Design And Optimization Of High Frequency And High Efficiency LLC Matrix Transformer

Matrix transformer has been proved to be an effective scheme to improve the power efficiency of data centers.However,the parasitic parameters and ac resistance generated at high frequencies will affect the efficiency and performance of the matrix transformer.Therefore,it is of great significance to study the parasitic parameters,loss distribution and integration of matrix transformers at high frequencies.Based on the semi-bridge series and parallel resonant converter(LLC type),a design method and a concrete implementation method of matrix transformer with high efficiency and high power density is been proposed in this thesis,and analyzes the key problems of parasitic parameters,loss and magnetic integration of matrix transformer.The main work is as follows:(1)the parasitic parameters and loss model of the matrix transformer are established.According to the model,the optimal solution of the resonance inductance,leakage inductance,winding width and winding copper thickness of the matrix transformer can be obtained.(2)a symmetric matrix transformer PCB winding distribution structure is proposed to realize the current sharing among parallel transformers.By simply extending the primary winding,LLC converter can be realized to obtain the leakage sensitivity required for output voltage regulation.(3)the matrix transformer magnetic integration design is proposed,which integrates the transformer and the inductive magnetic core with a single magnetic core structure to reduce the loss of the magnetic core and improve the efficiency of the converter,and through the cross winding of the inductor and transformer windings to produce the equipartition current and reduce the loss of the winding.ANSYS Maxwell simulation results show that the optimized magnetic integrated 2×2:1 matrix transformer has a small magnetic core loss and winding loss,meets the resonance condition of leakage sensitivity and low parasitic capacitance,and is suitable for high power density and high efficiency power supply systems.Based on 96V/12V and 800W half-bridge LLC resonant converter,the matrix transformer designed is verified.The test results show that the peak efficiency of the transformer is 98.02%and the power density is 50.32w/cm~3 at 1MHz operating frequency,which meets the requirements of the design indexes.