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A control method for mid-point potential balance of npc inverter with sub-area modulation

A potential balance, inverter technology, applied in electrical components, output power conversion devices, AC power input into DC power output and other directions, can solve problems such as system collapse, mid-point potential fluctuation, AC output voltage distortion, etc.

Active Publication Date: 2019-02-26
STATE GRID JIANGXI ELECTRIC POWER CO LTD RES INST +1
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  • Claims
  • Application Information

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Problems solved by technology

[0004] The purpose of the present invention is to solve the problem that the midpoint clamped three-level inverter topology will cause fluctuations in the midpoint potential, which will cause AC output voltage distortion, and even cause the system to collapse. The present invention proposes a sub-area Modulated NPC Inverter Midpoint Potential Balance Control Method

Method used

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  • A control method for mid-point potential balance of npc inverter with sub-area modulation
  • A control method for mid-point potential balance of npc inverter with sub-area modulation
  • A control method for mid-point potential balance of npc inverter with sub-area modulation

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Embodiment Construction

[0043] The specific implementation of the present invention will be described in detail below in conjunction with the accompanying drawings and working principles.

[0044] figure 1 Shown is a schematic diagram of the area divided by the three-level space voltage vector.

[0045] figure 2 is the area circle Z 1 The core diagram of the control algorithm; image 3 is the area circle Z 2 The core diagram of the control algorithm. like figure 2 and image 3 It can be seen that the control method of this embodiment includes the following steps:

[0046] (1) Refer to the traditional SVPWM algorithm to determine the position of the reference vector, define:

[0047]

[0048]

[0049]

[0050]

[0051] Among them, S 1 Indicates the reference vector 1, S 2 Indicates the reference vector 2, S 3 Indicates the reference vector 3, S 4 Indicates the reference vector 4; Udc Indicates the magnitude of the DC side voltage; U ref Indicates the magnitude of the refere...

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Abstract

A mid-point potential balance control algorithm for NPC inverters with sub-area modulation, including the following steps: (1) Divide the three-level vector space into a circle Z 1 Area and circle Z 2 (2) Due to the participation of the medium vector, the circular area cannot only consider controlling redundant small vectors to achieve the goal, but introduces virtual vectors for algorithmic control to balance the midpoint potential. The algorithm of the present invention regulates the three-level space vector graph by region: within the scope of region I, the characteristics of redundant small vectors and the influence of non-redundant small vectors on the midpoint current are fully utilized to select; within the scope of region II, Due to the influence of the medium vector, the virtual medium vector and the virtual small vector are introduced, so that the average current at the midpoint of the virtual medium vector and the virtual small vector is zero when they act. The invention has good effect on the balance control of the midpoint potential.

Description

technical field [0001] The invention relates to a midpoint potential balance control method of an NPC inverter modulated by regions, and belongs to the technical field of photovoltaic power generation. Background technique [0002] With the maturity of power electronics technology, multilevel inverters used in high-voltage and high-power fields have attracted great attention from the power electronics industry. However, most of the medium-voltage high-power multi-level inverters below 10KV have been implemented using a diode-clamped three-level structure. The balance of the mid-point potential of the three-level inverter is an important symbol to ensure the safe and efficient operation of the motor. If the mid-point potential is unbalanced, it will not only increase the harmonic distortion of the output current, generate low-order and even-order harmonics, and It will also increase the voltage borne by the switching device, and even damage the switching device and the volta...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/487
CPCH02M7/487H02M7/4833
Inventor 余运俊孙旻曾伟辛建波纪清照徐在德何昊陈波
Owner STATE GRID JIANGXI ELECTRIC POWER CO LTD RES INST
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