Method and apparatus for stability control of open loop motor drive operation

Patent metadata

Field	Value
Publication number	US-9287812-B2
Application number	US-201414193329-A
Country	US
Kind code	B2
Filing date	Feb 28, 2014
Priority date	Jun 29, 2013
Publication date	Mar 15, 2016
Grant date	Mar 15, 2016

Abstract

Motor drives and control methods are presented for sensorless motor speed control in which inverter output currents are sampled from the inverter output and a frequency modulation value is determined based on the current feedback. A speed or frequency setpoint is adjusted at least partially according to the frequency modulation value to provide an adjusted frequency or speed setpoint value that is then used in controlling the inverter to provide stability control to mitigate hunting or motor stoppage.

First claim

The following is claimed:

1. A method for sensorless motor speed control in a motor drive, the method comprising:
sampling at least one multiphase AC output current feedback signal or value from an output of an inverter of the motor drive;
computing a frequency modulation value in a stationary reference frame based on the at least one multiphase AC output current feedback signal or value;
adjusting a frequency or speed setpoint value based at least partially on the frequency modulation value to provide an adjusted frequency or speed setpoint value; and
controlling the inverter according to the adjusted frequency or speed setpoint value.

2. A method for sensorless motor speed control in a motor drive, the method comprising:
sampling at least one AC output current feedback signal or value from an output of an inverter of the motor drive;
computing a frequency modulation value based on the at least one AC output current feedback signal or value;
adjusting a frequency or speed setpoint value based at least partially on the frequency modulation value to provide an adjusted frequency or speed setpoint value; and
controlling the inverter according to the adjusted frequency or speed setpoint value:
wherein adjusting the frequency or speed setpoint value comprises:
rate limiting the frequency or speed setpoint value to provide a rate limited frequency or speed setpoint value; and
subtracting the frequency modulation value from the rate limited frequency or speed setpoint value to provide the adjusted frequency or speed setpoint value.

3. The method of claim 2 , wherein adjusting the frequency or speed setpoint value comprises subtracting the frequency modulation value from the frequency or speed setpoint value to provide the adjusted frequency or speed setpoint value.

4. The method of claim 3 , wherein computing the frequency modulation value comprises:
computing an estimated per unit output current signal or value based on the at least one AC output current feedback signal or value; and
computing the frequency modulation value based at least partially on the estimated per unit output current signal or value.

5. The method of claim 4 , wherein computing the frequency modulation value comprises:
high pass filtering the estimated per unit output current signal or value to provide a filtered estimated per unit output current signal or value; and
computing the frequency modulation value based at least partially on the filtered estimated per unit output current signal or value.

6. The method of claim 5 , wherein computing the frequency modulation value comprises:
amplifying the filtered estimated per unit output current signal or value by a gain factor to provide an amplified signal;
selectively limiting a range of the amplified signal to provide a range limited amplified signal; and
computing the frequency modulation value based at least partially on the range limited amplified signal.

7. A method for sensorless motor speed control in a motor drive, the method comprising:
sampling at least one AC output current feedback signal or value from an output of an inverter of the motor drive;
computing a frequency modulation value based on the at least one AC output current feedback signal or value;
adjusting a frequency or speed setpoint value based at least partially on the frequency modulation value to provide an adjusted frequency or speed setpoint value; and
controlling the inverter according to the adjusted frequency or speed setpoint value:
wherein adjusting the frequency or speed setpoint value comprises subtracting the frequency modulation value from the frequency or speed setpoint value to provide the adjusted frequency or speed setpoint value.

8. The method of claim 7 , wherein computing the frequency modulation value comprises:
computing an estimated per unit output current signal or value based on the at least one AC output current feedback signal or value; and
computing the frequency modulation value based at least partially on the estimated per unit output current signal or value.

9. The method of claim 8 , wherein computing the frequency modulation value comprises:
high pass filtering the estimated per unit output current signal or value to provide a filtered estimated per unit output current signal or value; and
computing the frequency modulation value based at least partially on the filtered estimated per unit output current signal or value.

10. The method of claim 9 , wherein computing the frequency modulation value comprises:
amplifying the filtered estimated per unit output current signal or value by a gain factor to provide an amplified signal;
selectively limiting a range of the amplified signal to provide a range limited amplified signal; and
computing the frequency modulation value based at least partially on the range limited amplified signal.

11. A method for sensorless motor speed control in a motor drive, the method comprising:
sampling at least one AC output current feedback signal or value from an output of an inverter of the motor drive;
computing a frequency modulation value based on the at least one AC output current feedback signal or value;
adjusting a frequency or speed setpoint value based at least partially on the frequency modulation value to provide an adjusted frequency or speed setpoint value; and
controlling the inverter according to the adjusted frequency or speed setpoint value:
wherein computing the frequency modulation value comprises:
computing an estimated per unit output current signal or value based on the at least one AC output current feedback signal or value; and
computing the frequency modulation value based at least partially on the estimated per unit output current signal or value.

12. The method of claim 11 , wherein computing the frequency modulation value comprises:
high pass filtering the estimated per unit output current signal or value to provide a filtered estimated per unit output current signal or value; and
computing the frequency modulation value based at least partially on the filtered estimated per unit output current signal or value.

13. The method of claim 12 , wherein computing the frequency modulation value comprises:
amplifying the filtered estimated per unit output current signal or value by a gain factor to provide an amplified signal;
selectively limiting a range of the amplified signal to provide a range limited amplified signal; and
computing the frequency modulation value based at least partially on the range limited amplified signal.

14. The method of claim 1 , A method for sensorless motor speed control in a motor drive, the method comprising:
sampling at least one AC output current feedback signal or value from an output of an inverter of the motor drive;
computing a frequency modulation value based on the at least one AC output current feedback signal or value;
adjusting a frequency or speed setpoint value based at least partially on the frequency modulation value to provide an adjusted frequency or speed setpoint value; and
controlling the inverter according to the adjusted frequency or speed setpoint value:
wherein computing the frequency modulation value comprises:
high pass filtering the at least one AC output current feedback signal or value to provide a filtered estimated output current signal or value and
computing the frequency modulation value based at least partially on the filtered estimated output current signal or value.

15. The method of claim 14 , wherein computing the frequency modulation value comprises:
amplifying the filtered estimated output current sig

Assignees

• Nondahl Thomas
• Liu Jingbo
• Schmidt Peter
• Royak Semyon
• Rowan Timothy M
• Rockwell Automation Tech Inc

Inventors

• Nondahl Thomas
• Liu Jingbo
• Schmidt Peter
• Royak Semyon
• Rowan Timothy M

Classifications

• H02P21/00 Primary

  Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation · CPC title

• H02P6/08 Primary

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