Method of controlling the speed of a D.C. motor and device for carrying out the method

摘要

A device for controlling the speed of a d.c. motor (M) employs a method in which the motor supply voltage (V) is controlled by a control voltage (Vo) supplied by a comparator circuit (11) which compares a reference signal (Sref) with a signal (SV) representing the motor speed. The signal (SV) is derived from a signal (SM) induced by the motor rotation via a signal processing circuit (21). The motor supply voltage (V) is controlled by the control voltage (Vo) by means of a negative resistance circuit (31) (-R), which at least partly compensates for the internal resistance (r) of the motor.