小型电动汽车中双向dcdc变换技术研究-research on bidirectional dcdc conversion technology in small electric vehicle.docx

ABSTRACT Automotive industry has been developed continuously for hundreds of years, it reflects the glorious history of the development of science and technology civilization, promotes global economic growth rapidly and provides convenient transportation simultaneously, but energy crisis and environmental pollution problems which are caused by it become seriously outstanding, Traditional internal combustion engine technology and current social problems become a contradiction, development of new energy vehicles receives more attention. Many auto makers at home and abroad and scientific research units spend a lot of manpower and material resources on core problems related to electric vehicles, vehicles need to implement the condition that energy flow run between electric power energy storage and load in two directions, bi-directional DC/DC converter is the key component of realizing two-way flow of energy, the study also becomes more popular recently, mainly concentrates in new circuit topology and control strategy, and how to improve the efficiency of the converter, in order to realize energy saving target. This paper states the current research in bi-directional DC/DC converter topology, analyses the isomorphic topology and suited applications of bi-directional DC/DC series resonance converter (SRC), and determine the topological circuit in this paper. Then analyzes the working principle of the bi-directional full bridge SRC and establishes equivalent circuit for different loads using a new method according to its work mode, gets soft switching conditions, does the modeling of main circuit using extended description function method simply and accurately, The effectiveness of this method is verified by comparing amplitude frequency response of transfer function from theoretical analysis by MATLAB simulation and amplitude frequency response of the main circuit by PSIM AC sweep. It optimizes parameters of full bridge SRC with two types of load before simulation ， two