Design of a Speed Control System for Electrical Motors with Random Variable Parameters

Abstract

The speed of a DC motor is controlled by using a semi-converter supply in a feedback structure. The firing angle of the converter thyristors is self-adjusted, being internally generated in a negative feedback manner. Using an averaging method, the non-linear differential equations that describe the dynamic behaviour of the power system: converter-motor over the whole switching period are found. These equations are used to find a linear ‘equivalent’ description of the system, without using small-signal approximations. Then, the compensators of the feedback structure are designed so that the motor speed lies within prescribed bounds, regardless of any variation in the system parameters or in the load values.