Speed control apparatus for a synchronous motor.

摘要

A speed control apparatus for a synchronous motor is provided with a resolver fixedly connected to a rotor of the motor, which produces a phase modulated signal corresponding to an angular position of revolving magnetic field in the motor, a circuit for converting the phase modulated signal into a rotational speed signal of the motor, a phase compensation circuit for advancing in phase a reference signal in accordance with the rotational speed signal, a multiplier for multiplying the phase modulated signal and a rotational speed instruction signal, a synchronous rectifier for synchronously rectifying the output of the multiplier by an output of the phase compensation circuit, and a current control loop circuit for receiving an output of the synchronous rectifier and for producing a signal having a phase angle delayed as much as the phase angle is advanced in the phase compensation circuit.