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Method for controlling balance of capacitive voltages of five-level diode neutral point clamped converter

A technology of balance control and capacitor voltage, applied in the direction of converting AC power input to DC power output, electrical components, and output power conversion devices, which can solve the problems of reducing the number of output levels, poor output waveform quality, and complexity.

Inactive Publication Date: 2013-08-07
XI AN JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Among them, the zero-sequence voltage injection method is widely used in the DC capacitor voltage control of the three-level NPC converter, and the five-level NPC converter has three midpoints, so this method will become complicated and difficult to control; the virtual vector SVM can theoretically guarantee the balance of the DC voltage in each control cycle, but it increases the switching loss and the complexity of the control; although the unbalanced vector method can realize the balance control of the DC capacitor voltage, it reduces the output level number, the quality of the output waveform is poor; the implementation of the objective function optimization method is simple, and it is more suitable for the five-level NPC topology, but it is not suitable for the full modulation degree

Method used

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  • Method for controlling balance of capacitive voltages of five-level diode neutral point clamped converter
  • Method for controlling balance of capacitive voltages of five-level diode neutral point clamped converter
  • Method for controlling balance of capacitive voltages of five-level diode neutral point clamped converter

Examples

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Effect test

example 1

[0119] Example 1: When the reference voltage vector is located in the I-th region, the switching state selection of the θ∈(0,π / 6] part of the redundant vector

[0120] According to ①, i=i a According to ②, judge the positive or negative of i. According to ③, if i>0: if the voltage of capacitor C1 is the largest, select the switch state 100; if the voltage of capacitor C2 is the largest, select the switch state 211; if the voltage of capacitor C3 is the largest, select the switch state 322; If the voltage of the capacitor C4 is the largest, select the switch state 433, if i<0: if the voltage of the capacitor C1 is the smallest, select the switch state 100; if the voltage of the capacitor C2 is the smallest, select the switch state 211; if the voltage of the capacitor C3 is the smallest, select the switch state 322; if The capacitor C4 has the minimum voltage, and the switch state 433 is selected.

example 2

[0121] Example 2: When the reference voltage vector is located in the θ∈(π / 6,π / 3] partial redundant vector switch state selection in the second region

[0122] According to ①, i=-i c According to ②, the positive or negative of i is judged. According to ③, if i>0: if the voltage of capacitor C1 is the largest, select the switch state 110; if the voltage of capacitor C2 is the largest, select the switch state 221; if the voltage of capacitor C3 is the largest, select the switch state 332; If the voltage of the capacitor C4 is the largest, select the switch state 443, if i<0: if the voltage of the capacitor C1 is the smallest, select the switch state 110; if the voltage of the capacitor C2 is the smallest, select the switch state 221; if the voltage of the capacitor C3 is the smallest, select the switch state 332; if The capacitor C4 has the minimum voltage, and the switch state 443 is selected.

[0123] 4.5), add transition switch state

[0124] Sort the switching states corre...

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Abstract

The invention discloses a method for controlling the balance of capacitive voltages of a five-level diode neutral point clamped converter. The method has the advantages that an integral modulation degree area is divided into a low modulation degree area (with an m<SV> smaller than or equal to 0.5) and a high modulation degree area (with an m<SV> larger than 0.5), and direct-current-side voltages of different modulation degree areas are controlled by different processes; a process for optimizing objective functions and a process for decomposing a reference voltage are combined with each other in a process for controlling the direct-current capacitive voltages in the low modulation degree area, the process for controlling the direct-current capacitive voltages in the low modulation degree area can be implemented easily, redundant switch states of various vectors are sufficiently utilized, and waveforms outputted by a system are improved; and complicated overlap area judging algorithms are omitted in an optimized process for selecting balancing vectors in the high modulation degree area, and the system is high in the response speed.

Description

【Technical field】 [0001] The invention relates to the technical field of power electronics; in particular, it relates to a method for controlling DC capacitor voltage balance of a five-level diode-clamped converter. 【Background technique】 [0002] Under the current circumstances, power devices cannot achieve breakthroughs in voltage and power in the short term. For this reason, the research points for improving the voltage and power level of converters are mainly in topology and control methods. Multi-level topology is high-voltage high-power A very important implementation of the converter. Among the multilevel topologies, the diode-clamped (NPC) topology is the most widely used because of its simple structure and high cost performance. [0003] In the relevant research contents of multilevel NPC circuits, the problem of DC capacitor voltage balance control is of outstanding importance. If the DC capacitor voltage is unbalanced, it will not only affect the output voltage ...

Claims

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Application Information

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IPC IPC(8): H02M7/5387H02M7/487
Inventor 李宁王跃厉肃王兆安
Owner XI AN JIAOTONG UNIV
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