Hybrid multi-level grid-connected converter based on Si and SiC devices and control method of hybrid multi-level grid-connected converter

Abstract

The invention relates to a hybrid multi-level grid-connected converter based on Si and SiC devices and a control method thereof, the converter comprises a three-phase three-level circuit unit and a cascaded H-bridge shaping circuit unit, the structures of all phases in the cascaded H-bridge shaping circuit unit are the same, and each phase comprises a high-frequency sub-module and a low-frequency sub-module connected in series with the high-frequency sub-module; the high-frequency sub-module comprises a single-phase full-bridge converter consisting of two Si IGBTs (Silicon Insulated Gate Bipolar Translator) connected in series and two SiC MOSFETs (Silicon Carbide Metal-Oxide-Semiconductor Field Effect Transistors) connected in series; and the low-frequency sub-module comprises a single-phase full-bridge converter consisting of four Si IGBTs The output voltage uo of the converter is a sine wave formed by shaping the high-voltage three-level voltage unpc output by the three-level circuit unit by the shaping voltage uchb output by the cascaded H-bridge shaping circuit unit. According to the invention, a small number of SiC MOSFET devices and Si IGBT devices are mixed and used in the topology, so that the efficiency and the power density of the device can be improved, and the cost can be reduced.

Description

technical field [0001] The invention relates to the technical field of voltage converters, in particular to a hybrid multilevel grid-connected converter based on Si and SiC devices and a control method thereof. Background technique [0002] In recent years, with the rapid development of power electronics technology, multi-level converters have been widely used in many industrial scenarios such as electric drive, electric traction and new energy power generation due to the advantages of many output levels, low harmonic content and low voltage stress of switching devices. application. Among them, the Cascaded H-bridge (CHB) multi-level topology is widely used in static var compensators, active power filters due to its simple structure, easy modularization, good output waveform quality, and high redundancy. and dynamic voltage restorer and other power quality management devices. However, in high-voltage and high-power application scenarios, the drawbacks of CHB-type converter...

AI Technical Summary

Problems solved by technology

However, the CHB circuit module is usually composed of a single Si device, and the switching loss of the hybrid topology high-frequency module is still high, and it is difficult to further improve the device efficiency.

In order to further optimize the topology performance, the CHB topology based on all-SiC devices has been proposed one after another, but the cost of SiC devices is high, and the conduction loss is large under high-current conditions.

Images