CLLC Resonant Converter Based On Silicon Carbide Device

In order to cope with the global energy shortage problem,the new green energy technology has been developed rapidly in recent years.Wind energy and solar energy are gradually used for distributed generation systems as an auxiliary power supply due to the impact of weather conditions.The two-way flow of power demand for storing up and providing energy makes the bi-directional DC-DC converter become a hotspot of social research.The development of power electronics technology is closely related to semiconductor devices and the traditional Si material devices are weak at high frequency,high power levels and high reliability.New SiC device can bring about high power density and high reliability of the converter due to its higher voltage and lower switching losses.This paper mainly studies the bidirectional CLLC resonant converter based on SiC MOSFET.Firstly,the switching characteristics of SiC MOSFET are analyzed,and the driving circuit with the function of electrical isolation and over current protection is made.The dynamic characteristics of the driving and selecting device are tested by the double pulse test method,and the driving circuit is evaluated based on the result of the test.This paper describes the working process of the bidirectional CLLC resonant converter,modeling method for solving circuit is summarized and harmonic approximation method based on state space equation is chosen for modeling of converter.According to the circuit model,the parameters of the converter are designed,and the prototype was verified.This paper proposes a CLLC type AC-AC resonant converter by using a four quadrant switch.The principle of the converter is introduced in detail,and the drive circuit for primary side and secondary side are designed respectively.A simulation model is built by the Psim software,and the AC output is successfully achieved in the condition of retaining the similar resonant characteristics and voltage gain.The designed driving circuit is also suitable for the synchronous rectification strategy of the DC-DC type converter,which can significantly improve the efficiency of the converter at low voltage and high current condition.