Variable speed DC drive

Abstract

A thyristor controlled separately excited DC drive is described using a microprocessor controller. The microprocessor controller is used for both synchronisation control and firing control of the three-phase full-wave thyristor convertor. Maximum use of the microprocessor controller is achieved by also using it to implement a PID controller and to calculate the velocity feedback by using a very fast speed update algorithm. An inner current loop is employed to enhance system operation. Variable speed adjustment is via input through the microprocessor controller.