TWI896014B - Motor control device and motor control method - Google Patents

Abstract

The present invention is to provide a motor control device and motor control method capable of calculating the position and speed of a motor rotor with higher accuracy. The motor control device of the present invention controls the operation of an inverter by using a control signal based on a voltage command, thereby controlling the actuator of a permanent magnet synchronous motor. The device comprises: a first control unit that generates an inverter control signal when the permanent magnet synchronous motor is operating normally; and a second control unit that generates an inverter control signal when the permanent magnet synchronous motor is idling. The second control unit generates an inverter control signal when the permanent magnet synchronous motor is idling. In the idling state, a voltage command is output to cause a DC current of a predetermined initial value to flow through the permanent magnet synchronous motor. Based on the voltage command and the current value of the permanent magnet synchronous motor corresponding to the voltage command, the rotor position and speed of the permanent magnet synchronous motor are calculated. Based on the calculated speed, the induced voltage of the permanent magnet synchronous motor is estimated. The voltage command is adjusted to be greater than the estimated induced voltage.

Description

Motor control device and motor control method

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

Motor drive systems, consisting of inverters that convert DC power to AC power and permanent magnet synchronous motors, are widely used in home appliances and industrial machinery. To efficiently drive these permanent magnet synchronous motors, information about the motor's rotor position is generally required. While the motor's rotor position can be directly detected using position detectors such as encoders, this method presents cost and reliability issues. Therefore, in recent years, sensorless control, which detects the rotor position of permanent magnet synchronous motors without using a position detector, has been proposed and applied to a variety of products.

Another issue in sensorless control of permanent magnet synchronous motors is restarting the motor from an idling rotor state (known as a "free-run start"). For example, motors in washing machines and other applications may already be rotating due to load inertia before starting. In such cases, without information about the rotor's position, speed, and direction during the idling state, the motor must wait until it stops, or forcibly brake to stop the motor. Restarting the motor after it has come to a stop can then be a long process.

Therefore, for example, the prior art described in Patent Documents 1 and 2 focuses on the induced voltage generated when a permanent magnet synchronous motor is idling. They have developed a method of short-circuiting the motor windings using an inverter and estimating the rotor position based on the current flowing at this time.

In Patent Document 1, the three upper (lower) arm elements of the switching element constituting the motor-driven inverter are simultaneously turned on, causing a short-circuit current to flow through the motor windings. The rotor position and speed are calculated based on the detection information of the three-phase motor current.

Furthermore, Patent Document 2 uses a motor-driven inverter to simultaneously switch elements in two different arms of the inverter on and off, detecting the DC bus (shunt) current on the inverter's DC side to calculate the motor's rotor position and speed. [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Publication No. 2015-73361 [Patent Document 2] Japanese Patent Publication No. 2018-170928

[Identify the problem you want to solve]

However, the above prior art has the following problems.

In the prior art described in Patent Document 1, the short-circuit current of the motor winding during short-circuit operation of the inverter is determined by the motor's inductive voltage, winding resistance, and inductance. Therefore, depending on the idling speed, there is a risk of overcurrent during short-circuit operation.

The prior art described in Patent Document 2 uses a special PWM (Pulse Width Modulation) control mode and current detection processing to detect the current flowing through the bus (shunt) resistor. This complicates the calculation of the motor's rotor position and speed, and the estimated results are prone to errors.

The present invention was completed in light of the above-mentioned circumstances, and its purpose is to provide a motor control device and motor control method capable of calculating the position and speed of a motor rotor with higher accuracy. [Technical Solution]

The present invention includes a plurality of means for solving the above-mentioned problems. One example thereof is a motor control device that controls the operation of a converter that converts DC power into AC power and supplies the AC power to a permanent magnet synchronous motor by using a control signal based on a voltage command, thereby controlling the operation of the permanent magnet synchronous motor. The motor control device includes: a first control unit that generates a control signal for the converter when the permanent magnet synchronous motor is operating normally; and a second control unit that generates a control signal for the converter when the permanent magnet synchronous motor is idling. The second control unit outputs a voltage command for flowing a DC current of a predetermined initial value through the permanent magnet synchronous motor when the permanent magnet synchronous motor is in an idling state; 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 corresponding to the voltage command; estimates the 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. [Effects of the Invention]

According to the present invention, the position and speed of the motor rotor can be calculated with higher accuracy.

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.

FIG1 schematically shows the overall structure of the motor control system of this embodiment, as well as the motor control device and its related structures.

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

As the DC power source 1, for example, a power conversion device (such as a diode rectifier or a stabilized power supply) 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, etc. is used.

Converter 2 is composed of two arm circuits in which a semiconductor switching element (IGBT (Insulated Gate Bipolar Transistor) or MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor)) is connected in anti-parallel to a diode. In other words, the series-connected circuit in which the upper arm and the lower arm are connected in series is connected between a pair of positive and negative terminals of DC power source 1. Converter 2 has a number of series-connected circuits corresponding to the number of phases of the output AC. For example, in this embodiment, it is a three-phase converter having a number of series-connected circuits corresponding to the three phases. The upper arm and lower arm of converter 2 are connected to the high-potential side and the low-potential side of DC power source 1, respectively. The series connection point of the upper arm and the lower arm is connected to the AC terminal, and the AC terminal is connected to the permanent magnet synchronous motor 3.

The busbar on the low-potential side of the converter 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 an amplifier 6. For digital calculations in the motor control device 4, the output signal from the amplifier 6 to the motor control device 4 is converted into a digital signal by a sampling and holding circuit and an A/D (Analog/Digital) converter (not shown). In other words, the shunt resistor 5 and the amplifier 6 constitute a DC current detector that detects the DC current flowing through the busbar on the low-potential side of the converter 2 and outputs the current detection signal to the motor control device 4. Furthermore, other current detection mechanisms such as an inductive force sensor can also be used instead of the shunt resistor 5.

Furthermore, in the converter 2, a DC voltage detector 50 is installed between the high-potential busbar connected to the positive terminal of the DC power source 1 and the busbar connected to the negative terminal of the DC power source 1. This DC voltage detector 50 detects the DC voltage between the high-potential and low-potential 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 into a digital signal, similar to the DC current detector.

Furthermore, in this embodiment, as described below, the motor control device 4 performs so-called position sensorless control, that is, it detects the rotor position of the permanent magnet synchronous motor and performs synchronization without using a position detector. The permanent magnet synchronous motor 3 is not equipped with a magnetic pole position detection mechanism such as a Hall element to detect 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, which realizes various functions by executing a specified program.

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

The motor control device 4 calculates a voltage command applied to the permanent magnet synchronous motor 3 through d-q axis vector control. Based on this voltage command, it generates a PWM (Pulse Width Modulation) control signal for the inverter 2, 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 operation control) and controls the transition from the idling state to the normal operating state (startup control).

<Normal Operation Control> First, we will explain the operation of each functional block in the normal operation state.

The current reconstruction calculation unit 16 uses 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 to reconstruct the three-phase motor currents iu, iv, and iw from the inverter 2. The method for reconstructing the three-phase motor current based on the current signal from the shunt resistor 5 is well-known and will not be described in detail here.

Furthermore, in this embodiment, to reduce costs, the current reproduction calculation unit 16 employs a method of reproducing the three-phase motor currents iu, iv, and iw based on the current detection signal ish detected by the shunt resistor 5 and inputting these to the three-phase/two-phase conversion unit 15. However, this is not limiting. For example, a current detection mechanism such as an inductive current sensor may be used in place of the shunt resistor 5 to detect the AC current output from the converter 2, and the three-phase motor currents iu, iv, and iw detected by the current detection mechanism may be input to the three-phase/two-phase conversion unit 15.

Based on the three-phase motor 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, 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 according to the following (Equations 1) and (2). Furthermore, (Equation 1) represents the so-called three-phase/two-phase conversion, and (Equation 2) represents the conversion to a rotational coordinate system.

[Formula 1] (Formula 1)

[Formula 2] (Formula 2)

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

The speed-phase estimator 13 uses the DC-axis current detection value idc and the QC-axis current detection value iqc, as well as the DC-QC-axis voltage commands Vdc* and Vqc*, to estimate the rotor position and rotational speed, outputting these as phase information θd_est and estimated speed ωest. The specific estimation mechanism within the speed-phase estimator 13 can be conventionally used, and a detailed description thereof will be omitted.

The speed control unit 7 sets the qc-axis current command value Iqc* as follows: the deviation calculated by the calculation unit 25 based on the speed command value ω* generated by the functional unit (not shown) within the motor control device 4 in accordance with the external command and the estimated speed ωest estimated by the speed-phase estimation unit 13 approaches 0 (zero), that is, the estimated speed ωest is brought close to the speed command value ω*.

The d-axis current command generating unit 8 generates a dc-axis current command value Idc* for minimizing the three-phase motor currents iu, iv, and iw.

The current control unit 9 uses 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, as well as the speed command value ω* and the motor constant to calculate and output the dc-axis voltage command value Vdc* and the qc-axis voltage command value Vqc*.

Based on an external switching signal, the voltage command switching unit 10 outputs either the dc-qc axis voltage commands Vdc* and Vqc* calculated by the current control unit 9 or the α-β axis voltage commands Vα* and Vβ* calculated by the voltage command generating unit 12 to the two-phase/three-phase converter 11. Specifically, based on a switching signal during normal operation, the voltage command switching unit 10 outputs the dc-qc axis voltage commands Vdc* and Vqc* calculated by the current control unit 9 to the two-phase/three-phase converter 11. Furthermore, the voltage command switching unit 10 outputs the voltage commands Vα* and Vβ* of the α-β axis calculated by the voltage command generating unit 12 to the two-phase/three-phase conversion unit 11 based on the switching signal in the idling state (startup control).

During normal operation, the two-phase/three-phase converter 11 uses the DC-QC axis voltage commands Vdc* and Vqc* calculated by the current control unit 9 and input via the voltage command switching unit 10, as well as the phase information θd_est from the speed-phase estimation unit 13. It calculates and outputs the three-phase voltage commands Vu*, Vv*, and Vw* using the following (Equations 3) and (4). Furthermore, (Equation 3) represents the conversion from a rotating coordinate system to a fixed coordinate system, while (Equation 4) represents the so-called two-phase/three-phase conversion.

[Formula 3] (Formula 3)

[Formula 4] ···(Formula 4)

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 it to the converter 2.

<Startup Control> Next, the operation of each functional block in the control of the transition from idling to normal operation (startup control) is explained. Furthermore, only the differences from normal operation in startup control are described.

First, the basic principles of phase detection (estimation of rotor position and speed) during idling are explained.

When restarting the permanent magnet synchronous motor 3 from an idling state without using rotor position and speed information, it may be difficult to restart the motor using normal operation control, depending on the speed of the permanent magnet synchronous motor 3. Therefore, in this embodiment, the rotor position and speed of the permanent magnet synchronous motor 3 are calculated while the motor is idling and used for startup control.

FIG3 is a diagram illustrating the current vector when a DC current flows through a permanent magnet synchronous motor.

In FIG3 , when the permanent magnet synchronous motor 3 is not idling, a current Iα_DC corresponding to a DC current with respect to the α-axis flows through the permanent magnet synchronous motor 3. In this case, the β-axis current Iβ is 0 (zero).

On the other hand, when the permanent magnet synchronous motor 3 is idling (in the idling state), a current Iαβ (= Iα_DC + Ie) flows through the permanent magnet synchronous motor 3. This current Iαβ (= Iα_DC + Ie) is the sum of the current Ie corresponding to the effect of the induced voltage and the current Iα_DC, and the sum is vectorial. That is, as shown in Figure 3, the phase angle of the current Iαβ varies depending on the speed or rotational direction of the permanent magnet synchronous motor 3 in the idling state.

Therefore, in this embodiment, the rotation speed or rotation direction of the permanent magnet synchronous motor 3 in the idling state is estimated by utilizing the fact that the currents Iα and Iβ flowing in the permanent magnet synchronous motor 3 change according to the idling state.

Furthermore, this embodiment is described by taking the case where DC current flows through one phase of the permanent magnet synchronous motor 3 as a three-phase motor. However, DC current can also flow through multiple phases and the speed or rotation direction can be estimated for each phase.

FIG4 is a functional block diagram showing the processing contents of the idling state estimation unit.

In FIG4 , the idling state estimation unit 14 calculates the initial phase θd0, which represents the rotor position of the permanent magnet synchronous motor 3 in the idling state, and the initial speed ωe0, which represents the rotational speed. These are then output to the voltage command generation unit 12 and the functional units of the speed-phase estimation unit 13, which include 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 voltage commands Vα* and Vβ* for the α-β axes calculated by the voltage command generation unit 12 and the motor currents iα and iβ for the α-β axes calculated by the three-phase/two-phase conversion unit 15 to calculate the estimated magnetic fluxes Ψα_est and Ψβ_est using the following (Equations 5) and (6), and outputs them to the idling phase estimation unit 19. In (Equations 5) and (6), R is the motor winding resistance, and Ψα(0) and Ψβ(0) are the initial values of the estimated magnetic fluxes Ψα_est and Ψβ_est, respectively.

[Formula 5] ···(Formula 5)

[Formula 6] ···(Formula 6)

The idling phase estimating unit 19 calculates the initial phase θd0 using the estimated magnetic fluxes Ψα_est and Ψβ_est calculated by the magnetic flux estimating unit 18 according to the following (Equation 7), and outputs the value to the idling speed estimating unit 20 and the speed-phase estimating unit 13 .

[Formula 7] ···(Formula 7)

The idling speed estimating unit 20 calculates and outputs the initial speed ωe0 using the initial phase θd0 calculated by the idling phase estimating unit 19. Specifically, for example, the estimated speed ωest (=Δθd0/Δt) is calculated and output 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 are repeatedly calculated in a specified control cycle, by the time Δt (= t2 - t1) from time t1, when the previous value θd0_1 was calculated, to time t2, when the current value θd0_2 is calculated.

FIG5 is a functional block diagram showing the processing contents of the voltage command generating unit.

In Figure 5, the voltage command generator 12 calculates the α-β axis voltage commands Vα* and 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 two-phase/three-phase conversion unit 11). The functional unit includes an α-axis voltage command generator 21, a β-axis voltage command generator 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 assumed in the idling state (e.g., the speed assumed during low-speed operation), and outputs it as an initial α-axis voltage command value Vα0*.

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

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* output by the α-axis voltage command generation unit 21 to calculate a 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. Furthermore, 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), VCО is a correction value used to make the α-axis voltage command Vα* greater than the estimated induced voltage Eest, and is predetermined by calculation or experimental determination.

[Formula 8] ···(Formula 8)

[Formula 9] ···(Formula 9)

[Formula 10] ···(Formula 10)

The calculation unit 24 calculates the α-axis voltage command Vα* as the output of the voltage command generation unit 12 based on the following (Equation 11) using the voltage command Vα0* as the output of the α-axis voltage command generation unit 21 and the voltage command correction value ΔVα*.

[Formula 11] ···(Formula 11)

The speed-phase estimating unit 13 sets the initial speed ωe0 from the idling speed estimating unit 20 of the idling state estimating unit 14 and the initial phase θd0 of the motor rotor from the idling phase estimating unit 19 as initial values, and performs transition control (startup control) of the permanent magnet synchronous motor 3 from the idling state to the normal operation state.

The voltage command switching unit 10 outputs the voltage commands Vα* and Vβ* of the α-β axis calculated by the voltage command generating unit 12 to the two-phase/three-phase conversion unit 11 based on the switching signal from the outside during the idling state (startup control).

In the idling state (startup control), the speed control unit 7 sets the qc-axis current command value Iqc* in such a manner that the deviation between the speed command value ω* generated by a functional unit (not shown) within the motor control device 4 in response to an external command and the estimated speed ωest (=ωe0 (initial value)) from the speed-phase estimator 13 approaches 0 (zero). In other words, 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 axis 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*, and Vw* using (Equation 3) and (Equation 4).

The effects of this embodiment configured as described above will be described.

In prior art, the short-circuit current in the motor windings during inverter short-circuit operation is determined by the motor's inductive voltage, winding resistance, and inductance. This creates the risk of overcurrent during short-circuit operation depending on the idling speed. Furthermore, the need to detect the current flowing through the bus (shunt) resistors requires specialized PWM control modes and current detection processing, complicating the calculation of the motor's rotor position and speed, leading to errors in the estimated results.

In contrast, the present embodiment is a motor control device that controls the operation of an inverter that converts DC power into AC power and supplies the AC power to a permanent magnet synchronous motor by a control signal based on a voltage command, thereby controlling the actuator of the permanent magnet synchronous motor. The device comprises: a first control unit that generates a control signal for the inverter when the permanent magnet synchronous motor is operating normally; and a second control unit that generates a control signal for the inverter when the permanent magnet synchronous motor is idling. The second control unit is configured to generate a control signal for the inverter when the permanent magnet synchronous motor is idling. When the permanent magnet synchronous motor is in an idling state, a voltage command is output to cause a DC current of a predetermined initial value to flow through the permanent magnet synchronous motor. The rotor position and speed of the permanent magnet synchronous motor are calculated based on the voltage command and the current value of the permanent magnet synchronous motor corresponding to the voltage command. The induced voltage of the permanent magnet synchronous motor is estimated based on the calculated speed. The voltage command is adjusted to be greater than the estimated induced voltage, thereby enabling the position and speed of the motor rotor to be calculated with higher accuracy.

<Note> Furthermore, the present invention is not limited to the above-described embodiments and includes various modifications and combinations within the scope of the present invention. Furthermore, the present invention is not limited to embodiments having all of the components described in the above-described embodiments and includes embodiments in which some of the components are deleted.

For example, in the motor control device 4, in order to avoid the influence of interference and noise, moving average processing or low-pass filtering processing can also be performed on the values required for various calculations.

Furthermore, the various components and functions of the motor control device 4 described in this embodiment may be partially or entirely implemented, for example, by designing an integrated circuit. Furthermore, the aforementioned components and functions may be implemented by software, with a processor interpreting and executing programs that implement the respective functions.

1: DC power supply 2: Inverter 3: Permanent magnet synchronous motor 4: Motor control unit 5: Shunt resistor 6: Amplifier 7: Speed control unit 8: D-axis current command generator 9: Current control unit 10: Voltage command switching unit 11: Two-phase/three-phase conversion unit 12: Voltage command generator 13: Speed-phase estimation unit 14: Idle state estimation unit 15: Three-phase/two-phase conversion unit 16: Current reconstruction calculation unit 17: Control signal generator 18: Magnetic flux estimation unit 19: Idle phase estimation unit 20: Idle speed estimation unit 21: α-axis voltage command generator 22: β-axis voltage command generator 23: Voltage Command Correction Value Calculation Unit 24: Calculation Unit 25: Calculation Unit 50: DC Voltage Detector Idc*: DC-axis current command value Ie: Current Iqc*: QC-axis current command value Iα_DC: Current Iαβ: Current idc: DC-axis current iqc: QC-axis current ish: Current detection signal iu,iv,iw: Three-phase motor currents iα: Alpha-axis current iβ: Beta-axis current Vdc*: DC-axis voltage command value Vqc*: QC-axis voltage command value Vu*,Vv*,Vw*: Three-phase voltage commands Vα*: Alpha-axis voltage command Vα0*: Initial α-axis voltage command value Vβ*: β-axis voltage command θd0: Initial phase θd_est: Phase information Ψα_est,Ψβ_est: Estimated magnetic flux ω*: Speed command value ωe0: Initial speed ωest: Estimated speed ΔVα*: Voltage command correction value

Figure 1 schematically illustrates the overall configuration of the motor control system, including the motor control device and its related components. Figure 2 is a functional block diagram showing the processing of the motor control device. Figure 3 is an explanatory diagram showing the current vector when DC current flows through a permanent magnet synchronous motor. Figure 4 is a functional block diagram showing the processing of the idling state estimation unit. Figure 5 is a functional block diagram showing the processing of the voltage command generation unit.

7: Speed Control Unit

8: D-axis current command generation unit

9: Current Control Unit

10: Voltage command switching unit

11: Two-phase/three-phase conversion unit

12: Voltage command generation unit

13: Speed-Phase Estimation Unit

14: Idle state estimation unit

15: Three-phase/two-phase conversion unit

16: Current reproduction calculation unit

17: Control signal generation unit

25: Operations Department

Idc*: DC axis current command value

Iqc*:qc axis current command value

IDC: DC axis current

iqc:qc axis current

ish: current detection signal

iu,iv,iw: three-phase motor current

iα:α-axis current

iβ:β-axis current

Vdc*: DC axis voltage command value

Vqc*: qc axis voltage command value

Vu*, Vv*, Vw*: Three-phase voltage command

Vα*: α-axis voltage command

Vβ*: β-axis voltage command

θd0: Initial phase

θd_est: Phase information

ω*: Speed command value

ωe0: Initial velocity

ωest: estimated speed

Claims (5)

A motor control device is characterized in that it controls the operation of an inverter that converts DC power into AC power and supplies it to a permanent magnet synchronous motor by controlling the operation of the inverter based on a control signal based on a voltage command, thereby controlling the actuator of the permanent magnet synchronous motor. The device comprises: a first control unit that generates a control signal for the inverter when the permanent magnet synchronous motor is operating normally; and a second control unit that generates a control signal for the inverter when the permanent magnet synchronous motor is idling. When the permanent magnet synchronous motor is idling, the second control unit outputs a voltage command to cause a DC current of a predetermined initial value to flow through the permanent magnet synchronous motor. Based on the voltage command and the current value of the permanent magnet synchronous motor corresponding to the voltage command, the rotor position and rotational speed of the permanent magnet synchronous motor are calculated; Based on the calculated rotational speed, the induced voltage of the permanent magnet synchronous motor is estimated; and The voltage command is adjusted to be greater than the estimated induced voltage. The motor control device of claim 1, wherein the second control unit outputs a voltage command for causing a DC current of the initial value to flow through one of the plurality of phases provided in the armature of the permanent magnet synchronous motor. The motor control device of claim 1, wherein the initial DC current is a current value that can estimate the speed assumed when the permanent magnet synchronous motor is operating at low speed. The motor control device of claim 1, wherein: the second control unit estimates the induced voltage based on the rotational speed and induced voltage constant of the permanent magnet synchronous motor; calculates a deviation between a voltage command for a DC current flowing at the initial value and the induced voltage; calculates a difference between a predetermined correction value and the deviation as a voltage command correction value; and adjusts the voltage command by adding the voltage command correction value to the voltage command for a DC current flowing at the initial value. A motor control method is characterized in that it controls the operation of an inverter that converts DC power into AC power and supplies it to a permanent magnet synchronous motor by controlling the operation of the inverter based on a control signal based on a voltage command, thereby controlling the actuator of the permanent magnet synchronous motor. The method comprises the following steps: When the permanent magnet synchronous motor is in an idling state, outputting a voltage command to cause a DC current of a predetermined initial value to flow through the permanent magnet synchronous motor; Based on the voltage command and the current value of the permanent magnet synchronous motor corresponding to the voltage command, calculating the rotor position and rotational speed of the permanent magnet synchronous motor; Based on the calculated rotational speed, estimating the induced voltage of the permanent magnet synchronous motor; and Adjust the voltage command to be greater than the estimated induced voltage.