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[转载]【电力电子】【2020.02】利用导抗式三相双有源桥DC-DC变换器实现宽范围高效率的拓扑结构和调制方案

已有 1155 次阅读 2021-6-27 19:09 |系统分类:科研笔记|文章来源:转载

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本文为中国香港理工大学(作者:AKIF ZIA KHAN)的博士论文,共208页。

 

三相双有源桥(3p-DAB)变换器是大功率应用中双向功率变换的一种有吸引力的选择,在不同的输入输出电压比和不同的负载条件下,循环电流引起的导通损耗和软开关区域的收缩是严重影响其效率性能的主要瓶颈。为了解决这些问题,本文提出了三种不同的基于导抗的3p-DAB转换器拓扑结构和调制方案。提出的拓扑结构和调制方案的目标是在整个工作范围内同时最小化开关损耗和传导损耗,以实现宽范围高效率性能。基于这一背景,本文共分为六章。

 

第一章介绍了隔离双向dc-dc变换器(IBDC)的研究背景、重要性、一些新兴应用和功能概述。通过详细讨论,3p-DAB变换器被认为是大功率IBDC的首选拓扑结构,并指出了其局限性。此外,本章提出了本论文的主要目标,包括克服传统3p-DAB变换器的局限性,在不同的输入输出电压比下实现宽范围的高效率性能。最后,在第一章中对全文进行了概述。

 

第二章从拓扑结构和控制角度对传统的3p-DAB变换器进行了概述。本章还提供了一个全面的文献综述,以更新读者对3p-DAB变换器所做的工作,以提高其效率和性能。此外,本章还突出了现有文献中的研究空白,指出了目前的研究工作试图弥补的不足。

 

第三章提出了一种3p-DAB谐振导抗(3p-DAB-RI)变换器,该变换器可以在所有交流端口实现单位功率因数运行,从而降低端口电流的均方根值,降低导通损耗,完全消除无功功率。此外,它还可以实现全量程零电压开关(ZVS),而不受输入输出电压比变化的影响,以减小开关损耗。然而,对于单位功率因数运行,33%的开关是硬开关,导致开关损耗增加,而对于全量程ZVS运行,3p-DAB-RI变换器由于循环电流增加而导致高导通损耗。此外,由于采用占空比调制对两种模式的输出功率进行调制,3p-DAB-RI变换器在轻载条件下(当电压波形占空比较小时)循环电流较大,导致轻载效率较低。

 

第四章提出了一种3p-DAB可重构谐振(3p-DAB-RR)变换器,以克服第三章提出的3p-DAB-RI变换器的局限性。本章提出的3p-DAB-RR变换器可以在3p-DAB-RI变换器和3p-DAB串联谐振(3p-DAB-SR)变换器之间进行变换,从而在塑造3pDAB变换器的效率性能和提高其轻载效率方面提供额外的自由度。3p-DAB-RR变换器通过适当选择变换器的工作模式,在不同的工作条件下,具有单位功率因数、全量程零电压开关和提高轻载效率的灵活性。在仔细分析损耗并通过实验测量验证损耗模型的基础上,有人建议使用3p-DAB-SR转换器和3p-DAB-RI转换器,前者采用单相移相(SPS)调制,用于中低功率电平,后者采用单位功率因数操作,以实现大范围的高效率性能。然而,3p-DAB-RI变换器单位功率因数运行中33%的硬开关和高循环电流的缺点,以及3p-DAB-SR变换器在大范围输入输出电压比变化下的硬开关问题仍然没有解决。

 

第五章提出了一种3p-DAB可重构可调谐谐振(3p-DABRTR)变换器,以实现宽范围的零环流和全范围的ZVS操作,而不考虑输入输出电压比的大范围变化。对于低-中功率电平,该变换器采用阻抗调制方式作为可调谐3p-DAB-SR变换器工作。在这种工作模式下,输出功率是通过在保持开关频率和相移不变的情况下,利用主控芯片调节串联LC谐振网络的阻抗来控制的。对于中高功率电平,变换器作为一个可调3p-DAB-RI变换器与动态频率匹配(DFM)调制。在这种工作模式下,输出功率由开关控制电容器(SCC)与开关频率同步变化导抗网络的谐振频率来控制。两种运行方式的结合,使所有开关同时实现宽范围零循环电流和全量程零电压开关操作,具有广泛的高效率性能。

 

第六章为论文的总结,重点介绍了论文的贡献。此外,本章还提出了所提出的拓扑结构的应用和功率等级,以及未来的研究方向。最后,对所提出的拓扑结构进行了综合比较,以期对论文的结论进行总结。

 

Three-phase dual-active-bridge (3p-DAB)converter is an attractive choice for bidirectional power conversion inhigh-power applications, however, conduction loss caused by circulating currentand shrinkage of soft-switching region under varying input-to-output voltageratios and different load conditions are the main bottlenecks that severelyaffect its efficiency performance. To address these issues, three differentimmittance based topologies and modulation schemes have been proposed in thiswork for the 3p-DAB converter. The proposed topologies and modulation schemesare targeted to minimize the switching loss and conduction loss simultaneouslyover the entire operating range to achieve wide-range highefficiencyperformance. Based on this backdrop, the thesis has been classified in sixchapters. A brief description of each chapter is presented below: Chapter 1discusses about the background, importance, some emerging applications andfunctional overview of isolated bidirectional dc-dc converters (IBDCs). Throughdetailed discussions, 3p-DAB converter is identified as a preferred IBDCtopology for high-power applications and its limitations are presented.Moreover, the main objectives of the thesis are presented in this chapter thatincludes overcoming the limitations of conventional 3p-DAB converter to achievewide-range high efficiency performance under varying input-to-output voltageratios. Finally, an outline of the thesis concludes chapter 1. Chapter 2 givesan overview of the conventional 3p-DAB converter from the topology and controlperspective. A comprehensive literature review is also presented in thischapter to update the readers about the work done on the

3p-DAB converter to improve its efficiencyperformance. Moreover, the research gaps in the existing literature are alsohighlighted in this chapter that the current research work has attempted tobridge.

Chapter 3 proposes a 3p-DAB resonantimmittance (3p-DAB-RI) converter that can achieve unity-power-factor operationat all of its ac ports leading to reduced RMS port current, lower conductionloss and complete elimination of reactive power. Moreover, it can also achievefull-range zero-voltage-switching (ZVS) irrespective of variations ininput-to-output voltage ratios to diminish the switching loss. However, forunity-power-factor operation, 33 % of the switches are hard-switched leading toincreased switching loss whereas for full-range ZVS operation, 3p-DAB-RI convertersuffers from high conduction loss due to increased circulating current.Moreover, as the duty cycle modulation is employed to modulate output power forboth modes, 3p-DAB-RI converter suffers from high circulating current underlight-load conditions (when the duty cycle of voltage waveforms is small)leading to poor-light load efficiency.

Chapter 4 proposes a 3p-DAB reconfigurableresonant (3p-DAB-RR) converter to overcome the limitations of 3p-DAB-RIconverter proposed in chapter 3. The 3p-DAB-RR converter proposed in thischapter can transform between 3p-DAB-RI converter and a 3p-DAB series resonant(3p-DAB-SR) converter to offer additional degree-of-freedom in shaping theefficiency performance of 3pDAB converter and enhance its light-load efficiency.The 3p-DAB-RR converter offers the flexibility to operate with unity powerfactor, full-range ZVS and enhanced light-load efficiency under varyingoperating conditions by appropriate selection of the converters operation mode.Based on a careful loss analysis and verification of the loss model byexperimental measurements, it has been proposed to operate the converter as3p-DAB-SR converter with single phase-shift (SPS) modulation for low-mediumpower levels and operate as 3p-DAB-RI converter with unity-power-factoroperation for medium-high power levels to achieve overall wide-rangehigh-efficiency performance. However, the drawbacks of hardswitching of 33 %switches in the unity-power-factor operation of 3p-DAB-RI converter and highcirculating current, hard-switching of switches in 3p-DABSR converter underwide-range variations in input-to-output voltage ratios still remain unsolved.Chapter 5 proposes a 3p-DAB reconfigurable and tunable resonant (3p-DABRTR)converter to achieve wide-range zero circulating current and full-range ZVSoperation irrespective of wide-range variations in input-to-output voltageratios. For low-medium power levels, the converter operates as a tunable3p-DAB-SR converter with impedance modulation method. Under this mode of operation,the output power is controlled by modulating the impedance of series LCresonant network with the aid of SCC while keeping the switching frequency andphase-shift constant. For medium-high power levels, the converter operates as atunable 3p-DAB-RI converter with dynamic frequency matching (DFM) modulation.Under this mode of operation, the output power is controlled by synchronouslyvarying the resonance frequency of the immittance network with the switchingfrequency by using switch-controlled capacitor (SCC). The combination of bothoperation modes jointly leads to wide-range zero circulating current andfull-range ZVS operation for all the switches simultaneously yieldingwide-range high-efficiency performance. Chapter 6 concludes the thesis and highlightsthe contributions of the work. Moreover, suggested applications and powerlevels for the proposed topologies and potential future research directions arealso presented in this chapter. Finally, a comprehensive comparison of theproposed topologies are presented in this chapter to conclude the thesis.

 

1.  引言

2. 三相双有源桥变换器概述

3. 采用三相谐振导抗网络的双有源桥DC-DC变换器的设计、分析和性能表征

4. 一种具有可重构谐振网络的三相双有源桥DC-DC变换器

5. 一种多结构、多模、宽范围高效率三相双有源桥DC-DC变换器

6. 结论与展望


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