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Unipolar SPWM (Sine Pulse Width Modulation) dead-time-free modulation method of H-bridge cascade multilevel converter

A technology of cascading multi-level and modulation methods, which is applied in the direction of converting irreversible DC power input into AC power output, can solve the problems of adding dead time and occupying large processor resources, etc., to solve the imbalance problem, Solve thermal imbalance, facilitate heat dissipation design and long-term operation effect

Active Publication Date: 2014-03-12
XIAN HIGH VOLTAGE APP RES INST CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Traditional carrier phase-shifting SPWM generally adopts bipolar frequency doubling SPWM modulation method. Therefore, each power sub-module needs two PWM generators to generate driving signals. For H-bridge cascaded multilevel converters, each The driving signal of each switching device must occupy a large amount of processor resources
In addition, in order to prevent the upper and lower bridge arms of the H-bridge converter from passing through, it is necessary to add a dead time
The addition of the dead time has a certain impact on the harmonic content of the output current of the H-bridge cascaded multi-level converter and the balance of the DC side voltage.

Method used

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  • Unipolar SPWM (Sine Pulse Width Modulation) dead-time-free modulation method of H-bridge cascade multilevel converter
  • Unipolar SPWM (Sine Pulse Width Modulation) dead-time-free modulation method of H-bridge cascade multilevel converter
  • Unipolar SPWM (Sine Pulse Width Modulation) dead-time-free modulation method of H-bridge cascade multilevel converter

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Embodiment 1

[0046] The topology of a single-phase H-bridge cascaded multilevel converter is as follows: figure 1 As shown, when the number of cascaded submodules is 2, the triangular wave carrier phase angle difference between the submodules is 180 °, according to the unipolar SPWM no dead zone control modulation method based on carrier phase shifting of the present invention, each submodule The PWM drive signal such as image 3 shown. Depend on image 3 It can be seen that the driving signals of the direction arms of each sub-module are consistent. When DirCTL=1, the H-bridge switching device T _1 and T _2 As the direction arm, the H-bridge switching device T _3 and T _4 As a chopper arm; when DirCTL=0, the H-bridge switching device T _1 and T _2 As the chopper arm, the H-bridge switching device T _3 and T _4 as a steering arm. The exchange of the direction arm and the chopper arm is realized by introducing the control signal DirCTL. Figure 4 Output voltage waveforms for sing...

Embodiment 2

[0048] The invention is also applicable to single-phase H-bridge converters. According to the unipolar SPWM non-dead zone control modulation method of the present invention, the PWM driving signal of the single-phase H-bridge converter is as follows: Figure 5 shown. Figure 6 is the voltage waveform at the output terminal of the H-bridge converter.

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Abstract

The invention provides a unipolar SPWM (Sine Pulse Width Modulation) dead-time-free modulation method of an H-bridge cascade multilevel converter. The method realizes the dead-time-free control of a chopper arm of the H-bridge converter through a digital logical circuit and certain dead time is set for a direction arm of the H-bridge converter only at every half working frequency cycle, so that the problem that the voltage on the direct-current side of the H-bridge cascade multilevel converter and the harmonic content of output current is influenced due to the dead time can be ignored. By introducing a control signal, the direction arm and the chopper arm realize interchange by taking two-divided frequency of working frequency as a cycle, the problem that the action of the switching device of the H-bridge converter is unbalanced under the situation of unipolar SPWM dead-time-free control is effectively solved, the thermal stability is good and the heat dissipation design and the long-term operation of the device are facilitated.

Description

【Technical field】 [0001] The invention relates to a unipolar SPWM modulation method for an H-bridge converter, in particular to a modulation method for H-bridge cascaded converter unipolar SPWM without dead zone control. 【Background technique】 [0002] At present, cascaded multilevel converters based on H bridges have been rapidly developed in transmission and distribution networks, especially in the field of FACTS applications and flexible DC transmission MMC fields. It is already a hot spot for research and engineering applications. Modulation technology is the key technology of H-bridge cascaded multilevel converter. The modulation methods used in H-bridge cascaded multilevel converters mainly include step wave modulation, specific harmonic elimination PWM, carrier phase shifting SPWM and multilevel SVPWM, etc. Among them, carrier phase-shifting SPWM is a kind of modulation technology commonly used in cascaded multilevel converters at present. Traditional carrier phase...

Claims

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Application Information

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IPC IPC(8): H02M7/49
Inventor 王弋飞朱静
Owner XIAN HIGH VOLTAGE APP RES INST CO LTD
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