EMI Common-Mode Noise Suppression and Magnetic Elements Winding Loss Optimization Design Based on GaN Cascaded Power Module

In this paper, CM noise suppresion and magnetic elements winding loss optimization design of a cascade power module based on GaN design are carried out (the front stage is buck converter, the second stage is LLC resonant converter). To suppress CM noise, the front buck converter adopts planar stagger reverse coupling inductance, by establishing reverse stagger coupling buck converter CM noise model and conduction path model, the equivalent capacitance can effectively reduced, thus further reducing CM noise current. A staggered winding structure is proposed for second stage LLC resonant converter, compared and calculated LLC resonant transformer winding electromagnetic field characteristics with different structure. a novel shielding and cancellation technique is proposed for LLC resonant converter, by establishing LLC converter CM noise shielding model and the equivalent capacitance can effectively reduced, thus further reducing CM noise current. In order to improve the LLC resonant converter efficiency, winding copper foil optimal thickness is proposed. Experimental results show that power module with winding optimization and shielding technology can effectively suppress the CM noise and improve efficiency, CM noise can reduced 12-20dB, the peak efficiency improved about 1% after copper foil thickness is optimized.