SVPWAM modulation method based on three-level direct matrix converter

Abstract

The present invention relates to an SVPWAM modulation method based on a three-level direct matrix converter. The method comprises the following steps: (1) determining input phase current space vectors and output phase voltage space vectors desired by a three-level direct matrix converter; (2) performing virtualization of the three-level direct matrix converter to a serial circuit model comprising a virtual rectification stage and a virtual inversion stage; (3) employing SVPWAM modulation for the virtual rectification stage to determine switching signals of each switch tube of the virtual rectification stage; (4) employing the SVPWAM modulation for the virtual inversion stage to determine switching signals of each switch tube of the virtual inversion stage; and (5) converting the switching signals of each switch tube of the virtual rectification stage and the switching signals of each switch tube of the virtual inversion stage to switching signals of each two-way switch of the three-level direct matrix converter. Compared to the prior art, the number of off and on times is maximally reduced, switching loss is reduced, the harmonic wave content of an input current is reduced, and the quality of a power grid is improved.

Description

technical field [0001] The invention relates to a control method of a three-level direct matrix converter, in particular to a SVPWAM modulation method based on a three-level direct matrix converter. Background technique [0002] AC power converters can be divided into AC-DC-AC converters and AC-AC converters according to their forms. Among them: the AC-DC-AC converter is composed of a rectifier side, an inverter side and an intermediate DC link; the AC-AC converter generally does not include a DC link, and realizes direct conversion from AC to AC. AC-AC power converters mainly include traditional AC-AC converters and matrix converters. [0003] Although the research and utilization of the AC-DC-AC converter has made great progress, with the continuous deepening of the concept of energy conservation and environmental protection, there are still many deficiencies, such as the converter has an intermediate DC link, which increases the size of the device and Installation cost,...

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Problems solved by technology

This kind of converter also has many disadvantages, such as: more thyristors are used, and the wiring is more complicated; it uses phase-controlled rectification, and the power factor is low; the output frequency range is narrow, only 1 / 3 to 1 / 2 of the grid frequency

Therefore, the traditional AC-AC frequency conversion can only be used in large-capacity, low-speed and heavy-duty occasions, such as mine hoists, rock crushers, etc.

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