Efficient Control Strategies for Switched Reluctance Motor

Abstract

The speed of a rotating machine is a highly critical parameter. Also, the speed is typically affected by loads and nonlinear variation of circuit elements placed on the machine (in addition to the type of control employed). The inductance of the set of poles shall exhibit a nonlinear behavior in most of the machines and makes the control difficult. For example, when the rotor is aligned with any given pole pair, it is clearly mid-way between the other two pole pairs. Thus rotation in one direction will increase the inductance of one set of poles and decrease the inductance of the remaining set. In this paper, an optimal control method for the best motoring operation of SRM drives is attempted. The high motoring torque, high operating efficiency, and low torque ripple was considered as best motoring operation. The multi objective function developed in this work is to obtain a compromise between maximum average torque, maximum average torque per rms current (minimum copper loss), and maximum torque smoothness factor (minimum torque ripple). The proposed multi-objective function meets the requirement and accordingly, the turn-off and turn-on angles were optimized. Two angular controllers were proposed to adjust the turn-on and turn-off angles automatically to obtain the objective function. The simulation and experimental results exhibits that this method can be used to improve the best motoring operation of SRM drives in practical applications.