| The planar transformer has the characteristics of small size and low height,and also has the unique advantages of good self-heat dissipation performance,low leakage inductance,low loss and small AC resistance.Due to its high frequency and high power density switching power supply widely used for adaptability to high frequency power conversion.However,the proportion of the insulating material in the winding window of the traditional planar transformer magnetic core is large,which reduces the copper fill factor and the window utilization rate is low.Therefore,this paper proposes a new transformer design method to solve these problems.Firstly,this paper proposes a new type of plane transformer:the plane transformer based on Leeds line,the Liz line is used to configure the PCB board,so that the PCB board is completely covered by these wire bundles,so that the surface utilization can be improved,and the skin collection effect can be significantly reduced.Its structure is analyzed,including Leeds line configuration,window utilization,DC-DC converter and hysteresis current control inverter.Then,the theory of the new planar transformer is studied.The power loss including transfer and conduction is analyzed,and the soft switch technology is used to minimize the power loss and improve the overall efficiency.The state space method is used to deal with the equivalent circuit model,then the principle of hysteresis current controller and LC low pass filter is analyzed,and the relevant electromagnetic calculation theory is given.Secondly,the topological structure of planar Leeds transformer is designed,including winding layout,steel strand layout,insulation layer,PCB structure and core materials,etc.,and the working principle of DC-DC converter and DC-AC inverter filter is analyzed.Finally,the paper mainly modeled the given structure through drawing features.Maxwell 3D was used to draw two models:3D model of stranded line configuration and 3D model of solid conductor,and detailed design of thickness and width materials for conductors and PCB plates is given,then the current density distribution and skin effect are simulated for the two models,and the following simulation results are obtained:the current is uniformly distributed in the model with twisted line configuration,while for the solid conductor model,the current is mainly concentrated at its edge.It can be predicted that with the increase of the number of stranded wires,the skin effect will become less and less obvious,and the current distribution in the wire will become more and more even.It can be seen from the test results that the AC resistance of the stranded line is relatively small in the frequency range between 10kHz and 1.5MHz.Conversely,when the operating frequency exceeds 1.5MHz,it is higher than the AC resistance of the solid conductor model.Finally,the combined modeling and analysis of DC-DC converter and DC-AC inverter are presented,the combined system can convert DC signals through two stages of converter,namely DC-DC converter and DC-AC inverter,to obtain power frequency 50Hz alternating current.The amplitude of the final power frequency output signal is consistent with the amplitude of the given reference signal,and their phase difference is very small and can be ignored.There are 56 figures,2 tables,and 84 references in this paper. |
