Design of a 300-Watt Isolated Power Supply for Ultra-Fast Tracking Converters

This paper presents the design of a medium-powerrating isolated power supply for ultra-fast tracking converters and MOS-gate driver circuits in medium and high voltage applications. The key feature of the design is its very low circuit input-to-output parasitic capacitance, which maximizes its noise immunity from noise due to fast changes in voltage. The converter is a voltage-controlled current source, utilizing a transformer with extremely low inter-winding parasitic capacitance, which is achieved by separating the windings by a significant distance. Experimental measurements show that an overall circuit input-to-output parasitic capacitance of 10 pF in a 300 W prototype can be achieved. The circuit input-to-output capacitance per watt is therefore 30 times lower than that of existing approaches. A mathematical model of the inter-winding capacitance of the proposed transformer, circuit analysis, and experimental results are provided to prove the feasibility of the converter.