Research And Implementation On Onboard Charger Of Electric Vehicle

In order to improve the quality of life,the demand for cars is becoming more and more..However,the traditional fuel-powered cars bring convenience to people's life,but it also brings about the problem of environmental pollution and energy shortage.The electric vehicle has provided a solution to the contradiction between the demand of the car and the environmental pollution because of its zero emission.The power source of electric vehicles is electrical energy,which needs to be supplemented by a special charging device.As an important charging device,the on-board charger is a research hotspot of the current charging technology.In order to solve the charging problems of electric vehicles,it is of great significance to research and develop an on-board charger with high-efficiency,high-power density,high-reliability for the popularization of electric vehicles.Firstly,the research status of vehicle charger topology and the technical indicators of vehicle charger at home and abroad are investigated,and the relevant national electric vehicle charging technology standard was analyzed.Then,the overall scheme of vehicle charger with two stage topology is determined.The front stage of the main circuit of vehicle onboard charger was a lossless soft-switching bridgeless Boost APFC circuit,and a full-bridge LLC resonant converter with Series-parallel Connected Transformers was used at the back stage.There is a problem of switching loss in the hard-switching process of traditional bridgeless Boost PFC circuit.In order to further improve the efficiency,a lossless soft-switching bridgeless Boost APFC converter was studied and designed at this thesis.The working principle of the converter was analyzed in detail.The one cycle control strategy was used to control the circuit.Then the main circuit parameters were designed,and the control circuit was designed based on the IR1155 control chip.Finally the effectiveness of circuit was verified by using Saber software.In order to meet the charging requirements of high efficiency and wide output voltage range,a full-bridge LLC resonant converter with Series-parallel Connected Transformers was presented at this thesis,the working principle of the circuit was analyzed in depth.The steady-state gain characteristic of the converter was analyzed based on the fundamental analysis method.Combined with the design index,the calculation process of main circuit parameters and the selection of components were given.The control circuit was designed based on the UCC25600 control chip,the closed loop simulation model was established using SIMetrix/Simplis software to verify the Effectiveness.of circuit parameters.The prototype of the vehicle onboard charger was built and the experimental test was carried out.The experimental results showed that the prototype of the vehicle charger meets the design requirements,and achieves the technical requirements of high efficiency,high power factor and wide output voltage range,which verified the feasibility and effectiveness of the design scheme in this thesis.