The Benefits of Using Cascode GaN Power Devices in a Bidirectional DC-DC Buck/Boost Converter

Photovoltaic (PV) and wind energy conversion systems combined with battery energy storage are rapidly developing and being used for clean energy technologies. In these systems, non-isolated dc-dc bidirectional buck/boost converters are widely employed to interface between batteries and the dc-link/bus. However, these converters suffer from large semiconductor losses in silicon (Si) devices, which drastically limit the converter's performance and efficiency. Wide bandgap (WBG) power devices, gallium nitride (GaN) in particular, exhibit superior material properties with high operating capabilities promising tremendous potential for power conversion systems. The benefits of replacing Si devices with cascode GaN-FETs in a bidirectional buck/boost converter are not well defined. The focus of this paper is to investigate the impact of using new cascode GaN-FET devices on the converter's switching performance and energy efficiency. It involves designing Si-based and GaN-based converters to compare their performance under identical operating conditions. The switching behavior and energy loss of Si and GaN devices are examined through the double-pulse test (DPT). The total power loss in the two converters is analyzed to determine their efficiency. The outcomes reveal considerable benefits to using emerging cascode GaN-FETs in the bidirectional buck/boost converter, which has improved substantially in terms of switching performance and energy efficiency.