Design and Evaluation of a Novel Hybrid SiC-GaN Based Bidirectional Full-Bridge DC-DC Converter 2017-01-2032

Efficient, small, and reliable dc-dc power converters with high power density are highly desirable in applications such as aerospace and electric vehicles, where battery storage is limited. Bidirectional full-bridge (FB) dc-dc converters are very popular in medium and high-power applications requiring regenerative capabilities. Full-bridge topology has several advantages such as:

• Inherent galvanic isolation between input and output as well as high conversion ratio due to the transformer with a turns ratio n.
• Reduction in passive component sizes due to the increase in inductor current frequency to twice the switching frequency.
• Reduced voltage stresses on the low-voltage side switches and current stresses on the high-voltage side switches.

However, due to the high number of switches, device losses increase. Use of wide-band gap (WBG) devices, such as Silicon Carbide (SiC) and Gallium Nitride (GaN) devices, in power electronic converters has shown to reduce device losses and need for extensive thermal management systems in power converters. SiC and GaN have complementary properties. SiC devices offer superior thermal performance due to their high thermal conductivity and GaN devices offer superior switching performance due to their high carrier mobility. However, state-of-the-art commercially available GaN devices can only withstand breakdown voltages up to 650 V, while SiC devices can handle up to 1700 V. Because of this shortcoming, GaN devices cannot be used in power converters for high voltage applications, despite GaN’s capability to operate at high switching frequencies with high efficiency. This work aims to exploit both the high-voltage capability of SiC devices and exceptional switching capability of GaN devices in a novel hybrid SiC-GaN based bidirectional full-bridge dc-dc converter with improved efficiency, reliability, and power density for high power applications. The proposed bidirectional converter rated at 5 kW will be designed and simulation results obtained using LT Spice circuit simulator will be presented.