A Family of High Voltage Gain Three-Level Step-Up Converters for Photovoltaic Module Integration Applications

Abstract

This paper proposes a family of step-up three-level DC-DC converter topologies suitable for photovoltaic panel integration applications. The proposed family is suitable to convert the 10–30 V from photovoltaic panels to a 150 V direct current distribution bus. The proposed family enhances the three-level topology in terms of the voltage gain, power density, and filtering requirements at the input level. The filtration is reduced by interleaving. The three-level boost converter’s voltage gain is enhanced by utilizing several options such as switched capacitor cells, switched inductor cells, and flyback transformers or coupled inductors. The enhancement techniques are illustrated by providing the circuit diagram and a comparison of the voltage gain and the number of required components. An example converter of a hybrid three-level boost converter with a flyback transformer is presented to convert 20 V from a photovoltaic panel to a 400 V. The theory of operation and steady-state analysis are provided for the example converter operating in the continuous conduction mode. The converter is simulated to extract the power from three PVL-136 photovoltaic (PV) panels by applying a maximum power point tracking algorithm. The theory of operation and simulation are confirmed with an 80 W experimental prototype, which has an efficiency of around 95% at 40 W load power.