Dual-switch voltage balance topology used in partial shielding condition of photovoltaic string

Abstract

The invention discloses a dual-switch voltage balance topology used in a partial shielding condition of a photovoltaic string. The dual-switch voltage balance topology comprises an LLC resonant inverter and a voltage doubler, wherein the LLC resonant inverter comprises MOSFET tubes Qa and Qb, a resonant inductor Lr, a resonant capacitor Cr and a transformer; the MOSFET tubes Qa and Qb are providedwith parasitic output capacitors Ca and Cb and body diodes Da and Db respectively; the voltage doubler consists of n capacitors C1 to Cn transmitted by energy and 2n diodes D1 to D2n; two ends of thephotovoltaic string consisting of n serially-connected photovoltaic modules PV1 to PVn are connected to the input of the LLC inverter, the secondary winding of the transformer Lmg of the LLC inverteris connected to the voltage doubler, and each output of the voltage doubler is connected to each photovoltaic module. According to the dual-switch voltage balance topology, a photovoltaic curve multi-peak condition caused by partial shielding or other problems of the photovoltaic modules of the photovoltaic string is eliminated, the maximum output power of the photovoltaic string in a partial shielding condition is improved, and algorithmic simplification can be carried out on later photovoltaic maximum power output.

Description

technical field [0001] The invention relates to the field of photovoltaics, in particular to a dual-switch voltage equalization topology used in the case of partial shading of photovoltaic strings. Background technique [0002] With the development of photovoltaic power generation (Photovoltaic Generation, PVG) technology, photovoltaic power generation has become an indispensable member of renewable energy generation system (Renewable Energy Generation System, REGS). Considering the voltage and current requirements in daily use, the purpose of increasing the output voltage and current of the photovoltaic array (PV Array) is achieved by connecting the photovoltaic modules (PV Module) in series and in parallel. However, with the increase in the number of photovoltaic modules connected in series, the photovoltaic string (PV String) will be easily affected by environmental factors, such as partial shading, hot spots, or production errors of photovoltaic modules, resulting in the...

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Problems solved by technology

[0005] Aiming at the common partial shading phenomenon in photovoltaic strings, this invention proposes a new dual-switch voltage equalization topology to eliminate the multi-peak situation of photovoltaic curves caused by partial shading of photovoltaic strings or mismatches caused by other photovoltaic module problems

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