Isolated Bidirectional DC-DC Converter for Hybrid Electric Vehicle Applications

Hybrid electric vehicles (HEVs) offer many advantages, such as high fuel economy, low emissions, and silent operation. In HEVs, there are two or more different voltage buses for different purposes of the vehicle operation. There are needs of galvanically isolated bidirectional DC-DC converter to link different DC voltage bus and transfer energy back and forth. For example, on of the DC-DC converters convert the high voltage (200-300V) in the main battery to low voltage (~12V) for use in electrical equipment, while the other converts 300V battery voltage and supply the drive motor with 500V. High efficiency, compact size, lightweight, and reliability are all essential requirements for DC-DC converters for electric and hybrid vehicles. This paper introduces a bidirectional, isolated DC-DC converter for medium power applications. A dual fullbridge topology is developed to achieve the power rating. A 1kW prototype of the converter has been built and tested. The experimental results of the converter’s steady state operation confirm the simulation analysis. This converter is a first step to understanding the design and build of a medium power DC-DC converter.