Research On A Novel Auxiliary Resonant Soft-Switching Inverter With Simple Structure

The small and medium power inverters have extremely wide applications in the field of new energy grid-connected,uninterruptible power supply and motor drive.Under the trend of high frequency,the huge switching losses and electromagnetic interference of traditional hardswitching inverters are becoming more and more prominent.In order to solve these problems,soft-switching inverters are proposed,in which resonant DC link inverters using auxiliary resonant circuits and auxiliary resonant pole inverters are two very important topologies.Through the analysis and research on the research results of various typical auxiliary resonant circuits of soft-switching inverters,aiming at the problems of a high quality auxiliary resonant pole inverter that the auxiliary resonant circuit has a large number of components and a complex circuit structure,the auxiliary resonant circuit is improved.This paper proposes a simple auxiliary resonant pole inverter.The inverter does not need to set up an additional resonant circuit for the soft switching of the auxiliary switching devices while maintaining the soft switching of the switching devices in the circuit,and automatically realizes the zero voltage switching off of the auxiliary switching devices by virtue of the buffering effect of the parasitic capacitance of the inverter itself.Not only reduces the current stress of the auxiliary switch devices and the loss caused by the reactive energy conversion process in the circuit,but also reduces the number of components of the auxiliary resonant circuit,completes the simplification of the auxiliary resonant circuit,reduces the cost of the inverter,and improves the performance and practicability of the inverter.The auxiliary resonant pole inverter with simple structure has more outstanding performance,but it is not attractive in medium and small power applications when up to three sets of auxiliary resonant circuits are needed.To solve this problem,a simple resonant DC link inverter is further proposed by transferring the auxiliary resonant circuit to the DC link.The auxiliary resonant circuit of inverter is reduced from the original three sets to one set,which greatly reduces the number of components and further simplifies the circuit structure.In addition,the inverter resonant circuit has a small power level,the withstand voltage of all components is limited below the DC voltage,the circuit control is simple,and it is convenient for engineering implementation.This paper first analyzes the commutation process of the inverter,divides the operation modes and establishes a mathematical model according to the equivalent circuits in different operation modes,then analyzes the charging and discharging modes and their effects of the parasitic capacitance of the auxiliary switching devices,and elaborates the realization conditions of the soft switching of the switching devices,the circuit loss calculation and the inverter parameter design method.Finally,an experimental model is built using MATLAB simulation platform to verify the effectiveness of the proposed soft switching inverter and evaluate various characteristics of the inverter.