Design of an Interleaved High Step-Up DC-DC Converter with Multiple Magnetic Devices for Renewable Energy Systems Applications

Abstract

An interleaved high step-up converter topology based on the coupled inductor (CI) and built-in transformer (BIT) is proposed in this study to provide high step-up voltage gain and high efficiency with a low number of power electronic components for renewable energy applications. The voltage gain is increased by both of the turns’ ratio of CI and BIT, so there is no need to extend duty ratio to obtain high voltage gain. The proposed topology is much more flexible than those with only either CI or BIT. Moreover, the voltage stress across semiconductor devices can be relatively decreased by adjusting the turns’ ratio of the CI and BIT. In addition, the input current ripple can be reduced when the interleaved structure is applied at the input of this converter. Furthermore, turned-OFF and turned-ON zero current switching (ZCS) conditions for the diodes and power MOSFETs are achieved, respectively, thanks to the leakage inductances of the magnetic devices. Hence, due to the control of the falling current rate of the diodes by the leakage inductances, reverse recovery problem is alleviated. Moreover, the energy of the leakage inductances is recycled by the clamp capacitors avoiding high spikes across MOSFETs. As a result, according to the abovementioned advantages of the proposed converter, MOSFETs with low ON-state resistance and diodes with low forward voltage drop can be used to decrease the conduction losses. A 600 W laboratory prototype with 27–400 V voltage conversion at switching frequency 50 kHz is built to verify the performance of the proposed converter. Experimental results confirm the theoretical analysis. The efficiency reaches to 94.6% at full load which is close to the calculated of 95.8%.