A Novel Hybrid Control Strategy and Dynamic Performance Enhancement of a 3.3 kW GaN-HEMT-Based iL2C Resonant Full-Bridge DC-DC Power Converter Methodology for Electric Vehicle Charging Systems

The conventional resonant inductor-inductor-capacitor ((LC)-C-2) DC-DC converters have the major drawbacks of poor regulation, improper current sharing, load current ripples, conduction losses, and limiting the power levels to operate at higher loads for electric vehicle (EV) charging systems. To address the issues of the (LC)-C-2 converter, this paper proposes an interleaved inductor-inductor-capacitor (iL(2)C) full-bridge (FB) DC-DC converter as an EV charger with wide input voltage conditions. It comprises two (LC)-C-2 converters operating in parallel on the primary side with 8-GaN switches and maintains the single rectifier circuit on the secondary side as common. Further, it introduces the hybrid control strategy called variable frequency + phase shift modulation (VFPSM) technique for iL(2)C with a constant voltage charging mode operation. The design requirements, modeling, dynamic responses, and operation of an iL(2)C converter with a controller are discussed. The analysis of the proposed concept designed and simulated with an input voltage of 400 V-in at a load voltage of 48 V-0 presented at different load conditions, i.e., full load (3.3 kW), half load (1.65 kW), and light load (330 W). The dynamic performances of the converter during line and load regulations are presented at assorted input voltages. In addition, to analyze the controller and converter performance, the concept was validated experimentally for wide input voltage applications of 300-500 V-in with a desired output of 48 V-0 at full load condition, i.e., 3.3 kW and the practical efficiency of the iL(2)C converter was 98.2% at full load.