System and Method of Controlling Current Draw of a Switched Reluctance Motor

• US 20100083461A1
• Filed: 10/06/2009
• Published: 04/08/2010
• Est. Priority Date: 10/06/2008
• Status: Active Grant

• Current Assignee: Great Star Tools USA, Inc.
• Original Assignee: Shop-Vac Corporation (Hangzhou Great Star Industrial Company Limited)
• Inventors: Robitaille, James M., Norell, Neil N., Huff, Matthew L.
• Granted Patent: US 8,286,300 B2
• Time in Patent Office: Days
• US Class Current: 15/412
• CPC Class Codes: A47L 5/38 Built-in suction cleaner installations, i.e. with fixed tube system to which, at different stations, hoses can be connected
• CPC Class Codes: A47L 7/0076 adapted for vehicle cleaning vehicle cleaning apparatus for interior of land vehicles B60S3/008
• CPC Class Codes: A47L 9/1427 Means for mounting or attaching bags or filtering receptacles in suction cleaners; Adapters
• CPC Class Codes: A47L 9/1436 Connecting plates, e.g. collars, end closures
• CPC Class Codes: A47L 9/1463 specially adapted for rigid filtering receptacles
• CPC Class Codes: A47L 9/22 Mountings for motor fan assemblies
• CPC Class Codes: A47L 9/2831 Motor parameters, e.g. motor load or speed
• CPC Class Codes: A47L 9/2842 Suction motors or blowers
• CPC Class Codes: A47L 9/2884 Details of arrangements of batteries or their installation
• CPC Class Codes: A47L 9/2889 Safety or protection devices or systems, e.g. for prevention of motor over-heating or for protection of the user
• CPC Class Codes: B60S 1/64 for cleaning vehicle interiors, e.g. built-in vacuum cleaners
• CPC Class Codes: H02K 1/246 Variable reluctance rotors
• CPC Class Codes: H02K 19/103 Motors having windings on the stator and a variable reluctance soft-iron rotor without windings
• CPC Class Codes: H02P 25/08 Reluctance motors
• CPC Class Codes: H02P 25/089 Sensorless control direct torque control H02P23/30
• 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

Disclosed is a system and method for controlling current in a switched reluctance motor by changing a dwell state including starting the motor in a normal mode, measuring current in the motor, comparing the measured current to a first threshold, triggering an interrupt if the measured current exceeds the first threshold, keeping a count of consecutive readings exceeding the first threshold, changing the dwell state from a first state to a second state if the measured current exceeds the first threshold and the count equals a set value, changing the dwell state from a second state to a third state if the measured current exceeds a second threshold, and triggering a fault condition if the measured current in the third state exceeds a third threshold.

Claims

1. A method for controlling current in a switched reluctance motor by changing a dwell state, the motor receiving power in the range of 9 to 16 Volts DC, the method comprising:

measuring current in the motor;

comparing the measured current to a first threshold; and

changing the dwell state from a first state to a second state if the measured current exceeds the first threshold.

2. The method of claim 1, further comprising:

keeping a count of consecutive readings exceeding the first threshold; and

changing the dwell state from the first state to the second state only if the count equals a value x, wherein the value x is five.

4. The method of claim 1, wherein the first state is a higher dwell state and the second state is a lower dwell state and wherein the dwell state is changed from a higher state to a lower state when the current is higher than the first threshold.

5. The method claim 4, wherein the higher dwell state is 95% dwell and the lower dwell state is 85% dwell.

6. The method of claim 4, further comprising changing the dwell state to a third state if the current exceeds a second threshold.

7. The method of claim 6, wherein the third dwell state is a higher dwell state and wherein the dwell state is changed from a lower dwell state to a higher dwell state when the current is lower than the second threshold.

8. The method of claim 7, further comprising changing the dwell state to a fourth state if the current exceeds a third threshold.

9. The method of claim 8, wherein the fourth state is a fault condition.

10. The method of claim 1, wherein the first state is a lower dwell state and the second state is a higher dwell state.

11. The method of claim 1, wherein the first state is a higher dwell state and the second state is a fault condition

12. The method of claim 10, wherein the fault condition is triggered if the current is above the first threshold when operating in a higher dwell state.

20. The vacuum cleaner system as recited in claim 1, wherein the first and third state is a higher dwell state and the second state is a lower dwell state.

13. A method for controlling current in a switched reluctance motor by changing a dwell state, the method comprising:

starting the motor in a normal mode;

measuring current in the motor;

comparing the measured current to a first threshold;

triggering an interrupt if the measured current exceeds the first threshold;

keeping a count of consecutive readings exceeding the first threshold;

changing the dwell state from a first state to a second state if the measured current exceeds the first threshold and the count equals a set value;

changing the dwell state from a second state to a third state if the measured current exceeds a second threshold; and

triggering a fault condition if the measured current in the third state exceeds a third threshold.

14. The method of claim 13 wherein the first and third state is a higher dwell state and the second state is a lower dwell state.

15. The method of claim 14 wherein the higher dwell state is 95% dwell and the lower dwell state is 85% dwell.

16. The method of claim 13 wherein the first threshold and the third threshold are equal.

18. The method of claim 13, wherein an error code is loaded when the fault condition is triggered.

17. The method of a wherein a phase of the motor is shut off when the fault condition is triggered.

19. A vacuum cleaner system including a switched reluctance motor, comprising:

a control circuit used to control the operation of the motor;

the control circuit including a microcontroller to control the current by changing a dwell state of the motor; and

the microcontroller running a routine to measure current of the motor, keep a count of consecutive readings exceeding a first threshold, change the dwell state from a first state to a second state if the measured current exceeds a first threshold and the count equals a set value, change the dwell state from a second state to a third state if the measured current exceeds a second threshold, and trigger a fault condition if the measured current while in the third state exceeds a third threshold.