Study On PMSM Drive And Braking-Energy Recovery Optimization In Electric Vehicle

This thesis studies the item-the Research on Automoible Controlled by Permanent Magnet Synchronous Motor (PMSM) control system, to attempt theory analysis, research the optimization on the driving control method and braking-energy recovery solution for providing the primary practical proof and improving the efficiency of the PMSM system .First of all, an efficiency-optimization control strategy for PMSM system used in EV is presented in order to extend road haul per charge. In view of the operation characters of PMSM for EV application, a novel efficiency-optimization control strategy is presented to meet the demand of rapidity after analyzing the defect of efficiency-optimization control strategy of PMSM system with minimum input power in ordinary application. On the basis of ordinary efficiency-optimization control strategy with minimum input power, the new strategy adopts fuzzy logic control method and torque compensation strategy to accelerate convergence in process of optimizing controlled parameter. Results of experiment indicate the validity of the efficiency-optimization strategy.Sepond, direct torque control (DTC) strategy for PMSM in EV application is studied and DTC system is also developed. On the detailed analysis of PMSM DTC principle, the function of zero voltage vector and the choice method of voltage vector in EV driving are proposed. Restricted condition about stator flux linkage under DTC is analyzed. Afterwards, control rules on stator flux linkage reference are given, and then an efficiency-optimization method for PMSM system under DTC is presented. A fuzzy-DTC method is applied to improve the dynamic performance of EV. Simulation results of EV system show that PMSM system under DTC is able to meet the needs of EV driving.Finally, the design for braking energy recovery system is studied. During the braking process of EV, driving motor can run on the state regeneration and supply electric energy outside. If some kinetic energy of vehicle can be recovered and charge the storage battery, it would be a crucial way to elongate the driving miles of EV. Braking energy recovery involves transmission mechanical system of EV, driving motor and battery, and it is necessary to synthetically consider the characteristics of vehicle kinetics, generating motor, charging of battery and its safe guarantee. Currently, the study on braking energy recovery in China is still on the preliminary stage. The thesis makes some positive explore about this problem and achieve some valuable outcomes.