Analysis of Coupling Mechanism and Decoupling between Inductor and Active Filter in Hybrid EMI Filter

Inhalt:
As wide-band semiconductors mature, their higher switching frequency generates serious EMI. Hybrid EMI filters can effectively suppress EMI while reducing the size of the filter. In this paper, the effect of coupling between the active part and the common mode inductor in the hybrid EMI filter is investigated, and a cancellation part decoupling circuit is designed for the performance problems caused by its coupling to ensure the stability of the filter; after that, in order not to affect the performance of the active part, the decoupling design is carried out in the sense part on the basis of the previous design, so that the filter can work stably in the test frequency band without affecting its performance at the same time. Subsequently, the effect of the filter in a square wave noise source and an isolated DC/DC converter is tested, and the experimental results show that the HEF designed in this paper has a good noise suppression effect.