Abstract
Partial shading on photovoltaic (PV) strings consisting of multiple panels connected in series is known to trigger severe issues, such as reduced energy yield and the occurrence of multiple power point maxima. Various kinds of differential power processing (DPP) converters have been proposed and developed to prevent partial shading issues. Voltage stresses of switches and capacitors in conventional DPP converters, however, are prone to soar with the number of panels connected in series, likely resulting in impaired converter performance and increased circuit volume. This paper proposes a DPP converter using an LLC resonant voltage multiplier (VM) with a voltage divider (VD) to reduce voltage stresses of switches and capacitors. The VD can be arbitrarily extended by adding switches and capacitors, and the voltage stresses can be further reduced by extending the VD. Experimental verification tests for four PV panels connected in series were performed emulating partial shading conditions in a laboratory and outdoor. The results demonstrated the proposed DPP converter successfully precluded the negative impacts of partial shading with mitigating the voltage stress issues.
Highlights
Ordinary photovoltaic (PV) panels generally consist of two or three substrings, each comprising multiple cells connected in series
The results demonstrated the proposed differential power processing (DPP) converter successfully precluded the negative impacts of partial shading with mitigating the voltage stress issues
As long as panels are installed in a proper location, severe shading conditions rarely occur
Summary
Ordinary photovoltaic (PV) panels generally consist of two or three substrings, each comprising multiple cells connected in series. The bypassed panel no longer generates power as its voltage is subzero value, significantly reducing the power generation of the string as a whole. Advanced MPPT techniques have been proposed to certainly track the global
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