Research And Design Of Charging Module Based On Hybrid Full Bridge LLC Resonant Converter

Automobile industry is one of the main pillar industries of our national economy,and plays a vital role in the development of social economy.In recent years,due to the rapid growth of automobile production and sales and the quantity of possession,the energy shortage and environmental pollution problems caused by fuel vehicles have become increasingly prominent.In order to ensure the sustainable development of energy,it is an inevitable trend to develop energy-saving and environment-friendly new energy vehicles.In China,pure electric vehicles are the new energy vehicles with the largest number of users and the fastest growth rate.With the continuous promotion of electric vehicles,more and more manufacturers are producing them.Moreover,the battery parameters of electric vehicles of different manufacturers are not the same.Batteries are the core power of pure electric vehicles.According to the different application of electric vehicles,the voltage levels are different,varying from 200V to 800V at present.Passenger cars are generally between 200V and 400V,freight cars are generally around 500V,buses are between 500V and 750V,and the battery voltage of buses has a tendency of more than 900V.Therefore,the wide-span charging voltage puts higher requirements on the charging equipment.This paper mainly analyzes and studies the DC-DC converter topology circuit with wide output voltage range and high efficiency.As the core part of the charging device,the power module is divided into two parts:PFC and DC-DC.The role of the former part of the PFC is mainly to achieve the function of rectification and boosting.The function of the latter part of the DC-DC converter is mainly to meet the requirements of the required DC output voltage.This paper only studies the system of the latter stage DC-DC converter.Among many DC-DC converters,LLC resonant converters have high switching frequency,high transmission efficiency,and high power density compared with PWM converters.They are widely used in switching power supplies and have natural soft switching characteristics.It can perform more efficient power conversion over the entire load range.At present,most of the charging module DC-DC stage topology is an interleaved parallel LLC resonant converter.After comparative research,it is found that the topology still inherits the disadvantage that the output voltage range of a single H-bridge LLC resonant converter is not wide enough.In order to solve this problem,this paper combines LLC resonance technology to propose a hybrid full bridge LLC resonant converter applied to the charging module,and analyzes the topology working principle and voltage gain relationship in two-level mode and three-level mode in detail.The driving logic and digital implementation method of the switching tube were designed,and finally the target requirements were realized by closed-loop controlFinally,the simulation model of the compound full-bridge LLC resonant converter is established in PSIM.The model is used to simulate the theoretical analysis and proposed strategy.At the same time,the relevant experimental platform is built and the actual test is carried out.The results show that the theoretical research is correct and the proposed strategy is reasonable.Therefore,the hybrid full bridge LLC resonant converter not only solves the problem of wide span of output voltage but also ensures high-efficiency operation of the converter.