Method for controlling neutral point voltage balance of three level converter

A three-level inverter and voltage balancing technology, which is applied in the direction of converting AC power input to DC power output, electrical components, and output power conversion devices, can solve the problem of limiting the flexibility of hybrid space vector modulation strategies and large switching frequencies and other issues, to achieve the effect that is conducive to analysis and expansion of applications

Active Publication Date: 2012-02-22
TIANJIN UNIV
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Problems solved by technology

The fixed ratio limits the flexibility of the hybrid space vector modulation strategy, and compared with the NTV modulation method, its switching frequency is still large

Method used

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  • Method for controlling neutral point voltage balance of three level converter
  • Method for controlling neutral point voltage balance of three level converter
  • Method for controlling neutral point voltage balance of three level converter

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Embodiment Construction

[0025] The NTV modulation method has the advantage of lower switching frequency, NTV 2 The modulation method can control the neutral point voltage balance in the whole range under any load condition and under any operating condition. The present invention combines NTV and NTV 2 The two modulation methods are mixed, and the switching condition of the hybrid space vector modulation strategy with a fixed ratio is designed by using the redundant small vector allocation factor, and the ratio of the hybrid space vector modulation strategy is adjusted by designing the upper and lower limits of the judgment condition.

[0026] The present invention will be described in further detail below in conjunction with specific examples and accompanying drawings.

[0027] The implementation process of the present invention is as follows: first solve the redundant small vector allocation factor according to the modulation coefficient and power factor; then set the judgment condition as [0, 1] t...

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Abstract

The invention, which belongs to the power converter control field of the driving motor, relates to a method for controlling neutral point voltage balance of a three level converter, wherein the method is based on a voltage space vector pulse width modulation technology and is used for controlling a neutral point clamped three level inverter. The method comprises the following steps that: step one, an action time distribution factor of a redundant small vector is obtained; step two, an area where control on a neutral point potential balance can be realized by a nearest three vector (NTV) method is obtained; step three, an NTV action area in a mixed voltage space vector pulse width modulation method is obtained; step four, a switching condition of the mixed voltage space vector pulse width modulation method is designed; and step five, the mixed voltage space vector pulse width modulation method with a proportion of pm is realized. According to the invention, a redundant small vector distribution factor is employed to design a switching condition of a mixed voltage space vector pulse width modulation strategy; therefore, an essence of a space vector modulation method is embodied; themethod can be used flexibly and used variables are less, so that it is beneficial for analysis and development application.

Description

technical field [0001] The invention relates to the field of power converter control for driving motors, in particular to a multilevel converter space vector modulation method. Background technique [0002] In high-power applications, multi-level converters have been more and more widely used due to the advantages of low voltage withstand of switching devices, low harmonic content of output voltage, and low switching frequency. Among them, the NPC (Neutral Point Clamped) three-level converter is the most widely used multi-level structure. It only needs an independent DC voltage source and has low requirements on hardware. [0003] There is an inherent shortcoming in the NPC three-level converter, that is, there is a problem of unbalanced midpoint voltage. The commonly used method to control the neutral point voltage balance is to control the neutral point voltage balance by controlling the action time of the positive and negative small vectors in the NTV (Nearest Three Vect...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/483
CPCH02M7/487H02M7/53876
Inventor 夏长亮邵虹君张云史婷娜陈炜
Owner TIANJIN UNIV
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