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: 2010-06-30
TIANJIN UNIV
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  • Application Information

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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 p

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 discontinuous conduction mode (DCM) and continuous conduction mode (CCM). The continuous conduction mode can be divided into inductor independent energy supply mode and inductor. -Capacitor power supply 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 switching signal phase difference method to suppress the midpoint potential drift, the influence of the switching signal phase difference θ should be considered when calculating the critical inductance between different working m...

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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 boost converter; 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 the boosting 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 the 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 generator stator is connected to the grid through a converter, so the generator has less interference to the grid; the generator speed is not restricted by the grid frequency, so there is no need to increase speed 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 Shown is a typical direct...

Claims

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Application Information

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IPC IPC(8): H02M7/44H02M7/515
CPCY02E10/76
Inventor 夏长亮谷鑫史婷娜
Owner TIANJIN UNIV
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