Power decoupling circuit for alternating current side coupling

Abstract

A power decoupling circuit for alternating current side coupling comprises an inductor, main switching devices, parasitic diodes and a decoupling capacitor, wherein the main switching devices are seven switching tubes, and each switching tube is connected with one parasitic diode in inverse parallel. The power decoupling circuit comprises four work modes, including a PHC charging mode, a PHC discharging mode, an NHC charging mode and an NHC discharging mode. An input end of the power decoupling circuit is connected with an output side of an inverter in parallel, the voltage amplitude on the output side of the inverter is high and has positive and negative periodic variation, so that the decoupling capacitor in the decoupling circuit designed on the basis of boost and buck circuits can acquire higher average voltage and larger voltage variation range, the capacitance of the decoupling capacitor is greatly reduced, the polarity of the decoupling capacitor is fixed, the grid connection requirement of the inverter can be met without a large electrolytic capacitor, the system size and cost are greatly reduced, and thus the service life of a photovoltaic generation system is substantially prolonged.

Description

technical field [0001] The invention relates to a power decoupling circuit for AC side coupling, which belongs to the technical field of electric engineering. Background technique [0002] In a photovoltaic power generation system, photovoltaic modules are controlled by maximum power point tracking (MPPT) to generate a constant maximum power, while the instantaneous power transmitted to the grid presents periodic pulsations, which is common in single-phase grid-connected inverters. The instantaneous power mismatch problem. Usually, a large-capacity electrolytic capacitor is used as an energy storage element of the decoupling circuit, but the introduction of the electrolytic capacitor shortens the overall life of the photovoltaic power generation system. According to the position of the decoupling capacitor in the photovoltaic power generation system, it can be divided into photovoltaic array side decoupling, DC bus side decoupling and AC output side decoupling. The decoupl...

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Problems solved by technology

However, if the inductor is used as the energy storage element of the decoupling circuit, its decoupling ability is determined by the inductance value and the square of the passing current, which will greatly reduce the decoupling ability of the decoupling circuit. If the inductance value is increased, the volume of the photovoltaic power generation system will be greatly increased.

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