Inverter common mode voltage suppression method based on optimal selection of logic switching vector

Abstract

The invention discloses a method for suppressing the common mode voltage of the inverter based on the optimal selection of the logic switch vector, by detecting the inverter at t k The actual output value at time [i α (k), i β (k)] T , apply the optimal voltage vector S of the last cycle to the inverter x (k), x∈{a,b,c}, according to the prediction model, predict S x (k), x∈{a,b,c} under the action of t k+1 The current value at any time determines the selectable vector range based on the optimized vector range of the logic switch vector optimization method in the g-h coordinate system, and performs FCS on the effective voltage vector within the selectable vector range under the g-h coordinate ‑MPC prediction optimization, select to act on [(k+1)T s ,(k+2)T s ] period, so that t k+2 The vector S with the best current following performance index at all times x (k+1), x∈{g,h}, perform switching vector mapping from the g-h coordinate system to the a-b-c coordinate system, and select the vector with the smallest common-mode voltage as the final optimal vector Inverter control in the next cycle to achieve minimum common-mode voltage output control of redundant switching vectors.

Description

technical field [0001] The invention relates to the technical field of multi-level converter predictive control, in particular to a common mode voltage suppression method of an inverter based on the optimal selection of a logic switch vector. Background technique [0002] Energy shortage is one of the major problems facing the development of human society at present, and frequency conversion speed regulation is the most effective way to achieve energy saving and emission reduction. Thanks to the progress and development of power electronic technology, it has been widely used in high energy-consuming industrial fields High-power frequency conversion speed control device. However, in the operation of the inverter, the output side of the inverter will inevitably generate a common-mode voltage of a relatively large magnitude, which will bring many negative effects to the safe operation of electrical equipment such as motors, such as the formation of shaft currents on the motor s...

AI Technical Summary

Problems solved by technology

The method based on objective function optimization takes advantage of the characteristics of FCS-MPC to easily realize multi-objective optimal control. By adding the common-mode voltage suppression optimization performance index in the objective function, the control of the output common-mode voltage amplitude is realized, but the effect of common-mode voltage suppression is different from that of The selection of weight factors is closely related. Considering the conflict between optimization performance indicators, it is difficult to configure a single weight factor to meet the different control effects expected by the designer.

The core idea of ​​the method based on switch vector optimization is to eliminate the vector with large output common-mode voltage, and only select the vector with small output common-mode voltage, but for multi-level inverter and multi-objective comprehensive optimal control, Still have to solve the problem of excessive predictive computation and unweighted factor controller design

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