i m doing my final year project on speed control of induction motor using 8051 having a feedback loop ..we are supposed to use pi controllers as the feed back element ..we will use optical sensor to measure the speed of motor..
i don't know exactly how to proceed can anyone help me
thanks
shiv

 

Simple, just read the speed by taking a count for a fixed time, then compare the actual speed to the
setpoint, take the error times P gain plus the accumulated integral value and send it to the output.

I hope this helps (but not to help too much),
Bill

 

First, the choice of resolution of the encoder is very important. It depends on the precision of your project and the working speed range of the motor.

Install an enocder on the motor. You need to set a very small sampling period and be able to calculate the speed with this period. Give motor a step input and estimate the responce time(rising time) from data. Then the sampling period must be smaller than this time, say 1/3 or 1/4.

From the precision and known sampling period, you can calculate the required resolution of the encoder. The encoder is crucial for the project.

Based on that, you can design PI controler with known sampling period.

Tune the PI parameters to obtain good performance.

a software filter is normally required to filter the calculated speed