Motor control current zero crossing detector

Patent metadata

Field	Value
Publication number	US-9780706-B2
Application number	US-201615016351-A
Country	US
Kind code	B2
Filing date	Feb 5, 2016
Priority date	Feb 5, 2016
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A driver circuit is provided for driving a load, such as a multi-phase motor. The driver circuit includes a gate driver for providing a control signal to switching elements coupled to the driver circuit. A first switching element is coupled between a high supply voltage and a switching node of the load, and a second switching element is coupled between the switching node and a low supply voltage. To detect zero crossings of a current through the load, a zero crossing detector includes a first counter coupled to the switching node and a second counter coupled to the control signal. The first counter and second counter count in a predetermined direction based on a detected voltage of the switching node and based on a detected voltage of the control signal, respectively. The zero crossing detector generates an output signal based upon the difference between the first and the second counter.

First claim

We claim:

1. A driver circuit for driving a load, the driver circuit comprising:
a gate driver for providing an associated control signal to each of one or more switching elements coupled to the driver circuit, a first one of the switching elements coupled between a high supply voltage and a switching node of the load, and a second one of the switching elements coupled between the switching node and a low supply voltage; and
a zero crossing detector for detecting a zero crossing of a signal of the one or more switching elements and the load, the zero crossing detector comprising:
a first counter coupled to the switching node, wherein the first counter is configured to count in a predetermined direction based on a detected voltage of the switching node;
a second counter coupled to one of the control signals, wherein the second counter is configured to count in a predetermined direction based on a detected voltage of the control signal; and
an output comparator coupled to the first counter and the second counter, the output comparator to generate a difference between a count value of the first counter and a count value of the second counter, wherein the zero crossing detector is configured to generate a zero crossing output signal based, at least in part, upon the difference.

2. The driver circuit of claim 1 , wherein the driver circuit is implemented in a motor controller, and the load comprises a multi-phase motor.

3. The driver circuit of claim 2 , wherein the zero crossing detector is coupled to a switching node of a first phase of the multi-phase motor.

4. The driver circuit of claim 2 , comprising a plurality of zero crossing detectors, each zero crossing detector coupled to a switching node of an associated phase of the multi-phase motor.

5. The driver circuit of claim 2 , wherein the one or more switching elements are configured in a plurality of half-bridge circuit branches, each branch associated with a given phase of the multi-phase motor, each branch comprising:
a first switching element coupled between a high supply voltage and a switching node of the given phase, and a second switching element coupled between the switching node and a low supply voltage.

6. The driver circuit of claim 2 , further comprising:
a control signal generator to control a speed and a position of the multi-phase motor, based, at least in part, upon the zero crossing output signal.

7. The driver circuit of claim 6 , wherein the control signal generator drives the multi-phase motor in a phase advance mode, the phase advance mode to reduce a back electromotive force of the motor and align a phase of the current through the load and a phase of a voltage applied to the load.

8. The driver circuit of claim 6 , wherein the control signal generator determines, based at least in part upon the zero crossing output signal, a direction of motion of the multi-phase motor.

9. The driver circuit of claim 1 , wherein the output comparator is configured to receive an adjustable threshold value, the adjustable threshold value to set a number of counts of at least one of the first counter and the second counter that occur before generating the zero crossing output signal.

10. The driver circuit of claim 1 , wherein, during a dead time when the one or more switching elements are off, the first counter is configured to receive a signal indicative of the voltage of the switching node.

11. The driver circuit of claim 10 , further comprising an input comparator coupled to the switching node and a threshold voltage, the input comparator configured to generate the signal indicative of the voltage of the switching node.

12. The driver circuit of claim 1 , wherein the difference between the count value of the first counter and the count value of the second counter corresponds to a direction of motion of the multi-phase motor.

13. The driver circuit of claim 1 , wherein the one or more switching elements each comprise a field effect transistor, and wherein the driver circuit is implemented in an integrated circuit.

14. The driver circuit of claim 1 , wherein the zero crossing detector is configured to detect a zero crossing of a current through the one or more switching elements and the load.

15. The driver circuit of claim 14 , wherein the one or more switching elements are internal to the integrated circuit.

16. The driver circuit of claim 14 , wherein the one or more switching elements are external to the integrated circuit.

17. An electronic circuit for controlling operation of a multi-phase motor having a plurality of windings, the electronic circuit comprising:
a gate driver for each phase of the multi-phase motor, the gate driver for providing a control signal to an associated half-bridge circuit branch, each branch comprising a first switching element coupled between a high supply voltage and a switching node of the given phase, and a second switching element coupled between the switching node and a low supply voltage; and
a zero crossing detector for detecting a zero crossing of a current through the at least one winding of the multi-phase motor, the zero crossing detector comprising:
a first counter coupled to the switching node, wherein the first counter is configured to count in a predetermined direction based on a detected voltage of the switching node; and
a second counter coupled to one of the control signals, wherein the second counter is configured to count in a predetermined direction based on a detected voltage of the control signal;
wherein the zero crossing detector is configured to generate a difference between a count value of the first counter and a count value of the second counter, wherein the zero crossing detector is configured to generate a zero crossing output signal based, at least in part, upon the difference.

18. The electronic circuit of claim 17 , comprising a plurality of zero crossing detectors, each zero crossing detector associated with a given phase of the multi-phase motor.

19. The electronic circuit of claim 17 , further comprising:
a control signal generator to control a speed and a position of the multi-phase motor, based, at least in part, upon the zero crossing output signal.

20. The electronic circuit of claim 19 , wherein the control signal generator drives the multi-phase motor in a phase advance mode, the phase advance mode to reduce a back electromotive force of the motor and align a phase of the current through the load and a phase of a voltage applied to the load.

21. The electronic circuit of claim 19 , wherein the control signal generator determines, based at least in part upon the zero crossing output signal, a direction of motion of the multi-phase motor.

22. The electronic circuit of claim 17 , wherein the output comparator is configured to receive an adjustable threshold value, the adjustable threshold value to set a number of counts of at least one of the first counter and the second counter that occur before generating the zero crossing output signal.

23. The electronic circuit of claim 17 , wherein, during a dead time when the one or more switching elements are off, the first counter is configured to receive a signal indicative of the voltage of the switching node.

24. The electronic circuit of claim 23 , further comprising an input comparator coupled to the switching node and a threshold voltage, the input comparator configured to generate the signal indicative of the voltage of the switching node.

Assignees

• Allegro Microsystems Llc

Inventors

• Allegrini Gianluca
• Ross Thomas
• Mcintosh James
• Christie Robert Douglas

Classifications

• H02P6/085

  in a bridge configuration · CPC title

• H02P6/18 Primary

  without separate position detecting elements · CPC title

• H02P6/182 Primary

  using back-emf in windings · CPC title