Lossless Clamp Circuit With Turn-OFF Voltage and Current Reduction in High Step-Up DCDC Converter With Coupled Inductor

A high power density, high voltage gain soft-switching pulsewidth modulation dc-dc converter with a tapped inductor is proposed in this article as a front-end for low-voltage sources in energy generation systems. The leakage inductance is incorporated into the resonant tank, decreasing the component count. The use of the boost capacitor connected in series with the secondary windings of the tapped inductor causes high voltage gain at the low turn ratio of the coupled inductor. By incorporating a resonant passive clamp circuit, not only the voltage spikes on the transistor are restrained, but zero-voltage switching of the transistor and zero-current turning-OFF of the diodes are obtained. The resonant operation results in low power losses in the switches, providing high efficiency in a wide output power range. Owing to soft-switching operation, the transistor can be driven with a high switching frequency, providing a consolidated design of the high power density converter. The principles of operation of the converter were also analyzed theoretically. Finally, the converter is validated through a laboratory model with a power rating of 300 W and a switching frequency of 200 kHz.