Three-phase five-level inverter

Abstract

The embodiment of the invention discloses a three-phase five-level inverter, which comprises a direct-current unit and a three-phase inversion unit, wherein the first input end of the direct-current unit is connected to the anode of a direct-current power supply; the second input end of the direct-current unit is connected to the cathode of the direct-current power supply; the direct-current unit comprises three output ends, i.e., a two-level output end, a one-level output end and a zero-level output end; the three-phase inversion unit comprises three single-phase five-level full-bridge inversion units; each single-phase five-level full-bridge inversion unit comprises a two-level input end, a one-level input end, a zero-level input end, a first output end and a second output end, wherein the two-level input end is connected with the two-level output end; the one-level input end is connected with the one-level output end; the zero-level input end is connected with the zero-level output end; and the first output end and the second output end are used for outputting the alternating current voltage. According to the three-phase five-level inverter disclosed by the invention, the output voltage is correspondingly improved by one time, the boosting efficiency is improved, the line transmission loss in a medium-voltage transformer boosting process is reduced, and the problem of low boosting efficiency in the prior art is solved.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a three-phase five-level inverter. Background technique [0002] In high-power photovoltaic power plants, three-phase half-bridge inverters are generally used to output 270V or 315V voltage, and then connected to the medium-voltage grid through an external medium-voltage transformer. The higher the output voltage of the inverter, the smaller the line transmission loss during the step-up process through the medium-voltage transformer. Therefore, increasing the output voltage is one of the mainstream trends in the development of high-power photovoltaic power plant inverters. In the prior art, a stacked boost circuit is generally used to increase the voltage on the DC side of the inverter, thereby achieving the purpose of increasing the AC output voltage. However, since the voltage boosting range of the boost voltage boosting circuit is relatively wide, the voltage boost...

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Problems solved by technology

[0003] In view of this, the purpose of the present invention is to provide a three-phase five-level inverter to solve the problem of low boosting efficiency of the output voltage by inverters commonly used in existing high-power photovoltaic power plants

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