A Grid Resilient Wide EV Segment Portable DC Charger with Seamless Phase Transition Adaptability Over Consistent Power Processing

Line or phase outage is a frequent occurrence, often accompanied by various grid abnormalities such as persistent voltage fluctuations, deviations in frequency or phase, particularly during high-demand hour. During power outages and abnormalities in grid voltages, both AC type-II and DC wall-mounted chargers are unable to function properly. This is owing to their control and protection unit design. This paper proposes a portable DC charging concept that is impervious to grid issues. In this case, a three-phase delta rectifier is employed for active front-end power conversion, while full-bridge LLC resonating converters are applied to control charging rate. The proposed approach involves a front-end converter that ensures a steady power flow even in the event of an interruption in any of the phases in a three-phase grid. Furthermore, it ensures consistency in the intermediate DC voltage notwithstanding any irregularities or interruptions in the grid. The wide EV segment battery voltage is targeted with full-bridge LLC converter with modified control approach. For this, the control approach is refined with a hybrid utilization of both pulse-frequency and pulse-conduction angle technique. Additionally, the intermediate DC link is regulated to provide a broad range of voltage conversion ratios. The proposed concept is validated by developing a 5kW hardware design that supports a battery voltage charging range of 72V−400V.