LLC resonant converter can help achieve zero voltage switching (ZVS) for both primary side and secondary side switches, which makes it a great candidate for today’s high-frequency, high-efficiency applications. However, for high power applications like electrical vehicle (EV) charger, energy storage, photovoltaic (PV) power station, and railway applications, the influence of the secondary-side devices’ junction cap to commutation is no longer negligible, but rarely analyzed in literatures. In this paper, the detailed process of traditional commutation strategy is first analyzed for the cases where the secondary side junction caps are comparable to the primary side ones. Then another commutation strategy is compared, which could reduce the magnetizing current by half, by turning off primary side and secondary side devices separately. Furthermore, timing of driving signals and design of the magnetic inductance are also discussed based on the proposed strategy to guarantee ZVS.
.jpg "Chunyang Zhao photo")