The Design Of Charger Based On LLC Resonant Full-bridge Converter

Today,under pressures of the energy crisis and environmental pollution,it is necessary for developing green renewable energy to realize sustainable development of energy and environment.In recent years,electric automobile industry has made rapid development,because of the country's strong support.It makes Battery charger that match the electric automobile have an enormous potential.Charging system is composed of PFC(Power Factor Correction)and DC/DC(DC-DC Power Convert).The DC-DC Power Convert that directly affects the health status of the battery and the life of the battery is connected directly to battery of the electric automobile.Within the wide range out of voltage,the LLC Resonant Full Bridge Converter has the advantage of making the MOSFET on for ZVS and rectifier diode off for ZCS.Also it is very availbale to realize Battery charger high power density,high efficiency,high operating frequency.If LLC resonant full bridge converter is applied to DC/DC charger,It will be very easy to realize charging system requirements of the wide range out of voltage,high-power output,high efficiency and small size.The author applied LLC Resonant Full Bridge Converter in designing of 15 kW DC/DC charger to meet the needs of the electric automobile charging.The paper analyses the significance of the study and the development actuality about DC/DC charger in our country,then the charger demand index is put forward;The work of the paper obtained soft switching condition and a simplified model by basing on FHA under frequency converting control and the fixed frequency control.In order to further analysis,the paper researched some factors affecting,such as security constraints,soft switching constraints,efficiency constraint,the influence of load switch to quality factor Q or.control strategy.Then it gave the the optimal control strategy of the converter.On the basis of the above discussion analysis,A new and easy-used method of designing LLC resonant system is came up.,Finally,on the basis of indicators for the 15 k W DC/DC charger,the paper completed the whole hardware design which matches with LLC converter such as chip select,the design of he high frequency transformer and resonant inductor,the sampling circuit,control circuit,protection circuit or communication circuit.After simulated with MATLAB,the paper completed an experiemental test platform for the 15 kW DC/DC charger which was set up to prove the design of LLC converter and verification experiment indicators.The testing results show that desired design is correct.