A microcomputer-microprocessor-based DC motor speed controller for undergraduate electric machinery laboratory

A microcomputer-microprocessor-based control system is described for speed control of a 7.5 hp separately excited DC motor in the undergraduate electric machinery laboratory at Montana State University. The system uses a Hewlett-Packard (HP) 3497A data acquisition system and a HP/85B microcomputer in conjunction with a Z80 microprocessor. It is used by students to obtain the characteristic of the motor and control its speed under various load conditions. Increased efficiency has been observed in computerized data collection as compared with the traditional method of data collection using analog instrumentation. The control strategy is such that students at the junior level, with limited background in control theory and electronics, can understand its operation. Some experimental results are presented, laboratory experiences are reported, and student responses are evaluated. Additional experiments for the electrical machinery laboratory are also proposed