Novel bipolar output DC-DC converter for photovoltaic generation

A novel bipolar output DC-DC converter for front-end power conversion in photovoltaic generation system is proposed. According to the innovative idea of optimized combination of circuit topologies, by merging topological structures of Zeta converter and Buck-Boost converter, this converter shares one switch component and one power inductor in the input side. For the positive output rail, circuit structure of output side in Zeta converter is employed. Then, for the negative output rail, circuit structure of output side in Buck-Boost converter is adopted. The derivation of this novel topology is implemented and operation modes under inductor current continuous conduction condition are analyzed. Deduction of converter steady-state characteristics like voltage gain and component stress is carried out. Parameter design and component selection are also implemented. PSIM software is used to do the simulation analysis, and the captured simulation waveforms agree with theoretical analysis results. A 1 kW hardware prototype with 94.5% peak efficiency is fabricated and the operational waveforms are tested and verified to be consistent with theoretical analysis and simulation results. The research conclusions demonstrate the proposed converter features simple structure, bipolar output, voltage step-up/down, relative high efficiency and fitness in photovoltaic generation application.