Resonant Parameter Design for the LLC-Type Dual Active Bridge Converter with Considerations of Voltage Conversion Gain and Stability in the Cascaded System

The LLC-type dual active bridge (DAB) converter as an isolated DC-DC converter attracts increasing attention nowadays because of the popularity of the renewable energy generation. Constant voltage conversion gain (VCG) is an important indicator to assess its performance of power transfer, which may be undermined by the varying values of resonant parameters due to environmental conditions. Besides that, in practical applications, the DAB converter is often cascaded with other subsystems, which may lead to instability in the cascaded system because of impedance interactions. Therefore, the voltage conversion gain (VCG) as well as stability of the cascaded system are two design objectives for resonant parameter design for LLC-type DAB converter in this paper. A design approach is advanced to maintain both constant VCG and system stability simultaneously. In the end a design example is provided and experimentally verified.