Flux estimator for switched reluctance machines

Patent metadata

Field	Value
Publication number	US-9800192-B1
Application number	US-201615093477-A
Country	US
Kind code	B1
Filing date	Apr 7, 2016
Priority date	Apr 7, 2016
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

A control system for a multi-phase switched reluctance (SR) machine, having at least two phases, is disclosed. The control system may include a converter circuit and a controller. The controller may include a phase voltage estimator module configured to determine a first phase voltage and a second phase voltage associated with a second phase second phase for the SR machine. The controller may further include a flux estimator module configured to determine first and second estimated fluxes, the first estimated flux associated with the first phase and based on the first phase voltage and an associated first mutual voltage and the second estimated flux the second estimated flux associated with the second phase and based on the second phase voltage and an associated second mutual voltage, and a position observer module configured to determine a rotor position based at least partially on the first estimated flux, the second mutual flux.

First claim

What is claimed is:

1. A control system for a multi-phase switched reluctance (SR) machine having a rotor and a stator, the stator including, at least, a first phase winding and a second phase winding, the first phase winding corresponding with a first phase of the multi-phase SR machine and the second phase winding corresponding with a second phase of the multi-phase SR machine, the control system comprising:
a converter circuit in electrical communication between the stator and a common bus; and
a controller configured to monitor a bus voltage of the converter circuit and a phase current of the multi-phase SR machine, the controller including, at least, a phase voltage estimator module configured to determine, at least, a first phase voltage associated with the first phase and a second phase voltage associated with the second phase, each of the first and second phase voltages based on one or more pulses, a flux estimator module configured to determine a first estimated flux, the first estimated flux associated with the first phase and based on the first phase voltages, an associated first mutual voltage, and a second estimated flux, the second estimated flux associated with the second phase and based on the second phase voltage and an associated second mutual voltage, a position observer module configured to determine a rotor position based at least partially on the first estimated flux, the second estimated flux, and a main pulse control module configured to control the multi-phase SR machine based on the rotor position and a desired torque.

2. The control system of claim 1 , wherein the flux estimator module is further configured to decouple the first estimated flux and the second estimated flux.

3. The control system of claim 1 , wherein the controller further includes a stator resistance module configured to determine a stator resistance voltage and wherein the flux estimator module is further configured to determine one or both of the first estimated flux and the second estimated flux further based on the stator resistance voltage.

4. The control system of claim 3 , wherein the stator resistance module determines the stator resistance voltage based on a stator resistance and the phase current.

5. The control system of claim 4 , wherein the stator resistance module is further configured to determine the stator resistance based on temperature information associated with the multi-phase SR machine.

6. The control system of claim 1 , wherein the controller further includes a flux resetting module operatively associated with the flux estimator module, the flux resetting module configured to reset one or both of the first estimated flux and the second estimated flux based on one or both of a flux upper limit and a flux lower limit.

7. The control system of claim 6 , wherein the multi-phase SR machine is operating in a discontinuous conduction mode and the flux resetting module is configured to reset one or both of the first estimated flux and the second estimated flux during an idling period of each operating cycle in the discontinuous conduction mode.

8. The control system of claim 6 , wherein the multi-phase SR machine is capable of operating in a continuous conduction mode and the flux resetting module is configured to reset one or both of the first estimated flux and the second estimated flux during a cycle of the continuous conduction mode.

9. The control system of claim 1 , wherein the controller further includes a mutual voltage estimator module configured to determine, at least, the first mutual voltage and the second mutual voltage by referring to one or more preprogrammed maps defining relationships between mutual flux values, phase current values, and estimated rotor position values.

10. An electric drive, comprising:
a switched reluctance (SR) machine having a stator and a rotor rotatably disposed relative to the stator, the stator including, at least, a first phase winding and a second phase winding, the first phase winding corresponding with a first phase of the SR machine and the second phase winding corresponding with a second phase of the SR machine;
a converter circuit configured to electrically communicate with the stator and a common bus; and
a controller in electrical communication with at least the converter circuit, the controller being configured to monitor a bus voltage of the converter circuit and a phase current of the SR machine, generate main pulses and any diagnostic pulses, determine a first phase voltage associated with the first phase based on one of the main pulses and the diagnostic pulses, determine a mutual voltage for the first phase, the mutual voltage representative of coupling effects of, at least, the second phase, determine a decoupled estimated flux for the first phase based on the phase voltage and the mutual voltage, engage a position observer to determine a rotor position based at least partially on the decoupled estimated flux, and control the SR machine based on the rotor position and a desired torque.

11. The electric drive of claim 10 , wherein the controller is further configured to determine a rotor speed based at least partially on the decoupled estimated flux.

12. The electric drive of claim 10 , wherein the controller is configured to determine the mutual voltage by referring to one or more preprogrammed maps defining relationships between mutual flux values, phase current values, and estimated rotor position values.

13. The electric drive of claim 12 , wherein the one or more preprogrammed maps includes a one-dimensional look-up table relating estimated rotor position values to one or both of mutual voltage flux and phase current values.

14. The electric drive of claim 10 , wherein the controller is further configured to determine an estimated current based on the decoupled estimated flux, determine a current error based on a comparison between the estimated current and one or more phase currents of the SR machine, and determine the rotor position and a rotor speed based at least partially on the current error.

15. A method for determining rotor position of a switched reluctance (SR) machine being operated through a converter circuit, the SR machine having a stator and a rotor rotatably disposed relative to the stator, the stator including, at least, a first phase winding and a second phase winding, the first phase winding corresponding with a first phase of the SR machine and the second phase winding corresponding with a second phase of the SR machine, comprising:
monitoring a bus voltage of the converter circuit and a phase current of the first phase of the SR machine;
generating main pulses and any diagnostic pulses;
determining a phase voltage for the first phase based on one of the main pulses and the diagnostic pulses;
determine a mutual voltage for the first phase, the mutual voltage representative of coupling effects of, at least, the second phase;
determining an estimated decoupled flux for the first phase based on the phase voltage and the mutual voltage;
engaging a position observer to determine a rotor position of the SR machine based at least partially on the decoupled estimated flux; and
controlling an output torque of the SR machine based on the rotor position and a desired torque.

16. The method of claim 15 , further comprising determining a stator resistance voltage for the SR machine based on a modeled stator resistance and the phase current and wherein determining the estimated decoupled flux is further based on the stator resistance voltage.

17. The method of claim 16 , further comprising determining the

Assignees

• Caterpillar Inc

Inventors

• Han Seok-Hee
• Wai Jackson
• Khalil Ahmed
• Gerdes Jesse
• Thorne James Michael
• Sonth Sangameshwar

Classifications

• H02P23/14

  Estimation or adaptation of motor parameters, e.g. rotor time constant, flux, speed, current or voltage · CPC title

• H02P25/092 Primary

  Converters specially adapted for controlling reluctance motors · CPC title

• H02P25/089 Primary

  Sensorless control (direct torque control H02P23/30) · CPC title

• H02P6/185

  using inductance sensing, e.g. pulse excitation · CPC title