Control apparatus for electric motor

• US 20020163319A1
• Filed: 09/20/2001
• Published: 11/07/2002
• Est. Priority Date: 04/11/2001
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kaneko, Satoru, Masaki, Ryoso, Morooka, Yasuo, Katayama, Hiroshi, Hombu, Mitsuyuki
• Granted Patent: US 6,696,812 B2
• Time in Patent Office: Days
• US Class Current: 318/727
• CPC Class Codes: B60L 15/025 using field orientation; Vector control; Direct Torque Control [DTC]
• CPC Class Codes: B60L 2210/20 AC to AC converters
• CPC Class Codes: B60L 2220/14 Synchronous machines
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: H02P 21/04 specially adapted for very low speeds
• CPC Class Codes: H02P 21/18 Estimation of position or speed
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility
• CPC Class Codes: Y10S 903/903 having energy storing means, e.g. battery, capacitor
• CPC Class Codes: Y10S 903/916 with plurality of drive axles

Abstract

A control apparatus controls a voltage applied to an AC motor from a power converter with a PWM signal, and has two different magnetic pole position-estimating units which estimate a rotor magnetic pole position of the AC motor, and has a switching unit which selects any one of these two kinds of magnetic pole position-estimating units.

Claims

1. A control apparatus for a motor that controls a voltage applied to an AC motor from a power converter by a PWM signal, wherein the control apparatus for the motor estimates a rotor magnetic pole position of the AC motor with at least two different magnetic pole position-estimating methods, estimates the rotor magnetic pole position of the AC motor with selectively switching the at least two magnetic pole position-estimating methods according to an operating state of the AC motor throughout an operating range of the AC motor.

3. The control apparatus for a motor according to claim 1, wherein, when the at least two magnetic pole position-estimating methods are switched, a rotor magnetic pole position of the AC motor is calculated on the basis of an operating state of the AC motor in a predetermined period.

5. The control apparatus for a motor according to claim 1, wherein, when the at least two magnetic pole position-estimating methods are switched, a variation amount of the rotor magnetic pole position of the AC motor estimated by a magnetic pole position-estimating method after switching on the basis of an operating state of the AC motor in a predetermined period.

7. The control apparatus for a motor according to claim 1, wherein, when the at least two magnetic pole position-estimating methods are switched, current detection timing of the AC motor is changed.

9. The control apparatus for a motor according to claim 1, wherein, when the at least two magnetic pole position-estimating methods are switched, a rotor magnetic pole position of the AC motor is estimated by using the at least two magnetic pole position-estimating methods within a predetermined speed range of the AC motor.

11. The control apparatus for a motor according to claim 9, wherein abnormality of an apparatus is judged according to a rotor magnetic pole position of the AC motor estimated by using the at least two magnetic pole position-estimating methods.

13. The control apparatus for a motor according to claim 1, wherein one of the at least two magnetic pole position-estimating methods is used in a low speed period of the AC motor including a startup period and a stop period of the AC motor, and another one of the at least two magnetic pole position-estimating methods is used in a middle and high speed period of the AC motor.

15. The control apparatus for a motor according to claim 1, wherein one of the at least two magnetic pole position-estimating methods is used in a low speed period of the AC motor including a startup period and a stop period of the AC motor, also estimates a direction of a rotor magnetic pole position of the AC motor in a startup period of the AC motor, and discriminates whether the direction of a rotor magnetic pole position is a direction of a north pole or a direction of a south pole.

16. The control apparatus for a motor according to claim 15, wherein discrimination of the direction of a rotor magnetic pole position is performed by applying a predetermined amplitude of current in the direction of a rotor magnetic pole position which is estimated, and is performed on the basis of a variation amount of generated motor current every fixed time.

18. The control apparatus for a motor according to claim 17, wherein discrimination of the direction of a rotor magnetic pole position is performed by applying a predetermined amplitude of current in the direction of a rotor magnetic pole position which is estimated, and is performed on the basis of a variation amount of generated motor current every fixed time.

20. The control apparatus for a motor according to claim 19, wherein the switching means calculates a rotor magnetic pole position of the AC motor on the basis of an operating state of the AC motor in a predetermined period.

21. The control apparatus for a motor according to claim 19, wherein the switching means restricts a variation amount of a rotor magnetic pole position of the AC motor, which is estimated by magnetic pole position-estimating means after switching, on the basis of an operating state of the AC motor in a predetermined period.

22. The control apparatus for a motor according to claim 19, wherein the switching means changes current detection timing of the AC motor at the time of switching the magnetic pole position-estimating means.

23. The control apparatus for a motor according to claim 19, wherein the switching means estimates a rotor magnetic pole position of the AC motor by using the carrier synchronization type position-estimating means and the equal potential type position-estimating means within a predetermined speed range of the AC motor at the time of switching magnetic pole position-estimating means.

24. The control apparatus for a motor according to claim 23, wherein abnormality of an apparatus is judged according to a rotor magnetic pole position of the AC motor estimated by using the carrier synchronization type position-estimating means and the equal potential type position-estimating means.

25. The control apparatus for a motor according to claim 19, wherein the carrier synchronization type position-estimating means is used in a low speed period of the AC motor including a startup period and a stop period of the AC motor, and the equal potential type position estimation means is used in a middle and high speed period of the AC motor.

26. The control apparatus for a motor according to claim 19, wherein the carrier synchronization type position-estimating means comprises position calculating means estimating a direction of a rotor magnetic pole position of the AC motor, and polarity discriminating means discriminating whether the direction of a rotor magnetic pole position obtained by the position calculating means is a direction of a north pole, or a direction of a south pole, and the polarity discrimination means operates in a startup period of the AC motor.

27. The control apparatus for a motor according to claim 26, wherein the polarity discrimination means applies a predetermined amplitude of current in a direction of a rotor magnetic pole position which is estimated, and discriminates polarity of the rotor magnetic pole position on the basis of a variation amount of generated motor current every fixed time.

29. An electric vehicle, comprising:

an AC motor which drives wheels;

an on board power source;

a power converter which converts into alternating current power direct current power supplied from said on board power supply and supplies the alternating current power to the AC motor; and

a control apparatus which controls the power converter,

wherein the control apparatus is a control apparatus according to claim 1.

30. An electric vehicle, comprising:

an internal combustion engine which drives either of front or rear wheels;

an AC motor which drives the other wheels;

an on board power supply;

a power converter which converts into alternating current power the direct current power supplied from said on board power supply and supplies the alternating current power to the AC motor; and

a control apparatus which controls the power converter,

wherein the control apparatus is a control apparatus according to claim 1.

2. A control apparatus for a motor that controls a voltage applied to an AC motor from a power converter by a PWM signal, wherein the control apparatus for the motor estimates a rotor magnetic pole position of the AC motor with a magnetic pole position-estimating method based on a detected current value of the AC motor detected with at least synchronizing with a carrier of the PWM signal, and a magnetic pole position-estimating method based on a detected current value of the AC motor detected in an equal potential state of the AC motor, and estimates a rotor magnetic pole position of the AC motor by switching the at least two magnetic pole position-estimating methods according to an operating state of the AC motor throughout an operating range of the AC motor.

4. The control apparatus for a motor according to claim 2, wherein, when the at least two magnetic pole position-estimating methods are switched, a rotor magnetic pole position of the AC motor is calculated on the basis of an operating state of the AC motor in a predetermined period.

6. The control apparatus for a motor according to claim 2, wherein, when the at least two magnetic pole position-estimating methods are switched, a variation amount of the rotor magnetic pole position of the AC motor estimated by a magnetic pole position-estimating method after switching on the basis of an operating state of the AC motor in a predetermined period.

8. The control apparatus for a motor according to claim 2, wherein, when the at least two magnetic pole position-estimating methods are switched, current detection timing of the AC motor is changed.

10. The control apparatus for a motor according to claim 2, wherein, when the at least two magnetic pole position-estimating methods are switched, a rotor magnetic pole position of the AC motor is estimated by using the at least two magnetic pole position-estimating methods within a predetermined speed range of the AC motor.

12. The control apparatus for a motor according to claim 10, wherein abnormality of the apparatus is judged according to a rotor magnetic pole position of the AC motor estimated by using the at least two magnetic pole position-estimating methods.

14. The control apparatus for a motor according to claim 2, wherein a magnetic pole position-estimating method based on a detected current value of the AC motor detected by synchronizing with a carrier of the PWM signal is used in a low speed period of the AC motor including a startup period and a stop period of the AC motor and a magnetic pole position-estimating method based on a detected current value of the AC motor detected in an equal potential state of the AC motor is used in a middle and high-speed period of the AC motor.

17. The control apparatus for a motor according to claim 2, wherein a magnetic pole position-estimating method based on a detected current value of the AC motor detected by synchronizing with a carrier of the PWM signal estimates a direction of a rotor magnetic pole position of the AC motor in a startup period of the AC motor, and discriminates whether the direction of a rotor magnetic pole position is a direction of a north pole or a direction of a south pole.

19. A control apparatus for a motor that controls a voltage applied to an AC motor from a power converter by a PWM signal, comprising:

carrier synchronization type position-estimating means for estimating a rotor magnetic pole position of the AC motor on the basis of a detected current value of the AC motor detected by synchronizing with a carrier of the PWM signal;

equal potential type position-estimating means for estimating a rotor magnetic pole position of the AC motor on the basis of a detected current value of the AC motor detected in an equal potential state of the AC motor; and

means for switching magnetic pole position-estimating means from between the carrier synchronization type position-estimating means and equal potential type position-estimating means throughout an operating range of the AC motor according to an operating state of the AC motor.

28. A control apparatus for a motor that estimates a rotor magnetic pole position of an AC motor mounted in a vehicle and controls the AC motor, wherein the control apparatus for a motor applies a signal for a rotor magnetic pole position estimation of the AC motor to a control commander of the AC motor in a low speed period including a startup period and a stop period of the vehicle, inputs a current of the AC motor, estimates a rotor magnetic pole position of the AC motor by obtaining a current differential value by applying the signal for an rotor magnetic pole position estimation, and estimates the rotor magnetic pole position of the AC motor on the basis of an induced voltage of the AC motor in a middle and high speed period of the vehicle.