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A DC midpoint voltage balance control method for a three-level inverter

A technology of a three-level inverter and a control method, applied in the direction of converting AC power input to DC power output, electrical components, output power conversion devices, etc., can solve the problem of increased output voltage harmonics, decreased DC voltage utilization, and Complicated calculations and other issues to achieve the effect of guaranteeing sine degree, small amount of calculation, and simple realization

Active Publication Date: 2018-09-07
NO 719 RES INST CHINA SHIPBUILDING IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The SVPWM method usually achieves mid-point voltage balance by adjusting redundant small vectors, the calculation is very complicated, and the harmonics of the output voltage will increase
The traditional SPWM method usually achieves mid-point voltage balance by injecting zero-sequence voltage, which is also complex to calculate and will lead to a decrease in DC voltage utilization
[0004] At present, there are still various problems in the midpoint voltage balance of the three-level inverter, and these problems have not been resolved

Method used

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  • A DC midpoint voltage balance control method for a three-level inverter
  • A DC midpoint voltage balance control method for a three-level inverter
  • A DC midpoint voltage balance control method for a three-level inverter

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Embodiment Construction

[0033] The present invention will be further described below in conjunction with accompanying drawing.

[0034] figure 1 It is the topological structure diagram of three-phase three-level inverter. Such as figure 1 As shown, the three-phase three-level inverter includes a DC power supply V dc , DC side voltage stabilizing capacitors C1 and C2, phase A switching tube S a1 ~S a4 , A phase embedding diode D a1 and D a2 , Phase B switch S b1 ~S b4 , Phase B embedded diode D b1 and D b2 , C-phase switch S c1 ~S c4 , C-phase embedding diode D c1 and D c2 , and three-phase AC loads. Phase A switch tube S a1 ~S a4 , A phase embedding diode D a1 and D a2 Form A-phase midpoint clamping type bridge arm; B-phase switch tube S b1 ~S b4 , Phase B embedded diode D b1 and D b2 Form B-phase midpoint clamping type bridge arm; C-phase switching tube S c1 ~S c4 , C-phase embedding diode D c1 and D c2 Form C-phase midpoint embedding type bridge arm. The inverter also inc...

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Abstract

The invention discloses a three-level inverter DC midpoint voltage balance control method. In the control method of the invention, according to the fluctuation magnitude of the midpoint voltage, DC bias and amplitudes of positive and negative modulated waves are adjusted, and thus, balance control on the midpoint potential is thus realized. The control method of the invention has the advantages that the realization is simple; the response is quick; the DC voltage utilization rate has no loss; harmonic distortion can be ensured not to happen to the outputted voltage and the current in an unbalanced midpoint voltage condition; the balance control on the midpoint potential can be effectively realized; safety of a switching device can be ensured; and harmonics of the outputted voltage can be reduced.

Description

technical field [0001] The invention relates to a three-level DC-AC power conversion device, in particular to a method for controlling the DC midpoint potential of a three-level DC-AC power conversion device. Background technique [0002] Multilevel inverters can reduce the harmonic content of the output voltage and reduce the voltage stress of switching devices, and are widely used in high-voltage and high-power applications. Among them, the three-level neutral-point clamped inverter is the most extensively researched and applied. The prerequisite for the normal operation of the three-level neutral-point clamped inverter is that the neutral-point voltage remains balanced. The unbalanced midpoint voltage will lead to an increase in the harmonic content of the output voltage and current. If the voltage fluctuates sharply or there is a large steady-state deviation, it will lead to an increase in the voltage stress of the switch tube of the bridge arm, which may cause overvolt...

Claims

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Application Information

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IPC IPC(8): H02M7/487
CPCH02M7/487
Inventor 李锐吴浩伟李鹏李小谦邓磊蔡凯欧阳晖姚川姜波李可维周樑金惠峰邢贺鹏李兴东徐正喜陈涛魏华雷秉霖张辉睿
Owner NO 719 RES INST CHINA SHIPBUILDING IND
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