JP2024165742A - MOTOR CONTROL DEVICE AND MOTOR CONTROL METHOD - Google Patents

Abstract

[Problem] To provide a motor control device and a motor control method capable of calculating the position and speed of a motor rotor with high accuracy. [Solution] The operation of a permanent magnet synchronous motor is controlled by controlling the operation of an inverter with a control signal based on a voltage command, and the device includes a first control unit that generates a control signal for the inverter during normal operation of the permanent magnet synchronous motor, and a second control unit that generates a control signal for the inverter when the permanent magnet synchronous motor is in an idling state, and when the permanent magnet synchronous motor is in an idling state, the second control unit outputs a voltage command for passing a DC current of a predetermined initial value through the permanent magnet synchronous motor, calculates the rotor position and rotational speed of the permanent magnet synchronous motor based on the voltage command and the current value of the permanent magnet synchronous motor according to the voltage command, estimates an induced voltage of the permanent magnet synchronous motor based on the calculated rotational speed, and adjusts the voltage command so that the induced voltage is greater than the estimated induced voltage. [Selected Figure] Figure 2

Description

The present invention relates to a motor control device and a motor control method.

In the fields of home appliances and industrial equipment, motor drive systems consisting of an inverter that converts DC power to AC power and a permanent magnet synchronous motor are widely used. To drive such a permanent magnet synchronous motor with high efficiency, information on the rotor position of the motor is generally required. The rotor position of the motor can be directly detected using a position detector such as an encoder, but this has issues in terms of cost and reliability. Therefore, in recent years, position sensorless control has been proposed that detects the rotor position of a permanent magnet synchronous motor without using a position detector, and is being applied to a variety of products.

Meanwhile, one of the issues with position sensorless control of permanent magnet synchronous motors is the method of restarting the motor when the rotor is free-spinning (known as "coast-run start"). For example, the motor of a washing machine or other device may already be rotating before it is started due to the inertia of the load. In this case, if there is no information on the rotor position, rotation speed, and rotation direction in the free-spinning state, it is necessary to wait until the motor stops, or to forcibly stop the rotation by applying brake control and then restart the motor after it has stopped, which increases the time until it can be restarted.

For example, the prior art described in Patent Documents 1 and 2 focuses on the induced voltage that occurs when a permanent magnet synchronous motor spins, and develops a system that shorts the motor windings using an inverter and estimates the rotor position and other factors based on the current that flows at this time.

In Patent Document 1, among the switching elements that make up the motor drive inverter, three upper (lower) arm elements are simultaneously turned on to pass a short-circuit current through the motor windings, and the rotor position and rotation speed are calculated based on the detection information of the three-phase motor current.

In addition, in Patent Document 2, elements of two different phases of an inverter for driving a motor are simultaneously turned on and off to detect the bus (shunt) current on the DC side of the inverter, and the rotor position and rotation speed of the motor are calculated.

JP 2015-73361 A JP 2018-170928 A

However, the above conventional technology has the following problems:

In the conventional technology described in Patent Document 1, the short-circuit current of the motor winding when the inverter is in short-circuit operation is determined by the motor induced voltage, winding resistance, and inductance, so there is a risk of overcurrent occurring during short-circuit operation depending on the idling speed.

In the conventional technology described in Patent Document 2, a special PWM control mode and current detection processing are used to detect the current flowing through the bus (shunt) resistor, which makes the calculations for calculating the motor rotor position and rotation speed complicated and makes it easy for errors to occur in the estimation results.

The present invention has been made in consideration of the above, and aims to provide a motor control device and a motor control method that can calculate the position and speed of a motor rotor with higher accuracy.

The present application includes multiple means for solving the above problems. One example is a motor control device that controls the operation of a permanent magnet synchronous motor by controlling the operation of an inverter that converts DC power into AC power and supplies it to the permanent magnet synchronous motor using a control signal based on a voltage command. The motor control device includes a first control unit that generates a control signal for the inverter during normal operation of the permanent magnet synchronous motor, and a second control unit that generates a control signal for the inverter when the permanent magnet synchronous motor is in an idling state. When the permanent magnet synchronous motor is in an idling state, the second control unit outputs a voltage command to pass a DC current of a predetermined initial value through the permanent magnet synchronous motor, calculates the rotor position and rotation speed of the permanent magnet synchronous motor based on the voltage command and the current value of the permanent magnet synchronous motor according to the voltage command, estimates the induced voltage of the permanent magnet synchronous motor based on the calculated rotation speed, and adjusts the voltage command so that the induced voltage is greater than the estimated induced voltage.

The present invention allows the position and speed of the motor rotor to be calculated with greater accuracy.

FIG. 1 is a diagram showing a schematic diagram of an overall configuration of a motor control system together with a motor control device and its related configuration. FIG. 2 is a functional block diagram showing the processing contents of the motor control device. 3 is an explanatory diagram showing current vectors when a direct current flows through a permanent magnet synchronous motor; FIG. FIG. 4 is a functional block diagram showing the processing contents of a spin state estimation unit. FIG. 4 is a functional block diagram showing the processing content of a voltage command generating unit.

The following describes an embodiment of the present invention with reference to the drawings. In the following description, a permanent magnet synchronous motor (PMSM) is used as an example of a control target of the motor control device.

Figure 1 is a diagram showing the overall configuration of the motor control system according to this embodiment, together with the motor control device and its related configuration.

As shown in FIG. 1, the motor control device 4 controls the operation of the permanent magnet synchronous motor 3 by controlling the inverter 2 that converts DC power from a DC power source 1 into AC power and supplies it to the permanent magnet synchronous motor 3 that is to be driven. As the motor control device 4, for example, a semiconductor computing device such as a microcomputer or a DSP (digital signal processor) is used.

The DC power source 1 may be, for example, a power conversion device (e.g., a diode rectifier or a stabilized power source) that converts AC power received from an AC power source such as a commercial AC power source (not shown) into DC power, or a battery.

The inverter 2 is configured by connecting two arm circuits in which semiconductor switching elements (IGBTs, MOSFETs, etc.) and diodes are connected in anti-parallel, in other words, a series connection circuit in which an upper arm and a lower arm are connected in series, between a pair of positive and negative terminals of the DC power source 1. The inverter 2 is provided with the same number of series connection circuits as the number of phases of the AC output, and in this embodiment, for example, it is a three-phase inverter provided with series connection circuits for three phases. The upper arm and lower arm of the inverter 2 are connected to the high potential side and low potential side of the DC power source 1, respectively. The series connection point of the upper arm and lower arm is connected to an AC terminal, and the AC terminal is connected to the permanent magnet synchronous motor 3.

The low-potential busbar of the inverter 2 is connected to the negative terminal of the DC power supply 1 via a shunt resistor 5 for current detection. The current detection signal detected by the shunt resistor 5 is input to the motor control device 4 via the amplifier 6. The output signal from the amplifier 6 to the motor control device 4 is converted to a digital signal by a sampling and holding circuit and an A/D converter (not shown) for digital calculation in the motor control device 4. In other words, the shunt resistor 5 and the amplifier 6 constitute a DC current detector that detects the DC current flowing through the low-potential busbar of the inverter 2 and outputs a current detection signal to the motor control device 4. Note that instead of the shunt resistor 5, other current detection means such as a current sensor may be used.

In addition, in the inverter 2, a DC voltage detector 50 is installed between the high-potential busbar connected to the positive terminal of the DC power supply 1 and the busbar connected to the negative terminal of the DC power supply 1, which detects the DC voltage between the high-potential side and low-potential side busbars and outputs a DC voltage detection signal to the motor control device 4. The output signal from the DC voltage detector 50 to the motor control device 4 is converted to a digital signal, similar to the DC current detector.

In this embodiment, as described below, the motor control device 4 detects the rotor position of the permanent magnet synchronous motor without using a position detector and performs synchronization, so-called position sensorless control is performed, and the permanent magnet synchronous motor 3 is not provided with a magnetic pole position detection means such as a Hall element that detects the position of the rotor or rotating shaft.

Figure 2 is a functional block diagram showing the processing contents of the motor control device. As mentioned above, the motor control device 4 is a semiconductor computing device such as a microcomputer or DSP, and realizes each function by executing a specific program.

As shown in FIG. 2, the motor control device 4 includes a speed control unit 7, a d-axis current command generation unit 8, a current control unit 9, a voltage command switching unit 10, a two-phase/three-phase conversion unit 11, a speed/phase estimation unit 13, a voltage command generation unit 12, a spin state estimation unit 14, a three-phase/two-phase conversion unit 15, a current reproduction calculation unit 16, and a control signal generation unit 17 (PWM controller).

The motor control device 4 uses d-q axis vector control to calculate the voltage command to be applied to the permanent magnet synchronous motor 3, and generates a PWM (Pulse Width Modulation) control signal for the inverter 2 based on this voltage command, thereby controlling the operation of the permanent magnet synchronous motor 3. The motor control device 4 controls the operation of the permanent magnet synchronous motor 3 in its normal operating state (normal operating control), and controls the transition from an idling state to a normal operating state (start-up control).

<Normal operation control>
First, the operation of each functional block during operation control in a normal operating state will be described.

The current reproduction calculation unit 16 reproduces the three-phase motor currents iu, iv, and iw from the inverter 2 using the current detection signal ish output from the amplifier 6 constituting the DC current detector and the three-phase voltage commands Vu*, Vv*, and Vw* output from the two-phase/three-phase conversion unit 11 to the control signal generation unit 17. Any known method can be used to reproduce the three-phase motor current from the current signal of the shunt resistor 5, and a detailed description of this method will be omitted here.

In this embodiment, in order to reduce costs, the current reproduction calculation unit 16 reproduces the three-phase motor currents iu, iv, iw from the current detection signal ish detected by the shunt resistor 5, and inputs them to the three-phase/two-phase conversion unit 15, but this is not limiting. For example, instead of the shunt resistor 5, a current detection means such as a current sensor may be used to detect the AC current that is the output of the inverter 2, and the three-phase motor currents iu, iv, iw detected by the current detection means may be input to the three-phase/two-phase conversion unit 15.

The three-phase/two-phase conversion unit 15 calculates the α-axis current iα, the β-axis current iβ, the dc-axis current idc, and the qc-axis current iqc based on the three-phase output currents iu, iv, and iw reproduced by the current reproduction calculation unit 16 and the phase information θd_est estimated by the speed/phase estimation unit 13, according to the following (Equation 1) and (Equation 2). Note that the following (Equation 1) represents the so-called three-phase/two-phase conversion, and (Equation 2) represents the conversion to a rotating coordinate system.

The dc-qc axes are the estimated axes of the vector control system based on the estimated position information, and the d-q axes are the motor rotor axes. Here, the axis error between the d-q axes and the dc-qc axes is defined as Δθc.

The speed/phase estimation unit 13 estimates the rotor position and rotation speed using the dc-axis current detection value idc and the qc-axis current detection value iqc, and the dc-qc axis voltage commands Vdc* and Vqc*, and outputs the phase information θd_est and estimated speed ωest. Note that the specific estimation means used in the speed/phase estimation unit 13 may be publicly known, and a detailed description thereof will be omitted here.

The speed control unit 7 creates a qc-axis current command value Iqc* so that the deviation calculated by the calculation unit 25 from the speed command value ω* generated by a functional unit (not shown) in the motor control device 4 in response to an external command and the estimated speed ωest estimated by the speed/phase estimation unit 13 approaches 0 (zero), i.e., so that the estimated speed ωest approaches the speed command value ω*.

The d-axis current command generator 8 generates the dc-axis current command value Idc* to minimize the three-phase motor currents iu, iv, and iw.

The current control unit 9 calculates and outputs the dc-axis voltage command value Vdc* and the qc-axis voltage command value Vqc* using the dc-axis current command value Idc* provided by the d-axis current command generation unit 8, the qc-axis current command value Iqc* provided by the speed control unit 7, the dc-axis current detection value idc and the qc-axis current detection value iqc provided by the three-phase/two-phase conversion unit 15, the speed command value ω*, and the motor constant.

Based on a switching signal from the outside, the voltage command switching unit 10 outputs either the dc-qc axis voltage commands Vdc*, Vqc* calculated by the current control unit 9 or the α-β axis voltage commands Vα*, Vβ* calculated by the voltage command generating unit 12 to the two-phase/three-phase conversion unit 11. Specifically, the voltage command switching unit 10 outputs the dc-qc axis voltage commands Vdc*, Vqc* calculated by the current control unit 9 based on a switching signal in the normal operating state to the two-phase/three-phase conversion unit 11. The voltage command switching unit 10 outputs the α-β axis voltage commands Vα*, Vβ* calculated by the voltage command generating unit 12 based on a switching signal in the idling state (start control) to the two-phase/three-phase conversion unit 11.

In normal operation, the two-phase/three-phase converter 11 uses the dc-qc axis voltage commands Vdc*, Vqc* calculated by the current controller 9 and input via the voltage command switch 10, and the phase information θd_est from the speed/phase estimator 13 to calculate and output the three-phase voltage commands Vu*, Vv*, Vw* according to the following formulas (3) and (4). Note that the following formula (3) represents the conversion from the rotating coordinate system to the fixed coordinate system, and formula (4) represents the so-called two-phase/three-phase conversion.

The control signal generating unit 17 generates a control signal based on the three-phase voltage commands Vu*, Vv*, Vw* from the two-phase/three-phase conversion unit 11 and the detection value (DC voltage detection signal) from the DC voltage detector 50, and outputs the control signal to the inverter 2.

<Startup control>
Next, the operation of each functional block in the transition control (start-up control) from the idling state to the normal operation state will be described. Note that in the start-up control, only the differences from the normal operation state will be described.

First, we explain the basic principles of phase detection during idling (estimating rotor position and rotation speed).

When attempting to restart the permanent magnet synchronous motor 3 from an idling state without using rotor position and rotation speed information, depending on the rotation speed of the permanent magnet synchronous motor 3, starting using normal operation control may be difficult. Therefore, in this embodiment, the rotor position and rotation speed are calculated when the permanent magnet synchronous motor 3 is in an idling state and used for start-up control.

Figure 3 is an explanatory diagram showing the current vectors when DC current flows through a permanent magnet synchronous motor.

In FIG. 3, when the permanent magnet synchronous motor 3 is not rotating freely, a current Iα_DC corresponding to a direct current based on the α-axis flows through the permanent magnet synchronous motor 3. In this case, the β-axis current Iβ becomes 0 (zero).

On the other hand, when the permanent magnet synchronous motor 3 is rotating freely (in an idling state), the current Ie affected by the induced voltage is added to the current Iα_DC, and the current Iαβ (=Iα_DC+Ie) added as a vector flows through the permanent magnet synchronous motor 3. In other words, as shown in FIG. 3, the phase angle of the current Iαβ changes depending on the rotation speed and direction of the permanent magnet synchronous motor 3 in an idling state.

Therefore, in this embodiment, the rotation speed and direction of the permanent magnet synchronous motor 3 in an idling state are estimated by utilizing the fact that the currents Iα and Iβ flowing through the permanent magnet synchronous motor 3 change depending on the idling state.

In this embodiment, a case where a DC current flows through one phase of the permanent magnet synchronous motor 3, which is a three-phase motor, is described as an example, but a DC current may be passed through multiple phases and the rotation speed and rotation direction may be estimated for each of them.

Figure 4 is a functional block diagram showing the processing performed by the spin state estimation unit.

In FIG. 4, the idling state estimation unit 14 is a functional unit that calculates the initial phase θd0 as the rotor position of the permanent magnet synchronous motor 3 in an idling state and the initial speed ωe0 as the rotational speed, and outputs them to the voltage command generation unit 12 and the speed/phase estimation unit 13, and is composed of a magnetic flux estimation unit 18, an idling phase estimation unit 19, and an idling speed estimation unit 20.

The magnetic flux estimation unit 18 uses the α-β axis voltage commands Vα*, Vβ* calculated by the voltage command generation unit 12 and the α-β axis motor currents iα, iβ calculated by the three-phase/two-phase conversion unit 15 to calculate the estimated magnetic fluxes Ψα_est, Ψβ_est according to the following (Equation 5) and (Equation 6), and outputs them to the idling phase estimation unit 19. Note that in (Equation 5) and (Equation 6), R is the motor winding resistance value, and Ψα(0), Ψβ(0) are the initial values of the estimated magnetic fluxes Ψα_est, Ψβ_est, respectively.

The idling phase estimation unit 19 uses the estimated magnetic fluxes Ψα_est and Ψβ_est calculated by the magnetic flux estimation unit 18 to calculate the initial phase θd0 according to the following formula (7), and outputs it to the idling speed estimation unit 20 and to the speed/phase estimation unit 13.

The idling speed estimation unit 20 calculates and outputs the initial speed ωe0 using the initial phase θd0 calculated by the idling phase estimation unit 19. Specifically, for example, the idling speed estimation unit 20 calculates and outputs the estimated speed ωest (=Δθd0/Δt) by dividing the difference Δθd0 (θd0_2-θd0_1) between the previous value θd0_1 and the current value θd0_2 of the initial phase θd0, which is repeatedly calculated at a predetermined control period, by the time Δt (=t2-t1) from the time t1 when the previous value θd0_1 is calculated to the time t2 when the current value θd0_2 is calculated.

Figure 5 is a functional block diagram showing the processing contents of the voltage command generation unit.

In FIG. 5, the voltage command generation unit 12 is a functional unit that calculates the α-β axis voltage commands Vα*, Vβ* required to control the permanent magnet synchronous motor 3 in the idling state, and outputs them to the idling state estimation unit 14 and the voltage command switching unit 10 (in other words, the 2-phase/3-phase conversion unit 11), and is composed of an α-axis voltage command generation unit 21, a β-axis voltage command generation unit 22, and a voltage command correction value calculation unit 23.

The α-axis voltage command generating unit 21 obtains, for example, by calculation or experiment, an α-axis voltage command value that can estimate the maximum speed of the permanent magnet synchronous motor 3 expected in an idling state (e.g., the speed expected during low-speed operation), and outputs it as an initial α-axis voltage command value Vα0*.

The β-axis voltage command generator 22 sets the voltage command Vβ* to, for example, 0 (zero) as the β-axis voltage command value and outputs it.

The voltage command correction value calculation unit 23 uses the initial speed ωe0 calculated by the idling speed estimation unit 20 of the idling state estimation unit 14 and the voltage command Vα0* that is the output of the α-axis voltage command generation unit 21 to calculate the voltage command correction value ΔVα* based on, for example, the following (Equation 8), (Equation 9), and (Equation 10). In (Equation 8), Ke is the induced voltage constant of the permanent magnet synchronous motor 3, and Eest is the estimated induced voltage. In (Equation 9), ΔVVα0_E is the deviation between the estimated induced voltage Eest and the initial α-axis voltage command value Vα0*. In (Equation 10), VCO is a correction amount for making the α-axis voltage command Vα* larger than the estimated induced voltage Eest, and is determined in advance by calculation or experiment.

The calculation unit 24 uses the voltage command Vα0*, which is the output of the α-axis voltage command generation unit 21, and the voltage command correction value ΔVα* to calculate the α-axis voltage command Vα*, which is the output of the voltage command generation unit 12, based on the following (Equation 11).

The speed/phase estimation unit 13 sets the initial speed ωe0 from the idling speed estimation unit 20 of the idling state estimation unit 14 and the initial phase θd0 of the motor rotor from the idling phase estimation unit 19 to initial values, and performs transition control (start-up control) of the permanent magnet synchronous motor 3 from the idling state to the normal operating state.

The voltage command switching unit 10 outputs the voltage commands Vα* and Vβ* for the α-β axes calculated by the voltage command generating unit 12 to the two-phase/three-phase conversion unit 11 based on a switching signal from the outside when the motor is in an idling state (start-up control).

In the idling state (start-up control), the speed control unit 7 creates a qc-axis current command value Iqc* so that the deviation between the speed command value ω* generated by a functional unit (not shown) in the motor control device 4 in response to an external command and the estimated speed ωest (=ωe0 (initial value)) from the speed/phase estimation unit 13 approaches 0 (zero), i.e., so that the estimated speed ωest approaches the speed command value ω*.

In the idling state (start-up control), the two-phase/three-phase conversion unit 11 uses the voltage commands Vα*, Vβ* of the α-β axes calculated by the voltage command generation unit 12 and input via the voltage command switching unit 10, and the phase information θd_est (= θd0 (initial value)) from the speed/phase estimation unit 13 to calculate and output the three-phase voltage commands Vu*, Vv*, Vw* according to (Equation 3) and (Equation 4).

The effects of this embodiment configured as above are explained below.

In conventional technology, the short-circuit current of the motor winding when the inverter is in short-circuit operation is determined by the motor induced voltage, winding resistance, and inductance, so there is a risk of overcurrent occurring during short-circuit operation depending on the idling speed. In addition, because a special PWM control mode and current detection process are used to detect the current flowing through the bus (shunt) resistor, the calculations for calculating the motor rotor position and rotation speed are complex, making it easy for errors to occur in the estimated results.

In contrast, in the present embodiment, a motor control device controls the operation of a permanent magnet synchronous motor by controlling the operation of an inverter that converts DC power into AC power and supplies it to the permanent magnet synchronous motor using a control signal based on a voltage command. The motor control device includes a first control unit that generates a control signal for the inverter during normal operation of the permanent magnet synchronous motor, and a second control unit that generates a control signal for the inverter when the permanent magnet synchronous motor is in an idling state. When the permanent magnet synchronous motor is in an idling state, the second control unit outputs a voltage command to pass a DC current of a predetermined initial value through the permanent magnet synchronous motor, calculates the rotor position and rotation speed of the permanent magnet synchronous motor based on the voltage command and the current value of the permanent magnet synchronous motor according to the voltage command, estimates the induced voltage of the permanent magnet synchronous motor based on the calculated rotation speed, and adjusts the voltage command so that the induced voltage is larger than the estimated induced voltage. This allows the position and speed of the motor rotor to be calculated with higher accuracy.

<Additional Notes>
The present invention is not limited to the above-described embodiment, and includes various modifications and combinations within the scope of the gist of the present invention. Furthermore, the present invention is not limited to those having all of the configurations described in the above-described embodiment, and includes those in which some of the configurations are omitted.

For example, in the motor control device 4, moving average processing or low-pass filter processing may be performed on the values used in various calculations to avoid the effects of disturbances and noise.

Furthermore, each of the configurations, functions, etc. of the motor control device 4 described in this embodiment may be realized in part or in whole by, for example, designing them as an integrated circuit. Furthermore, each of the above configurations, functions, etc. may be realized in software by a processor interpreting and executing a program that realizes each function.

1...DC power supply, 2...Inverter, 3...Permanent magnet synchronous motor, 4...Motor control device, 5...Shunt resistor, 6...Amplifier, 7...Speed control unit, 8...d-axis current command generation unit, 9...Current control unit, 10...Voltage command switching unit, 11...2-phase/3-phase conversion unit, 12...Voltage command generation unit, 13...Speed/phase estimation unit, 14...Idle state estimation unit, 15...3-phase/2-phase conversion unit, 16...Current reproduction calculation unit, 17...Control signal generation unit, 18...Magnetic flux estimation unit, 19...Idle phase estimation unit, 20...Idle speed estimation unit, 21...α-axis voltage command generation unit, 22...β-axis voltage command generation unit, 23...Voltage command correction value calculation unit, 24, 25...Calculation unit, 50...DC voltage detector

Claims (5)

A motor control device that controls an operation of a permanent magnet synchronous motor by controlling an operation of an inverter that converts DC power into AC power and supplies the AC power to the permanent magnet synchronous motor using a control signal based on a voltage command, the motor control device comprising:
A first control unit that generates a control signal for the inverter during normal operation of the permanent magnet synchronous motor;
a second control unit that generates a control signal for the inverter when the permanent magnet synchronous motor is running idle;
The second control unit is
When the permanent magnet synchronous motor is in an idling state,
outputting a voltage command for causing a direct current of a predetermined initial value to flow through the permanent magnet synchronous motor;
calculating a rotor position and a rotation speed of the permanent magnet synchronous motor based on the voltage command and a current value of the permanent magnet synchronous motor corresponding to the voltage command;
An induced voltage of the permanent magnet synchronous motor is estimated based on the calculated rotation speed;
A motor control device comprising: a motor control unit that adjusts the voltage command so that the voltage command is greater than the estimated induced voltage. 2. The motor control device according to claim 1,
The motor control device according to claim 1, wherein the second control unit outputs a voltage command for causing a direct current of the initial value to flow through one phase of a plurality of phases provided in an armature of the permanent magnet synchronous motor. 2. The motor control device according to claim 1,
The motor control device according to claim 1, wherein the initial value of the direct current is a current value that enables estimation of an expected speed during low-speed operation of the permanent magnet synchronous motor. 2. The motor control device according to claim 1,
The second control unit is
Estimating the induced voltage based on a rotation speed of a permanent magnet synchronous motor and an induced voltage constant;
Calculating a deviation between a voltage command for flowing the initial value of the direct current and the induced voltage;
A difference between a predetermined correction value and the deviation is calculated as a voltage command correction value;
A motor control device comprising: a voltage command correction value added to a voltage command for flowing a direct current of the initial value, thereby adjusting the voltage command. 1. A motor control method for controlling an operation of a permanent magnet synchronous motor by controlling an operation of an inverter that converts DC power into AC power and supplies the AC power to the permanent magnet synchronous motor using a control signal based on a voltage command, comprising:
a step of outputting a voltage command for causing a direct current of a predetermined initial value to flow through the permanent magnet synchronous motor when the permanent magnet synchronous motor is in an idling state;
calculating a rotor position and a rotation speed of the permanent magnet synchronous motor based on the voltage command and a current value of the permanent magnet synchronous motor corresponding to the voltage command;
A step of estimating an induced voltage of the permanent magnet synchronous motor based on the calculated rotation speed;
and adjusting the voltage command so that the voltage command is greater than the estimated induced voltage.

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