US 7,460,974 B2 · Multiple-point smoothing method for motor-speed estimation

Abstract

A multiple-point smoothing method for motor-speed estimation. The output of an encoder is over-sampled to obtain over-sampled position differences according to an over-sampling factor M. The over-sampled position differences are averaged to obtain an initial speed estimation. The initial speed estimation is low-pass filtered to obtain a final speed estimation. The final speed estimation is sent to a speed controller to control the speed of a motor. Alternatively, in a composite multiple-point smoothing scheme, the initial speed estimations based on two over-sampling factors are obtained. One of the initial speed estimations is selected based on an average of the two estimations, and the selected initial speed estimation is further processed to obtain a final speed estimation. The method of the present invention can reduce ripple in estimated speed of motor when the motor is operated at high speed.

Claims7

Dependent claims

A multiple-point smoothing method for motor speed estimation, the method determining a speed estimation for a motor according to an output of an encoder and sending the speed estimation to a motor controller, the method comprising:

determining an over sampling factor M which is an integer larger than one;
reading the output of the encoder;
counting the output of the encoder;
performing an over sampling to the output of the encoder according to the over sampling factor M and a rated sampling frequency fs;
and
averaging the over sampled result to obtain an initial speed estimation.

3 more elements

determining a first over sampling factor M1 and a second over sampling factor M2;
reading the output of the encoder;
counting the output of the encoder;
obtaining a first initial speed estimation V1, wherein the output of the encoder is over-sampled according to the first over sampling factor M1 and a rated sampling frequency fs, and the over-sampled output of the encoder is averaged to obtain the first initial speed estimation V1;
obtaining a second initial speed estimation V2, wherein the output of the encoder is over-sampled according to the second over sampling factor M2 and the rated sampling frequency fs, and the over-sampled output of the encoder is averaged to obtain the second initial speed estimation V2;
calculating an averaged speed estimation Vavg by averaging the first initial speed estimation V1 and the second initial speed estimation V2;
and
selecting one of the first initial speed estimation V1 and the second initial speed estimation V2 as an initial speed estimation according to the averaged speed estimation Vavg.

5 more elements

Dependencies are inferred from the claim text.

Multiple-point smoothing method for motor-speed estimation

Life of this patent

Multiple-point smoothing method for motor-speed estimation

Life of this patent

Abstract

Claims7