Research On Electric Vehicle Charging Circuit Based On Phase-Shifting Full-Bridge

With the rapid development of electric vehicle industry,electric vehicle charging industry has also attracted more and more attention.The high reliability,high efficiency,high power density and the control method of electric vehicle charger are the focus of current research.It is important to achieve Highfrequency operation when the high power density and high integration are necessary for power electronic converters,but at the meanwhile the switching loss will be more serious along with the increase of frequency.The full bridge phase shift converter solves this problem well,as it containing soft switching,which is beneficial to reduce the switching loss,and the full bridge phase shift converter can also return the residual energy of the transformer leakage inductance and the vibration inductance back to the DC bus efficiently.In addition,in the case of low voltage with high current,the on state loss of the rectifier tube is large,which seriously affects the efficiency improvement,while the synchronous rectification technology can solve the problem well.In order to meet the design requirements of high power density,high efficiency and low cost,the phase-shifted full-bridge circuit is selected as the main circuit of the converter,and an improved phase-shifted full-bridge topology is designed based on the topology of traditional soft-switching.In this paper,the working principle and working process of the full-bridge phase-shifted converter are deeply analyzed.Firstly,the influence of each parameter on the converter characteristics is given and the parameters are designed.Secondly,in order to reduce the number of devices and reduce costs,using UC3875 chip to output PWM wave.In addition,according to the working characteristics of phase shifted full bridge,a control method based on synchronous rectification of main chip is proposed,which can realize synchronous rectifier simply and effectively.Finally,in this paper we build an experimental prototype of the maximum power of 1.2 kW to verify the correctness and validity of the theory.The operating frequency of the converter is about 85 kHz,and the soft switching of the full bridge switch is realized,and the synchronous rectification is realized at the secondary side,and the efficiency of the whole unit is greatly improved.