Turn-on angle searching strategy for optimized efficiency drive of switched reluctance motors

This paper describes an adaptive turn-on angle searching strategy for the switched reluctance motor (SRM) to optimize the system drive efficiency and speed up the transient response at the specified operating conditions. The control strategy implemented in this paper first is to fulfill the desired speed at the required load torque. When the SRM operates in the steady state, an on-line adaptive searching approach then is performed by continuously tuning the turn-on angle to minimize the total power consumption of the drive system. The variation of the motor´s phase current is used to control the tuning of the turn-on angle. The searching time of optimal efficiency is strongly dependent on the energizing commutation angles. A set of starting control parameters (θ_on-s , θ_off-s and I_ref) is obtained from the online calculation and interpolation of the lookup tables, which are built based on the accurate characterized model of the SRM, to speed up the dynamic response, satisfy the torque-speed demand, and shorten the searching time. Simulation and implementation in a TI 2407 DSP controller has been developed to verify the proposed method. Experimental tests on a 4-phase 8/6 pole SRM at different operation conditions are given. A comparison with the conventional mode-shift control method shows that well improvement in system drive efficiency has been achieved by the described control strategy.