Photovoltaic grid-connected three-level inverter

Abstract

The invention discloses a photovoltaic grid-connected three-level inverter, and relates to equipment which is used for converting irreversible direct-current power input of a semiconductor device with a control grid into alternating current power output and is used together with a power supply system of a power supply. The inverter consists of a photovoltaic array module, six identical switching tubes, two identical diodes, two groups of identical capacitors, two identical inductors and a power grid. The photovoltaic grid-connected three-level inverter does not generate common mode current, has low differential mode voltage, low current ripple and high efficiency, and overcomes the defect that the three-level inverter needs direct-current input voltage which is about two times that of a full-bridge inverter in the prior art.

Description

technical field [0001] The technical solution of the present invention relates to a device for converting the irreversible DC power input of a semiconductor device with a gate electrode into an AC power output and for use with a power supply system of a power supply, specifically a photovoltaic grid-connected three-level inverter. Background technique [0002] Solar photovoltaic power generation technology is the most promising way of new energy and renewable energy, and photovoltaic grid-connected power generation technology has become the mainstream of solar photovoltaic applications. The latest statistics show that: as of the end of 2008, the total installed capacity of the world has reached 13.4GW; compared with 2007, the total installed capacity of photovoltaic systems in 2008 increased by 50%; 99% of capacity. [0003] Usually in the prior art, the photovoltaic grid-connected inverter includes a power frequency transformer to achieve electrical isolation to meet safe...

AI Technical Summary

Problems solved by technology

State-of-the-art 3-level inverters and their modifications do not generate a common-mode voltage, but their main disadvantage is that they require approximately twice the DC input voltage of a full-bridge inverter

If the output voltage of the inverter is AC 220V, the input voltage of the three-level inverter in the prior art is higher than 700V, which requires more photovoltaic arrays to be connected in series or a pre-stage booster circuit connected in series, and the withstand voltage level should be higher. The high switching tube affects the switching frequency and increases the switching loss (see the paper "Multilevel converters for single-phase grid connected photovoltaic systems-an overview" (IEEE International Symposium on Industrial Electronics, Pertoria, South Africa, 1998.) and the paper "A cost-effective single-stage inverter with maximum power point tracking" (IEEE Transactions on Power Electronics, 2004, 19(5): 1289-1294.))

Images