A new energy optimal control scheme for a separately excited DC motor based incremental motion drive

This paper considers minimization of resistive and frictional power dissipation in a separately excited DC motor based incremental motion drive (IMD). The drive is required to displace a given, fixed load through a definite angle in specified time, with minimum energy dissipation in the motor windings and minimum frictional losses. Accordingly, an energy optimal (EO) control strategy is proposed in which the motor is first accelerated to track a specific speed profile for a pre-determined optimal time period. Thereafter, both armature and field power supplies are disconnected, and the motor decelerates and comes to a halt at the desired displacement point in the desired total displacement time. The optimal time period for the initial acceleration phase is computed so that the motor stores just enough energy to decelerate to the final position at the specified displacement time. The parameters, such as the moment of inertia and coefficient of friction, which depend on the load and other external conditions, have been obtained using system identification method. Comparison with earlier control techniques is included. The results show that the proposed EO control strategy results in significant reduction of energy losses compared to the existing ones. Milan A. Sheta received the bachelor degree in electrical engineering from Vyavasayi Vidya Pratishthan Engineering College, Rajkot, Gujarat, India in 2002, and the M. Tech. degree in systems and control engineering at the Indian Institute of Technology Bombay, India, in 2005. Vivek Agarwal received the bachelor degree in physics from St. Stephen’s college, Delhi University, USA, the Master degree in electrical Engineering from the Indian Institute of Science, India, and the Ph.D. degree in the Depterment of Electrical and Computer Engineering, University of Victoria, Canada in 1994. He worked for Statpower Technologies, Burnaby, Canada, as a research engineer. In 1995, he joined the Department of Electrical Engineering, Indian Institute of Technology, Bombay, India, where he is currently a professor. He is a senior member of IEEE, fellow of IETE, and a life member of ISTE. His research interests include power electronics, modeling and simulation of new power converter configurations, intelligent and hybrid control of power electronic systems, power quality, EMI/EMC, and conditioning of energy from non-conventional energy sources. Paluri S. V. Nataraj received the Ph.D. degree in process dynamics and control from Indian Institute of Technology Madras, India in 1987. He is a faculty of the systems and control engineering at Indian Institute of Technology, Bombay, India. His research interests include robust control, process automation, nonlinear system analysis and control, and reliable computing.