Inter-partition dual-vector model predictive control method for parallel PWM rectifier

Abstract

The invention discloses an inter-partition dual-vector model predictive control method for a parallel PWM rectifier. The method comprises the steps that voltage vector inter-partition calculation is introduced into model predictive control, and a vector duty cycle modulation method is combined, so that the reduction of zero sequence circulating current and the decrease of processor computation time can be effectively achieved; the influence of different voltage vector combinations on circulating current in a control system is directly analyzed, then 36 voltage vector combinations are divided into 4 partitions, so that the zero sequence circulating current and processor computation burden are reduced; by optimizing effective vector duty cycles of a selected partition, a control cycle is divided into two parts, effective vectors only act on a part of the control cycle, and the remaining time selects zero vectors to further improve the system circulating current suppression precision; andfinally, cyclic optimizing computation is carried out on voltage vectors in the selected partition. The problem of uneven current and waveform distortion caused by the circulating current can be solved without additional hardware devices, and the reliability and efficiency of the system are improved.

Description

technical field [0001] The invention belongs to the application field of power electronics, and in particular relates to a dual-vector model predictive control system between parallel PWM rectifier sections. Background technique [0002] Parallel PWM rectifiers can improve system rated power, reliability, and efficiency, and have the advantages of low cost and small current ripple. At the same time, the parallel structure is very suitable for modular system design and system reconfiguration, and has better flexibility. However, due to the common DC bus of the parallel PWM converters and the direct parallel connection of the AC side, a zero-sequence circulation path is formed; due to the difference in control effects and hardware parameters, the control system will generate zero-sequence circulation. Circulating current will cause uneven current and three-phase current distortion. At the same time, circulating current will increase loss, reduce system efficiency and cause ser...

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Problems solved by technology

[0003] Model predictive control is a calculation based on the dynamic model of the system. It can design value functions according to different design requirements. Due to its simple concept, fast dynamic response, easy consideration of system constraints, and excellent multi-variable control capabilities, it has attracted attention in recent years. Many scholars at home and abroad have studied its application in the field of power transmission and power electronics, but there are few literatures that apply model predictive control to the circulation suppression of parallel PWM converters.

The traditional parallel PWM rectifier control system has poor circulation suppression effect and the processor calculation time is too long, which reduces the reliability and efficiency of the control system

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