Research On Reactive Power Optimization Modulation Strategy For Auxiliary Resonant Commutated Pole Inverter

In recent years,with the development of inverter technology,high frequency has become the important trend of the development of inverters.The improvement of the switching frequency is helpful to reduce the volume of the inverter,reduce the audio noise,and improve the quality of the waveform.However,with the improvement of the switching frequency,the problems of switching loss and electromagnetic interference have become increasingly serious.In order to solve the above problems,soft-switching inverter technology has been widely concerned by researchers all over the world.Among many soft-switching inverter topologies,because auxiliary resonant commutated pole inverters(ARCPIs)have the advantages of high voltage utilization and low stresses of main power switches,ARCPIs are more suitable for high-power applications.By the analysis and research of many typical ARCPI topologies and modulation strategies,there are two key technical problems that must be solved in ARCPIs:? Due to the influence of parasitic circuit elements from the wiring process of snubber circuits,auxiliary switches are difficult to achieve reliable zero-voltage-switching(ZVS)turn-off;? The circulating current loss and the current stress of auxiliary switches in the auxiliary snubber circuit are high.Aimed at the above problems,this thesis presents a double ARCPI(DARCPI)topology and reactive power optimization modulation strategy.The topology can effectively avoid the influence of parasitic inductance and capacitance from the wiring process on ZVS turn-off of auxiliary switches,which can achieve reliable ZVS turn-off of auxiliary switches;avoid the superposition of resonant current and load current at commutation moments,which makes the loss in the auxiliary snubber circuits become minimum;solve the key technical problems that the current peak stress of auxiliary switches is high and the efficiency of the DARCPI is lower than that of hard-switching inverter when the output power is less than 50%of rated power.The soft-switching inverter realizes the high conversion efficiency in the whole load range.The research results can provide solid theoretical basis and key technical support for the engineering application of high-power soft-switching power conversion system and the high-efficiency conversion of electric energy.According to the equivalent circuits in different operation modes under the reactive power optimization modulation strategy,this thesis analyses the operation principle,soft-switching implementation condition,power loss and parameter design procedure of the DARCPI.Finally,the Matlab simulation and 10kW/16kHz prototype experimental results are given to demonstrate the validity of the proposed DARCPI and various characteristics of the inverter are evaluated.