Hybrid multilevel converter based on full-bridge and half-bridge modules and its control method

Abstract

The invention discloses a hybrid multilevel converter based on a full-bridge and a half-bridge module, including a three-phase unit connected between positive and negative DC bus bars, each phase unit consisting of an upper bridge arm and a lower bridge arm, Each bridge arm includes N half-bridge modules and one full-bridge module with a DC power supply, the N half-bridge modules and one full-bridge module with a DC power supply are connected in series, and N is a positive integer. The invention also discloses a control method for the hybrid multilevel converter. The present invention utilizes as few half-bridge modules as possible to achieve a higher output level of the converter, and when performing a sorting algorithm on the voltages of the half-bridge modules, the calculation takes less time and is more efficient, and the module input speed is accelerated, which can Reduce capacitor voltage fluctuations.

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; Cascaded structural form; the third type is a structural form in which sub-module units are composed of capacitors and half-bridge switching devices, and the sub-module units are connected in series between the positive and negative DC bus bars of the co...

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

Images