CONTROLLER FOR A MOTOR AND A METHOD OF CONTROLLING THE MOTOR

• US 20100080714A1
• Filed: 09/24/2009
• Published: 04/01/2010
• Est. Priority Date: 10/01/2008
• Status: Active Grant

• Current Assignee: Regal Beloit America, Inc.
• Original Assignee: A. O. Smith Corporation
• Inventors: Mehlhorn, William L., Branecky, Brian T.
• Granted Patent: US 8,354,809 B2
• Time in Patent Office: Days
• US Class Current: 417/44.110
• CPC Class Codes: F04B 2203/0201 Current
• CPC Class Codes: F04B 2203/0202 Voltage
• CPC Class Codes: F04B 2203/0208 Power
• CPC Class Codes: F04B 49/065 and making use of computers
• CPC Class Codes: F04B 51/00 Testing machines, pumps, or pumping installations
• CPC Class Codes: F04D 15/0088 Testing machines
• CPC Class Codes: F04D 15/0236 Lack of liquid level being detected by analysing the parameters of the electric drive, e.g. current or power consumption
• CPC Class Codes: H02H 3/027 with automatic disconnection after a predetermined time H02H3/033, H02H3/06 take precedence ; timing in overcurrent protection circuits H02H3/093; in undervoltage protection circuits H02H3/247; staggered disconnection H02H7/30
• CPC Class Codes: H02H 3/04 with warning or supervision in addition to disconnection, e.g. for indicating that protective apparatus has functioned watching of pilot wires H02H1/0084; protection of protective arrangements H02H7/008; indication of the state of electronic switches H03K17/18
• CPC Class Codes: H02H 3/12 responsive to underload or no-load for motors H02H7/0827
• CPC Class Codes: H02H 3/382 involving phase comparison between current and voltage or between values derived from current and voltage
• CPC Class Codes: H02H 3/42 responsive to product of voltage and current
• CPC Class Codes: H02H 7/08 for dynamo-electric motors

Abstract

A pump system. The pump system includes a pump, a motor coupled to the pump, a sensor coupled to a power source, and a controller. The motor operates the pump. The sensor detects an electrical characteristic of the power source. The controller executes a fault check, controls the motor, detects a change in the electrical characteristic, and suspends the execution of the fault check for a predetermined period of time when the detected change in the electrical characteristic is outside of a valid characteristic range.

Claims

1. A pump system coupled to a power source, comprising:

a pump;

a motor coupled to the pump, the motor operating the pump;

a sensor coupled to the power source, the sensor detecting an electrical characteristic of the power source; and

a controller coupled to the sensor and the motor, the controller

executing a fault check,

controlling the motor,

detecting a change in the sensed electrical characteristic, and

suspending the executing of the fault check when the detected change in the electrical characteristic is outside of a valid characteristic range.

2. The pump system of claim 1, wherein the controller generates a first running average of the electrical characteristic for a first length of time and a second running average of the electrical characteristic for a second length of time, the first length of time substantially longer than the second length of time.

3. The pump system of claim 2, wherein the valid characteristic range is between the first running average minus a first constant and the first running average plus a second constant.

4. The pump system of claim 1, wherein the electrical characteristic is voltage.

5. The pump system of claim 1, wherein the electrical characteristic is a power factor.

6. The pump system of claim 1, wherein executing the fault check includes generating a derivative based on the sensed electrical characteristic.

7. The pump system of claim 6, wherein the fault check includes monitoring the derivative, and determining whether the derivative indicates an undesired flow of fluid through the pump.

8. The pump system of claim 7, wherein the controller stops the motor when the derivative indicates the undesired flow of fluid through the pump.

9. The pump system of claim 1, wherein the executing of the fault check is suspended for a predetermined period of time.

10. The pump system of claim 1, wherein the executing of the fault check is suspended until the detected change in the electrical characteristic is within the valid characteristic range.

11. A method of operating a pump system including a pump, a motor, a sensor, and a controller, the method comprising:

operating the motor;

executing a fault check;

determining an electrical characteristic related to a power supplied by a power source coupled to the motor;

determining that the electrical characteristic is outside of a valid characteristic range; and

suspending execution of the fault check for a predetermined period of time after determining the electrical characteristic is outside the valid characteristic range.

12. The method of claim 11, further comprising generating a first running average of the electrical characteristic and a second running average of the electrical characteristic.

13. The method of claim 12, wherein the first running average is generated for a first length of time, and the second running average is generated for a second length of time, the first length of time substantially longer than the second length of time.

14. The method of claim 12, wherein the valid characteristic range is between the first running average minus a first constant and the first running average plus a second constant.

15. The method of claim 11, wherein the electrical characteristic is voltage.

16. The method of claim 11, wherein executing the fault check includes generating a derivative based on the sensed electrical characteristic.

17. The method of claim 16, wherein the fault check includes monitoring the derivative, and determining whether the derivative indicates an undesired flow of fluid through the pump.

18. The method of claim 17, wherein the controller stops the motor when the derivative indicates the undesired flow of fluid through the pump.

19. A controller for a motor, comprising:

a memory;

a sensor configured to sense an electrical characteristic of the motor; and

a processor coupled to the memory and the sensor, the processor

executing a fault check,

controlling the motor,

detecting a change in the sensed electrical characteristic, and

suspending the executing of the fault check when the detected change in the sensed electrical characteristic is outside of a valid characteristic range.

20. The controller of claim 19, wherein the executing of the fault check is suspended for a predetermined period of time.

21. The controller of claim 19, wherein the processor generates a first running average of the electrical characteristic for a first length of time and a second running average of the electrical characteristic for a second length of time, the first length of time substantially longer than the second length of time.

22. The controller of claim 19, wherein the valid characteristic range is between the first running average minus a first constant and the first running average plus a second constant.

23. The controller of claim 19, wherein the electrical characteristic is voltage.