Power decoupling circuit for photovoltaic grid-connected inverter

Abstract

The invention provides a power decoupling circuit for a photovoltaic grid-connected inverter, and relates to circuit devices of alternating-current main lines or alternating-current power distribution networks. The power decoupling circuit is composed of a filter capacitor, an inductor, a decoupling capacitor A, a decoupling capacitor B, a switch tube A and a switch tube B. The decoupling capacitor A is in parallel connection with the filter capacitor after being in series connection with the decoupling capacitor B, a collector of the switch tube A in series connection with the switch tube B is connected to a positive pole node of the part, in parallel connection with the filter capacitor, of the decoupling capacitor A in series connection with the decoupling capacitor B,, an emitter of the switch tube B in series connection with the switch tube A is connected to a negative pole node of the part, in parallel connection with the filter capacitor, of the decoupling capacitor A in series connection with the decoupling capacitor B, and an intermediate node enabling the decoupling capacitor A to be in series connection with the decoupling capacitor B is connected to the connecting point of an emitter of the switch tube A and a collector of the switch tube B through the inductor. The defects that an existing photovoltaic grid-connected inverter needs large-capacity and large-size decoupling capacitors and is complex in structure and high in cost are overcome.

Description

technical field [0001] The technical proposal of the present invention relates to a circuit device of an AC main line or an AC power distribution network, specifically a power decoupling circuit for a photovoltaic grid-connected inverter. Background technique [0002] In a single-phase photovoltaic grid-connected inverter, in order to make the output power factor of the inverter close to 1, it is necessary to control the output current waveform of the inverter to be sinusoidal and in phase with the grid voltage, which makes the output power of the inverter is the pulsating power twice the grid frequency. This pulsating power will generate low-frequency ripples on the DC bus, which in turn will cause fluctuations in the voltage and current of the photovoltaic array. However, in order to maximize the energy emitted by a photovoltaic array, it must be operated sufficiently close to its maximum power point. In order to limit the low-frequency ripple generated on the DC bus, th...

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Problems solved by technology

[0005] The technical problem to be solved by the present invention is to provide a power decoupling circuit for photovoltaic grid-connected inverters, which can ensure that the DC bus voltage is stable at about 400V, and overcome the need for large Decoupling capacitors with large capacity and large volume, complex structure, large volume and high cost

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