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Method for restricting midpoint potential drifting of three-level inverter in direct drive wind power system

A three-level inverter, wind power system technology, applied in wind power generation, irreversible DC power input conversion to AC power output, electrical components, etc. Drift etc.

Inactive Publication Date: 2012-01-04
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

During the working process of the three-level inverter, there is a problem of midpoint potential drift on the DC side. At present, the method to solve this problem at home and abroad is to improve the modulation algorithm of the inverter, which increases the complexity of the modulation algorithm of the inverter.

Method used

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  • Method for restricting midpoint potential drifting of three-level inverter in direct drive wind power system
  • Method for restricting midpoint potential drifting of three-level inverter in direct drive wind power system
  • Method for restricting midpoint potential drifting of three-level inverter in direct drive wind power system

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Embodiment Construction

[0026] 1. Selection of boost inductor for three-level Boost converter

[0027] Compared with the conventional Boost converter, the three-level Boost converter in the present invention also has a discontinuous conduction mode (DCM) and a continuous conduction mode (CCM), and the continuous conduction mode can be divided into an inductor independent energy supply mode and an inductor -Capacitor powered mode. The working mode of the converter mainly depends on the size of the boost inductor. When the load condition remains relatively stable and the switching frequency remains constant, the critical inductance is only related to the duty cycle d (when the difference is not equal to π, it is called the boost ratio). Since the present invention designs a controllable switch signal phase difference method for suppressing the midpoint potential drift, the influence of the switch signal phase difference θ should be considered when calculating the critical inductance between different ...

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Abstract

The invention belongs to the control field of energy conversion devices of high capacity direct drive permanent magnet synchronous wind power systems, relating to a method for restricting the midpoint potential drifting of a three-level inverter. The method comprises the following steps of: determining the work mode of a three-level boost converter, calculating a critical inductance value, and determining a boosting inductance value; collecting a generator rotate speed signal of a direct drive wind power system and two capacitor voltage signals at direct current sides of the three-level boostconverter; carrying out PI regulation according to a difference value between an actual rotate speed and a reference rotate speed by a microcontroller, and then outputting a reference value d* of theboosting ratio of the three-level boost converter; calculating a difference value between the two capacitor voltage signals at the direct current sides, carrying out PI regulation of the other path on a difference value between the difference value and zero, and outputting a difference reference value theta * between switching signals; and calculating respective conducting and shutting time of two switching devices, and controlling the on / off of the two switching devices. The invention can effectively restrict the midpoint potential drifting at the direct current sides of the three-level inverter on the premise of not increasing circuits for regulating the midpoint potential.

Description

technical field [0001] The invention belongs to the field of energy conversion device control of a large-capacity direct-drive permanent magnet synchronous wind power generation system, and relates to a method for suppressing midpoint potential drift of a three-level inverter. Background technique [0002] The structure and control of the direct-drive permanent magnet wind power system are relatively simple; the stator of the generator is connected to the grid through a converter, so the generator interferes less with the grid; Gearboxes relatively save equipment and maintenance costs; in addition, with the popularization of high-power switching devices and the emergence of large-capacity converter topologies, large-capacity direct-drive wind power generation systems have broken through the capacity limitations of energy conversion devices. [0003] figure 1 The structure of a typical direct-drive permanent magnet synchronous wind power generation system is shown, in which ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/44H02M7/515
CPCY02E10/76
Inventor 夏长亮谷鑫史婷娜
Owner TIANJIN UNIV
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