Study On Efficiency Optimization Control For Electric Vehicle Drive System

Electric vehicle has broad developmental prospects because of no pollutiveemission, low noise and independence of oil resources. At present, most of electricvehicles driving motors use induction motors, but induction motor is low efficient atlight load. While the energy of electric vehicle is limited, any form of energy wastewill all cause driving range reduction of electric vehicle. Therefore, the study ofefficiency optimization control has an important practical significance for savingenergy, increasing driving range. This paper studies the efficiency optimizationcontrol for induction motor drive system of electric vehicle, to improve theefficiency of induction motor at light load.Firstly, this paper analyzes the loss charateristic and the efficiency charateristicof electric vehicle drive system. And on the basis of analyzing vector controlideology, the efficiency optimization principle of induction motor is studied. Forvector-controlled induction motor, the motor loss can be reduced by reducing flux,and achieves efficiency optimization.Taken iron loss into consideration, the mathematical model of induction motoris established, and vector control strategy is studied. For induction motorconsidering iron loss using vector control needs iron loss compensation. Thesimulation results verify the correctness and effectiveness of the model and strategy.The loss model of induction motor is established based on equivalent circuit ofinduction motor, efficiency optimization control based on loss model consideringthe constrain condition of high speed area of induction motor is derived. Efficiencyoptimization control is embeded into vector control system, the simulation resultsshow that this method can effectively reduce motor loss and improve motorefficiency. The influence of parameters’s change on efficiency optimization controlis analyzed, the research results indicate that the change of parameters will makemotor run in efficiency suboptimal state. Due to the complex calculation of optimalflux in the loss model control, genetic algorithm is applied into efficiencyoptimization control, the simulation results verify the correctness of this strategy.Finally, the influence of efficiency optimization control on induction motor’sdynamic response is analyzed, fast dynamic response of induction motor controlstrategy is studied. The simulation results show that this method can effectivelyimprove adverse impacts of efficiency optimization control on dynamic response.