This work explores the design and fabrication of ultra-thin power converters, which utilize the advantageous form factor and inductor size reduction of flying capacitor multi-level converters (FCML). For the high voltage (i.e. 400V) applications considered here, careful attention is paid to meeting stringent creepage and clearance requirements. A hardware prototype is developed and tested to evaluate a novel low inductance commutation loop design which utilizes PCB embedded local capacitors. The vertically embedded capacitors yield small parasitic inductance, while simultaneously allowing excellent creepage/clearance through physical separation of high voltage terminals on opposite sides of the PCB. An ultra-low-profile form factor is achieved through additional recessing of the remaining passive components, yielding a 4.72 mm total height (including PCB thickness), in a 6-level, 400V, 1.6 kW hardware prototype, with a power density above 3 kW/in3 , and a peak efficiency of 98.7%
