Methods and apparatus for monitoring average current and input power in an electronically commutated motor

• US 20100052590A1
• Filed: 08/29/2008
• Published: 03/04/2010
• Est. Priority Date: 08/29/2008
• Status: Active Grant

• Current Assignee: Regal Beloit America, Inc.
• Original Assignee: Regal Beloit America, Inc.
• Inventors: Brattoli, Mark A., Bonner, Guy JR.
• Granted Patent: US 8,368,331 B2
• Time in Patent Office: Days
• US Class Current: 318/490
• CPC Class Codes: G01R 21/06 by measuring current and voltage G01R21/08 - G01R21/133 take precedence
• CPC Class Codes: H02P 6/28 Arrangements for controlling current H02P6/10 takes precedence

Abstract

A method for monitoring input power to an electronically commutated motor (ECM) is described. The method includes determining, with a processing device, an average input current to the motor, the average input current based on a voltage drop across a shunt resistor in series with the motor, measuring an average input voltage applied to the motor utilizing the processing device, multiplying the average input current by the average voltage to determine an approximate input power, and communicating the average input power to an external interface.

Claims

1. A method for monitoring input power to an electronically commutated motor (ECM), said method comprising:

determining, with a processing device, an average input current to the motor, the average input current based on a voltage drop across a shunt resistor in series with the motor;

measuring an average input voltage applied to the motor utilizing the processing device;

multiplying the average input current by the average voltage to determine an approximate input power; and

communicating the average input power to an external interface.

2. A method according to claim 1 wherein measuring an average input voltage applied to the motor comprises:

rectifying and filtering an AC input voltage to the ECM;

proportionally voltage dividing the rectified and filtered AC input voltage to a level compatible with an analog-to-digital converter (ADC); and

averaging multiple readings of the divided voltage over a fixed time interval to determine the average input voltage.

3. A method according to claim 1 wherein measuring an average input voltage applied to the motor comprises:

proportionally voltage dividing a DC input voltage to a level compatible with an analog-to-digital converter (ADC); and

averaging multiple readings of the divided voltage over a fixed time interval to determine the average input voltage.

4. A method according to claim 1 wherein determining an average input current to the motor comprises applying the voltage dropped across the shunt resistor to an analog-to-digital converter.

5. A method according to claim 1 wherein determining an average input current to the motor comprises:

integrating the voltage dropped across the shunt resistor; and

applying the integrated voltage to an analog-to-digital converter.

6. A method according to claim 5 wherein:

integrating the voltage dropped across the shunt resistor comprises averaging the voltage drop across the shunt resistor according to;

7. A method according to claim 1 wherein communicating the average input power to an external interface comprises transmitting the calculated input power to at least one external device via a digital serial interface.

8. A method according to claim 7 wherein the calculated input power is transmitted upon request from an end user I/O device.

9. A method according to claim 1 further comprising using the communicated average power as an indication in an airflow delivery system to control the amount of power used by the system.

10. An electronically commutated motor (ECM) comprising:

a rotor;

a plurality of windings for causing a rotation of said rotor; and

an ECM control circuit comprising;

a switching circuit operable to selectively couple said windings to a power source;

a shunt resistor in series with said switching circuit;

a processing device configured to control said switching circuit; and

at least one analog-to-digital converter (ADC) coupled to said processing device, said processing device configured to control operation of said ADC such that that an average input current to the motor can be determined based on a voltage drop across said shunt resistor and an average input voltage applied to the motor can be measured.

11. An ECM according to claim 10 wherein said processing device and said ADC comprise a microcontroller that comprises an ADC thereon.

12. An ECM according to claim 10 wherein to determine an average voltage applied to said ECM, said ECM control circuit comprises:

a rectifier;

a filter, said rectifier and said filter operable to rectify and filter an AC input voltage to said ECM; and

a voltage divider operable to voltage divide the rectified and filtered AC input voltage to a level compatible with said at least one analog-to-digital converter (ADC), said processing device programmed to average multiple readings of the divided voltage over a fixed time interval to determine the average input voltage.

13. An ECM according to claim 10 wherein to determine an average voltage applied to said ECM, said ECM control circuit comprises a voltage divider operable to voltage divide a DC input voltage to a level compatible with said at least one analog-to-digital converter (ADC), said processing device programmed to average multiple readings of the divided voltage over a fixed time interval to determine the average input voltage.

14. An ECM according to claim 10 wherein to determine an average voltage applied to said ECM, said ECM control circuit is configured to integrate the voltage dropped across said shunt resistor and apply the integrated voltage to said analog-to-digital converter.

15. An ECM according to claim 14 wherein to integrate the voltage drop across said shunt resistor, said ECM control circuit is programmed to:

integrate the voltage drop across said shunt resistor according to;

16. An ECM according to claim 10 wherein to communicate the average input power to an external interface, said ECM comprises a digital serial interface communicatively coupled to said processing device.

17. An ECM according to claim 16 wherein the calculated input power is transmitted by said processing device upon request from an end user I/O device.