Ultra low-profile flying capacitor 7-level 3kW PFC with optimized high frequency layout and active balancing using 100V GaN

A detailed design and evaluation of a high-power density Power Factor Correction (PFC) system, targeting a power output of 3kW is presented. To achieve a compact power stage, a flying capacitor multi-level (FCML) totem-pole boost PFC topology using 100V GaN devices is employed. By increasing the number of levels in the boost stage, the size of the boost choke and EMI filter can be shrunk, resulting in exceptional low profiles. The innovative modular layout provides tight commutation loops while accommodating a higher number of devices in the power stage. Furthermore, active capacitor balancing enhances ruggedness and reliability, enabling mass production of this design and lower cost as less capacitance is required. Through experimental evaluation in DC, a peak efficiency of 99.45% and of 99.36% at full load are obtained with the proposed design. Including the heatsink, boost inductor and unfolding stage, the presented power stage achieves a higher than state of the art power density of around 900W/in3.