VARIABLE LINK SENSORLESS BRUSHLESS DIRECT CURRENT MOTOR CONTROLLER FOR SPACE AND HARDENED APPLICATIONS

• US 20140239864A1
• Filed: 02/22/2013
• Published: 08/28/2014
• 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.
• Granted Patent: US 9,444,376 B2
• Time in Patent Office: Days
• US Class Current: 318/400.35
• 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; and

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 dynamically controlled by the field programmable gate array.

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

5. 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.

6. 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.

9. 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.

10. 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.

11. 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.

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

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

7. The motor controller system of claim 7, wherein the rotor position signal mimics the waveform signal of a 120°

switching pattern.

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

14. A motor controller system comprising:

a hardened field programmable gate array; and

a forward convertor controlled by the field programmable gate array and configured to regulate power supplied to a motor by amplitude modulation of a direct current link voltage.

15. The motor controller system of claim 14, wherein the power is supplied to the motor by one or more field effect transistors, 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;

conditioning the back electromotive force signal with a filter in the decoder circuit, the filter having at least one cutoff frequency, wherein the at least one cutoff frequency is dynamically controlled 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. A satellite comprising:

a motor;

a motor controller that receives a signal from the 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 configured to condition a back electromotive force signal, the filter having at least one cutoff frequency, wherein the at least one cutoff frequency is dynamically controlled by the field programmable gate array; and

a target device driven by the motor.

19. The satellite of claim 18, wherein the target device is a pump which operates to distribute fluid for maintaining an operating temperature of the satellite.