System and method for motor speed estimation of an electric motor

• US 8,203,298 B2
• Filed: 08/26/2009
• Issued: 06/19/2012
• Est. Priority Date: 08/26/2009
• Status: Active Grant

• Current Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Original Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Inventors: Lu, Bin, Yan, Ting, Luebke, Charles John, Sharma, Santosh Kumar
• Primary Examiner(s): Benson, Walter
• Assistant Examiner(s): LUO, DAVID S
• Application Number:
  US12/547,723
• Publication Number:
  US 20110050142A1
• Time in Patent Office: 1,028 Days
• Field of Search: 318/461, 318/490, 318466-470
• US Class Current: 318/461
• CPC Class Codes: H02P 23/14 Estimation or adaptation of motor parameters, e.g. rotor time constant, flux, speed, current or voltage
• CPC Class Codes: H02P 27/045 whereby the speed is regulated by measuring the motor speed and comparing it with a given physical value

Abstract

A system and method for a motor management system includes a computer readable storage medium and a processing unit. The processing unit configured to determine a voltage value of a voltage input to an alternating current (AC) motor, determine a frequency value of at least one of a voltage input and a current input to the AC motor, determine a load value from the AC motor, and access a set of motor nameplate data, where the set of motor nameplate data includes a rated power, a rated speed, a rated frequency, and a rated voltage of the AC motor. The processing unit is also configured to estimate a motor speed based on the voltage value, the frequency value, the load value, and the set of nameplate data and also store the motor speed on the computer readable storage medium.

Claims

1. A motor management system comprising:

a non-transistory computer readable storage medium; and

a processing unit configured to;

determine a voltage value of a voltage input to an alternating current (AC) motor during operation of the AC motor;

determine a frequency value of at least one of a voltage input and a current input to the AC motor during operation of the AC motor;

determine a load value from the AC motor during operation of the AC motor;

access a set of motor nameplate data, wherein the set of motor nameplate data comprises a rated power, a rated speed, a rated frequency, and a rated voltage of the AC motor;

estimate a motor speed of the AC motor in operation based on the voltage value, the frequency value, the load value, and the set of nameplate data; and

store the motor speed on the non-transistory computer readable storage medium.

2. The motor management system of claim 1 wherein the processing unit is configured to estimate the motor speed via estimation operations free of frequency-domain signal processing operations.

3. The motor management system of claim 1 further comprising a variable frequency drive coupled to the AC motor, wherein the AC motor is driven by the variable frequency drive.

4. The motor management system of claim 1 wherein the processing unit is further configured to adjust motor speed based on the estimation of the motor speed.

5. The motor management system of claim 1 wherein the determination of a load value is based on at least one of a power output value of power input to the AC motor, a load percentage value, and a power input value of power input to the AC motor.

6. The motor management system of claim 1 wherein the determination of a load value is further based on an efficiency value of the AC motor.

7. The motor management system of claim 1 wherein the frequency value is a measured value.

8. The motor management system of claim 1 wherein the frequency value is a calculated value.

9. The motor management system of claim 1 wherein the AC motor is one of a multi-phase motor and a single-phase motor.

10. The motor management system of claim 1 wherein the motor management system is a device removably coupleable to a motor drive.

11. A method for controlling motor speed comprising:

determining a voltage of energy input into a motor in operation via a voltage sensing device;

determining a frequency of energy input into the motor in operation;

determining a load value of the motor in operation;

estimating a motor speed of the motor in operation based on the voltage, the frequency, and the load value, wherein estimating the motor speed is free of free of fast frequency-domain signal processing operations;

accessing a set of motor rating values of the motor, the set of motor rating values comprises a rated speed, a rated frequency, and one of a rated output power and a rated voltage, wherein estimating the motor speed is further based on the set of motor rating values; and

storing the motor speed on a non-transistory computer readable storage medium.

12. The method of claim 11 further comprising modifying the motor speed via a motor drive.

13. The method of claim 11 further comprising displaying the motor speed on a display screen to a user.

14. The method of claim 11 further comprising:

accessing an efficiency value of the motor; and

determining a power input into the motor in operation, wherein determining a load value of the motor is based on the efficiency value of the motor and the power input into the motor.

15. The method of claim 11 wherein the AC motor is coupled to a soft-starter.

16. The method of claim 11 wherein the AC motor is driven by a variable frequency drive.

17. The method of claim 11 wherein determining the load value comprises determining an output power without determining the output power via a power sensor.

18. A motor speed estimation system, the motor speed estimation system programmed to:

estimate a motor speed of a motor based on a frequency of energy input to the motor during operation, a voltage of the energy input to the motor during operation, a load value from the motor during operation, a rated output power of the motor, a rated speed of the motor, a rated voltage of the motor, and a rated frequency of the motor; and

store the motor speed on a non-transistory computer storage device.

19. The motor speed estimation system of claim 18 further programmed to adjust the motor speed after estimation of the motor speed.

20. The motor speed estimation system of claim 18 wherein the motor speed estimation system is a removable device coupled to a motor drive of the motor.

21. The motor speed estimation system of claim 18 wherein the load value is estimated from an input power value and an efficiency value of the motor in operation.

22. The motor speed estimation system of claim 18 wherein the AC motor is driven by an inverter.

23. The motor speed estimation system of claim 18 wherein the estimation of the motor speed is free of fast Fourier transform (FFT) operations and wavelet analysis operations.

24. The motor speed estimation system of claim 23 wherein the frequency of the energy input is different than the rated frequency and the voltage of the energy input is different than the rated voltage.