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PWM modulation method for improving harmonic characteristic of output current of three-phase photovoltaic inverter

A photovoltaic inverter, harmonic characteristics technology, applied in photovoltaic power generation, output power conversion device, AC power input conversion to DC power output and other directions, to achieve good modulation effect, improve the effect of harmonic characteristics

Active Publication Date: 2017-11-28
JIANGSU GOODWE POWER SUPPLY TECHNOLOGY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0013] The purpose of the present invention is to provide a PWM modulation method aiming at the problem of harmonic characteristics caused by the excessive change of the slope of the third harmonic, thereby improving the industrial mode current and further improving the harmonic characteristics of the output current

Method used

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  • PWM modulation method for improving harmonic characteristic of output current of three-phase photovoltaic inverter
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  • PWM modulation method for improving harmonic characteristic of output current of three-phase photovoltaic inverter

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Embodiment 1

[0034] Embodiment 1: A PWM modulation method for improving the harmonic characteristics of the output current of a three-phase photovoltaic inverter is: changing the waveform of the third harmonic injected into the SPWM modulation wave through an algorithm, that is, injecting a smooth waveform into the sinusoidal SPWM modulation wave The third harmonic of the SVPWM modulation wave is obtained, and the PWM modulation is performed by using the SVPWM modulation wave. In this way, the problem of large changes in the common-mode voltage slope can be solved, the working-mode current can be improved, and then the harmonic characteristics of the output current can be improved. Usually, the third harmonic with a smooth waveform can be obtained by making the peak slope of the waveform of the third harmonic tend to 0.

[0035] For example, the third harmonic is obtained by the following three formulas:

[0036] Formula 1:

[0037] Formula 2:

[0038] Formula three:

[0039] In ...

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Abstract

The invention relates to a PWM modulation method for improving harmonic characteristic of an output current of a three-phase photovoltaic inverter. According to the method, a sine SPWM modulation wave is injected with third harmonics with smooth waveform to obtain SVPWM modulation wave; the SVPWM modulation wave is adopted for PWM modulation; and the waveform peak value slope in the third harmonics is close to be zero. By adoption of the PWM modulation method, the problem caused by sudden change of the common-mode voltage slope can be solved, the harmonic characteristic of the output current can be improved, and a better modulation effect can be obtained.

Description

technical field [0001] The invention belongs to the field of photovoltaic power generation, and in particular relates to a PWM modulation method capable of improving the output current harmonic characteristics of a three-phase photovoltaic inverter. Background technique [0002] The commonly used topology of the existing three-phase string photovoltaic grid-connected inverter is T-type three-level topology. The system structure is shown in the attached figure 1 shown. [0003] The system consists of a DC input source E dc , T-type three-level topology, LC filter, grid composition. u an , U bn , U cn is the inverter output voltage (also known as modulation voltage), I a , I b , I c For the inverter output current, L and C1 form an output filter. Wherein, in order to suppress the common mode current of the photovoltaic inverter, the neutral point of the filter capacitor C1 of the output filter is connected to the midpoint of the DC bus. Available modulation methods i...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/483H02M1/12
CPCH02M1/12H02M7/483H02M1/123Y02E10/56
Inventor 曾维波蒋峰杨勇黄敏方刚卢进军
Owner JIANGSU GOODWE POWER SUPPLY TECHNOLOGY CO LTD
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