Two-Stage Step-up Converter with Different Voltage Transformation Ratios depending on the Duty Cycle

Abstract

A two-stage converter with high output voltage ratio and reduced current stress of the inductors and partly reduced voltage stress is discussed. The function is explained with the help of voltage and current diagrams. The voltage transformation ratio changes between a quadratic step-up for duty cycles lower 0.5 and a double Boost converter for duty cycles higher than 0.5. Dimensioning hints, the control lawfor feed-forward controls, the transient when the supply is turned onis discussedand some simulations are given.A comparison to other two-stage converters is also treated.