An Improved Two-Dimensional Calculation Method for PCB Winding Loss of Planar Transformers

Abstract

Accurate winding-loss calculation is critical for the design of printed circuit board (PCB) planar transformers, especially for considering the edge effects of the PCB winding. In conventional winding-loss modeling, the winding is uniformly divided into a limited number of segments due to computational constraints. However, this approach fails to accurately represent the nonuniform current distribution within the winding under high-frequency operating conditions. To address this issue, an improved winding segmentation algorithm is proposed, based on an iterative procedure. Each PCB turn of the winding is modeled as multiple parallel-connected conductors with nonuniform dimensions, and the segmentation size is adaptively determined according to the actual current distribution. An 8-turn planar transformer is used as a sample, and the winding-loss calculation results are validated against those obtained from two-dimensional (2-D) finite element method (FEM). The results indicate that the proposed algorithm reduces the maximum winding-loss calculation error from 2.9% to 0.22% compared with conventional uniform segmentation methods, in which each turn is divided into eight segments for calculation. The experiment results show that the winding AC resistance is lower than 8% up to 1 MHz, which verifies that the proposed method is correct and flexible.