A Multi-Mode Full-Bridge/Modified-Stacked- Switches Structured CLLC Resonant Converter for Energy Storage Applications

In this article, a new full-bridge/modified-stacked-switches multimode
CLLC
isolated resonant converter is presented for energy storage applications. In particular, a multimode wide voltage gain control system is proposed, which takes advantage of the topology reconfiguration method in both the inverter and the rectifier blocks in the proposed circuit to regulate the output voltage while preventing the switching frequency from drifting away far from the resonant frequency. The impact of the parasitic elements in the isolated
CLLC
resonant circuit is also investigated in this article. In addition, a smooth mode transition is provided to avoid any transients caused by a rapid frequency change. The operating principles of the control system is analyzed extensively. Compared with the traditional pulsefrequency modulated resonant converters, the proposed control system attains enhanced efficiency even at extremely low voltage gains while sustaining a nearly consistent high-efficiency profile. Furthermore, it mitigates voltage regulation instability under light loads attributed to parasitic components by constraining the frequency spectrum. The proposed control system presents an appealing solution for high-voltage, high-power energy storage applications that demand a broad range of voltage gains and where the influence of switch
R_ds
ON
is reduced due to the low current characteristics typical of these applications. Finally, a 500 W 100 V-350 V input, 96 V output prototype has been built to verify the performance of the proposed converter system.