Speed control circuit for async. motor - has limiter diode in series with operational amplifier producing voltage proportional to difference between reference and motor voltages

摘要

The control circuit has the output of the regulator which compares a variable reference voltage with the voltage at the motor's terminals-connected to a device that ensures that the control voltage produced by the regulator remains below a given limit. The limiting device contains a diode in series with an operational amplifier that produces a voltage proportional to the difference between the reference voltage and the motor's voltage. The amplifier also receives another input signal that appears when the current in the rectifier bridge exceeds a given max.