Generalized three-level SVPWM modulation algorithm

A modulation algorithm and three-level technology, applied to electrical components, output power conversion devices, AC power input conversion to DC power output, etc., to achieve the effect of simple vector calculation process, optimized program code, and common mode improvement

Active Publication Date: 2017-05-24
SHANGHAI CHINT POWER SYST
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The invention patent with the publication number CN101917132A relates to a new vector modulation method for a three-phase three-wire three-level inverter. situation doesn't work

Method used

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  • Generalized three-level SVPWM modulation algorithm
  • Generalized three-level SVPWM modulation algorithm
  • Generalized three-level SVPWM modulation algorithm

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Embodiment Construction

[0024] In order to make the present invention more comprehensible, preferred embodiments are described below in detail with accompanying drawings.

[0025] The common mode voltage is related to the topology and modulation mode of the three-phase inverter. Such as figure 1 Shown three-level inverter system structure, common mode voltage V cm The size of can be described by equation (1).

[0026] V cm =(u ao +u bo +u co ) / 3 (1)

[0027] In formula (1), u xO , X=a, b, c is the voltage of the three-phase inverter output to the midpoint of the BUS.

[0028] Define switch variable S a , S b , S c Indicates the output state of the three bridge arms, and taking O point as the reference potential, the voltage of each phase is expressed as formula (2):

[0029]

[0030] In formula (2), E is the entire BUS voltage, x=a, b, c.

[0031] by figure 1 Easily get formula (3):

[0032]

[0033] In formula (3), v xN , X=a, b, c is figure 1 Middle three-phase output a / b / c to voltage at point N of t...

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Abstract

The invention relates to a generalized three-level SVPWM modulation algorithm which is characterized by comprising the following steps: 1) judging a big sector and a small sector in which a reference voltage vector is located; 2) selecting the acting time of vector calculation and resultant vector; and 3) arranging a vector sequence and calculating a duty ratio. The algorithm provided by the invention is mainly used for solving the problem of serious common mode when a modulation ratio of a high-pressure system is small, the common mode voltage of the system is reduced, and smaller THDI can be guaranteed. According to the algorithm provided by the invention, the judgment for the small sector is simplified as two small sectors, procedure codes are optimized, and the vector calculation process is simpler. After the algorithm provided by the invention is adopted, the common mode within a full-voltage modulation degree scope can be improved, the EMI can be effectively reduced, and the smaller THDI can be guaranteed.

Description

Technical field [0001] The present invention relates to a new modulation algorithm, in particular to a generalized three-level SVPWM new modulation algorithm, which is applied to three-phase three-level inverter topology and is used in photovoltaic inverters, wind power converters, UPS, frequency converters , Active filters, rectifiers and other high-voltage and high-power fields are widely used. Background technique [0002] For three-phase three-level converters, modulation strategies include SPWM and SVPWM. The SVPWM modulation strategy has higher BUS voltage utilization and smaller harmonics and is widely used. Due to the numerous switching devices of the three-level inverter, there are more space voltage vectors, especially the existence of redundant space voltage vectors, which makes the zero sequence component of the three-level inverter have its particularity and flexibility. The same reference vector can be achieved by choosing different voltage vectors, so there are m...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/5395
CPCH02M7/5395
Inventor 徐锡军黄佳佳张玉林张俊
Owner SHANGHAI CHINT POWER SYST
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