Unity-scale Model And Short-time Scale Characteristics Analysis Of Power Electronic Converters

The failure on short-time scale of power electronic converters caused by overvoltage,overcurrent and overheating has become a crucial issue affecting its reliable operation.However,the existing modeling and calculation methods based on single-scale cannot accurately describe the failure process on short-time scale,which restricts the analysis and research of the characteristics of power electronic converters.Therefore,modeling and characteristics analysis of power electronic systems considering multiple scales has become a hot topic in recent years.Supporting by a national key research and development project,this paper has done the following works to solve the problem of accurate modeling and characteristic analysis of power electronic converters on short-time scale.1.Aiming at the problem that the existing models for power electronic converters are single-scale models or simply combined by models on different scales,establish a model of the power electronic converter considering both macro-and micro-scale,based on the study of the coupling relationship between the micro-scale model of the switching device and the macro-scale model of the circuit.2.To solve the contradiction between the macro-scale model and the micro-scale model of choosing simulation calculation step,on the basis of the multi-scale analysis method based on wavelet transform,put forward the algorithm of wavelet decomposition and reconstruction for model considering different scales.The algorithm shows that when calculation step is less than or equal to a quarter of the switching off time of the device,through wavelet decomposition and reconstruction,the result accurately descried the performance of the power electronic converters.3.Establish the model considering different scales for a Buck converter and analyzed its characteristics on short-time scale by the algorithm of wavelet decomposition and reconstruction.The simulation proved that compared with the existing modeling and simulation methods,it effectively increased the calculation accuracy and efficiency.And the experimental result verified the simulation result.4.Establish the model considering different scales for a dual-active-bridge type power electronic transformer and analyzed its characteristics on short-time scale by the algorithm of wavelet decomposition and reconstruction,and the multi-physics analysis and the evaluation of the device safety domain are completed on this basis.The study shows that the simulation accuracy and efficiency are increased and the result is coincided with the experiment.5.Establish the model considering different scales for a modular multilevel converter and analyzed its characteristics on short-time scale by the algorithm of wavelet decomposition and reconstruction,the application value of the joint-scale modeling and calculation methods in the analysis of the characteristics of large-capacity and complex power electronic converters is verified.And laid a foundation for further short-time scale analysis of large-capacity power electronic converters.6.Based on the above research,a general short-time scale multi-field coupling simulation software for power electronic converters is developed.The software has the functions of analyzing and evaluating the electrical characteristics,physical field characteristics and the safety of power electronic converters,and its application can be promoted.