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This paper proposes an improved boost converter with coupled inductors and buck-boost type of active-clamp feature, PWM control and zero-voltage switching in both main and auxiliary switches. In the converter, the active-clamp circuit is used to eliminate voltage spike induced from the leakage inductor of the coupled inductors. The active switch of the converter can still sustain a proper duty cycle when it operates with a high stepup voltage ratio, reducing voltage stress significantly. A set of passive-clamping circuit is adopted to eliminate undesired resonance between leakage inductor of the coupled inductors and stray capacitor of the boost diode, recovering trapped energy. Thus, conversion efficiency can be improved significantly. A 200 W prototype of the proposed boost converter was built from which experimental results have shown that efficiency can reach as high as 92% and surge can be suppressed effectively. I. INTRODUCTIONIn a boost converter with coupled inductors, the active switch can sustain proper duty cycle while operated with high step-up voltage ratio, reducing voltage stress significantly. However, leakage inductor of the coupled inductors would induce voltage spike which results in high component stress, low conversion efficiency and high noise level. A resistorcapacitor-diode snubber can alleviate voltage stress of the switch, but the energy trapped in the leakage inductor is dissipated. A boost converter with active clamp and pulse width modulated (PWM) control can result in zero-voltage switching (ZVS) in both main and auxiliary switches, which makes the converter more viable. Additionally, leakage inductor of the coupled inductors can limit the decreasing rate of the boost-diode current, reducing diode reverse-recovery loss.

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