Fabrication and Evaluation of a Magnetically Coupled EMI Filter Designed With Topology Optimization

In this article, topology optimization was used to design a magnetic core structure on a π-type filter circuit. The newly designed magnetic core canceled the noise generated by conducted and induced currents, and as a result, showed dramatically improved electromagnetic interference (EMI) filter performance. Topology optimization was executed using three-dimensional electromagnetic field analysis to capture the magnetic coupling effect. The designed magnetic core was fabricated by machined milling and its performance was evaluated by measuring the noise reduction effect of a simple EMI filter equipped with the core. The EMI filter equipped with our optimized magnetic core showed about 30 dB higher performance than a filter with conventional ring-shaped cores.These results show that the performance of an EMI filter can be improved by optimizing the structure of its magnetic core.