Differential Power Processing converter with cell balancing operation of multiple photovoltaic module systems

This paper deals with DPP(Differential Power Processing) converter architecture for partial shading MPPT and cell balancing operation of the Photovoltaic systems using a couple of dc-dc converter topology. As the interest in solar systems evolves, various architectures of Power Conditioning System (PCS) have been studied. Among the conventional architectures, there are two-stage multi-level micro-inverter which is required DC-link voltages balancing between high-side and low-side capacitors for the second-stage multilevel inverter.[2] In this paper, a new architecture employing a DPP converter to the two-stage multi-level inverter is proposed. The proposed architecture consists of a central boost converter and DPP converters of multi-output flyback, converters. If there is no power difference between the solar modules, most of the power passes through the boost converter except the power to maintain the DC-link voltage balancing under CCM mode in the flyback converters. When the power difference occurs, remaining power passes through the boost converter while the differential power is transmitted through the flyback converters. Since the common current among the PV modules at each MPPT operating point is transmitted through the high-efficiency central boost converter, the total conversion efficiency is high. For the verification of this advantage of the proposed scheme, a 150W hardware prototype of the DPP is implemented and tested along with a comparison to a multi-output flyback converter scheme presented in previous studies.