High boost ratio hybrid transformer DC-DC converter for photovoltaic module applications

This paper presents a non-isolated, high boost ratio hybrid transformer dc-dc converter with applications for low voltage renewable energy sources. The proposed converter utilizes a hybrid transformer to transfer the inductive and capacitive energy simultaneously, achieving a high boost ratio with a smaller size magnetic component. As a result of incorporating the resonant operation mode into the traditional high boost ratio PWM converter, the turn off loss of the switch is reduced, increasing the efficiency of the converter under all load conditions. The input current ripple is also reduced because of the linear-sinusoidal hybrid waveforms. The voltage stresses on the active switch and diodes are maintained at a low level and are independent of the changing input voltage over a wide range as a result of the resonant capacitor transferring energy to the output. The effectiveness of the proposed converter was experimentally verified using a 220 W prototype circuit. Utilizing an input voltage ranging from 20V to 45V and a load range of 30W to 220W, the experimental results show system of efficiencies greater than 96% with a peak efficiency of 97.4% at 35V input, 160W output. Because of high efficiency over wide output power range and the ability to operate with a wide variable input voltage, the proposed converter is an attractive design for alternative low dc voltage energy sources, such as solar photovoltaic (PV) modules.