Yan ang naintindihan kong explanation! Salamat sir. May I get your opinion on this www.vhipe.com/product-private/SuperPID.htm
It's been getting good reviews since it was introduced.
Walang akong experience using this product. However, I can comment by analyzing how I think it works and how would I do it if someone were to ask me to make such a controller. Here goes.
I think its speed control works by phase control of the AC power the same way a light dimmer works. There is a zero crossing detector of the AC power and the detector is input to the MCU. The MCU in turn fires the triac at a programmed delay depending upon a PID based algorithm.
Does it work? If you believe the user feedback, it apparently does.
What are the sort of problems to expect with this method? Phase control effectively controls the average voltage to the motor. However, the series connected universal motor is less suitable for this kind of control than a shunt connected motor. The reduced voltage to the motor will surely reduce the field current and thus reduce the torque at low speed. But this can be compensated by the closed loop feedback in the optical sensor.
One problem using an optical sensor is that it can easily be blinded in a dusty environment. Baka mag runaway ang speed pag nabulag. Sana kung double ended shaft and you can put the sensor sa taas. I would recommend using a small inductive proximity sensor that is fast enough to detect the rpm. For example, at 12000 rpm, that is a 200Hz pulse. Verify na lang sa datasheet ng sensor na kaya ng sensor that frequency.
Another problem I see is ikaw pa bahala sa enclosure ng speed controller. Not that mahirap yan but still.