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Current reconstruction method of NPC three-level converter based on model predictive control

A technology of model predictive control and current reconstruction, applied in the direction of converting AC power input to DC power output, output power conversion devices, electrical components, etc., can solve the problems of unbalanced three-phase current and different sensitivity of AC current sensors, etc. To achieve the effect of improving control performance

Pending Publication Date: 2022-05-13
ZHENGZHOU UNIVERSITY OF LIGHT INDUSTRY
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Problems solved by technology

In the direct measurement method, even in the case of three-phase load balance, the measured three-phase current may be unbalanced due to the different sensitivity of the AC current sensor

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  • Current reconstruction method of NPC three-level converter based on model predictive control
  • Current reconstruction method of NPC three-level converter based on model predictive control
  • Current reconstruction method of NPC three-level converter based on model predictive control

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Embodiment Construction

[0055] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

[0056] Conventional current reconfiguration of MPC: When the AC current sensor fails, usually for figure 1 The shown structure adopts the conventional MPC-based current reconstruction method to reconstruct the three-phase current. Taking the A-phase sensor failure as an example, the A-phase current can be determined by the B-phase current i b , DC line current i dc and phase voltage state P(U dc / 2), O(0), N(-U dc / 2) get.

[0057] Since th...

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Abstract

The invention provides a current reconstruction method of an NPC three-level converter based on model predictive control. The current reconstruction method is used for solving the CUAs problem of a traditional method. The method comprises the following steps: firstly, collecting direct current and power grid voltage; secondly, sampling twice in a sub-vector action period according to the optimal virtual vector of the last period, and calculating a three-phase current; thirdly, performing Clark conversion on the three-phase current and the power grid voltage to obtain alpha and beta components, obtaining a power grid angle through a phase-locked loop, setting a reference current, and calculating a reference voltage; then, constructing a virtual voltage vector control set according to the on-off state of the three-level NPC grid-connected converter; and finally, a cost function is constructed, the minimum value of the cost function is calculated according to the reference voltage and the virtual voltage vector, and the virtual voltage vector corresponding to the minimum value is used for controlling current prediction control of the next period. According to the invention, the problem that the DC voltage utilization rate is reduced in a conventional MPC current reconstruction scheme is solved, and accurate reconstruction current can be provided.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a current reconstruction method of an NPC three-level converter based on model predictive control. Background technique [0002] Compared with two-level converters, NPC three-level converters are widely used in grid-connected converter systems because of their low switching frequency, small output current harmonic components, and small switching stress. Accurate three-phase current acquisition is very important in most grid-connected converter control strategies. Direct measurement and current reconstruction are the two main methods for obtaining three-phase currents. In the direct measurement method, even in the case of three-phase load balance, the measured three-phase current may be unbalanced due to the different sensitivity of the AC current sensor. Direct measurement requires more sensors than current reconstruction. Therefore, current reconfiguration has attra...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/483H02M7/487H02M7/5387H02J3/38
CPCH02M7/483H02M7/487H02M7/53871H02J3/381
Inventor 金楠侯智文代东任肖晗武洁王锐谢欢樊武闯夏英巽马梓洋
Owner ZHENGZHOU UNIVERSITY OF LIGHT INDUSTRY