Motor speed control system.

摘要

A motor speed control system comprises an encoder (12) which produces a series of indicator pulses related to the motor's speed. The period of the pulse is compared with that of a crystal-controlled reference period produced by a period generator (14). Comparison is made by means of a period comparator (16) consisting of logic elements, including flip-flops (F1, F2, F3) and gates (G1 and G2). Digital outputs of the period comparator control UP and DOWN charge pumps whose integrated value controls the motor through a power driver. Advantages of the system are precise digital control with crystal accuracy.