Study On Hybrid Power Supply System For Electric Vehicle

With the increasingly serious energy and environment problems,electric vehicle has become a research hotspot.At present,the performance of electric vehicle energy storage system is hard to meet the needs of its industrialization development.In the research of the energy storage system,how to increase the vehicle mileage and prolong the service life of the power supply are two important issues.In order to solve the above problems,the HPSS of fuel cell and super capacitor was presented.Fuel cell has the advantages of high efficiency and zero emission,and has wide application prospects.However,it still has defects of poor dynamic performance and short service life.In this paper,the HPSS of fuel cell and super capacitor is taken as the research object,which is researched from the perspective of Electrical Engineering.There are two parts in this paper.The first part includes the second chapter and the third chapter.This part focuses on the core components of the HPSS,the DC-DC converter.According to the characteristics of super capacitor charging and discharging current,the basic theory of multiple parallel converter is introduced.The topology and operating principle of the basic half bridge DC-DC converter and the parallel converter are analyzed.The system modeling is carried out by taking the two-phase parallel half bridge DC-DC converter as an example.The current sharing and interleaving control methods for parallel multiple DC-DC converters are discussed.Based on DSP,a kind of digital control method is designed.Reliability optimization is carried out in the design of converter regulators.A prototype of a two phase interleaved half bridge DC-DC converter is designed to verify the feasibility of the proposed digital control method.The second part includes the fourth chapter and the fifth chapter,this part mainly studies a kind of fuel cell super capacitor HPSS and corresponding energy management strategy.The characteristics of fuel cell and super capacitor are analyzed in the field of Electrical Engineering.The isolated full-bridge DC-DC converter and the parallel interleaved DC-DC converter are used.An energy management strategy based on frequency decoupling control is adopted to achieve complementary advantages.By computer simulation,the feasibility of HPSS and energy management strategy is verified.A general stability criterion based on impedance is introduced to the HPSS.By analyzing the small signal model of the converter,the closed-loop impedances of DC-DC converter using frequency decoupling control are derived.Then the general impedance criterion is used to assess and adjust the stability of the system.The results of the assessment and adjustment are consistent with the results of computer simulation,and the feasibilities of the energy management strategy and the impedance criterion are verified.