I have an Harmonic drive and would like to design a PLL (phase-locked loop) controller for speed control of it. Here is a block diagram of a motor-speed control system based on PLL techniques:
My Question is about power amplifier (servo amplifier) (see image above).
- What is best circuit for servo amplifier of DC motors?
Desired circuit must have poles at much higher frequencies than the poles of the motor. Any ideas would be appreciated.
Best Answer
I'd use a PWM converter that feeds to a push-pull MOSFET output stage. You could probably use a power op-amp circuit but you'd be running it hot although it would still work. Your power supply should be OK if it can supply 30V at 6A. For a circuit I'd consider looking at the LT1160 data sheet. It has the following circuit for a 200W class D amplifier.
It needs checking what components other than the one I marked that needs bypassing to allow proper DC control but this would be a good starting point I reckon.
A pointer about terminology - a servo amplifier is more than a simple amplifier like what you have in your diagram. A servo amplifier takes the demand input and processes the feedback signal to ensure the motor is kept in closed-loop control
Wiki has an article.
I also asked in my comment about the lowest speed demand and the number of notches in the disk. I asked to make sure you were properly accounting for low speed running in the loop filter.