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A non-isolated zero-voltage transition interleaved high step-up converter with built-in transformer is proposed for high step-up and large current applications. The proposed converter consists of an interleaved structure, a built-in transformer and two sets of active clamp circuits. The built-in transformer can provide high voltage conversion ratio and increase the system efficiency without an extreme duty cycle compared with the conventional boost converter. The leakage inductance of the built-in transformer removes the output diode reverse-recovery problem, which results in low reverse-recovery losses. The active clamp scheme can suppress the surge voltage of the power MOSFETs and recycle the leakage energy, which is helpful to improve the circuit efficiency and reliability. Furthermore, zero-voltage switching soft switching performance is achieved for both the main and the clamp switches during the whole switching transition, which reduces the switching losses. The operation principle of the converter is analysed and verified. At last, some experimental results of a 1 kW prototype with 48 V input and 380 V output are given to demonstrate the effectiveness of the proposed converter.
Date of Publication: May 2011