Variable link sensorless brushless direct current motor controller for space and hardened applications

• US 9,444,376 B2
• Filed: 02/22/2013
• Issued: 09/13/2016
• Est. Priority Date: 02/22/2013
• Status: Active Grant

• Current Assignee: Hamilton Sundstrand Corporation (Rtx Corporation)
• Original Assignee: Hamilton Sundstrand Corporation (Rtx Corporation)
• Inventors: Hansen, Harold J., Wichowski, Robert P., Hawes, Kevin G., Sears, Patrick J.
• Primary Examiner(s): Ro, Bentsu
• Assistant Examiner(s): TRUNEH, ZEMENAY T
• Application Number:
  US13/774,504
• Publication Number:
  US 20140239864A1
• Time in Patent Office: 1,299 Days
• Field of Search: 318/400.35
• US Class Current: 1/1
• CPC Class Codes: H02P 6/12 Monitoring commutation; Providing indication of commutation failure
• CPC Class Codes: H02P 6/182 using back-emf in windings
• CPC Class Codes: H02P 7/06 for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current

Abstract

A sensorless motor controller includes a variable link control, including a radiation-hardened field programmable gate array (FPGA) and a back electromotive force (EMF) decoder circuit. The back EMF decoder infers the position of a rotor of the motor. A filter on the decoder conditions the back EMF signal and has multiple cutoff frequencies which can be dynamically controlled by the FPGA in order to compensate for phase shift in the back EMF signal. The FPGA also controls a variable DC link and its digital speed control loop.

Claims

1. A motor controller system comprising:

a hardened field programmable gate array;

a back electromotive force decoder circuit at least partially controlled by the field programmable gate array;

a filter configured to condition a back electromotive force signal in the decoder circuit, the filter having at least one cutoff frequency, wherein the at least one cutoff frequency is continuously conditioned by the field programmable gate array to reduce phase shift of the back electromotive force signal; and

a current limiter circuit configured to protect the motor, wherein the current limiter circuit is configured to respond separately to an average current and to a peak current.

2. The motor controller system of claim 1, wherein the hardened field programmable gate array is radiation hardened.

3. The motor controller system of claim 1, additionally comprising a digital control loop configured to regulate the speed of a motor.

4. The motor controller system of claim 1, wherein the field programmable gate array includes commutation logic to prevent activation of the motor in an incorrect switching state.

5. The motor controller system of claim 1, wherein a rotor position signal is inferred based on the back electromotive force signal with respect to a direct current link return.

6. The motor controller system of claim 5, wherein the rotor position signal mimics the waveform signal of a 120°

switching pattern.

7. The motor controller system of claim 6, wherein the field programmable gate array is configured to adjust a phase of the rotor position signal to compensate for manufacturing and electrical error.

8. The motor controller system of claim 1, wherein the motor is started by application of an asynchronous field by the field programmable gate array, and wherein the asynchronous field switches to a synchronous field after a back electromotive force is detected.

9. The motor controller system of claim 1, wherein the motor controller system is configured to control a motor, wherein the motor drives a target device on a spacecraft.

10. The motor controller system of claim 1, wherein the motor controller system is configured to control a motor which drives a target device, the target device being one of a pump, a fan, or an actuator.

11. The motor controller of claim 1, wherein the decoder circuit additionally comprises an alternating current (AC)-coupled amplifier.

12. The motor controller of claim 1, wherein the decoder circuit additionally comprises a zero-crossing detector.

13. The motor controller of claim 1, wherein the at least one cutoff frequency is configured to be constantly controlled by the field programmable gate array with respect to a speed of a motor.

14. A motor controller system comprising:

a hardened field programmable gate array;

a forward convertor controlled by the field programmable gate array and configured to regulate power supplied to a motor from one or more field-effect transistors by amplitude modulation of a direct current link voltage;

wherein a frequency spectrum of a motor-driving magnetic field is constant; and

a current limiter circuit configured to protect the motor, wherein the current limiter circuit is configured to respond separately to an average current and to a peak current.

15. The motor controller system of claim 14, wherein the one or more field effect transistors are radiation hardened.

16. The motor controller system of claim 14, wherein the one or more field effect transistors can accommodate bidirectional current flow.

17. A method for controlling a motor, comprising:

receiving a back electromotive force signal from a rotor of a motor at a back electromotive force decoder circuit in a motor controller, the decoder circuit at least partially controlled by a hardened field programmable gate array, and the motor protected by a current limiter circuit, wherein the current limiter circuit is configured to respond separately to an average current and to a peak current;

conditioning the back electromotive force signal with a filter in the decoder circuit to reduce phase shift of the back electromotive force signal by continuously conditioning at least one cutoff frequency of the filter by the field programmable gate array;

determining a position of the rotor from the conditioned back electromotive force signal; and

supplying a voltage to commutate the motor based on the position of the rotor.

18. The method of claim 17, wherein conditioning comprises minimizing a phase shift of the back electromotive force signal.

19. The method of claim 17, wherein a frequency spectrum of electromagnetic interference is constant.

20. A satellite comprising:

a motor;

a motor controller that receives a signal from an upper level control device, the motor controller including a hardened field programmable gate array;

a back electromotive force decoder circuit at least partially controlled by the field programmable gate array; and

a filter in the decoder circuit, the filter configured to condition a back electromotive force signal, and the filter having at least one cutoff frequency, wherein the at least one cutoff frequency is continuously conditioned by the field programmable gate array to reduce phase shift of the back electromotive force signal;

a current limiter circuit configured to protect the motor, wherein the current limiter circuit is configured to respond separately to an average current and to a peak current; and

a target device driven by the motor.

21. The satellite of claim 20, wherein the target device is a thermocontrol pump.