Study On Driving System Of EV Based On Super Capacitor Auxiliary

Energy shortage and environmental pollution are gradually becoming the tworestriction factors of the development about the traditional fuel vehicle. EV has showna good development momentum with relatively higher energy efficiency andenvironmental protection advantages, BEV will become the future developmentdirection of automobile industry. As the core of BEV its power system has manyproblems, so designing a new energy storage device to assist or replace the traditionalbattery system is highly valued.This paper analyzes the problem of BEV energy systems and charge/dischargecharacteristics of super capacitors. Use the batteries as the main vehicle energy，thesuper capacitors as the auxiliary energy, bidirectional DC/DC converters of them asthe main study object, then study on the characteristics of super capacitor auxiliaryunit based on PMSM drive system. This paper focuses on selection and design ofbi-directional DC/DC converter based on batteries and super capacitors, especiallypresents an improved bidirectional half bridge converter for the super capacitorgroups, provides the corresponding control method and does a detailed analysis ofworking mode judgment in the practical application, then designs the overall systemsimulation mode contains the battery unit, the super capacitor unit, three-phaseinverter and load based on PMSM vector control drive system and make thesimulation of the whole system in various conditions. Simulation results show that thesuper capacitor auxiliary unit and its control method not only can well provide peakpower when the motor is running but also recycle the braking energy. At the sametime it can effectively prevent the large discharge current of batteries and improvesthe reliability and energy utilization efficiency of the whole power system.