Four-level three-phase grid-connection inverter and modulation method and power generation system thereof

Abstract

The invention relates to a nested neutral point clamping four-level three-phase grid-connection inverter. The three-phase grid-connection inverter comprises three nested neutral point clamping four-level bridge arms; each bridge arm comprises a first power electronic switching tube, a second power electronic switching tube, a third power electronic switching tube, a fourth power electronic switching tube, a fifth power electronic switching tube and a sixth power electronic switching tube which are connected in sequence, and a first power diode connected between the midpoint of the second powerelectronic switching tube and the third power electronic switching tube and the neutral point, a second power diode connected between the midpoint of the fourth power electronic switching tube and the fifth power electronic switching tube and the neutral point, a first flying capacitor connected between the midpoint of the first power electronic switching tube and the second power electronic switching tube and the neutral point, and a second flying capacitor connected between the midpoint of the fifth power electronic switching tube and the sixth power electronic switching tube and the neutral point. The three-phase grid-connection inverter can improve input voltage and inversion performance and is easy to control.

Description

technical field [0001] The invention belongs to the technical field of electric energy inverter, and in particular relates to a nested neutral point clamp four-level three-phase grid-connected inverter. The nested neutral point clamp four-level three-phase grid-connected inverter adopts The modulation method and the power generation system applying the nested neutral point clamped four-level three-phase grid-connected inverter. Background technique [0002] With the gradual depletion of energy and the increasingly serious environmental problems, new energy sources (such as solar energy, wind energy, biomass energy, etc.) are increasingly utilized to generate electricity. Among various renewable energy sources, solar energy is a new energy source with great development potential. The output of the solar panel is direct current, which needs to be converted into alternating current by an inverter to supply the load or to the grid. The inverter is the interface between photovo...

AI Technical Summary

Problems solved by technology

[0004] With the rapid development of photovoltaic power generation technology, there are currently high-voltage photovoltaic panels in the market. After the high-voltage photovoltaic panels are connected in series and parallel, the DC input voltage reaches 1500V, while the conventional commercial power below 50KW T-type three-level three-phase inverter The input voltage of the transformer is less than 1000V, and the input voltage of 1500V cannot be realized

For a three-phase photovoltaic power generation system with 1500V DC input, the structure of the existing four-level three-phase grid-connected inverter is mainly a combination of a diode-clamped four-level inverter and a flying-capacitor four-level inverter. Partial structure, but the number of semiconductor devices in the traditional diode-clamped four-level inverter and flying-capacitor four-level inverter is large

In addition, five-level inverters can also be used for three-phase photovoltaic power generation systems with 1500V DC input, but five-level three-phase inverters have the disadvantages of many power electronic switching devices and complex control.

Images