Constant speed control for a motor

摘要

A motor having a power switching circuit adapted to be connected between a power source and its winding for selectively energizing the winding to generate a magnetic field which causes a rotating assembly to rotate. A position sensing circuit provides a position signal representative of the position of the rotating assembly and a commutating circuit controls the power switching circuit to commutate the power switching circuit at a commutating angle to achieve a desired rotating speed of the rotating assembly. The commutating circuit varies the commutating angle in response to the position signal to maintain the substantially constant rotating speed of the rotating assembly. As result, the efficiency of the motor is varied to maintain the substantially constant rotating speed.