The Application Of Phase Shift Soft Switch Technology In The Battery Charger

In recent years,the development of EMU project is particularly prominent in China,as a result,higher requirements are raised in all aspects.Lighter,smaller,more efficient and more energy-saving on locomotive and EMU project,this will become the development trend of the new generation locomotive.The biggest breakthrough of auxiliary power supply is reflected in the efficiency of the whole auxiliary power supply,the efficiency of auxiliary power supply not only saves energy,but also improves the quality of auxiliary power supply.As a result,the power electronic soft switching technology gets increasingly attention,soft switch technology will be widely used in small and medium power to zero voltage switching(Zero-voltage-switching,ZVS)and zero current switching(Zero-current-switching,ZCS)switch,greatly reduces the switching loss and improve the conversion efficiency,and greatly improves the switching frequency,reduce the volume and the weight.In response to the high efficiency and energy saving requirements of locomotive,it is very important to study the application of phase shifting soft switching technology on the battery charger.This paper mainly states the battery charger redesign of charging efficiency from the original EMU 85%up to 90%with using new phase shifted soft switch control technology.phase shift soft switching technique mainly solves the switch loss of switch components such as IGBT in the application of high frequency,and switch components will produce loss in the switching process,if switching frequency is high,the loss of the switch will be very impressive,but with the technology of phase shift soft switching,this can be reduced to very low level,even to zero,thereby effectively improve the overall efficiency of products.The improvement of the switching frequency of the main circuit,the design of the high frequency transformer and reactor,the design of duty cycle loss,the design of the phase shifted soft switching circuit and the design of the electromagnetic compatibility will be the focus of this paper.This paper focus on the main target of improving the battery charger charging efficiency up to 90%.Firstly,study the basic circuit theory,improve topological circuit,transform the half-bridge circuit with large loss into the full-bridge circuit with high efficiency,also analyze and study the control strategy of full-bridge circuit.Secondly,based on the type selection experience and enough theoretical calculation,the parameters of high-frequency transformer and isolation capacitor are determined,and the PSIM simulation circuit is built to verify the correctness of the designed circuit parameters.Then,demand analysis and underlying software development were carried out for the functional interface requirements of the new type of charger,and external interfaces such as functions and fault diagnosis were sorted out,also,the code conly ompilation and simulation test for the application layer were conducted.Finally,routine test is conducted on the assembled charger,a large amount of data is collected for analysis and routine test report is completed,and qualified third-party testing institutions are searched for type test verification to obtain the loading qualification.