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Three-level inverter carrier modulation method under neutral-point potential deflection condition

A three-level inverter and potential offset technology, which is applied to electrical components, output power conversion devices, and conversion of AC power input to DC power output. It can solve the problems of complex space vector modulation algorithm and difficult implementation. Achieve the effects of easy implementation, reduced harmonic content, and simple modulation method

Inactive Publication Date: 2015-04-29
ANHUI WANHONG ELECTRICAL EQUIP
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AI Technical Summary

Problems solved by technology

However, in the case of midpoint potential offset, the space vector modulation method of vector synthesis in the traditional way is no longer applicable. If the midpoint potential is to be controlled, the space vector modulation algorithm will become more complicated and difficult to implement

Method used

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  • Three-level inverter carrier modulation method under neutral-point potential deflection condition
  • Three-level inverter carrier modulation method under neutral-point potential deflection condition
  • Three-level inverter carrier modulation method under neutral-point potential deflection condition

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Embodiment Construction

[0020] A carrier modulation method for a three-level inverter in the case of a midpoint potential shift, specifically comprising the following steps:

[0021] (1) Use the voltage sensor to collect the capacitor voltage u on the DC side C1 and the lower capacitor voltage u C2 ;

[0022] (2) The given voltage u of the external link of the controller d , u q , through Park inverse transformation and Clark inverse transformation, the two-phase voltage u d , u q Transform from the two-phase rotating coordinate system to the three-phase stationary coordinate system to obtain the three-phase modulation voltage u a , u b , u c , as follows:

[0023]

[0024] u a u b u c =...

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Abstract

The invention discloses a three-level inverter carrier modulation method under the neutral-point potential deflection condition. The three-level inverter carrier modulation method includes the following steps: (1) collecting the upper capacitor voltage uC1 and the lower capacitor voltage uC2 on the direct current side through a voltage sensor; (2) giving the voltage ud and the voltage uq, converting the two-phase voltage ud and the two-phase voltage uq from a two-phase rotating coordinate system to a three-phase static coordinate system through Park inverse conversion and Clark inverse conversion, and obtaining the three-phase modulation voltage ua, ub and uc (please see the formula in the specification); (3) using the upper capacitor voltage uC1 and the lower capacitor voltage uC2 which are collected through the voltage sensor as peak values of carrier signals in carrier modulation, wherein the uC1 is the height of an upper carrier, and the uC2 is the height of a lower carrier; (4) using ux obtained through coordinate conversion as modulating signals in carrier modulation, wherein x is equal to a, b and c; (5) comparing the upper carrier and the lower carrier with a modulating wave, and outputting a three-phase switch sequence of a three-level inverter. By means of the three-level inverter carrier modulation method, the harmonic content of the voltage output by the inverter can be effectively reduced, and particularly the low-frequency even harmonic content of the voltage output by the inverter is restrained.

Description

technical field [0001] The invention relates to a modulation method for a three-level inverter, in particular to a carrier modulation method for a three-level inverter under the condition of a midpoint potential shift. Background technique [0002] With the development of power electronics technology, the application of three-level topology in power electronics is becoming more and more extensive, and the technology is becoming more and more mature. The three-level topology mainly has the following advantages: (1) The voltage that each power tube bears is half of the DC side, which is more suitable for large-capacity and high-voltage occasions; (2) It can generate multi-layer ladder-shaped output voltage, Further modulation can get a very good approximate sine wave. In theory, increasing the level number can approach the standard sine wave, which can effectively reduce the harmonic content of the inverter output voltage; (3) The problem of electromagnetic interference (EMI) ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/483H02M1/12
CPCH02M7/483H02M1/12
Inventor 张守勇姜卫东
Owner ANHUI WANHONG ELECTRICAL EQUIP
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