Research on Three-Level Boost-Type DC-DC Photovoltaic Converter Based on Interleaved Control

A front-end three-level boost DC-DC converter and control method are introduced for non-isolated photovoltaic (PV) grid-connected systems in this paper. The boost three-level (Boost-TL) topology is adopted in this PV DC-DC converter. The working principle of the DC-DC Boost-TL converter is analyzed and the mathematical model is built. In order to reduce the ripple of the PV inductor current and the DC output voltage, the interleaved control scheme is proposed by using two switches with driver signal phase shift of 180 degrees. Simultaneously, the balancing voltage of capacitor can be achieved by control the conducting times of the switches. The Boost-TL converter with double closed loop control could reduce the volume of converters, lower of switching device voltage stress, reduce the diode reverse recovery loss and switching loss. Finally, a 23 kW prototype is designed and implemented for the whole PV DC-DC system. The validity of the presented control method is verified by experiment results.