410, a three-phase-dq conversion unit 420, a d-axis current control unit 430, a q-axis current control unit 440, a dq-three-phase conversion unit 450, and a drive unit 460.

[0110] Furthermore, when the three-phase-dq converter 420 of the main control unit 400 is described separately from other three-phase-dq converters, it is referred to as the "main three-phase-dq converter 420".

[0111] The terminal current detection unit 410 detects the terminal currents Ix, Iy, and Iz flowing at the motor terminals X, Y, and Z. Various known current detection units can be used as the terminal current detection unit 410. The methods for detecting the terminal currents Ix, Iy, and Iz can include direct detection using a detector or calculation based on other detected values ​​obtained from the detector.

[0112] The three-phase-dq conversion unit 420 converts the terminal currents Ix, Iy, and Iz detected by the terminal current detection unit 410 into d-axis current Id and q-axis current Iq. The three-phase-dq conversion unit 420 includes: a three-phase-to-two-phase conversion unit that converts three phases (Ix, Iy, Iz) into two phases (Iα, Iβ); and a two-phase-dq conversion unit that converts from fixed coordinates (Iα, Iβ) to rotating coordinates (Id, Iq). The rotor rotation angle θ is used when converting from fixed coordinates to rotating coordinates.

[0113] The d-axis current control unit 430 outputs the d-axis voltage command Vd based on the d-axis current Id and the d-axis current command Ids. The d-axis current command Ids is given by an appropriate method.

[0114] The q-axis current control unit 440 outputs the q-axis voltage command Vq based on the q-axis current Iq and the q-axis current command Iqs. The q-axis command Iqs is given by an appropriate method. For example, the q-axis command is set based on the difference between the rotational speed ω of the rotor of the motor 10 and the speed command ωs.

[0115] The dq-three-phase conversion unit 450 converts the d-axis voltage command Vd and the q-axis voltage command Vq into terminal voltage commands Vxa, Vya, and Vza for the terminal voltages Vx, Vy, and Vz. The dq-three-phase conversion unit 450 includes: a dq-two-phase conversion unit that converts the rotating coordinates (Vd, Vq) into fixed coordinates (Vα, Vβ); and a two-phase-to-three-phase conversion unit that converts two phases (Vα, Vβ) into three phases (Vxa, Vya, Vza). The rotor's rotation angle θ is also used when converting from rotating to fixed coordinates.

[0116] The drive unit 460 drives the switching elements 121a to 121f that constitute the inverter 121 based on the terminal voltage commands Vxa, Vya, and Vza.

[0117] The voltage correction unit 500 includes an inter-terminal voltage detection unit 510, a virtual neutral point voltage calculation unit 520, and a correction voltage output unit 530.

[0118] The inter-terminal voltage detection unit 510 detects the inter-terminal voltage Vxy between motor terminal X and motor terminal Y, the inter-terminal voltage Vyz between motor terminal Y and motor terminal Z, and the inter-terminal voltage Vzx between motor terminal Z and motor terminal X. As a method for detecting the inter-terminal voltages Vxy, Vyz, and Vzx, methods can be used that involve direct detection using a detector or calculation based on other detected values ​​obtained by the detector.

[0119] The virtual neutral point voltage calculation unit 520 calculates the virtual neutral point voltage Vnc based on the inter-terminal voltages Vxy, Vyz, and Vzx. The method for calculating the virtual neutral point voltage Vnc will be described later.

[0120] The correction voltage output unit 530 outputs a correction voltage Vc based on the inter-terminal voltages Vxy, Vyz, Vzx and the virtual neutral point voltage Vnc. The calculation method for the correction voltage Vc will be described later.

[0121] The main control unit 400 corrects the terminal voltages Vx, Vy, and Vz supplied from the inverter 121 based on the correction voltage Vc output from the correction voltage output unit 530 of the voltage correction unit 500. The correction method based on the correction voltage Vc will be described later. By correcting the terminal voltages Vx, Vy, and Vz based on the correction voltage Vc, the harmonics contained in the terminal voltages Vx, Vy, and Vz are reduced.

[0122] Next, refer to Figures 7-10 The structure of this embodiment will be described in detail below.

[0123] First, the structure of the virtual neutral point voltage calculation unit 520 of the voltage correction unit 500 will be explained.

[0124] In this embodiment, the inter-terminal voltages Vxy, Vyz, and Vzx detected by the inter-terminal voltage detection unit 510 are used to calculate the virtual voltages Vxc, Vyc, and Vzc using the following equations (1) to (3).

[0125]

[0126] Equations (1) to (3) are obtained by analyzing the states without harmonics and the states with harmonics.

[0127] Then, the virtual voltages Vxc, Vyc, and Vz are synthesized to calculate the virtual neutral point voltage Vnc.

[0128]

[0129] Figure 8 A circuit diagram of an example of the virtual neutral point voltage calculation unit 520 is shown.

[0130] Figure 8 The virtual neutral point voltage calculation unit 520 shown has calculation units 521 to 523.

[0131] The arithmetic unit 521 has an action amplifier 521a and resistors 521b~521e, and calculates the virtual voltage Vxc.

[0132] The arithmetic unit 522 has an action amplifier 522a and resistors 522b~522e, and calculates the virtual voltage Vyc.

[0133] The arithmetic unit 523 has an action amplifier 523a and resistors 523b~523e, and calculates the virtual voltage Vzc.

[0134] The virtual neutral point voltage Vnc is calculated by synthesizing the virtual voltages Vx, Vy, and Vz using resistors 524a~524c.

[0135] The virtual neutral point voltage Vnc calculated as described above contains harmonics that cannot be detected in conventional motor control devices.

[0136] Therefore, by correcting the terminal voltages Vx, Vy, and Vz based on the virtual neutral point voltage Vnc, harmonics can be reduced compared to control using conventional motor control devices.

[0137] Various methods can be used to correct the terminal voltages Vx, Vy, and Vz based on the virtual neutral point voltage Vnc.

[0138] In this embodiment, the virtual neutral point voltage Vnc is used to calculate the correction terminal voltages Vxyc, Vyzc, and Vzxc, and the calculated correction terminal voltages Vxyc, Vyzc, and Vzxc are transformed into the d-axis correction voltage Vdc and the q-axis correction voltage Vqc.

[0139] That is, such as Figure 7 As shown, the voltage correction unit 500 includes a correction voltage calculation unit 540 and a three-phase-dq conversion unit 560 in the correction voltage output unit 530.

[0140] Furthermore, when the three-phase-dq conversion unit 560 of the correction voltage calculation unit 540 is described separately from other three-phase-dq conversion units, it is referred to as "three-phase-dq conversion unit 560 for voltage correction".

[0141] The correction voltage calculation unit 540 calculates the correction inter-terminal voltages Vxyc, Vyzc, and Vzxc based on the inter-terminal voltages Vxy, Vyz, Vzx and the virtual neutral point voltage Vnc.

[0142] Figure 9A circuit diagram of an example of the correction voltage calculation unit 540 is shown.

[0143] Figure 9 The correction voltage calculation unit 540 shown has calculation units 541 to 544.

[0144] The arithmetic unit 541 includes an operational amplifier 541a and resistors 541b to 541d. Furthermore, [VD / 2] is used to define the center of the correction terminal voltages Vxyc, Vyzc, and Vzxc.

[0145] The arithmetic unit 542 includes an action amplifier 542a and resistors 542b to 542d, and calculates the correction inter-terminal voltage Vxyc based on the inter-terminal voltage Vxy and the virtual neutral point voltage Vnc.

[0146] The arithmetic unit 543 includes an action amplifier 543a and resistors 543b to 543d, and calculates the correction inter-terminal voltage Vyzc based on the inter-terminal voltage Vyz and the virtual neutral point voltage Vnc.

[0147] The arithmetic unit 544 includes an action amplifier 544a and resistors 544b to 544d, and calculates the correction inter-terminal voltage Vzxc based on the inter-terminal voltage Vzx and the virtual neutral point voltage Vnc.

[0148] exist Figure 9 In this process, the virtual neutral point voltage Vnc is subtracted from the voltages Vxy, Vyz, and Vzx between each terminal to calculate the corrected voltages Vxyc, Vyzc, and Vzxc. However, the method for calculating the corrected voltages between terminals is not limited to this.

[0149] Figure 10 Circuit diagrams of different embodiments of the correction voltage calculation unit 540 are shown.

[0150] Figure 10 The correction voltage calculation unit 550 shown has calculation units 551 to 554.

[0151] The arithmetic unit 551 includes an action amplifier 551a and resistors 551b to 551d, and outputs a correction signal corresponding to the virtual neutral point voltage Vnc.

[0152] The arithmetic unit 552 includes an operational amplifier 552a, resistors 552b and 552c, and a variable resistor 552d. The variable resistor 552d varies according to the correction signal output from the arithmetic unit 551. As a result, the arithmetic unit 552 outputs a corrected inter-terminal voltage Vxyc, which is obtained by amplifying the inter-terminal voltage Vxy at an amplification rate corresponding to the virtual neutral point voltage Vnc.

[0153] The arithmetic unit 553 includes an operational amplifier 553a, resistors 553b and 553c, and a variable resistor 553d. The variable resistor 553d varies according to the correction signal output from the arithmetic unit 551. As a result, the arithmetic unit 553 outputs a corrected inter-terminal voltage Vyzc, which is obtained by amplifying the inter-terminal voltage Vyz at an amplification rate corresponding to the virtual neutral point voltage Vnc.

[0154] The arithmetic unit 554 includes an operational amplifier 554a, resistors 554b and 554c, and a variable resistor 554d. The variable resistor 554d varies according to the correction signal output from the arithmetic unit 551. As a result, the arithmetic unit 554 calculates the corrected inter-terminal voltage Vzxc obtained by amplifying the inter-terminal voltage Vzx at an amplification rate corresponding to the virtual neutral point voltage Vnc.

[0155] The three-phase-dq conversion unit 560 converts the inter-terminal voltages Vxyc, Vyzc, and Vzxc calculated by the correction voltage calculation unit 540 into the d-axis correction voltage Vdc and the q-axis correction voltage Vqc. The three-phase-dq conversion unit 560 uses the rotor's rotation angle θ to convert from fixed coordinates to rotating coordinates.

[0156] The main control unit 400 of the inverter control device 300 performs correction based on the d-axis correction voltage Vdc and q-axis correction voltage Vqc output from the correction voltage output unit 530 (three-phase-dq conversion unit 560) of the voltage correction unit 500.

[0157] In this embodiment, a current control unit 431 and a d-axis voltage command correction unit 432 are provided in the d-axis current control unit 430.

[0158] The current control unit 431 outputs the d-axis voltage command Vdt based on the d-axis current Id and the d-axis current command Ids.

[0159] The d-axis voltage command correction unit 432 outputs the corrected d-axis voltage command Vd based on the d-axis voltage command Vdt and the d-axis correction voltage Vdc.

[0160] Similarly, the q-axis current control unit 440 is provided with a current control unit 441 and a q-axis voltage command correction unit 442.

[0161] The current control unit 441 outputs the q-axis voltage command Vqt based on the q-axis current Iq and the q-axis current command Iqs.

[0162] The q-axis voltage command correction unit 442 outputs the corrected q-axis voltage command Vq based on the q-axis voltage command Vqt and the q-axis correction voltage Vqc.

[0163] Figure 11The waveforms of each part are shown when the motor 30 is controlled using the motor control device of the first embodiment.

[0164] exist Figure 11 The waveforms of the inter-terminal voltage Vxy, the target voltage Vxys of the inter-terminal voltage Vxy, and the virtual neutral point voltage Vnc are shown.

[0165] exist Figure 11 In the intervals T1 (times t1~t5) and T3 (times t11~t15), the inter-terminal voltage Vxy is less than the target voltage Vxys, while in the interval T2 (times t5~t11), the inter-terminal voltage Vxy is greater than the target voltage Vxys.

[0166] Therefore, in intervals T1 and T3, the correction polarity (the direction of correction used to bring the inter-terminal voltage Vxy close to the target voltage Vxys) is positive, and in interval T2, the correction polarity is negative.

[0167] Here, in Figure 11 The diagram shows the existence of a virtual neutral point voltage Vnc.

[0168] In conventional motor control devices, the virtual neutral point voltage Vn cannot be detected, so the inverter 121 is controlled solely based on the correction polarity.

[0169] In this situation, the balance of the control system is disrupted.

[0170] On the other hand, in the motor control device of this embodiment, the inverter 121 is also controlled based on the variation of the virtual neutral point voltage Vnc. That is, the inverter 121 is controlled based on the correction polarity and the polarity of the virtual neutral point voltage.

[0171] exist Figure 11 In this process, the control quantities (a) to (h) are changed according to each interval Q1 to Q14 corresponding to the polarity of the virtual neutral point voltage Vnc.

[0172] Furthermore, (a) indicates "significantly reducing (grossly reducing) the control amount towards the negative side," (b) indicates "slightly reducing (minimally reducing) the control amount towards the negative side," (c) indicates "significantly reducing the control amount towards the positive side," and (d) indicates "slightly reducing the control amount towards the positive side." Additionally, (e) indicates "significantly increasing (grossly increasing) the control amount towards the negative side," (f) indicates "slightly increasing (minimally increasing) the control amount towards the negative side," (g) indicates "significantly increasing the control amount towards the positive side," and (h) indicates "slightly increasing the control amount towards the positive side."

[0173] Therefore, the balance of the control system is not disrupted, and harmonics can be reliably suppressed.

[0174] Figure 12 The waveforms of the inter-terminal voltages Vxy, Vyz, and Vzx, and the virtual neutral point voltage Vnc, are shown when the motor 30 is controlled using a conventional motor control device.

[0175] in addition, Figure 13 The waveforms of the inter-terminal voltages Vxy, Vyz, and Vzx, and the waveform of the virtual neutral point voltage Vnc, are shown when the motor 30 is controlled using the motor control device of this embodiment.

[0176] according to Figure 12 , Figure 13 It is known that when using conventional motor control devices, the waveforms of the inter-terminal voltages Vxy, Vyz, and Vzx contain harmonics, but when using the motor control device of this embodiment, the waveforms of the inter-terminal voltages Vxy, Vyz, and Vzx contain almost no harmonics.

[0177] Furthermore, it is known that when using the motor control device of this embodiment, the amplitude Vnc(2) of the virtual neutral point voltage Vnc is reduced to approximately 15% of the amplitude Vnc(1) of the virtual neutral point voltage Vnc when using the conventional motor control device.

[0178] Therefore, the effectiveness of the motor control device of this embodiment can be confirmed.

[0179] In the motor control device of the first embodiment, a correction voltage is calculated and the terminal voltages Vx, Vy, and Vz are corrected based on the correction voltage. However, a correction current can also be calculated and the terminal voltages Vx, Vy, and Vz are corrected based on the correction current.

[0180] Reference Figure 14 The second embodiment of the electric motor control device of this disclosure will now be described. Figure 14 The motor control device shown corresponds to the motor control device disclosed in the second disclosure.

[0181] The motor control device of the second embodiment is the same as the motor control device of the first embodiment, and includes a power supply device 100 and an inverter control device 600.

[0182] The inverter control unit 600 includes a main control unit 700 and a current correction unit 800.

[0183] The main control unit 700 differs from the main control unit 400 of the first embodiment in the structure of the d-axis current control unit and the q-axis current control unit.

[0184] Therefore, the following mainly describes the structure that differs from the motor control device of the first embodiment.

[0185] The main control unit 700 is similar to the main control unit 400 in the first embodiment, and includes a terminal current detection unit 710, a three-phase-dq conversion unit 720, a d-axis current control unit 730, a q-axis current control unit 740, a dq-three-phase conversion unit 750, and a drive unit 760.

[0186] The structures of the d-axis current control unit 730 and the q-axis current control unit 740 will be described later.

[0187] The current correction unit 800 includes an inter-terminal current detection unit 810, a virtual neutral point current calculation unit 820, and a correction current output unit 830.

[0188] The inter-terminal current detection unit 810 detects the inter-terminal current Ixy flowing between motor terminal X and motor terminal Y, the inter-terminal current Iyz flowing between motor terminal Y and motor terminal Z, and the inter-terminal current Izx flowing between motor terminal Z and motor terminal X. As a method for detecting the inter-terminal currents Ixy, Iyz, and Izx, methods can be used that involve direct detection using a detector or calculation based on other detected values ​​obtained by the detector.

[0189] The virtual neutral point current calculation unit 820 calculates the virtual neutral point current Inc based on the inter-terminal currents Ixy, Iyz, and Izx. The method for calculating the virtual neutral point current Inc will be described later.

[0190] The correction current output unit 830 outputs a correction current Ic based on the inter-terminal currents Ixy, Iyz, Izx and the virtual neutral point current Inc. The calculation method for the correction current Ic will be described later.

[0191] The main control unit 700 corrects the terminal voltages Vx, Vy, and Vz supplied from the inverter 121 based on the correction current Ic output from the correction current output unit 830 of the current correction unit 800. The correction method based on the correction current Ic will be described later. By correcting the terminal voltages Vx, Vy, and Vz based on the correction current Ic, the harmonics contained in the inter-terminal currents Ixy, Iyz, and Izx are reduced.

[0192] Next, refer to Figures 15-18 The structure of this embodiment will be described in detail below.

[0193] First, the structure of the virtual neutral point current calculation unit 820 of the current correction unit 800 will be explained.

[0194] In this embodiment, the inter-terminal currents Ixy, Iyz, and Izx detected by the inter-terminal current detection unit 810 are used to calculate the virtual currents Ixc, Iyc, and Izc using the following equations (4) to (6).

[0195]

[0196] Equations (4) to (6) are obtained by the same method as those (1) to (3).

[0197] Then, the virtual currents Ixc, Iyc, and Iz are synthesized to calculate the virtual neutral point current Inc.

[0198]

[0199] Figure 16 A circuit diagram of one embodiment of the virtual neutral point current calculation unit 820 is shown.

[0200] Figure 16 The virtual neutral point current calculation unit 820 shown has arithmetic units 821 to 823.

[0201] Arithmetic Units 821-823 and Figure 7 Similarly, the virtual neutral point voltage calculation unit 520 shown also has operation amplifiers 821a~823a and resistors 821b~821e, 822b~822e, 823b~823e, and calculates virtual currents Ixc, Iyc, and Izc based on the inter-terminal currents Ixy, Iyz, and Izx.

[0202] The virtual neutral point current Inc is calculated by synthesizing the virtual currents Ixc, Iyc, and Izc using resistors 824a~824c.

[0203] The virtual neutral point current Inc calculated as described above contains harmonics that cannot be detected in conventional motor control devices.

[0204] Therefore, by correcting the terminal voltages Vx, Vy, and Vz based on the virtual neutral point current Inc, harmonics can be reduced compared to control using conventional motor control devices.

[0205] Various methods can be used to correct the terminal voltages Vx, Vy, and Vz based on the virtual neutral point current Inc.

[0206] In this embodiment, the virtual neutral point current Inc is used to calculate the correction terminal currents Ixyc, Iyzc, and Izxc, and the calculated correction terminal currents Ixyc, Iyzc, and Izxc are transformed into the d-axis correction current Idc and the q-axis correction current Iqc.

[0207] That is, such as Figure 15 As shown, the current correction unit 800 includes a correction current calculation unit 840 and a three-phase-dq conversion unit 860 in the correction current output unit 830.

[0208] Furthermore, when the three-phase-dq conversion unit 860 of the correction current calculation unit 840 is described separately from other three-phase-dq conversion units, it is referred to as "three-phase-dq conversion unit 860 for current correction".

[0209] The correction current calculation unit 840 calculates the correction terminal currents Ixyc, Iyzc, and Izxc based on the inter-terminal currents Ixy, Iyz, and Izx and the virtual neutral point current Inc.

[0210] Figure 17 A circuit diagram of one embodiment of the correction current calculation unit 840 is shown.

[0211] Figure 17 The correction current calculation unit 840 shown has calculation units 841 to 844.

[0212] Arithmetic units 841~844 and Figure 9 Similarly, the arithmetic units 541-544 shown also have action amplifiers 841a-844a and resistors 841b-841d, 842b-842d, 843b-843d, and 844b-844d. Furthermore, [Im] is used to define the center of the calibration terminal currents Ixyc, Iyzc, and Izxc.

[0213] The arithmetic units 842-844 calculate the corrected inter-terminal currents Ixyc, Iyzc, and Izxc based on the inter-terminal currents Ixy, Iyz, and Izx and the virtual neutral point current Inc.

[0214] exist Figure 17 In this method, the virtual neutral point current Inc is subtracted from the currents Ixy, Iyz, and Izx between each terminal to calculate the corrected inter-terminal currents Ixyc, Iyzc, and Izxc. However, the method for calculating the corrected inter-terminal currents is not limited to this.

[0215] Figure 18 Circuit diagrams of different embodiments of the correction current calculation unit 840 are shown.

[0216] Figure 18 The correction current calculation unit 840 shown has calculation units 851 to 854.

[0217] The arithmetic units 851 to 854 include action amplifiers 851a to 854a, resistors 851b to 851d, 852b, 852c, 853b, 853c, 854b, 854c, and variable resistors 842d, 843d, and 844d.

[0218] Arithmetic Units 852-854 and Figure 9Similarly, the arithmetic units 552-554 shown calculate the corrected inter-terminal currents Ixyc, Iyzc, and Izxc obtained by amplifying the inter-terminal currents Ixy, Iyz, and Izx with an amplification rate corresponding to the virtual neutral point current Inc.

[0219] The three-phase-dq conversion unit 860 converts the correction terminal currents Ixyc, Iyzc, and Izxc calculated by the correction current calculation unit 840 into the d-axis correction current Idc and the q-axis correction current Iqc. The three-phase-dq conversion unit 860 uses the rotor's rotation angle θ to convert from fixed coordinates to rotating coordinates.

[0220] The main control unit 700 of the inverter control device 600 corrects the terminal voltages Vz, Vy, and Vz based on the d-axis correction current Idc and q-axis correction current Iqc output from the correction current output unit 830 (three-phase-dq conversion unit 860) of the current correction unit 800.

[0221] In this embodiment, the d-axis current control unit 730 outputs the d-axis voltage command Vd based on the d-axis current Id, the d-axis current command Ids, and the d-axis correction current Idc.

[0222] Furthermore, the addition and subtraction operations of the d-axis current Id, d-axis current command Ids, and d-axis correction current Idc can also be performed in multiple steps. For example, one can first subtract the d-axis current Id from the d-axis current command Ids, and then subtract the result from the d-axis correction current Idc.

[0223] In addition, the q-axis current control unit 740 outputs the q-axis voltage command Vq based on the q-axis current Iq, the q-axis current command Iqs, and the q-axis correction current Iqc.

[0224] Furthermore, the addition and subtraction operations of q-axis current Iq, q-axis current command Iqs, and q-axis correction current Iqc can also be performed in multiple steps.

[0225] The other structures are the same as those of the main control unit 400 in the first embodiment.

[0226] The electric motor control device disclosed herein is not limited to the structure described in the embodiments, and various changes, additions, and deletions can be made.

[0227] As a method for detecting voltage, methods for detecting other electrical quantities that represent voltage can also be used.

[0228] As a method for detecting current, methods for detecting other electrical quantities that represent current can also be used.

[0229] The method of correcting the terminal voltage based on the correction voltage or correction current is not limited to the method described in the embodiments.

[0230] In one implementation, the correction voltage (correction current) is converted into d-axis correction voltage and q-axis correction voltage (d-axis correction current and q-axis correction current) and output to the main control unit. However, the correction voltage (correction current) can also be directly output to the main control unit. In this case, the main control unit can be used either as correction voltage (correction current) or as a state where it has been converted into d-axis correction voltage and q-axis correction voltage.

[0231] In this embodiment, the voltage between terminals is detected, but the terminal voltage can also be detected. Detecting the terminal voltage also falls within the technical scope of the motor control device disclosed herein.

[0232] In this embodiment, the current between terminals is detected, but the terminal current can also be detected. Detecting the terminal current also falls within the technical scope of the motor control device disclosed herein.

[0233] The motor control device described in the embodiments can be applied to motors in which the first to third windings are connected in a delta configuration and motors in which the first to third windings are connected in a star configuration.

[0234] The structures described in the implementation can be used individually or in combination with appropriately selected structures.

[0235] Explanation of reference numerals in the attached figures

[0236] 10, 20, 30: Electric motor; X, Y, Z: Electric motor terminals; 21U, 21V, 21W, 31U, 31V, 31W: Windings; 100: Power supply unit; 110: DC power supply unit; 111: Battery; 112: Three-phase rectifier unit; 113: Single-phase rectifier unit; 120: AC power supply unit; R, S, T: Power supply terminals; 121: Inverter; 121a~121f: Switching elements; 200, 300, 600: Inverter control unit; 210, 410, 710: Terminal current detection unit; 220, 420, 560, 720, 860: Three-phase-to-dq conversion unit; 230, 430, 7 30: d-axis current control unit; 240, 440, 740: q-axis current control unit; 250, 450, 750: dq-three-phase conversion unit; 260, 460, 760: drive unit; 400, 700: main control unit; 431, 441: current control unit; 432: d-axis voltage command correction unit; 442: q-axis voltage command correction unit; 500: voltage correction unit; 510: inter-terminal voltage detection unit; 520: virtual neutral point voltage calculation unit; 521~523, 541~544, 551~554, 821~823, 841~844, 851~854: arithmetic unit; 530: correction voltage output unit; 5 40: Correction voltage calculation unit; 521a~523a, 541a~544a, 551a~554a, 821a~823a, 841a~844a, 851a~854a: Action amplifier; 521b~521e, 522b~522e, 523b~523e, 524a~524c, 541b~541d, 542b~542d, 543b~543d, 544b~544d, 551b~551d, 552b, 552c, 553b, 553c, 554b, 554c, 821b~821e, 822b~822e, 823b~823 e, 824a~824c, 841b~841d, 842b~842d, 844b~844d, 851b~851d, 852b, 852c, 853b, 853c, 854b, 854c: Resistors; 521a, 522a, 523a: Action amplifiers; 521b~521e, 522b~522e, 523b~523e: Resistors; 542d~544d, 842d~844d: Variable resistors; 800: Current correction unit; 810: Inter-terminal current detection unit; 820: Virtual neutral point current calculation unit; 830: Correction current output unit; 840: Correction current calculation unit.

Claims

1. A motor control device comprising: an inverter supplying a first AC voltage, a second AC voltage, and a third AC voltage to first motor terminals, second motor terminals, and third motor terminals connected to a first winding, a second winding, and a third winding; and an inverter control device controlling the inverter to make the first AC voltage, the second AC voltage, and the third AC voltage sinusoidal waves, characterized in that: The inverter control device includes a voltage correction unit. The voltage correction unit includes an inter-terminal voltage detection unit, a virtual neutral point voltage calculation unit, and a correction voltage output unit. The terminal voltage detection unit detects the first terminal voltage between the first motor terminal and the second motor terminal, the second terminal voltage between the second motor terminal and the third motor terminal, and the third terminal voltage between the third motor terminal and the first motor terminal. The virtual neutral point voltage calculation unit calculates a first virtual voltage based on the sum of the second and third terminal voltages and the first terminal voltage; it calculates a second virtual voltage based on the sum of the third and first terminal voltages and the second terminal voltage; it calculates a third virtual voltage based on the sum of the first and second terminal voltages and the third terminal voltage; and it further calculates a virtual neutral point voltage based on the first, second, and third virtual voltages. The correction voltage output unit outputs a correction voltage based on the virtual neutral point voltage. The inverter control device controls the inverter based on the correction voltage to correct the waveforms of the first AC voltage, the second AC voltage, and the third AC voltage.

2. The motor control device according to claim 1, characterized in that, The virtual neutral point voltage calculation unit calculates the virtual neutral point voltage using [first virtual voltage = (second terminal voltage + third terminal voltage - first terminal voltage) / (2 × 3)]. 1 / 2 The first virtual voltage is calculated using [Second virtual voltage = (Third terminal voltage + First terminal voltage - Second terminal voltage) / (2 × 3)]. 1 / 2 The second virtual voltage is calculated using [the third virtual voltage = (voltage between the first terminal + voltage between the second terminal - voltage between the third terminal) / (2 × 3)]. 1 / 2 The third virtual voltage is calculated using the formula [Virtual neutral point voltage = First virtual voltage + Second virtual voltage + Third virtual voltage].

3. The motor control device according to claim 2, characterized in that, The correction voltage output unit also includes a correction voltage calculation unit. The correction voltage calculation unit calculates a correction voltage, which includes a first correction voltage corresponding to the difference between the first terminal voltage and the virtual neutral point voltage, a second correction voltage corresponding to the difference between the second terminal voltage and the virtual neutral point voltage, and a third correction voltage corresponding to the difference between the third terminal voltage and the virtual neutral point voltage. The correction voltage output unit outputs the correction voltage calculated by the correction voltage calculation unit.

4. The motor control device according to claim 2, characterized in that, The correction voltage output unit also includes a correction voltage calculation unit. The correction voltage calculation unit calculates a correction voltage, which includes a first correction voltage obtained by amplifying the first terminal voltage with an amplification rate corresponding to the virtual neutral point voltage, a second correction voltage obtained by amplifying the second terminal voltage with an amplification rate corresponding to the virtual neutral point voltage, and a third correction voltage obtained by amplifying the third terminal voltage with an amplification rate corresponding to the virtual neutral point voltage. The correction voltage output unit outputs the correction voltage calculated by the correction voltage calculation unit.

5. The motor control device according to claim 3 or 4, characterized in that, The correction voltage calculation unit includes a three-phase-dq conversion unit, which converts the first correction voltage, the second correction voltage, and the third correction voltage into d-axis correction voltage and q-axis correction voltage. The correction voltage output unit outputs a correction voltage comprising the d-axis correction voltage and the q-axis correction voltage obtained by the three-phase-dq conversion unit of the correction voltage calculation unit. The inverter control device includes a three-phase to dq conversion unit, a d-axis current control unit, a q-axis current control unit, a dq to three-phase conversion unit, and a drive unit. The three-phase dq converter transforms the first terminal current flowing at the first motor terminal, the second terminal current flowing at the second motor terminal, and the third terminal current flowing at the third motor terminal into d-axis current and q-axis current. The d-axis current control unit outputs a correction d-axis voltage command, which is obtained by correcting the d-axis voltage command calculated based on the d-axis current and the d-axis current command using the correction d-axis voltage. The q-axis current control unit outputs a q-axis voltage correction command, which is obtained by correcting the q-axis voltage command calculated based on the q-axis current and the q-axis current command using the q-axis correction voltage. The dq-three-phase converter transforms the d-axis voltage correction command and the q-axis voltage correction command into a first AC voltage command, a second AC voltage command, and a third AC voltage command. The drive unit drives the inverter based on the first AC voltage command, the second AC voltage command, and the third AC voltage command.

6. A motor control device comprising: an inverter supplying a first AC voltage, a second AC voltage, and a third AC voltage to first motor terminals, second motor terminals, and third motor terminals connected to a first winding, a second winding, and a third winding; and an inverter control device controlling the inverter to make the first AC voltage, the second AC voltage, and the third AC voltage sinusoidal waves, characterized in that: The inverter control device includes a current correction unit. The current correction unit includes an inter-terminal current detection unit, a virtual neutral point current calculation unit, and a correction current output unit. The inter-terminal current detection unit detects a first inter-terminal current flowing between the first motor terminal and the second motor terminal, a second inter-terminal current flowing between the second motor terminal and the third motor terminal, and a third inter-terminal current flowing between the third motor terminal and the first motor terminal. The virtual neutral point current calculation unit calculates a first virtual current based on the sum of the second inter-terminal current and the third inter-terminal current, and the first inter-terminal current; it calculates a second virtual current based on the sum of the third inter-terminal current and the first inter-terminal current, and the second inter-terminal current; it calculates a third virtual current based on the sum of the first inter-terminal current and the second inter-terminal current, and the third inter-terminal current; and it further calculates a virtual neutral point current based on the first virtual current, the second virtual current, and the third virtual current. The correction current output unit outputs a correction current based on the virtual neutral point current. The inverter control device controls the inverter based on the correction current to correct the waveforms of the first AC voltage, the second AC voltage, and the third AC voltage.

7. The motor control device according to claim 6, characterized in that, The virtual neutral point current calculation unit calculates the virtual neutral point current by using [first virtual current = (second terminal current + third terminal current - first terminal current) / (2 × 3)]. 1 / 2 The first virtual current is calculated using [the second virtual current = (the current between the third terminal + the current between the first terminal - the current between the second terminal) / (2 × 3)]. 1 / 2 The second virtual current is calculated using [the third virtual current = (current between the first terminal + current between the second terminal - current between the third terminal) / (2 × 3)]. 1 / 2 The third virtual current is calculated using [virtual neutral point current = first virtual current + second virtual current + third virtual current].

8. The motor control device according to claim 7, characterized in that, The correction current output unit also includes a correction current calculation unit. The correction current calculation unit calculates a correction current, which includes a first correction current corresponding to the difference between the first terminal current and the virtual neutral point current, a second correction current corresponding to the difference between the second terminal current and the virtual neutral point current, and a third correction current corresponding to the difference between the third terminal current and the virtual neutral point current. The correction current output unit outputs the correction current calculated by the correction current calculation unit.

9. The motor control device according to claim 7, characterized in that, The correction current output unit also includes a correction current calculation unit. The correction current calculation unit calculates a correction current, which includes a first correction current obtained by amplifying the first inter-terminal current with an amplification rate corresponding to the virtual neutral point current, a second correction current obtained by amplifying the second inter-terminal current with an amplification rate corresponding to the virtual neutral point current, and a third correction current obtained by amplifying the third inter-terminal current with an amplification rate corresponding to the virtual neutral point current. The correction current output unit outputs the correction current calculated by the correction current calculation unit.

10. The motor control device according to claim 8 or 9, characterized in that, The correction current calculation unit has a three-phase-dq conversion unit, which converts the first correction current, the second correction current, and the third correction current into d-axis correction current and q-axis correction current. The correction current output unit outputs a correction current that includes the d-axis correction current and the q-axis correction current obtained by the three-phase-dq conversion unit of the correction current calculation unit. The inverter control device includes a three-phase to dq conversion unit, a d-axis current control unit, a q-axis current control unit, a dq to three-phase conversion unit, and a drive unit. The three-phase dq converter transforms the first terminal current flowing at the first motor terminal, the second terminal current flowing at the second motor terminal, and the third terminal current flowing at the third motor terminal into d-axis current and q-axis current. The d-axis current control unit outputs a d-axis voltage command based on the d-axis current, the d-axis current command, and the d-axis correction current. The q-axis current control unit outputs a q-axis voltage command based on the q-axis current, the q-axis current command, and the q-axis correction current. The dq-three-phase converter transforms the d-axis voltage command and the q-axis voltage command into a first AC voltage command, a second AC voltage command, and a third AC voltage command. The drive unit drives the inverter based on the first AC voltage command, the second AC voltage command, and the third AC voltage command.

11. The motor control device according to any one of claims 1-4 and 6-9, characterized in that, The first winding, the second winding, and the third winding are connected in a delta configuration to the first motor terminal, the second motor terminal, and the third motor terminal.

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