A precise dc motor speed control using deadbeat response technique

Abstract

An approach to the design of a simple and low‐cost digital system for precise DC motor speed control is introduced. A microcomputer is employed to measure the motor speed, implement the control algorithm, and generate the controlling signal. The motor speed is measured in terms of feedback pulse width. The control algorithm is a digital PI controller with specific parameters such that the system has deadbeat response to step input. The controlling signal is converted by a digital circuit to specify the conducting period for the SCRs of a three‐phase full‐wave controlled rectifier which provides the DC source for the DC motor. The interface between the microcomputer and the outside world needs only three lines. The experiment on a 2 HP separately excited DC motor shows that the speed is regulated within 0.05% and the settling time is about 1.5 seconds under 25% load disturbance for some specific speeds.