DC/DC Charger Power Loss Analysis And Circuit Design

With the increasing depletion of oil resources and the deterioration of the global climate, people began to explore the green clean energy. Electricity as a clean energy has been paid more and more attention. In this environment, more and more investment was given by countries in the electric vehicle industry. According to incomplete statistics, China currently has about 120 thousand cars of new energy vehicles, has built 30 thousand charging pile, charging pile size is far less than the demand. The next five years, the scale of the industry could reach 10 million, has a very good market prospects. The development of electric vehicles, charging system is a very important link. Charging systems are connected in parallel by a plurality of charging modules together, the rechargeable battery charging part and is directly connected to the main DC/DC converters.DC/DC converter is one kind of another DC/DC conversion. With the research of DC/DC converter, the current DC/DC converter showing the trend of a high-frequency, soft switching, multi-level, high power density. Based on the analysis of the working principle of the common DC/DC converter and the loss on the basis, a design method based on the non-ZVS half-bridge phase-shift control mode was proposed in the three-level DC/DC converter. It uses soft switching technology,developed with a 7.5KW car charger module.Firstly, in this thesis, the PSPICE model is established for power switch tube and rectifier diode in power electronic converter, the formula of the loss of power switch tube in the process of opening and closing is derived. By establishing a comparative switch static and dynamic models, and data sheets, so that we may better understand the switch work in the process of loss sources. Secondly, based on the establishment of the switch loss model, by analyzing the principle of common DC/DC converter and loss situation, put forward the shortcomings of traditional hard DC/DC switching converter, which made a half-bridge ZVS three-level DC/DC conversion the program.Combined with specific projects, a charger module was designed. The prototype rated output power of 7.5KW, operating frequency is 100 KHZ. The main work includes:design and selection of high-frequency transformer design parameters of the main circuit input capacitance design, output LC filter and switching tube. Finally, in the building of experimental test platform, the experimental results were tested.Experimental results show that the scheme can achieve ZVS, the temperaturedistribution is consistent with the theoretical calculation of the loss analysis, the DC/DC converter efficiency increased to 93%, to achieve the results expected to meet the requirements.