Calculation Of Core And Winding Losses Of High-frequency And High-power Transformers

With the rapid development of power electronics technology and equipment,power equipment is developing towards high power and miniaturization.Therefore,in order to solve the problems existing in traditional transformers,the application of power electronics technology in the field of power transformers and the research and development of high frequency transformers have become a research hotspot.Based on the high frequency transformer made of amorphous alloy core and Leeds wire winding,the losses of the core and winding are analyzed and calculated in this thesis.The main work is as follows:According to the characteristics of high frequency transformer,a simplified circuit model and an equivalent circuit model with complete distributed parameters of high frequency transformer are established.According to the design process of high frequency transformer,some key parameters of transformer are deduced and calculated,and the calculation of core and winding loss in the redesign process is emphatically analyzed.According to the relevant parameters of magnetic materials,the measurement methods and devices for the characteristics of magnetic core materials are introduced,and the characteristics and application occasions of different materials are analyzed.In view of the application situation of high frequency transformer in this paper,the related characteristics of common high frequency magnetic materials are introduced.Combining with the experiment,the characteristics of high frequency sinusoidal and non-sinusoidal excitation are measured and analyzed.The traditional hysteresis model is deduced,the relevant variables and parameters are analyzed in detail,and the eddy current loss and abnormal loss which are greatly affected by high frequency are introduced.The high frequency dynamic hysteresis loss model is established for calculating the loss of high frequency transformer excited by sinusoidal and non sinusoidal voltage in the circuit..Intelligent algorithm is applied to extract the parameters of J-A model from the experimental data,which improves the accuracy of the model parameters.Based on the theoretical analysis of skin effect and proximity effect of conductors and the Leeds line structure,an accurate analysis model for calculating eddy current losses of high frequency inductors and transformers with frequency variation is derived.Comparing the analysis model with the traditional high frequency winding calculation model,the difference between the improved calculation model and the traditional one is illustrated.The effect and influence of twist and strand characteristics on the eddy current loss of conductor are shown.The necessity and correctness of the model considering this factor are proved.The theoretical analysis and calculation results are verified by the experimental tests of different Leeds windings.The frequency-dependent losses of single-turn coreless coils and multi-turn coreless coils and multi-turn coils with cores are measured.The total loss of theoretical calculation is compared with the measured data,and the accuracy is confirmed.According to the grid connection of multi-winding cascaded new energy sources and the loss model,the optimal design of high frequency transformer with amorphous alloy core and Leeds wire winding is carried out.The research and design of high frequency transformer loss and the actual situation in the calculation has certain guiding significance.