A High-Power-Density Four-switch Buck-boost Converter using 3D Multi-PCB Structure

A high-power-density four-switch buck-boost (FSBB) converter based on 3D multi-PCB structure is proposed in this paper. Compared with the conventional planar solution, the two half-bridges of the FSBB converter are divided into two PCBs, which are arranged symmetrically on the left and right sides of the planar inductor. The control board is arranged on the bottom side of the planar inductor. PCBs of the power and control stage are wrapped around the planar inductor to form a 3D structure, which is similar to the expanded view of a cuboid. The 3D structure can effectively reduce the area wasted by the planar layout and thus improve power density. Moreover, the power loop in the 3D structure is optimized to reduce parasitic inductance as well as high-frequency voltage overshoot. Finally, a 280W FSBB prototype is built to verify the proposed structure, which achieves the peak efficiency of 98.1% at 1MHz switching frequency. Compared with the conventional planar structure, the power density increases from 90W/in3 to 432W/in3.