Control device of AC motor

Patent metadata

Field	Value
Publication number	US-9065365-B2
Application number	US-201314055280-A
Country	US
Kind code	B2
Filing date	Oct 16, 2013
Priority date	Oct 16, 2012
Publication date	Jun 23, 2015
Grant date	Jun 23, 2015

Abstract

A control device for controlling an AC motor with an inverter includes: a current acquisition device of a sensor phase current sensed value of the motor in a sensor phase current sensing cycle; a rotation angle acquisition device of a rotation angle sensed value of the motor; a current command value operation device for updating a current command value in a command update cycle; a current estimation device; a voltage command value operation device; a drive signal generation device; and a sudden change prevention device for preventing the voltage command value from a sudden change according to a sudden change in the current estimated value. The sudden change of the current estimated value is caused by a sudden change in the current command value.

First claim

What is claimed is:

1. A control device for controlling a driving state of a three-phase alternating current motor, in which a voltage to be applied to the motor is controlled by an inverter, the control device comprising:
a current acquisition device for acquiring a sensor phase current sensed value in a sensor phase current sensing cycle from a current sensor disposed in a sensor phase, which is one of three phases of the alternating current motor;
a rotation angle acquisition device for acquiring a rotation angle sensed value from a rotation angle sensor for sensing a rotation angle of the alternating current motor;
a current command value operation device for updating a current command value relating to the driving state of the alternating current motor in a command update cycle, which is longer than the sensor phase current sensing cycle;
a current estimation device for calculating a current estimated value according to the sensor phase current sensed value, the rotation angle sensed value, and the current command value;
a voltage command value operation device for calculating a voltage command value according to the current command value and the current estimated value that is fed back;
a drive signal generation device for generating a drive signal relating to a driving state of the inverter according to the voltage command value; and
a sudden change prevention device for preventing the voltage command value from a sudden change according to a sudden change in the current estimated value that is fed back,
wherein the sudden change of the current estimated value is caused by a sudden change in the current command value,
wherein the sudden change of the voltage command value is defined by a change period equal to or shorter than a predetermined time interval, and a change amount equal to or larger than a predetermined change amount,
wherein the sudden change of the current estimated value is defined by a change period equal to or shorter than a predetermined time interval, and a change amount equal to or larger than a predetermined change amount, and
wherein the sudden change in the current command value is defined by a change period equal to or shorter than a predetermined time interval, and a change amount equal to or larger than a predetermined change amount.

2. The control device of an alternating current motor according to claim 1 ,
wherein the sudden change prevention device includes a current command value change device for changing the current command value, which is used in the current estimation device.

3. The control device of an alternating current motor according to claim 2 ,
wherein the current command value change device updates the current command value in a high-speed update cycle, which is shorter than the command update cycle.

4. The control device of an alternating current motor according to claim 3 ,
wherein the high-speed update cycle is equal to the sensor phase current sensing cycle.

5. The control device of an alternating current motor according to claim 3 ,
wherein the voltage command value operation device operates the voltage command value according to the current command value updated in the high-speed update cycle.

6. The control device of an alternating current motor according to claim 2 ,
wherein the current command value change device executes a low-pass filter processing of the current command value.

7. The control device of an alternating current motor according to claim 1 , further comprising:
a sudden change determination device for determining whether the current command value is suddenly changed,
wherein, when the sudden change determination device determines that the current command value is suddenly changed, the sudden change prevention device reduces a feedback gain of the current estimated value, which is used in an operation of the voltage command value operation device.

8. The control device of an alternating current motor according to claim 1 , further comprising:
a sudden change determination device for determining whether the current command value is suddenly changed,
wherein, when the sudden change determination device determines that the current command value is suddenly changed, the sudden change prevention device directly limits a variation range of the voltage command value.

Assignees

• Denso Corp

Inventors

• Omata Ryuji
• Itoh Takeshi
• Kako Hirofumi

Classifications

• H02P21/10

  Direct field-oriented control; Rotor flux feed-back control · CPC title

• H02P6/10 Primary

  Arrangements for controlling torque ripple, e.g. providing reduced torque ripple · CPC title

• H02P21/05

  specially adapted for damping motor oscillations, e.g. for reducing hunting · CPC title