Improved Analytical Modeling Of High Frequency Winding Losses In Planar Magnetic Components

With the rapid development of power electronics technology,high frequency switching power supply has been widely used.And it brings challenges to the design of magnetic components,and causes the widely using of planar magnetic elements.Therefore,it is important to evaluate the loss of high frequency planar magnetic components in the design process.Due to the skin effect and proximity effect,the AC loss of planar magnetic component windings increases with the frequency.Therefore,it is necessary to establish a high precision calculation model for evaluating the winding loss of planar magnetic components in wide frequency range.The wave equation is deduced according to Maxwell's equations based on high frequency time-varying magnetic field.The hypothesis and calculation formula of 1-D solution of high frequency winding loss is established,and the limitation of the 1-D model is analyzed by using FEM simulation.Based on the limitations,a 2-D model for calculating winding losses is established by taking into account the 2-D edge effect of rectangular conductors.For an isolated rectangular conductor,an equivalent line current model is established to solve the boundary value of the 2-D model,and obtained the 2-D analytical formula of high frequency loss.According to the distribution of planar inductor windings,a high-precision analytical model of planar inductance winding loss based on 2-D model is derived from single-layer conductor to multi-layer planar winding.The correctness,accuracy and applicability of the 2-D model applied to planar inductor winding loss calculation are verified by FEM simulation and experimental measurements.The influence of air gap on winding loss is analyzed,and the optimization scheme of inductor air gap magnetic field is put forward.The accuracy and optimization degree of the optimization method are verified by FEM simulation.The influence of planar transformer core on winding loss and the characteristics of 1-D and 2-D distribution of magnetic field are analyzed.Different calculation models are used to calculate the loss of different structure windings,and the calculation accuracy of different models is analyzed.The FEM simulation results verify that the 2-D model can accurately evaluate the high-frequency loss of planar transformer windings.A practical winding loss measurement method for the planar transformer in high frequency condition is built and verify the validity and applicability of the 2-D model in calculating the winding loss of planar transformer.