An improved boost converter with coupled inductors and buck-boost type of active clamp

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 step-up 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.