Analysis of Overcurrent Protection for Topology Morphing LLC Converters by Diode Clamping applicable to EV chargers

Recently, EVs (Electric Vehicles) increased their pack voltage from 400V to 800V. It has shortened the charging time, but EVs with 800V now have to carry an extra boost converter with their OBCs (onboard chargers) since most fast chargers support only 400V systems. This consumes extra weight and volume from EVs. Therefore, chargers need to handle both 400V and 800V systems to make EVs more competitive in the market. However, the chargers’ efficiency will decrease due to the broader expected output voltage range. As a solution, this paper suggests a Topology morphing technique. Nonetheless, the main scope of this paper is the overcurrent protection of such applications since there isn’t much research about overcurrent protection schemes for topology morphing. This paper proposes diode clamping of a resonant capacitor in a capacitor-shared LLC converter applicable to EV chargers for overcurrent protection with simulation results.