A study of current controllers and development of a novel current controller for high performance SRM drives

Switched reluctance motor (SRM) drives are under consideration in various applications including high performance applications such as in servomotor drives, electric vehicle drives and jet engine starter-generators. Current and hence torque control constitutes the heart of control in such drive systems to obtain the desired high bandwidth in torque and speed responses. It is invariably assumed that either hysteresis or PI current control strategies are adequate in the literature. This paper proves that current controllers are not satisfactory in the case of PI controllers and infeasible in the case of hysteresis current controllers for high performance applications. To overcome the drawbacks of these current controllers, a novel current controller based on unipolar switching of the power converter with the decoupling of the induced EMF is proposed in this paper for high performance applications. A comparative study of the regular PI and hysteresis current controllers with the proposed unipolar switching based current controller incorporating the induced EMF decoupling is made to ascertain the superiority of the proposed scheme. The paper presents the systematic development of the algorithms for current controllers and their modeling, dynamic simulation analysis, and design procedure.