Three-level three-phase four-bridge arm converter

Abstract

The invention discloses a three-level three-phase four-bridge arm converter which comprises a direct-current part, a converting part, a converting part controller, a fourth bridge arm and a fourth bridge arm controller, wherein the converting part is a diode clamp type three-level inverter, the fourth bridge arm is a T-type three-level structure, the exchange of energy at a direct-current side and an alternating-current side is realized by controlling the states of first three bridge arm power switching tubes of the converting part, and a neutral point voltage at the direct-current side is changed by controlling the state of a power switching tube of the fourth bridge arm to realize the balance of neutral point potential. The fourth bridge arm of the three-level three-phase four-bridge arm converter adopts a T-type three-level topology and omits 2 clamp diodes compared with the diode clamp-type three-level inverter, thus saving the cost, and being more balanced in power loss and higher in efficiency; the control of neutral point balance is not affected by a power factor, the modulation degree and a modulation strategy; and as the deviation permission range of the neutral point voltage at the direct-current side is controllable, the permission range can be adjusted according to actual working conditions to improve the efficiency of a system.

Description

technical field [0001] The invention relates to the field of power electronic conversion technology, in particular to a three-level three-phase four-arm converter, which is especially suitable for photovoltaic grid-connected power generation and wind power generation based on the combination of power electronic conversion technology and computer control technology. Transformation system. Background technique [0002] In today's pursuit of a low-carbon society, solar energy and wind energy, as clean and renewable energy sources, are increasingly valued by countries all over the world. From 2006 to 2009, the annual growth rate of global solar photovoltaic cell production was 60%. In 2010, the global photovoltaic power generation market reached 15GW, and there are 9 countries in the world whose photovoltaic power generation market exceeds 250MW. At the same time, the global wind power industry is also growing at an astonishing rate. Since 1996, the cumulative global wind power...

AI Technical Summary

Problems solved by technology

So far, scholars at home and abroad have proposed a variety of algorithms for the midpoint balance of diode-clamped three-level converters, but most of them use the method of adjusting the positive and negative redundant small vectors, and the suppression effect is related to the power factor of the system , modulation degree and modulation strategy are closely related, and the scope of application is limited

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