An improved analysis considering harmonic components for high-frequency isolated dual-active-bridge series resonant DC-DC converter

This paper proposes an improved way to analyze high-frequency isolated dual-active-bridge (DAB) series resonant dc-dc converter. Compared with the existing analytical method, it takes harmonic components of voltage and transformer internal resistance into consideration. Using the proposed method, the switching frequencies to achieve ZCS and the output voltage expression are deduced and verified with simulation. The results show the efficiency of the high-frequency transformer can be calculated more precisely than methods which consider fundamental components only. It also provides a way to design the resonant tank to keep output voltage stable when the load changes a lot.