Alternating-current motor control apparatus

• US 8,450,955 B2
• Filed: 05/12/2010
• Issued: 05/28/2013
• Est. Priority Date: 05/13/2009
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Yaskawa Denki, Seung-Ki Sul, Sungmin Kim
• Original Assignee: Kabushiki Kaisha Yaskawa Denki, Seung-Ki Sul, Sungmin Kim
• Inventors: Ide, Kozo, Morimoto, Shinya, Kim, Sungmin, Sul, Seung-ki
• Primary Examiner(s): DUDA, RINA I
• Application Number:
  US12/778,991
• Publication Number:
  US 20100308757A1
• Time in Patent Office: 1,112 Days
• Field of Search: 318/400.02, 318/727, 318/801, 318/432, 318/434
• US Class Current: 318/400.02
• CPC Class Codes: H02P 21/06 Rotor flux based control involving the use of rotor position or rotor speed sensors
• CPC Class Codes: Y02P 80/10 Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier

Abstract

An alternating-current motor control apparatus includes an inverter unit, a current-command divider, a current controller, a torque-variation calculator, and a phase angle generator. The current-command divider is configured to divide a command current amplitude into command current components based on a phase-angle command value that is a sum of the phase angle and an alternating current signal. The torque-variation calculator is configured to calculate a motor electric power based on the command voltage and either the motor current or the command current components and to calculate a torque variation based on the motor electric power. The phase angle generator is configured to generate a phase angle based on the torque variation.

Claims

1. An alternating-current motor control apparatus comprising:

an inverter unit configured to output a command voltage to an alternating-current motor;

a current-command divider configured to divide a command current amplitude into command current components based on a phase-angle command value;

a current controller configured to control current to match a motor current flowing through the motor with the command current components to output the command voltage to the motor;

a torque-variation calculator configured to calculate a motor electric power based on the command voltage and the motor current and configured to calculate a torque variation based on the motor electric power;

a phase angle generator configured to generate a phase angle based on the torque variation; and

an adder configured to add a sinusoidal signal to the phase angle to generate the phase-angle command value.

2. The alternating-current motor control apparatus according to claim 1, further comprising:

a signal generator configured to generate a search signal having a sine wave; and

a gain multiplier configured to multiply the search signal by a gain to generate the sinusoidal signal,

wherein the torque-variation calculator comprises;

a band-pass filter configured to extract a signal component from the motor electric power, the signal component having a same frequency as a frequency of the search signal;

a multiplier configured to multiply the signal component by the search signal; and

a low-pass filter configured to extract a linear component from a multiplication result output by the multiplier.

3. The alternating-current motor control apparatus according to claim 1,

wherein the phase angle generator is configured to generate the phase angle so as to reduce the torque variation to zero.

4. The alternating-current motor control apparatus according to claim 1, further comprising:

a signal generator configured to generate a search signal having a sine wave; and

a gain multiplier configured to multiply the search signal by a gain to generate the sinusoidal signal,

wherein the torque variation is calculated based on an amplitude of a component of a mechanical output included in the motor electric power, the component having a same frequency as a frequency of the search signal.

5. The alternating-current motor control apparatus according to claim 1,

wherein the current-command divider is configured to divide the command current amplitude into a command current component for a d-axis along a magnetic-flux direction of the motor and a command current component for a q-axis that is perpendicular to the d-axis, and

wherein the current controller is configured to control current for the command current component for the d-axis and for the command current component for the q-axis to output the command voltage to the motor.

6. The alternating-current motor control apparatus according to claim 1, further comprising:

a signal generator configured to generate a search signal having a sine wave.

7. The alternating-current motor control apparatus according to claim 6, further comprising:

a gain multiplier configured to multiply the search signal by a gain to generate the sinusoidal signal.

8. The alternating-current motor control apparatus according to claim 1, further comprising:

a signal generator configured to generate a search signal having a sine wave; and

a gain multiplier configured to multiply the search signal by a gain to generate the sinusoidal signal,

wherein the torque-variation calculator includes a torque variation extractor configured to calculate the torque variation based on the motor electric power and the search signal.

9. An alternating-current motor control apparatus comprising:

an inverter unit configured to output a command voltage to an alternating-current motor;

a speed controller configured to output a command current amplitude to make a motor speed equal to a command speed;

a current-command divider configured to divide the command current amplitude into command current components based on a phase-angle command value;

a current controller configured to control current to match a motor current flowing through the motor with the command current components to output the command voltage to the motor;

a current-variation calculator configured to calculate a current variation based on the phase-angle command value and the motor current; and

a phase angle generator configured to generate the phase-angle command value based on the current variation.

10. The alternating-current motor control apparatus according to claim 9, wherein the current-variation calculator comprises:

a divider configured to divide a change in an amplitude of the motor current by a change in the phase-angle command value.

11. The alternating-current motor control apparatus according to claim 9,

wherein the phase angle generator is configured to generate the phase-angle command value so as to reduce the current variation to zero.

12. The alternating-current motor control apparatus according to claim 9,

wherein the current-command divider is configured to divide the command current amplitude into a command current component for a d-axis along a magnetic-flux direction of the motor and a command current component for a q-axis that is perpendicular to the d-axis, and

wherein the current controller is configured to control current for the command current component for the d-axis and for the command current component for the q-axis to output the command voltage to the motor.

13. The alternating-current motor control apparatus according to claim 9,

wherein the current-variation calculator is configured to store a previous phase-angle command value generated by the phase angle generator in a previous cycle,

wherein the current-variation calculator is configured to calculate, as a phase angle difference, a difference between the previous phase-angle command value and the phase-angle command value generated by the phase angle generator in a current cycle, and

wherein the current-variation calculator is configured to calculate the current variation based on the phase angle difference and the motor current.

14. An alternating-current motor control apparatus comprising:

an inverter unit configured to output a command voltage to an alternating-current motor;

a torque-ripple compensator configured to calculate a torque-ripple-compensation current value using a speed of the motor;

a current-command divider configured to divide a sum of a command current amplitude and the torque-ripple-compensation current value into command current components based on a phase-angle command value;

a current controller configured to control current to match a motor current flowing through the motor with the command current components to output the command voltage to the motor;

a power-loss-variation calculator configured to calculate a motor electric power based on the command voltage and the motor current and configured to calculate a power loss variation based on the motor electric power;

a phase angle generator configured to generate a phase angle based on the power loss variation; and

an adder configured to add a sinusoidal signal to the phase angle to generate the phase-angle command value.

15. The alternating-current motor control apparatus according to claim 14, further comprising:

a signal generator configured to generate a search signal having a sine wave; and

a gain multiplier configured to multiply the search signal by a gain to generate the sinusoidal signal,

wherein the power-loss-variation calculator comprises;

a band-pass filter configured to extract a signal component from the motor electric power, the signal component having a same frequency as a frequency of the search signal;

a multiplier configured to multiply the signal component by the search signal; and

a low-pass filter configured to extract a linear component from a multiplication result output by the multiplier.

16. The alternating-current motor control apparatus according to claim 14,

wherein the phase angle generator is configured to generate the phase angle so as to reduce the power loss variation to zero.

17. The alternating-current motor control apparatus according to claim 14, further comprising:

a signal generator configured to generate a search signal having a sine wave; and

a gain multiplier configured to multiply the search signal by a gain to generate the sinusoidal signal,

wherein the power loss variation is calculated based on an amplitude of a component of power loss included in the motor electric power, the component having a same frequency as a frequency of the search signal.

18. The alternating-current motor control apparatus according to claim 14,

wherein the current-command divider is configured to divide the command current amplitude into a command current component for a d-axis along a magnetic-flux direction of the motor and a command current component for a q-axis that is perpendicular to the d-axis, and

wherein the current controller is configured to control current for the command current component for the d-axis and for the command current component for the q-axis to output the command voltage to the motor.