SiC-GaN-Based Universal DC-DC Converter for Plug-In Electric Vehicles

In this thesis, a two-phase full-directional dc-dc converter is designed for the application of plug-in electric vehicles. It is a universal dc-dc converter in which two power electronic modules, the battery charger dc-dc converter and the power management dc-dc converter, are integrated in order to improve the power density, which is a crucial factor in plug-in electric vehicles. The state-of-the-art wide band gap silicon carbide (SiC) and gallium nitride (GaN) switching devices are used in the proposed converter. Especially the GaN device has the lowest switching loss among the power electronic devices causes higher efficiency and higher power density in the hard-switched applications. To cope the power rating limitation of the GaN device and evade the complexity and infeasibility of the multi-phase converters with excessive number of phases, a GaN phase is paralleled with a SiC phase in a half-bridge configuration. An asymmetrical current sharing is applied between the phases in such a way to maximize the utilization of the GaN device. Mathematical model of the proposed converter is derived and verified. A comprehensive power loss analysis investigates the superiority of the proposed converter. Dead-time loss analysis is performed with a new method of power loss calculation. A cascade PI controller is designed to provide satisfactory performance of the converter in the all modes of operation. Finally, a gate-driver multi-objective parameterization method is also presented to improve efficiency and EMI level of a GaN-based one inverter leg case study.