Motor control device

Patent metadata

Field	Value
Publication number	US-11075597-B2
Application number	US-201916703123-A
Country	US
Kind code	B2
Filing date	Dec 4, 2019
Priority date	Dec 4, 2018
Publication date	Jul 27, 2021
Grant date	Jul 27, 2021

Abstract

A motor control device controls driving of a motor in response to d-axis and q-axis current commands set on the basis of a torque command. The motor control device includes: an electrical angle estimation unit configured to estimate an electrical angle of the motor according to at least one of methods of estimating the electrical angle on the basis that a leakage current in a q axis becomes zero by applying a voltage to a d axis, on the basis that at least one of a phase current difference and a line current difference caused by an induced voltage generated due to rotation of the motor becomes zero, and on the basis of a voltage equation, depending on an angular velocity of the motor, a modulation rate of a pwm signal, and whether a magnetic flux change is included in a nonlinear region.

First claim

What is claimed is:

1. A motor control device that controls driving of a motor provided with a permanent magnet in response to a d-axis current command and a q-axis current command that are set on the basis of a torque command, the motor control device comprising:
an electrical angle estimation unit configured to estimate an electrical angle of the motor according to at least one of a first method of estimating the electrical angle of the motor on the basis that a leakage current in a q axis becomes zero by applying a voltage to a d axis, a second method of estimating the electrical angle of the motor on the basis that at least one of a phase current difference and a line current difference caused by an induced voltage generated due to rotation of the motor becomes zero, and a third method of estimating the electrical angle on the basis of a voltage equation, depending on an angular velocity of the motor, a modulation rate of a pwm signal, and whether a magnetic flux change is included in a nonlinear region in which the magnetic flux change is nonlinear, wherein
in a case where the electrical angle of the motor is estimated according to at least one of the first method and the third method, with respect to the electrical angle estimated according to the second method, the electrical angle estimation unit is configured to replace the electrical angle estimated according to at least one of the first method and the third method with the electrical angle estimated according to the second method.

2. The motor control device according to claim 1 , wherein
the electrical angle estimation unit is configured to estimate the electrical angle according to the first method and the second method in a case where the angular velocity of the motor is low, and estimate the electrical angle according to the second method and the third method in a case where the angular velocity of the motor is high.

3. The motor control device according to claim 1 , wherein
in a case of overmodulation in which the modulation rate of the pwm signal is 1 or greater and in the nonlinear region in which the magnetic flux change is nonlinear, the electrical angle estimation unit is configured to estimate the electrical angle according to the second method.

4. The motor control device according to claim 3 , wherein
in the second method in the nonlinear region in which the magnetic flux change is nonlinear, the electrical angle estimation unit is configured to estimate a plurality of predetermined electrical angles, and estimate an electrical angle between the predetermined electrical angles through interpolation calculation.

5. The motor control device according to claim 1 , wherein
in the second method, when the phase current difference is not zero and when the line current difference is not zero, the electrical angle estimation unit is configured to estimate an electrical angle at which the phase current difference is zero and an electrical angle at which the line current difference is zero on the basis of the following Equations 1 and 2:
θ0 c{circumflex over ( )}=θ 0 t{circumflex over ( )}−Δi*×ω{circumflex over ( )}/ΔΔ 1*  Equation 1)

θ10{circumflex over ( )}=θ01 t{circumflex over ( )}−Δi*×ω{circumflex over ( )}/ΔΔ 1*  Equation 2)

where, θ0t{circumflex over ( )} and θ01t{circumflex over ( )} respectively indicate target values, Δi* indicates a current difference, ΔΔ1* indicates a change rate of Δi*, and * indicates the d axis or the q axis.

6. The motor control device according to claim 1 , wherein
in the second method, the electrical angle estimation unit is configured to compensate for a delay of the electrical angle estimated according to the second method on the basis of an equipment constant of the motor.

7. The motor control device according to claim 1 , wherein
the second method includes a method based on a current value in a stationary coordinate system and a method based on a current difference when two phases are short-circuited to each other, in addition to a method based on the phase current difference and a method based on the line current difference.

8. The motor control device according to claim 7 , wherein
in the method based on the current value in the stationary coordinate system, the electrical angle estimation unit is configured to estimate the electrical angle of the motor on the basis of current values in two phases in which absolute values of current values or absolute values of change amounts of currents are greater among three phases.

9. The motor control device according to claim 7 , wherein
in the method based on the current value in the stationary coordinate system, the electrical angle estimation unit is configured to reduce noise on the basis of a d-axis current value and a q-axis current value.

10. The motor control device according to claim 7 , wherein
an angular velocity of the motor to which the method based on the current value in the stationary coordinate system is applied is higher than an angular velocity of the motor to which the method based on the current difference when the two phases are short-circuited to each other is applied.

11. The motor control device according to claim 7 , wherein
in a case where a current supplied to the motor is detected by a single shunt resistor, in the second method, the electrical angle estimation unit is configured to estimate the electrical angle according to the at least one of the method based on the line current difference and the method based on the current difference when the two phases are short-circuited to each other, instead of using the method based on the phase current difference and the method based on the current value in the stationary coordinate system.

12. The motor control device according to claim 7 , wherein
in a case where a current supplied to the motor is detected by a single shunt resistor ( 20 ), the second method further includes a method of estimating the electrical angle on the basis of an induced voltage in an off vector state.

13. The motor control device according to claim 1 , wherein
in the second method, the electrical angle estimation unit is configured to estimate the electrical angle by performing a plurality of times of sampling for detecting an electrical angle such that the number of times of sampling is increased as the angular velocity of the motor becomes lower, and performing movement averaging on results of the plurality of times of sampling.

14. The motor control device according to claim 1 , wherein
in the first method, the electrical angle estimation unit is configured to reduce an interval of sampling for estimating the electrical angle according to the first method in a case where a change rate of a q-axis current is high more than in a case where the change rate of the q-axis current is low.

15. The motor control device according to claim 1 , wherein
in the first method, the electrical angle estimation unit is configured to correct an electrical angle estimated when magnetic flux is saturated on the basis of the following Equation:
θ vd{circumflex over ( )}=θvd {circumflex over ( )}×(ω{circumflex over ( )}× Kt{circumflex over ( )}idn 0+( Ld{circumflex over ( )}idn 0− Lq{circumflex over ( )}idn 0)×(ω{circumflex over ( )}× idrefn−piqrefn ))/(ω{circumflex over ( )}× Kt{circumflex over ( )}idn +( Ld{circumflex over ( )}idn−Lq{circumflex over ( )}idn )×(ω{circumflex over ( )}× idrefn−piqrefn ))

where, ω indicates an angular velocity, Kt indicates a counter-electromotive force constant, Ld indicates d-axis inductance, Lq indicates q-axis inductance, idrefn indicates a d-axis current command value, iqref

Assignees

• Aisin Seiki

Inventors

• Todu Kenji
• Maeda Misato
• Onosaka Naoki
• Lin Keirei
• Yamashita Genki

Classifications

• H02P21/32

  Determining the initial rotor position (H02P21/34 takes precedence) · CPC title

• H02P21/09

  Field phase angle calculation based on rotor voltage equation by adding slip frequency and speed proportional frequency · CPC title

• H02P6/08

  Arrangements for controlling the speed or torque of a single motor (H02P6/10, H02P6/28 take precedence) · CPC title

• H02P21/18 Primary

  Estimation of position or speed · CPC title

• H02P21/22

  Current control, e.g. using a current control loop · CPC title