Frequency domain auto-tune for an internal motor controller

• US 6,622,099 B2
• Filed: 06/05/2001
• Issued: 09/16/2003
• Est. Priority Date: 08/14/2000
• Status: Expired due to Fees

• Current Assignee: Kollmorgen Corporation (Regal Rexnord Corp.)
• Original Assignee: Kollmorgen Corporation (Regal Rexnord Corp.)
• Inventors: Cohen, Ilan, Katzir, Eran, Kidron, Oren
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Suarez, Felix
• Application Number:
  US09/874,729
• Publication Number:
  US 20020019715A1
• Time in Patent Office: 833 Days
• Field of Search: 702/65, 702/66, 702/68, 702/69, 702/79, 702/106, 702/107, 702/111, 702/177, 702/75, 700/28, 700/31, 700/37, 700/170, 318/560, 318/565.22, 318/606
• US Class Current: 702/75
• CPC Class Codes: G05B 13/024 in which a parameter or coefficient is automatically adjusted to optimise the performance
• CPC Class Codes: G05B 13/025 using a perturbation signal

Abstract

A built-in auto-tuning system of a motor control system provides an auto-tuning of the motor control system. The built-in tuning system generates and applies a random noise test signal to the controller. In response to the test signals, the tuning system obtains response data such as the gains and phases over a wide range of operating frequencies. Based on the received data, the tuning system generates an open-loop Bode plot of the control system. The tuning system then calculates the phase and gain margins of the control system. The calculated gain and phase margins are compared with a set of predetermined values by the tuning system to automatically adjust the compensation parameters of the motor control system for a stable operation.

Claims

1. A built-in auto-tuning system within a controller of a motor control system comprising:

(i) means for injecting a random noise test signal into a loop of the controller;

(ii) means for receiving frequency response data which reflects the responses of the motor control system to said random noise test signal;

(iii) means for determining gain and phase crossover frequencies based on the received data;

(iv) means for calculating a gain margin from said response data;

(v) means for calculating a phase margin from said response data; and

(vi) means for adjusting compensation parameters of the controller to set the gain and phase margins within a set of predetermined values.

2. The auto-tuning system of claim 1 further comprising means for providing a video display for displaying a Bode plot based on said response data.

3. The auto-tuning system of claim 2, wherein said video display is on a personal computer.

4. The auto-tuning system of claim 1, wherein said random noise test signal is injected together with the normal command signal.

5. The auto-tuning system of claim 1, wherein said compensation parameters are one or more of the proportional, integral and derivative gains of the controller.

6. A method of tuning a controller of a motor control system with a built-in auto-tuning system including the step of:

(i) injecting a random noise test signal into a loop of the controller;

(ii) receiving frequency response data which reflects the responses of the motor control system to said random noise test signal;

(iii) determining gain and phase crossover frequencies based on the received data;

(iv) calculating a gain margin from said response data;

(v) calculating a phase margin from said response data; and

(vi) adjusting compensation parameters of the controller to set the gain and phase margins within a set of predetermined values.

7. The method of claim 6 further providing a video display for displaying a Bode plot based on the response data.

8. The method of claim 7, wherein said video display is on a personal computer.

9. The method of claim 6, wherein said random noise test signal is injected together with the normal command signal.

10. The method of claim 6, wherein said compensation parameters one or more of the proportional, integral and derivative gains of the controller.

11. A built-in auto-tuning system within a controller of a motor control system comprising:

(i) a random noise signal generator for providing a random noise signal and to apply said random noise signal to a loop of the controller;

(ii) a response receiver for receiving data reflecting the responses of the motor control system to said random noise signal;

(iii) a gain controller for adjusting gains of the controller to set the gain and phase margins;

(iv) a computer comprising a memory unit, a processing unit and a display unit, and being programmed to;

(a) issue a command to the gain controller to set the gains for the controller;

(b) issue a command to the random noise signal generator to inject a test signal to the controller;

(c) receive the response data of the controller in response to the random noise signal;

(d) determine the phase and gain crossover frequencies;

(e) calculate phase and gain margins based on said crossover frequencies;

(f) compare the calculated phase and gain margins with predetermined values; and

(g) issue a command to said gain controller to adjust the gains when outside the range of said predetermined values.

12. The built-in auto-tuning system of claim 11, wherein said response data is displayed on a personal computer.

13. The built-in auto-tuning system of claim 11, wherein said random noise signal is injected together with the normal command signal.