Low Common-Mode Noise Full-Bridge LLC Resonant Converter With Balanced Resonant Tank

This article proposes a low common-mode (CM) noise full-bridge LLC resonant converter with two balanced resonant tanks. In the proposed converter, each resonant inductor and capacitor is divided into two components with the same value. The CM current flowing through parasitic capacitors of the transformer is reduced due to the balanced resonant tank. Moreover, the CM noise can be significantly reduced by adjacently locating the primary and secondary layers with the same dv/dt characteristic. Therefore, the proposed converter decreases the CM noise generated from the planar transformer (PT) by the balanced resonant tank and proposed layer arrangement of PT and achieves a high power density with a decreased size of the electromagnetic interference filter. The validity of the proposed converter is verified by a 1.5-kW prototype with 400-V input and 270-420-V output.