Inverting Two-Stage Step-Up Converters

Apart from combining two converters by connecting them in parallel at the input and the output sides, one can connect them in parallel at the inputs and in series at the outputs of the stages to increase the power rate and to modify the voltage transformation ratio. Four converter topologies with a limited duty-cycle range are studied for their application as stages for a converter combination, which operates as an inverting two-stage step-up converter. The operation of the converter combinations is studied in the steady state, and the dynamic models (for large and small signals) are derived. The start-up of the converters is analyzed. The stress across the components is calculated, and hints for dimensioning are given. The considerations are proved by LTSpice simulations. The advantages and the disadvantages of the four converters are included.