Synchronous and Reluctance Motors in Position Servo Loops

At the present state of the control art, it is economical to replace dc motors in servo systems with ac synchronous and induction motors, in spite of the generally more complex circuitry induction motors, in spite of the generally more complex circuitry required by the ac principle. This report deals with synchronous motors that rely on shaft position reference to fit them into high-performance position feedback systems. It is shown analytically that any synchronous motor, including the reluctance motor, becomes a direct replacement for a converter driven dc motor if the phase voltages are the result of properly modulated shaft resolver outputs.