1. I have to control the rpm of motor. There is feedback in pulses by which I can see what is the rpm of motor.
2. I am planning to do it by phase control.
a. Read PWM signal of motor for 1 sec.
b. Calculate the speed
c. control the phase.
d. go to step a.

3. I am not able to control phase precisely. RPM of phase shows variation of +-40 rpm then what I set.

4. What I have noticed is even if I give constant voltage 220vac directly, even then the rpm/pwm keeps of changing.

5. Any other precise method to control rpm of motor. Motor runs on 220Vac. Its shaded pole motor

 

Need more circuit details, what do you mean by 'PWM signal of the motor' ? Also a shaded pole 1ph AC motor is not a really good candidate for motor control.
Max.

 

optocoupler is attached with a wheel. Giving around 300Hz at full speed

 

optocoupler is attached with a wheel. Giving around 300Hz at full speed

There must be more to it than that?
Max.

 

I have to read this freq signal & then vary the phase or voltage to control the motor.