Research On A Novel Resonant DC-link Soft-switch Inverter

Auxilliary resonant DC link inverter is a kind of important soft switching inverter topology to realize the power conversion system green which has an important influence in the world.It will play an huge role on the new energy power generation,aeroapace,military industry,power transmission,distributed power and grid and other small power in the future.There are some problems existing in the inverter topology which have been proposed,such as some topologies,resonant inducter need to set resonant threshold which resulting the difficult to achieve the circuit in a range of full load;some topologies have used coupled inductor increase the volume,the weight and the cost of the resonant DC link inverter;some topologies have used large capacity electrolytic capacitor which leads to the change of the neutral point potential.In view of the above problems,a new type of auxiliary resonant DC link inverter topology and a improved modulation strategy are proposed in this thesis.This topology structure realizes the soft switching operation of all switches.All the same time,the disadvantages of the high voltage stress of the switch tube and the high resonant peak voltage in the tratidional resonant DC link inverter are also solved.At the same time,the zero voltage of the topology is controllable,so it is convenient to use all kinds of modulation strategy,which makes the circuit design more convenient.After the detailed analysis of the topology,the problem of the current stress of the auxiliary resonant circuit is found.Thereforce,this thesis proposes an improved modulation strategy,which reduces the current stress and improves the efficency.This paper has analysed the working principle of the topological structure deeply,given the equivalent circuit in different working modes,established the mathematical model of each mode and the method of parametric.In order to verify the loop's feasibility and the superiority of the improved modulation strategy with shunt region,this thesis has carried the simulation on the MATLAB simulation platform on the basis of the theoretical analysis.