SYSTEMS AND METHODS FOR SENSING A LINE POWERING AN ELECTRIC MOTOR

• US 20160226422A1
• Filed: 01/29/2015
• Published: 08/04/2016
• Est. Priority Date: 01/29/2015
• Status: Active Grant

• Current Assignee: Regal Beloit America, Inc.
• Original Assignee: Regal Beloit America, Inc.
• Inventors: NARDIN, STEVEN ALBERT, KOLLER, MICHAEL R.
• Granted Patent: US 10,008,968 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02P 27/06 using dc to ac converters or inverters H02P27/05 takes precedence

Abstract

A system includes an electric motor controller configured to be coupled to an electric motor is provided. The controller includes a first power input, a second power input, and a third power input, each of the first, second, and third power inputs are configured to receive power from an alternating current (AC) power source. The controller also includes a microcontroller configured to generate a radio frequency (RF) signal in each of the first, second, and third power inputs. The controller further includes an RF based line sensing device configured to sense which one of said first, second, and third power inputs has received power from the AC power source based on the RF signal.

Claims

1. An electric motor controller configured to be coupled to an electric motor, said controller comprising:

a first power input, a second power input, and a third power input, each of said first, second, and third power inputs configured to receive power from an alternating current (AC) power source;

a microcontroller configured to generate a radio frequency (RF) signal in each of said first, second, and third power inputs; and

an RF based line sensing device configured to sense which one of said first, second, and third power inputs has received power from the AC power source based on the RF signal.

2. A controller in accordance with claim 1, wherein said microcontroller is configured to toggle an oscillator above a predetermined rate of speed such that the RF signal appears to be conducted through said first, second, and third power inputs.

3. A controller in accordance with claim 2, wherein said oscillator comprises one of dedicated hardware located within said microcontroller and motor windings of the electric motor.

4. A controller in accordance with claim 2, wherein said RF based line sensing device comprises a first sensor coupled to said first power input and a second sensor coupled to said second power input.

5. A controller in accordance with claim 4, wherein one of said first and second sensors is configured to output a voltage level when the one of said first and second sensors is energized.

6. A controller in accordance with claim 4, wherein said third power input is sensorless, said microcontroller determines that said third power input is energized when the RF signal is produced and no signal is sensed by said first and second sensors.

7. A controller in accordance with claim 1, wherein said microcontroller is configured to:

operate the electric motor at a lowest speed when power is received;

monitor harmonics existing on said first, second, and third power inputs, the harmonics internally generated by the electric motor; and

sense the energized power input based on the monitored harmonics.

8. A controller in accordance with claim 1, wherein said RF based line sensing device further comprises an RF generator coupled to said first, second, and third power inputs, wherein each of said first, second, and third power inputs has a different frequency and an energized one of said first, second, and third power inputs excites said RF generator.

9. A controller in accordance with claim 8, wherein said microcontroller further comprises a receiver configured to detect the frequency being generated and determine which power input is energized.

10. A controller in accordance with claim 1, further comprising:

a rectifier for rectifying the power received from the AC power source to a direct current (DC) power; and

an inverter for inverting the rectified power to three-phase power for operating the electric motor.

11. An electric motor controller configured to be coupled to an electric motor, said controller comprising:

a first power input and a second power input, each of said first and second power inputs configured to receive power from an alternating current (AC) power source;

a first thermistor coupled to said first power input and a second thermistor coupled to said second power input, said first and second thermistors configured to provide inrush current protection during startup of the electric motor;

an input line thermal sensing device coupled to said first and second thermistors, said input line thermal sensing device configured to sense a temperature of said first and second thermistors and output a unique temperature signal; and

a microcontroller configured to determine which power input is energized based on the unique temperature signal output by said input line thermal sensing device.

12. A controller in accordance with claim 11, wherein said microcontroller is further configured to determine which power input is energized by detecting which of said first and second thermistors experiences a rapid increase in temperature within a predetermined time period.

13. A controller in accordance with claim 11, wherein said input line thermal sensing device comprises:

a first temperature sensor coupled to said first thermistor; and

a second temperature sensor coupled to said second thermistor.

14. A controller in accordance with claim 13, wherein each of said first and second temperature sensors comprises one of a temperature sensitive resistor and a silicone based sensing element.

15. A controller in accordance with claim 11, wherein said microcontroller is further configured to determine an operating profile for the electric motor based on the signal.

16. A method of sensing a line powering an electric motor, said method comprising:

providing a first power input, a second power input, and a third power input, each of the first, second, and third power inputs configured to receive power from an alternating current (AC) power source;

generating, by a microcontroller, a radio frequency (RF) signal in each of the first, second, and third power inputs; and

sensing, by an RF based line sensing device, which one of the first, second, and third power inputs has received power from the AC power source based on the RF signal.

17. A method in accordance with claim 16, further comprising toggling an oscillator above a predetermined rate of speed such that the RF signal appears to be conducted through the first, second, and third power inputs.

18. A method in accordance with claim 16, wherein sensing which one of the first, second, and third power inputs has received power from the AC power source further comprises:

providing a first sensor coupled to the first power input and a second sensor coupled to the second power input; and

outputting, by one of the first and second sensors, a voltage level when the one of the first and second sensors is energized.

19. A method in accordance with claim 18, further comprising:

providing a sensorless third power input; and

determining that the third power input is energized when the RF signal is generated and no signal is sensed by the first and second sensors.

20. A method in accordance with claim 16, further comprising:

operating the electric motor at a lowest speed when power is received;

monitoring harmonics existing on said first, second, and third power inputs, the harmonics internally generated by the electric motor; and

sensing the energized power input based on the monitored harmonics.