Partly isolated three-port DC-DC converter based on impedance network

Abstract

This study proposed a novel partly isolated three port converter (PITPC) based on a quasi-Z source converter for photovoltaic applications. Compared with the conventional quasi-Z source converter, the proposed DC-DC converter has dual input sources and uses the switched capacitors and coupled inductor techniques, helping the converter to gain a high voltage. To achieve the power flow control, the proposed converter uses only three power switches with low voltage stress and it is developed for hybridising photovoltaic panels, rechargeable batteries and isolated loads. For this purpose, the proposed PITPC can be easily reconfigured into dual-input single-output, single-input dual-output and single-input single-output modes; so it can even operate when the photovoltaic panel fails to provide energy to the load. Moreover, the study thoroughly discusses various converter operating modes and provides explanations and necessary relationships for circuit operations. The study also explains the control strategy as well as the pulse width modulation waveforms for the proposed converter. Simulation results from MATLAB/Simulink examine the proposed topology performance. The experimental results confirm the advantages claimed for the proposed converter; the results also show a well-distributed efficiency curve and a peak of 96.3%.