Modeling and Suppression of Common-Mode Electromagnetic Interference in GaN-Based LLC Converter

Gallium Nitride (GaN HEMTs) are widely used in high-speed switching power supplies. Due to their heightened sensitivity in comparison to Silicon and Silicon Carbide (SiC) devices, GaN HEMTs produce significant dv/dt and di/dt during switching transients, which interact with the parasitic inductance and capacitance in the circuit, consequently causing substantial electromagnetic interference (EMI) issues. An immediate necessity arises for the development of modeling and suppression technique in power electronics. This paper analyzes CM EMI of GaN-based full-bridge LLC converter, and also derive its CM EMI circuit model. Finally, the feasibility of the proposed suppression method is experimentally verified, and a maximum suppression effect of approximately 35 dB was achieved in the frequency range of 150 kHz to 30 MHz.