Flux optimization strategy for efficiency enhancement of induction motor–driven electric vehicle under dynamic operating conditions

Energy-efficient electric transportation systems offer reduced power demand and also increase the runtime for a single charge. Efficiency of an electric vehicle can be enhanced up to certain extent by operating it with reduced flux level. However, straightforward minimization of flux level may lead to drive instability. Therefore, this paper presents a loss model control approach to minimize the losses by optimal weakening of the flux for the drive. Flux optimization is achieved with constraints and bounds on the key variables like stator current. The performance of an electric vehicle propelled by a poly-phase induction motor is analyzed with the proposed approach. The performance of the drive is also compared with rated rotor flux, differentially calculated rotor flux, copper loss, and core loss equalizing rotor flux estimator. The effectiveness of the proposed strategy is analyzed in terms of efficiency, transient behavior, power factor, and parameter sensitivity under various operating conditions.