High Step-Up Full Bridge DC-DC Converter with Multi-Cell Diode-Capacitor Network

The full bridge boost isolated DC-DC converter achieves high voltage gain by setting the turns ratio of high-frequency transformer. Compared with the transformer, diode-capacitor voltage boost cell is more suitable to achieve high voltage gain with both high efficiency and power density. However, multi-cell diode-capacitor network has inrush current issue and strict LC filter requirement which is not suitable to achieve high efficiency in relatively low switching frequency and large power application. In order to meet high step-up voltage regulation and compulsory electrical isolation due to public safety, this paper proposes a high step-up full bridge isolated DC-DC converter with multi-cell diode-capacitor network which exploits the features of multi-winding transformer and diode-capacitor voltage boost cell. It has the following advantages 1). increases voltage boost capability and avoid extreme large duty ratio. 2) achieves almost zero output voltage ripples which reducing the inductance in output LC filter, 3) reduces transformer turns ratio and magnetic component volume. Furthermore, it can use the transformer leakage inductor and resonant capacitor to achieve zero-current switching (ZCS), which is beneficial to increase efficiency.