Research On High Performance Control Strategy For Electric Drive System Of Electric Vehicles

With the advantages of no pollution emissions and low noise, electric vehicles (EV), which integrate in lots of high-tech, are creating a revolution in the world auto industry. Because of the limited energy, EV has a high demand for energy conservation. A majority of the energy is consumed by electric drive system of EV, therefore the improvement of electric drive system's efficiency has a great value to increasing driving range.Induction motor(IM) with advantages of small size, light weight, low cost, maintenance-free, is widely used in the EV's electric drive systems. But in the conventional vector-controlled method, the flux is generally set to rated value, which greatly decreases the efficiency of IM especially in light-load condition.This paper first discusses the composition of the EV's electric drive system and the control technologies of electric drive system, and then indicates main topic of the research and the arrangement of chapters.On the basis of detailed analysis of the electric drive system's loss model, a kind of loss model control strategy is deduced and the variety law of the optimal flux linkage is illustrated. Then, the on-line efficiency optimization for IM is designed to improve the efficiency of IM in light-load condition.The improvement of the efficiency is at the cost of deterioration of the dynamic response. Aimed at the problem above, a fast response control strategy is studied based on the current dynamic assignment. Inspired by the ideas of direct torque control, a new strategy which directly composes the voltage vector is proposed. Compared with the current dynamic assignment, this scheme has excellent dynamic performance showed by simulation and experiment results.A squirrel-cage IM is used to verify our method. The conventional rotor-flux oriented vector control theory is implemented. TMS320LF2407A produced by TI is chosen to be the main control unit. The control system is accomplished, including SVPWM, FOC, efficiency optimization control, fast dynamic response control and ADRC, etc. The full digital high performance control system is realized.