| Summary: | 碩士 === 南台科技大學 === 電機工程系 === 96 === The thesis aims at designing the drives for permanent magnet synchronous motors at low speed range. Incremental-type encoder is widely used for speed detection in servo system. However, the system usually becomes unstable at low speed range due to the speed controller using average speed estimation method. To improve the system performance, three algorithms are studied in the thesis, in-parallel interlaced sampling, the encoder resolution increasing, and instantaneous speed observer design.
The architecture of in-parallel interlaced sampling may provide larger speed-loop bandwidth to get higher resolution. To increase the encoder resolution, the phase delay method for square waveforms is proposed. This method will raise the frequency of the encoder pulses such that the encoder resolution will be increased. A digital filtering system is employed to filter out the noise on the encoder signal. As a result, the effect of phase delay method on encoder pulses is shown.
The error between the motor speed and the designed observer output is applied to a PID controller such that the torque disturbance of the motor system will be compensated. As a result, the instantaneous low motor speeds will be effectively obtained.
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