Basic unit for multilevel converter, and three-level and m-level topological structures

Abstract

The invention discloses a basic unit for a multi-level converter. The basic unit comprises an insulated gate bipolar transistor and two diodes, wherein the two diodes are connected in series and then are connected in reverse parallel to the both sides of the insulated gate bipolar transistor, and three terminals are led out between the both sides of the insulated gate bipolar transistor and the two diodes. The basic unit is provided with three terminals forming three different types of bi-directional current paths, the problem that the existing structural basic unit has a single current path can be solved, and multilevel is easily formed. The invention also discloses a three-level topological structure, which has the advantages that the number of used devices is few, the number of output levels is more, the voltage stress is the same as that of the traditional T-type three-level structure, and the problem that the traditional two-level structure has low switching frequency when is used on high-power occasions can be solved. The invention also discloses an m-level topological structure, which has the advantages that a large number of clamping devices in the diode clamping multi-level structure is eliminated, and the problem that the loss is imbalanced in the clamping type multi-level topological structure can be solved.

Description

technical field [0001] The invention belongs to the technical fields of electric engineering, power electronics, and motor application, and in particular relates to a basic unit, three-level and m-level topological structures for multilevel converters. Background technique [0002] At present, the voltage source two-level topology inverter system has been widely used in many industrial fields such as motor drive, rail transit, and electric energy conversion. However, this topology inverter system withstands high voltage stress and large dv / dt , High harmonic distortion rate of output current, large volume of output filter and other limitations. [0003] Using the voltage source type multi-level topology inverter system can well solve the shortcomings brought about by the two-level converter. However, in several types of traditional multi-level inverter systems, different multi-level topologies not only have the maximum number of output levels that can only be odd, but also ...

AI Technical Summary

Problems solved by technology

[0008] Technical problem: The technical problem to be solved by the present invention is to provide a basic unit for a multilevel converter. The basic unit has three terminals, which can form three different types of bidirectional current paths, and can solve the problem of existing structures. The problem of a single current path in the basic unit makes it easier to form multi-level

It also provides a three-level topology based on the above-mentioned basic unit. This structure uses a small number of devices and a large number of output levels. It has the same voltage stress as the traditional T-type three-level structure, and can solve the traditional two-level structure for large Low switching frequency, high current harmonic distortion rate, large output filter, unbalanced loss and other issues in power applications; and provide an m-level topology based on the above-mentioned basic unit, which eliminates the need for a diode-clamped multi-level structure A large number of clamping devices can solve the problem of unbalanced loss in the clamping multilevel topology and have higher fault tolerance

This structure can also solve the problem of a large number of independent power supplies and flying capacitors in the flying capacitor type and cascaded multilevel structure

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