A high-efficiency miniature photovoltaic grid-connected inverter that suppresses input low-frequency ripple

Abstract

The invention discloses a high-efficiency miniature photovoltaic grid-connected inverter for suppressing input low-frequency ripples. The main circuit typology of the high-efficiency miniature photovoltaic grid-connected inverter comprises a DC power supply, an input capacitor, a primary side switching tube, a primary side diode, an auxiliary switching tube, an auxiliary diode, an auxiliary capacitor, an isolation transformer, a secondary side diode, a secondary side switching tube, a filtering circuit and a power grid. According to the high-efficiency miniature photovoltaic grid-connected inverter, an auxiliary circuit composed of the auxiliary switching tube, the auxiliary diode, an auxiliary winding of the isolation transformer and the auxiliary capacitor is added to the input side of the inverter, the low-frequency ripples in an input current are effectively suppressed, grid connection is realized, and the service life of the high-efficiency miniature photovoltaic grid-connected inverter is greatly prolonged.

Description

technical field [0001] The invention relates to a high-efficiency micro-photovoltaic grid-connected inverter for suppressing input low-frequency ripples, which belongs to isolated, micro-grid-connected inverters, and uses an added auxiliary circuit to suppress low-frequency current ripples at the input side of a DC power supply. Background technique [0002] Due to problems such as energy crisis and environmental pollution, photovoltaic power generation with a series of advantages such as cleanness and sustainability has attracted people's attention, making the photovoltaic industry develop rapidly. As we all know, photovoltaic panels need to use maximum power tracking to achieve their maximum power constant output, while the output power of grid-connected inverters contains power ripples twice the frequency of the grid. If the power ripples are not decoupled, it will lead to inverter The input current of the inverter contains a large number of low-frequency ripple component...

AI Technical Summary

Problems solved by technology

It is the easiest way to directly connect a large-capacity electrolytic capacitor in parallel on the DC side to filter out low-frequency ripple currents. However, electrolytic capacitors have problems such as large volume and short life, which not only affect the power density of the system, but also cause relatively high maintenance costs.

In the circuit, the LC resonant circuit whose resonant frequency is twice the grid frequency can also filter out the low-frequency current ripple and reduce the capacitance value, but the inductance and capacitance required by this method are still relatively large, to a certain extent Affects system power density

All in all, the method of using passive devices to suppress the low-frequency current ripple on the input side of the inverter has problems such as large volume and low reliability.

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