高频变压器绕组损耗解析计算分析

Analysis of Winding Loss Calculation Methods for High Frequency Transformers

高频变压器的绕组损耗是固态变压器整机功率密度与效率的一大决定因素。然而,不同绕组结构下绕组损耗的计算存在多种解析公式,精度随绕组空间结构变化,且部分解析公式存在漏写或错误;绕组导体的厚度最优选择也是一个关键问题。为了解决上述问题,分别讨论铜箔绕组、绝缘实心圆导线绕组和利兹线绕组3种导体绕组损耗的解析计算方法,并据此揭示绕组损耗与变压器工作频率、结构参数的关系,同时推导特定工作频率下的最优导体厚度。对适用于利兹线绕组的Bartoli公式与Tourkhani公式源文献中的错误进行修正,并根据实际工作条件简化Tourkhani公式。对于实心圆导线绕组,绕制2个样例变压器绕组,使用网络分析仪测量其交流电阻,分析不同绕组解析算法的计算误差。实验测量结果显示,改进Ferreira算法具有最小的计算误差,为高频变压器绕组的选型与效率优化提供参考。

The winding loss of high frequency transformers is a key factor to determine the power density and efficiency of solid state transformers.However,there are different analytical formulas for calculating the winding loss under different winding structures,the accuracy varies with the spatial structure of the winding,and small errors are found in these formulas.At the same time,the optimal choice of thickness of the winding conductor is also a considerable issue.In order to solve these problems,this paper analyzed losses of three different winding conductors:the foil conductor,the solid round conductor and the Litz wire conductor.Different analytical algorithms were all given and compared,then the relationship between winding loss and transformer structure parameters was derived as well.Errors in the original papers of Bartoli formula and the Tourkhani formula suitable for Litz wire windings were corrected,and simplification was made to Tourkhani formula according to the actual working conditions.As to transformer implementing solid round conductor,the accuracy of different closed-form calculation expressions is verified based on the measurement results of two prototypes.Results reveals that Modified Ferreira algorithm yields highest accuracy in predicting winding losses of transformer with solid round wire and could be used as reference when designing high frequency transformer.