SYSTEM AND METHOD FOR TRANSIENT-BASED MOTOR SPEED ESTIMATION WITH TRANSIENT EXCITATION

• US 20070247099A1
• Filed: 04/28/2007
• Published: 10/25/2007
• Est. Priority Date: 04/24/2006
• Status: Active Grant

• Current Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Original Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Inventors: Nondahl, Thomas A., Lu, Haihui, Messersmith, David M.
• Granted Patent: US 7,538,507 B2
• Time in Patent Office: Days
• 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 a the motor and individually operative to selectively couple a corresponding motor lead to the power source according to a corresponding switch control signal, 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.

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 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.

5. 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.

6. The motor speed estimation system of claim 1, wherein the transient excitation system selectively removes 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.

7. The motor speed estimation system of claim 1, wherein the transient excitation system selectively removes 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.

8. 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.

9. The motor speed estimation system of claim 8, wherein the transient excitation system selectively increases spacings between pulses of select pulse pairs in the switching control signal to excite the motor transient.

10. The motor speed estimation system of claim 8, wherein the transient excitation system selectively decreases spacings between pulses of select pulse pairs in the switching control signal to excite the motor transient.

11. 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.

12. The motor speed estimation system of claim 11, 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.

13. The motor speed estimation system of claim 11, 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.

14. The motor speed estimation system of claim 13, wherein the modulation waveform is one of a sine wave, a square wave, or a sawtooth wave.

15. The motor speed estimation system of claim 1, further comprising 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.

16. 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.

17. 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.

18. A motor control system operatively coupled with a switching system of a motor controller to control a 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, the control system comprising:

a motor controller providing a motor controller output to the switching system to control the motor at least partially according to a rotor speed estimate;

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 transient speed-related signal or value associated with the motor and providing the rotor speed estimate at least partially according to the at least one transient speed-related signal or value.

19. The motor control system of claim 18, 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.

20. A motor control system for controlling the speed of an electric motor, comprising:

means for providing a plurality of switch control signals to a switching system for selective coupling of motor leads to an electric power source to control the motor at least partially according to a rotor speed estimate;

means for selectively modifying at least one of the switch control signals to excite a motor transient;

means for measuring a transient speed-related signal associated with the motor transient; and

means for providing the rotor speed estimate at least partially according to the transient speed-related signal.