Bidirectional Multi-resonant Converter With Wide-voltagr Range For Vehicle Charger

Vehicles have become indispensable for people's daily travel.It is imminent to solve the energy shortage and environmental pollution caused by traditional fuel vehicles.The popularization and promotion of electric vehicles are very necessary.The voltage range of vehicle batteries is wide,so battery charging technology which can satisfy wide-range voltage is critical.The bidirectional vehicles charger,as a device that provides stable power to batteries or discharges battery power,should have the ability to transmit power in both directions and achieve wide voltage range,which requires bidirectional DC/DC converter with wide gain range.Based on this,a bidirectional multi-resonant DC/DC converter applied to vehicles charger is proposed,which can achieve wide voltage range and meet the charge and discharge requirements of electric vehicle battery packs.Firstly,after analyzing the research status of bidirectional resonant converters at home and abroad,a multi-resonant network is introduced to bidirectional DC/DC converter.The bidirectional multi-resonant converter that can achieve wide voltage range is proposed.The proposed converter has a symmetrical structure.The switches are drived by synchronous and variable frequency control method in both forward mode and reverse mode,and the working principle is analyzed.Secondly,the gain characteristics of the bidirectional multi-resonant converter are analyzed,and the resonant network parameters of the converter are optimized from the perspective of converter gain and energy utilization.Then the parameters of the converter are verified from the perspective of soft switching implementation.Based on the above research work,the hardware design and software design of the 3.3k W bi-directional multi-resonant converter are carried out.Finally,the working principle and excellent characteristics of the bidirectional multi-resonant converter are verified by PSIM simulation software.The system experiment is completed on a 3.3kW bidirectional multi-resonant experimental prototype,and the experimental results of the prototype are given.At the same time,the efficiency curves under different secondary voltage in forward mode and reverse mode are given.The peak efficiency of the converter in forward mode is 97.7%,and the peak efficiency of the converter in reverse operation is 97.6%.