With the increasing demand for high efficiency and power density of power supplies, full-bridge(FB) LLC converter and planar transformers(PTs) are widely adopted in medium-to-high power conversion applications. However, the common-mode(CM) noise generated by PTs and converter remains a significant obstacle due to high dv/dt and large parasitic capacitances in overlapping primary and secondary layers of PTs. By minimizing CM noise, the proposed method prevents bulky CM chokes, helping to keep flat converter with high power density. This paper explains the root cause of CM noise in FB LLC converter and develops a combined method to suppress CM noise. Meanwhile, differential mode(DM) noise can be reduced due to the interleaving topology. Simulation results show that the novel method generated above 50dB less CM noise than a traditional converter.

Low common-mode noise,Plannar matrix transformer,Full-bridge LLC converter,DM noise reduction