Full-bridge module and half-bridge module-based mixed multi-level converter and control method thereof

Abstract

The invention discloses a full-bridge module and half-bridge module-based mixed multi-level converter, which comprises three phase units; the three phase units are connected between an anode direct current bus and a cathode direct current bus; each phase unit is formed by an upper bridge arm and a lower bridge arm; each bridge arm comprises N half-bridge modules and one full-bridge module with a direct current power supply; the N half-bridge modules and the full-bridge module with the direct current power supply are serially connected and N is a positive integer. The invention also discloses a control method of the full-bridge module and half-bridge module-based mixed multi-level converter. According to the full-bridge module and half-bridge module-based mixed multi-level converter and the control method thereof, higher output level number is realized by fewer half-bridge modules as far as possible, when the voltage of the half-bridge modules is subjected to sorting algorithm, the time used by computation is less, the efficiency is higher, the module put-into-use speed is faster and the fluctuation of voltage and capacitance is reduced.

Description

technical field [0001] The invention relates to the field of modular multilevel converters, in particular to a hybrid multilevel converter based on full-bridge and half-bridge modules and a control method thereof. Background technique [0002] In the field of DC transmission based on voltage source converters, two-level topologies were first used, and the withstand voltage and transmission power of switching devices are limited, and output filtering devices need to be added. In order to solve these problems, multilevel voltage source converters began to appear and received more and more attention. These multi-level converters can be divided into three categories in principle: the first type is clamped multi-level structure; the second type is the direct series superposition of single-phase full-bridge converters (ie H-bridges). Cascaded structural form; the third type is a structural form in which sub-module units are composed of capacitors and half-bridge switching devices...

AI Technical Summary

Problems solved by technology

Among them, as the number of output levels increases in the first type of topology, the required clamping diodes or floating capacitors will increase sharply, which will bring great difficulties to system control, production and assembly.

Although the second type of topology realizes modularization and is easy to expand, it requires a large number of independent DC power supplies

However, the number of required modules and the number of switching devices are still large, and little progress has been made in increasing the number of output levels

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