An Optimal Design Method Considering Transformer Parasitic Capacitance of LLC Resonant Converters

LLC resonant converters have been widely used in DC-DC conversion applications due to the advantages of high efficiency and high power density. There are many design methods of LLC resonant converters in former research. However, none of them take transformer parasitic capacitance into consideration. This paper proposes an optimal design method considering transformer parasitic capacitance. Firstly, a brief summary of design process is introduced. Next, a wire-wound transformer is designed and the transformer parasitic capacitance is measured. After that, the resonant parameters are selected aiming at reducing device conduction loss and satisfying gain requirement. Finally, experiments are conducted on a 400V-12V 200W GaN-based LLC resonant converter. Experimental results show that the optimal design method has good performance and the efficiency of the prototype is up to 94.2%.