Switching Transition Control to Improve Efficiency of a DC/DC Power Electronic System

Increasing the switching frequency of the power semiconductor devices (PSDs) reduces the size and cost of the passive elements, thereby positively affecting the power density of a high-frequency (HF) power electronic system (PES). To achieve a higher switching frequency of a PES, yet low switching losses, the speed of switching transitions of PSDs need to be increased. However, such fast transitions adversely affect PES performance in terms of electromagnetic interference (EMI) and device stress. Hence, a switching transition control (STC) scheme is developed to create optimality between switching PSDs with higher transitions yet maintaining safe levels of parasitic oscillations, that result from reducing the transition time of these devices. The switching transition control (STC) framework helps the HF PES achieve a target efficiency improvement by controlling the high di/dt and dv/dt regions of a PSD on the fly. Results are shown to validate that this improvement of efficiency is not feasible with a passive gate drive. An HF Cuk PES using a Cree SiC MOSFET half-bridge module is fabricated for the testing purpose of the STC framework. The STC network is based on a simple switched resistor network, synthesized using high-speed GaN-FETs and built across two generations, Gen-1, and Gen-2. Practical operational issues of the STC network with fast switching GaN-FET in the Gen-1 board are analyzed and are overcome with design modification in Gen-2. The work has ramifications in meeting a system-level goal of an HF WBG PES, like a target efficiency increment, while not deteriorating the EMI performance and PSD stress levels that result due to parasitic oscillations in such PES.