System and method for transient-based motor speed estimation with transient excitation

• US 7,538,507 B2
• Filed: 04/28/2007
• Issued: 05/26/2009
• Est. Priority Date: 04/24/2006
• Status: Active Grant

• Current Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Original Assignee: Rockwell International Technologies Incorporated
• Inventors: Nondahl, Thomas A., Lu, Haihui, Messersmith, David M.
• Primary Examiner(s): Ro; Bentsu
• Application Number:
  US11/741,728
• Publication Number:
  US 20070247099A1
• Time in Patent Office: 759 Days
• Field of Search: 318461-465, 318/490, 318/727, 318798-805, 318807-811, 324160-166, 324177-180
• US Class Current: 318/461
• CPC Class Codes: H02P 23/20 Controlling the acceleration or deceleration
• CPC Class Codes: H02P 6/182 using back-emf in windings
• CPC Class Codes: H02P 6/185 using inductance sensing, e.g. pulse excitation

Abstract

Control systems and speed estimation systems are presented having a transient-based speed estimation system that provides a rotor speed estimate based on a measured speed-related motor transient signal, and a transient excitation system which selectively modifies at least one switch control signal to excite the measured motor transient.

Claims

1. A motor speed estimation system for estimating the speed of an electric motor driven by a switching system including a plurality of switching devices coupled between a power source and the motor and individually operative to selectively couple a corresponding motor lead to the power source according to a corresponding switch control signal from a switch control system, the speed estimation system comprising:

a transient excitation system operatively coupled with the switch control system to selectively modify at least one switch control signal to excite a motor transient; and

a transient-based speed estimation system receiving at least one feedback signal or value from the switching system and providing a rotor speed estimate at least partially according to the feedback signal or value;

wherein the transient excitation system selectively removes individual pulses from a series of pulses forming the at least one switching control signal controlling a corresponding one of the switching devices to excite the motor transient.

2. The motor speed estimation system of claim 1, wherein the transient-based speed estimation system measures at least one transient speed-related signal in the at least one feedback signal or value, the transient speed-related signal being associated with the motor transient, the transient-based speed estimation system determining the rotor speed estimate at least partially according to the transient speed-related signal.

3. The motor speed estimation system of claim 2, wherein the transient speed-related signal is one of a phase error signal, a phase lag signal, a peak current signal, a voltage integral signal, a motor winding voltage signal, a switching device voltage, and a voltage zero crossing signal.

4. The motor speed estimation system of claim 1 wherein the transient excitation system selectively modifies spacings between select pulses in a series of pulses forming the at least one switching control signal controlling a corresponding one of the switching devices to excite the motor transient.

5. The motor speed estimation system of claim 1, wherein the transient excitation system selectively modifies spacings between pulses of select pulse pairs of a series of pulse pairs forming the at least one switching control signal controlling a corresponding one of the switching devices to excite the motor transient.

6. The motor speed estimation system of claim 5, wherein the transient excitation system selectively increases spacings between pulses of select pulse pairs in the switching control signal to excite the motor transient.

7. The motor speed estimation system of claim 5, wherein the transient excitation system selectively decreases spacings between pulses of select pulse pairs in the switching control signal to excite the motor transient.

8. The motor speed estimation system of claim 1, wherein the transient excitation system selectively modifies spacings between pulses of consecutive pulse pairs of a series of pulse pairs forming the at least one switching control signal controlling a corresponding one of the switching devices to excite the motor transient.

9. The motor speed estimation system of claim 8, wherein the transient excitation system selectively increases and decreases spacings between pulses of consecutive pulse pairs in the at least one switching control signal based at least partially on the rotor speed estimate to excite the motor transient.

10. The motor speed estimation system of claim 8, wherein the transient excitation system selectively increases and decreases spacings between pulses of consecutive pulse pairs in the at least one switching control signal based at least partially on a modulation waveform to excite the motor transient.

11. The motor speed estimation system of claim 10, wherein the modulation waveform is one of a sine wave, a square wave, or a sawtooth wave.

12. The motor speed estimation system of claim 1, wherein the transient excitation system periodically modifies the at least one switch control signal to excite a motor transient.

13. The motor speed estimation system of claim 1, wherein the transient-based speed estimation system measures at least one transient speed-related signal in the at least one feedback signal or value, the transient speed-related signal being associated with the motor transient, and wherein the transient excitation system selectively modifies at least one switch control signal to excite a motor transient at least partially according to an amplitude of the measured transient speed-related signal.

14. A motor speed estimation system for estimating the speed of an electric motor driven by a switching system including a plurality of switching devices coupled between a power source and the motor and individually operative to selectively couple a corresponding motor lead to the power source according to a corresponding switch control signal from a switch control system, the speed estimation system comprising:

a transient excitation system operatively coupled with the switch control system to selectively modify at least one switch control signal to excite a motor transient; and

a transient-based speed estimation system receiving at least one feedback signal or value from the switching system and providing a rotor speed estimate at least partially according to the feedback signal or value;

wherein the transient excitation system selectively removes at least one pulse from select pulse pairs of a series of pulse pairs forming the at least one switching control signal controlling a corresponding one of the switching devices to excite the motor transient.

15. The motor speed estimation system of claim 14, wherein the transient excitation system selectively removes both pulses of select pulse pairs from a series of pulse pairs forming the at least one switching control signal controlling a corresponding one of the switching devices to excite the motor transient.

16. A motor speed estimation system for estimating the speed of an electric motor driven by a switching system including a plurality of switching devices coupled between a power source and the motor and individually operative to selectively couple a corresponding motor lead to the power source according to a corresponding switch control signal from a switch control system, the speed estimation system comprising:

a transient excitation system operatively coupled with the switch control system to selectively modify at least one switch control signal to excite a motor transient;

a transient-based speed estimation system receiving at least one feedback signal or value from the switching system and providing a rotor speed estimate at least partially according to the feedback signal or value; and

a rotor flux initialization system operatively coupled with the switch control system to selectively initialize rotor flux in the motor during starting prior to activation of the transient excitation system.