What we propose is a new integrated magnetic structure in which the CM filtering and DM filtering are combined. The DM filter is achieved by increasing the effective leakage of the CM windings and adjusting the effective permeability of the leakage path. Ferromagnetic shunts (in ring shapes) are inserted in between the CM filter windings, so as to increase the effective permeability of the leakage path. Then, the shape and thickness of the leakage ferromagnetic shunts allows to set the effective leakage inductance and the saturation flux of the leakage path. Two variants of the ferromagnetic shunt are proposed. The proposed method effectively increases the differential-mode inductance contents of a general common-mode EMI filter without sacrificing the power density and power loss of such an EMI filter stage. With the proposed method applied, a power electronics system engineer can re-think to eliminate the dedicated DM inductor if existing in the system, which saves significantly the system cost and volume. We believe that the contents to be presented will be highly interesting to the targeted audience and will contribute significantly to the power electronics industry.
