CONTROL DEVICE OF ALTERNATING-CURRENT ELECTRIC MOTOR

• US 20160072424A1
• Filed: 04/23/2013
• Published: 03/10/2016
• Est. Priority Date: 04/23/2013
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: YOKOZUTSUMI, Ryo, YAMASAKI, Hisanori, KATO, Sho, KOMETANI, Haruyuki, KANEKO, Kenta
• Granted Patent: US 10,103,675 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60L 15/025 using field orientation; Vector control; Direct Torque Control [DTC]
• CPC Class Codes: H02M 7/53875 with analogue control of three-phase output
• CPC Class Codes: H02M 7/53876 based on synthesising a desired voltage vector via the selection of appropriate fundamental voltage vectors, and corresponding dwelling times
• CPC Class Codes: H02P 21/0003 Control strategies in general, e.g. linear type, e.g. P, PI, PID, using robust control
• CPC Class Codes: H02P 21/22 Current control, e.g. using a current control loop
• CPC Class Codes: H02P 27/08 with pulse width modulation
• CPC Class Codes: H02P 27/085 wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency
• CPC Class Codes: H02P 27/14 with three or more levels of voltage
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility

Abstract

A control device includes a gate-signal generating unit that outputs a gate signal to an inverter circuit and a voltage-vector generating unit that generates a voltage command to the gate-signal generating unit on the basis of a torque command PTR from an upper unit, rotating speed FM of an alternating-current electric motor, and a direct-current voltage value EFC applied to the inverter circuit. The voltage-vector generating unit calculates, on basis of a modulation rate, which is a ratio of the direct-current voltage value EFC and a voltage amplitude command in the voltage command, a PWM current distortion rate serving as an index representing a degree of a current harmonic caused by PWM control, generates the voltage amplitude command value on the basis of the calculated PWM current distortion rate, and outputs the voltage amplitude command value to the gate-signal generating unit.

Claims

1-8. -8. (canceled)

9. A control device of an alternating-current electric motor, comprising:

an inverter circuit that converts direct-current power into alternating-current power and supplies the alternating-current power to an alternating-current electric motor;

a direct-current-voltage detecting unit that detects a direct-current voltage value applied to the inverter circuit; and

a gate-signal generating unit that outputs a gate signal to the inverter circuit on the basis of a ratio between a voltage amplitude command value and the direct-current voltage value,

the gate-signal generating unit has modulation modes including a synchronous multi-pulse mode, a 3-dash pulse mode, and a 1-pulse mode, and according to an increase in the modulation rate, the modulation modes are transitioned to the synchronous multi-pulse mode, the 3-dash pulse mode, and to the 1-pulse mode in this order.

10. The control device of the alternating-current electric motor according to claim 9, wherein the gate-signal generating unit transitions the modulation modes in such a manner as to keep continuity of a harmonic loss of the alternating-current electric motor.

11. The control device of the alternating-current electric motor according to claim 9, wherein the inverter circuit is a two-level inverter, and the gate-signal generating unit includes a modulation mode of a 3-dash pulse mode.

12. The control device of the alternating-current electric motor according to claim 9, wherein the inverter circuit is a three-level inverter, and the gate-signal generating unit includes a modulation mode of a 1-dash pulse mode.

13. The control device of the alternating-current electric motor according to claim 9, wherein the voltage-vector generating unit includes:

an optimum-magnetic-flux-calculation processing unit that calculates an optimum magnetic flux command value for reducing a PWM loss of the alternating-current electric motor on the basis of the PWM current distortion rate; and

a voltage-command generating unit that generates the voltage command value on the basis of the optimum magnetic flux command value, the rotating speed, and the direct-current voltage value and outputs the voltage command value to the gate-signal generating unit.

14. The control device of the alternating-current electric motor according claim 13, wherein

the voltage-vector generating unit further includes a fundamental-wave-loss-characteristic storing unit that outputs a fundamental wave component loss characteristic of the alternating-current electric motor on the basis of the torque command and the rotating speed, and

the optimum-magnetic-flux-calculation processing unit calculates an optimum magnetic flux command value for reducing an overall loss of the alternating-current electric motor on the basis of the PWM current distortion rate and the fundamental wave loss characteristic.

15. The control device of the alternating-current electric motor according to claim 9, further comprising:

a converter circuit that supplies direct-current power to the inverter circuit; and

a converter control unit that controls a direct-current voltage value output by the converter circuit, wherein

the voltage-vector generating unit outputs a direct-current voltage command value calculated on the basis of the PWM current distortion rate to the converter control unit.

16. A control device of an alternating-current electric motor, comprising:

an inverter circuit that converts direct-current power into alternating-current power and supplies the alternating-current power to an alternating-current electric motor;

a gate-signal generating unit that outputs a gate signal to the inverter circuit; and

a voltage-vector generating unit that outputs a voltage amplitude command value to the gate-signal generating unit;

wherein

the voltage-vector generating unit calculates an optimum magnetic flux such that a combined overall loss of a fundamental wave loss of the alternating-current motor and a PWM harmonic loss is a minimum, and generates the voltage amplitude command value from the optimum magnetic flux.

17. The control device of the alternating-current electric motor according to claim 16, wherein the inverter circuit is a two-level inverter, and the gate-signal generating unit includes a modulation mode of a 3-dash pulse mode.

18. The control device of the alternating-current electric motor according to claim 16, wherein the inverter circuit is a three-level inverter, and the gate-signal generating unit includes a modulation mode of a 1-dash pulse mode.

19. The control device of the alternating-current electric motor according to claim 16, wherein the voltage-vector generating unit includes:

an optimum-magnetic-flux-calculation processing unit that calculates an optimum magnetic flux command value for reducing a PWM loss of the alternating-current electric motor on the basis of the PWM current distortion rate; and

a voltage-command generating unit that generates the voltage command value on the basis of the optimum magnetic flux command value, the rotating speed, and the direct-current voltage value and outputs the voltage command value to the gate-signal generating unit.

20. The control device of the alternating-current electric motor according claim 19, wherein

the voltage-vector generating unit further includes a fundamental-wave-loss-characteristic storing unit that outputs a fundamental wave component loss characteristic of the alternating-current electric motor on the basis of the torque command and the rotating speed, and

the optimum-magnetic-flux-calculation processing unit calculates an optimum magnetic flux command value for reducing an overall loss of the alternating-current electric motor on the basis of the PWM current distortion rate and the fundamental wave loss characteristic.

21. The control device of the alternating-current electric motor according to claim 16, further comprising:

a converter circuit that supplies direct-current power to the inverter circuit; and

a converter control unit that controls a direct-current voltage value output by the converter circuit, wherein

the voltage-vector generating unit outputs a direct-current voltage command value calculated on the basis of the PWM current distortion rate to the converter control unit.