High-frequency planar transformer optimal design and analysis

Due to the rapid development of modern industry, there is an increasing demand for isolated switching power supplies (SMPS) with a high efficiency and a high power density. Magnetic components, which occupy most of the converter volume, have been a key bottleneck in achieving high power density. This paper presents an optimal design method for high power density planar transformers. Applying the principle of flux cancellation, a matrix transformer that originally needed an independent magnetic core was integrated into a single magnetic core to reduce the volume of the core. Meanwhile, a loss model of the transformer is established, and an optimized design method of the winding structure is given according to that model to further reduce the winding loss of the transformer. Finally, an LLC converter with a resonant frequency of 1 MHz is designed to verify the practical performance of the proposed transformer.