Generator operation of switched reluctance machine drives for electric vehicles

摘要

This contribution deals with the stringent control requirements of switched reluctance generators for electric vehicle (EV) applications. In EV applications, switched reluctance machines have to operate in generating mode over a wide torque-speed range, i.e. in the current controlled chopping mode at low speed as well as in the voltage controlled single-pulse operation at high speed. In addition, the d.c. -bus voltage varies with the load as a junction of the energy source. This voltage variation requires continuous variable adaptation when a wide speed range is required. Furthermore, a novel control strategy to implement a three-level hysteresis current regulator for generating mode is presented. This technique improves drive efficiency up to 8% over a wide operating area. In addition, the problem of uncontrollable overcurrents due to excessive back-EMF voltage during generating mode is discussed. Therefore, the variables, which are necessary to control the switched reluctance drive, and the resulting efficiency characteristics are presented.