A New Capacitive Coupled Step-up DC-DC Converter

This paper presents a new low count high efficiency step-up DC-DC converter with voltage gain equivalent to the conventional boost converter. However, through a capacitive coupling cell it is possible to limit the touch current, presenting a higher safety degree against electric shocks. The main operating stages and equations that describe the circuit are presented, for both power transfer and touch current limiting. Starting from the safety criteria and specifications of the converter a design guideline is presented. Simulation and experimental results are included, obtained with a prototype of 2 kW, 400 V output, operating at 200 kHz. In addition, efficiency curves for different input voltages were obtained, reaching a maximum efficiency around 97.8%. Finally, the touch current test demonstrated that the risk is automatically eliminated by the circuit in approximately 40 ms.