Three-phase inverter powered by overlapped double power supplies

Abstract

The invention discloses a three-phase inverter powered by overlapped double power supplies. The three-phase inverter consists of a pre-stage conversion circuit, a post-stage inversion circuit and an output filter, wherein the post-stage inversion circuit is a three-phase inversion circuit with four direct current side input ends; the pre-stage conversion circuit supplies power to the direct current sides of the post-stage inversion circuit through a high level line, a high middle level line, a low middle level line and a low level line on the direct current sides of the post-stage inversion circuit; three output ends of the post-stage inversion circuit are connected with the output filter respectively; the pre-stage conversion circuit can adjust the voltage of the high middle level line and the low middle level line. The pre-stage circuit powered by the overlapped double power supplies, which is used by the three-phase inverter, is suitable for creating a good working condition for the post-stage circuit, and is low in cost and loss; in the post-stage inversion circuit, the change amplitude of the voltage on a switching tube before and after switching on and off is small, so that the cost and the loss of the post-stage inversion circuit can be greatly reduced and the leakage current can be reduced.

Description

technical field [0001] The invention relates to a power electronic device for converting direct current into alternating current—inverter. Background technique [0002] An inverter is an electronic device that converts direct current into alternating current. For example, the direct current generated by a solar cell array must be converted into alternating current before it can be sent to the grid, or the uninterruptible power supply converts the direct current generated by the battery into alternating current to temporarily supply power to the load. [0003] Generally, the DC input voltage of the inverter will vary within a certain range. For example, the maximum power point voltage of a solar cell array will vary greatly with temperature and light. Generally, photovoltaic inverters are designed to allow a difference of more than 1.8 times between the highest and lowest values ​​of the maximum power point voltage of a solar cell array. In order to work normally under the l...

AI Technical Summary

Problems solved by technology

[0007] In the patent application submitted by the inventor with the application number 201410372122.3 and the name of a four-wire output converter and an inverter composed of four-wire output converters, a pre-stage converter with overlapping dual power supply is used. The front-stage circuit of the boost booster type has obvious advantages, but it has no components to adjust the voltage of the two intermediate level lines, and the voltage applied to the output filter reactor by the three-phase inverter circuit of the subsequent stage is still large, so that the output The cost and loss of the filter reactor cannot be greatly reduced

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