A novel primary side sampling system with low-loss applied to Double-Clamp Zero Voltage Switching converter

This paper proposed a novel primary side voltage sampling (PVS) system, which use the gate signal of secondary synchronous rectifier as a trigger to generate a short sampling pulse, and let this sampling pulse to control a switch to realize a short-on-time sampling. The proposed PVS system is based on a Double-Clamp, Zero Voltage Switching (DCZVS) converter. An auxiliary transformer, which is completely separate with the main transformer, is used to isolate primary side and secondary side. The auxiliary transformer using air as the core and can bury in the printed circuit board (PCB) to avoid occupying surface area and using demagnetization circuit. The area of the surface devices is about 13.86 mm
²
while the auxiliary transformer cost a 270 mm
²
, 4 layers space inside the PCB. Power loss of the auxiliary transformer is about 2.83 W in a worst case, and the maximum loss of the surface devices is about 129.3 mW.