SYSTEM AND METHOD OF ENSURING LEGITIMACY OF A SENSOR SIGNAL RECEIVED FROM A ROTOR POSITION SENSOR IN A MOTOR

• US 20060089818A1
• Filed: 10/21/2004
• Published: 04/27/2006
• Est. Priority Date: 10/21/2004
• Status: Active Grant

• Current Assignee: Shop-Vac Corporation (Hangzhou Great Star Industrial Company Limited)
• Original Assignee: Shop-Vac Corporation (Hangzhou Great Star Industrial Company Limited)
• Inventors: Robitaille, James M., Norell, Neil N.
• Granted Patent: US 7,050,929 B2
• Time in Patent Office: Days
• US Class Current: 702/151
• CPC Class Codes: G01D 5/24461 by redundancy or plausibility
• CPC Class Codes: G01D 5/3473 Circular or rotary encoders
• CPC Class Codes: H02P 6/153 wherein the commutation is advanced from position signals phase in function of the speed
• CPC Class Codes: H02P 6/20 Arrangements for starting H02P6/08 takes precedence

Abstract

A system and method of ensuring legitimacy of a sensor signal received from a rotor position sensor in a motor is provided that includes polling the sensor to determine a first state of the sensor signal, determining a first time delay by summing a first plurality of time constants, and initiating a first time delay. Also included is re-polling the sensor to determine a second state of the sensor signal, determining a second time delay by summing a second plurality of time constants, initiating a second time delay if the second state of the sensor signal is the same as the first state of the sensor signal, re-polling sensor to determine a third state of the sensor signal, and considering the sensor signal as a legitimate signal if the third state of the sensor signal is the same as the first and second states of the sensor signal.

Claims

1. A method of ensuring legitimacy of a sensor signal received from a rotor position sensor in a switched reluctance motor, the motor having a controller and a memory, the method comprising:

polling the rotor position sensor to determine a first state of the sensor signal;

determining a first time delay by summing a first plurality of time constants stored in the memory;

initiating a first delay equal to the first time delay;

re-polling the rotor position sensor upon completion of the first delay to determine a second state of the sensor signal;

determining a second time delay by summing a second plurality of time constants stored in the memory;

initiating a second delay equal to the second time delay if the second state of the sensor signal is the same as the first state of the sensor signal;

re-polling the rotor position sensor upon completion of the second delay to determine a third state of the sensor signal; and

considering the sensor signal as a legitimate signal if the third state of the sensor signal is the same as the first and second states of the sensor signal.

2. The method of claim 1, wherein the motor further has a stator winding, and wherein the stator winding is in one of a first state or a second state, the first state being the state where the stator winding is energized and the second state being the state where the stator winding is not energized, the method further comprising changing states in response to the sensor signal if the sensor signal is considered legitimate and different from a preceding legitimate sensor signal.

3. The method of claim 1, further comprising setting an initial value for a plurality of time constants.

4. The method of claim 1, further comprising considering the sensor signal as noise if the second state of the sensor signal is different from the first state of the sensor signal.

5. The method of claim 1, further comprising returning to an existing and active speed routine if the sensor signal is considered as noise.

6. The method of claim 1, further comprising determining a rotational speed of a rotor after a power up and initiating a delay if the rotational speed exceeds a threshold speed.

7. The method of claim 1, wherein the first plurality of time constants is the same as the second plurality of time constants.

8. A method of ensuring legitimacy of a sensor signal received from a rotor position sensor in a switched reluctance motor, the motor having a controller and a memory, the method comprising:

setting an initial value for a plurality of time constants;

polling the rotor position sensor to determine a first state of the sensor signal received from rotor position sensor;

determining a first time delay by summing a first plurality of time constants stored in the memory, the plurality of time constants each representing a time value;

initiating a first delay equal to the first time delay;

re-polling the rotor position sensor upon completion of the first time delay to determine a second state of the sensor signal;

determining a second time delay by summing a second plurality of time constants stored in the memory;

initiating a second delay equal to the second time delay if the second state of the sensor signal is the same as the first state of the sensor signal;

re-polling the rotor position sensor upon completion of the second delay to determine a third state of the sensor signal;

considering the sensor signal as a legitimate signal if the third state of the sensor signal is the same as the first and second states of the sensor signal; and

one of energizing or de-energizing a stator winding if the sensor signal is considered legitimate and different from the preceding legitimate sensor signal.

9. The method of claim 8, further comprising considering the sensor signal as noise if the second state of the sensor signal is different from the first state of the sensor signal.

10. The method of claim 8, further comprising returning to an existing and active speed routine if the sensor signal is considered as noise.

11. The method of claim 8, further comprising sensing a temperature in a control circuit using a voltage regulator.

12. The method of claim 8, wherein the first plurality of time constants is the same as the second plurality of time constants.

13. A control circuit for ensuring legitimacy of a sensor signal received from a rotor position sensor in a switched reluctance motor comprising:

a rotor position sensor to determine a rotational position of a rotor relative to a stator;

a controller operatively coupled to the rotor position sensor, the controller having a processor and a memory operatively coupled to the processor;

the controller being programmed to poll the rotor position sensor to determine a first state of the sensor signal;

the controller being programmed to determine a first time delay by summing a first plurality of time constants stored in the memory, the first plurality of time constants each representing a time value;

the controller being programmed to initiate a first delay equal to the first time delay;

the controller being programmed to re-poll the rotor position sensor upon completion of the first delay to determine a second state of the sensor signal;

the controller being programmed to determine a second time delay by summing a second plurality of time constants stored in the memory;

the controller being programmed to initiate a second delay equal to the second time delay if the second state of the sensor signal is the same as the first state of the sensor signal;

the controller being programmed to re-poll the rotor position sensor upon completion of the second delay to determine a third state of the sensor signal; and

the controller being programmed to consider the sensor signal as a legitimate sensor signal if the third state of the sensor signal is the same as the first and second states of the sensor signal.

14. The control circuit of claim 13, wherein the rotor position sensor is an optical encoder and wherein the controller is further programmed to determine a rotational speed of the rotor.

15. The control circuit of claim 13, wherein the controller is further programmed to control the energization of a plurality of stator windings if the sensor signal is considered legitimate and different from the preceding legitimate sensor signal.

16. The control circuit of claim 15, wherein energization of the plurality of stator windings comprises energizing a first pair of stator windings and removing electrical energy from a second pair of stator windings.

17. The control circuit of claim 13, wherein the controller is further programmed to set an initial value for a plurality of time constants.

18. The control circuit of claim 13, wherein the controller is further programmed to consider the sensor signal as noise if the second state of the sensor signal is different from the first state of the sensor signal.

19. The control circuit of claim 13, wherein the controller is further programmed to return to an existing and active speed routine if the sensor signal is considered as noise.

20. The control circuit of claim 13, wherein the controller is further programmed to determine a rotational speed of the rotor after a power up and initiate a delay if the rotational speed exceeds a predetermined threshold.

21. The control circuit of claim 13, wherein the first plurality of time constants is the same as the second plurality of time constants.

22. A system for ensuring legitimacy of a sensor signal received from a rotor position sensor in a switched reluctance motor comprising:

means for initializing a set of hardware components including a controller in a control circuit;

means for determining a rotational speed of a rotor;

means for polling the rotor position sensor to determine a first state of the sensor signal, the sensor operatively coupled to the controller;

means for determining a first time delay by summing a first plurality of time constants stored in the memory, the first plurality of time constants each representing a time value;

means for initiating a first delay equal to the first time delay;

means for re-polling the rotor position sensor upon completion of the first delay to determine a second state of the sensor signal;

means for determining a second time delay by summing a second plurality of time constants stored in the memory;

means for initiating a second delay equal to the second time delay if the second state of the sensor signal is the same as the first state of the sensor signal;

means for re-polling the rotor position sensor upon completion of the second delay to determine a third state of the sensor signal; and

means for considering the first, second, and third states as a legitimate signal if the third state of the sensor signal is the same as the first and second states of the sensor signal.

23. The system of claim 22, further comprising means for one of energizing or de-energizing a plurality of stator windings if the sensor signal is considered legitimate and different from the preceding legitimate sensor signal.

24. The system of claim 22, further comprising means for considering the sensor signal as noise if the second state of the sensor signal is different from the first state of the sensor signal.

25. An article comprising a machine-accessible medium having stored thereon instructions that, when executed by a machine, cause the machine to:

poll a rotor position sensor to determine a first state of the sensor signal, the sensor operatively coupled to a controller;

determine a first time delay by summing a first plurality of time constants stored in the memory, the plurality of time constants each representing a time value;

initiate a first delay equal to the first time delay;

re-poll the rotor position sensor upon completion of the first delay to determine a second state of the sensor signal;

determine a second time delay by summing a second plurality of time constants stored in the memory;

initiate a second delay equal to the second time delay if the second state of the sensor signal is the same as the first state of the sensor signal;

re-poll the rotor position sensor upon completion of the second delay to determine a state of a third sensor signal; and

consider the sensor signal as a legitimate signal if the state of the third sensor signal is the same as the states of the first and second sensor signals.

26. The article of claim 25, having further instructions that, when executed by the machine, cause the machine to consider the sensor signal as noise if the state of the second sensor signal is different from the state of the first sensor signal.

27. The article of claim 25, having further instructions that, when executed by the machine, cause the machine to return to an existing and active speed routine if the sensor signal is considered as noise.

28. The article of claim 25, having further instructions that, when executed by the machine, cause the machine to determine a rotational speed of a rotor after a power up and initiate a delay if the rotational speed exceeds a predetermined threshold.