Microprocessor-Based High-Efficiency Drive of a DC Motor

This paper presents a method to improve the efficiency of dc motors, dc shunt motors, and dc series motors. The method is based upon the field control. It is derived that the ratio of the armature current to the field current should be maintained constant to maximize the efficiency at a specific speed. The power circuits and the control loops are suggested to realize the principle, and the real-time control is implemented with a microprocessor. Also, in order to assess the stability of the overall systems, the proposed systems are analyzed with the small signal linearization. Experimental results show that the remarkable improvement in efficiency has been accomplished by the proposed method and the suggested systems are stable.