A Hybrid Step-up DC-DC Converter based on Ladder Switched-capacitor and High-frequency Transformer

In this paper, a hybrid step-up DC-DC converter based on Ladder switched-capacitor and high-frequency (HF) transformer is proposed. Based on the traditional 3X Ladder switched-capacitor converter (SCC), one active switch is replaced by the secondary winding of the HF transformer, while the other active switch is substituted by a diode. Besides, the primary side circuit is constructed by one active switch and the primary winding of the HF transformer. Compared with the traditional Ladder SCC, the novel hybrid converter has the merits of high step-up gain, wide voltage-gain variation range, low component counts and electrical isolation, making it suitable for renewable energy harvesting system. A comprehensive analysis of operation principle, voltage gain expression, boundary condition and small signal model is given. A 36.3V~69.5V to 400V open-loop prototype with output power of 80W~120W was designed, built and tested to verify the theoretical analysis.