Design of a Non-isolated Single Phase Online UPS Topology with Parallel Battery Bank for Low Power Applications PDF
Preview Design of a Non-isolated Single Phase Online UPS Topology with Parallel Battery Bank for Low Power Applications
Springer Theses Recognizing Outstanding Ph.D. Research Muhammad Aamir Design of a Non-isolated Single Phase Online UPS Topology with Parallel Battery Bank for Low Power Applications Springer Theses Recognizing Outstanding Ph.D. Research Aims and Scope The series “Springer Theses” brings together a selection of the very best Ph.D. theses from around the world and across the physical sciences. Nominated and endorsed by two recognized specialists, each published volume has been selected foritsscientificexcellenceandthehighimpactofitscontentsforthepertinentfield of research. For greater accessibility to non-specialists, the published versions includeanextendedintroduction,aswellasaforewordbythestudent’ssupervisor explainingthespecialrelevanceoftheworkforthefield.Asawhole,theserieswill provide a valuable resource both for newcomers to the research fields described, and for other scientists seeking detailed background information on special questions. Finally, it provides an accredited documentation of the valuable contributions made by today’s younger generation of scientists. Theses are accepted into the series by invited nomination only and must fulfill all of the following criteria (cid:129) They must be written in good English. (cid:129) ThetopicshouldfallwithintheconfinesofChemistry,Physics,EarthSciences, Engineeringandrelatedinterdisciplinary fields such asMaterials,Nanoscience, Chemical Engineering, Complex Systems and Biophysics. (cid:129) The work reported in the thesis must represent a significant scientific advance. (cid:129) Ifthethesisincludespreviouslypublishedmaterial,permissiontoreproducethis must be gained from the respective copyright holder. (cid:129) They must have been examined and passed during the 12 months prior to nomination. (cid:129) Each thesis should include a foreword by the supervisor outlining the signifi- cance of its content. (cid:129) The theses should have a clearly defined structure including an introduction accessible to scientists not expert in that particular field. More information about this series at http://www.springer.com/series/8790 Muhammad Aamir Design of a Non-isolated Single Phase Online UPS Topology with Parallel Battery Bank for Low Power Applications Doctoral Thesis accepted by the University of Malaya, Kuala Lumpur, Malaysia 123 Author Supervisor Dr. Muhammad Aamir Prof. SaadMekhilef Power Electronics andRenewable Department ofElectrical Engineering, EnergyResearch Laboratory, Faculty ofEngineering Departmentof Electrical Engineering University of Malaya University of Malaya Kuala Lumpur Kuala Lumpur Malaysia Malaysia ISSN 2190-5053 ISSN 2190-5061 (electronic) SpringerTheses ISBN978-981-13-0492-7 ISBN978-981-13-0493-4 (eBook) https://doi.org/10.1007/978-981-13-0493-4 LibraryofCongressControlNumber:2018940892 ©SpringerNatureSingaporePteLtd.2019 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpart of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission orinformationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodologynowknownorhereafterdeveloped. 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Theregisteredcompanyaddressis:152BeachRoad,#21-01/04GatewayEast,Singapore189721, Singapore ’ Supervisor s Foreword This thesis covered in detail different aspects of Uninterruptible Power Supplies (UPS). With the development of the nonlinear load in the power system, clean power is of utmost important for the sensitive utilities. Therefore, UPS system gained attention due to its advantages of providing best power quality and proven reliabilityagainstalltypesoflinedisturbancesandpoweroutages.Inthisresearch, anewtopologyofbidirectionalDC–DCconverterhasbeenpresentedwhichcanact as a battery charger and discharger. The DC–DC converter uses only three active switches, a coupled inductor, and an additional voltage clamped circuit to perform the bidirectional operation. The important contribution of this Ph.D. thesis is the idea behind the usage of batteries in the UPS system. Comparison of series and parallel combination of batteries has been presented and the advantages are elab- orated.Besides,anewcascadedslidemodeandproportional-resonantcontrolhave been proposed. Slide mode control is recognized as the most robust control with high stability, while the proportional-resonant control shapes the output waveform closely according to the reference sinusoidal signal. Keeping in view the charac- teristics of slide mode and proportional-resonant control, a cascaded controller is proposedforthebipolarsingle-phaseUPSinverter.Theoutervoltageloopusesthe proportional-resonantcontrolwhiletheinnerloopusestheslidemodecontrol.This work claims high efficiency of 94% during battery mode and 92% during the normalmodeofoperationwhichisverylessthantheotherworksinthisarea.The proposedsystemhelpstheindustrytodesignhighefficient,lowcost,andsmallsize UPS system. Thisthesistitled“Designofanon-isolatedsinglephaseonlineupstopologywith parallel battery bank for low power applications” is organized into six chapters as follows: Chapter 1 presents the background information, general features, and common characteristic of the UPS system. Research methodology of the proposed work is explained briefly followed by thesis outline. Chapter 2 provides a detailed literature review of the UPS system. The classi- fication of the UPS is explained on the basis of their configuration and circuit topology. Important characteristics of the state-of-the-art work on both v vi Supervisor’sForeword transformer-based and transformerless UPS systems has been explained. Additionally, various control schemes for the UPS system are analyzed and their characteristics have been compared. Chapter3presentstheproposedtopologyoftransformerlessonlineUPSsystem anddescribesindetaildifferentpartsoftheUPSsystem.Modesofoperationofthe proposed system are described, whereas mathematical modeling and design pro- cedure of each part has been added to validate the feasibility of the implemented system. The control scheme for the online transformerless UPS system is presented in Chap. 4. The control scheme consists of the slide mode and proportional-resonant control for the inverter, constant current/ constant voltage control for the battery charger/discharger, and the average current control scheme for the rectifier of the proposed UPS system. Mathematical modeling and design process of each control in scheme is explained this chapter. The last chapter includes the simulation and experimental results from different parts of the UPS system. As the UPS system comprises the front-end rectifier, bidirectional battery charger/discharger, and the inverter connected to the load, the resultsofallthethreepartsarepresented.Thechapterisorganizedasfollows:both thesimulationandexperimentalresultsofeachcomponentareexplainedseparately first.Thisisfollowedbythepresentationoftheexperimentalresultsofthecomplete UPS system. The results depict the UPS system performance by displaying the inputpowerfactor,batterycharging,zerovoltageswitching,andinverteroutputfor different loading conditions. Likewise, experimental results of the changing of operational modes of the UPS system are also presented in this chapter. Finally, a comparison of the proposed UPS system is done with other state-of-the-art works. With the modern trends in technology development, more nonlinearities have beenkeepaddingtotheNationalGrid.Hence,anadvancedUPSsystemneedstobe available in the market to protect our sensitive loads. The proposed UPS system providesabalancedsolutioninordertoprotectoutsensitiveloads.Thisthesiswas performed between 11/2013 and 12/2016 at Power Electronics and Renewable Energy Laboratory (PEARL), leading to several publications and presentations at international conferences. Kuala Lumpur, Malaysia Dr. Saad Mekhilef December 2016 Abstract Uninterruptible Power Supplies (UPS) are widely used to provide reliable and high-quality power to critical loads such as airlines computers, data centers, com- municationsystems,andmedicalsupportsystemsinhospitalsinallgridconditions. Online UPS system is considered to be the most preferable UPS due to its highest level of power quality and proven reliability against all types of line disturbances and power outages. This research presents a new topology of the non-isolated online uninterruptible power supply system. The proposed system consists of bridgeless boost rectifier, battery charger/discharger, and an inverter. The rectifier performs power factor correction and provides regulated DC-link voltage. The rectifier operates with a minimum semiconductor device, reducing the conduction losses of the circuit significantly. A new battery charger/discharger has been implemented,whichensuresthebidirectionalpowerflowbetweentheDC-linkand thebatterybank,reducingthebattery bankvoltagetoonly24V,andregulatesthe DC-linkvoltageduringbatterymode.Thebidirectionaloperationoftheconverteris achieved by employing only three active switches, a coupled inductor, and an additionalvoltageclampedcircuit.Batteriesareconnectedinparalleldependingon thebackup time requirementofthesystem. Operating batteries inparallel improve the battery performance and resolve the problems related to conventional battery banks that arrange batteries in series. The inverter provides a regulated output voltage to the load. A new cascaded slide mode and proportional-resonant control have been proposed. Slide mode control is recognized as the most robust control with high stability while the proportional-resonant control shapes the output waveformcloselyaccordingtothereferencesinusoidalsignal.Keepinginviewthe characteristics of slide mode and proportional-resonant control, a cascaded con- trollerisproposedforthebipolarsingle-phaseUPSinverter.Theoutervoltageloop uses the proportional-resonant control, while the inner loop uses the slide mode control. The proposed control scheme regulates the output voltage for both linear and nonlinear loads and shows excellent performance during transients and step changesinload.Theproposedcontrollershowssignificantimprovementintermsof vii viii Abstract reducing the total harmonics distortion to 0.5% for linear load and 1.25% for nonlinearload,strongrobustness,andfastresponsetimeofonly0.3ms.Operation principleandexperimentalresultsof1kVAprototypehavebeenpresentedtoverify the validity of the proposed UPS. The efficiency of the proposed system is 94% during battery mode and 92% during the normal mode of operation. Parts of this thesis have been published in the following articles: 1. Aamir, M; Mekhilef, S; Jun K. H, “High-Gain Zero-Voltage Switching BidirectionalConverterWithaReducedNumberofSwitches,”IEEETransactions onCircuitsandSystemsII:ExpressBriefs,vol.62,no.8,pp.816–820,2015. 2. Aamir, M; Mekhilef, S; Ahmed. K, “Review: Uninterruptible Power Supply (UPS) System” Renewable and sustainable energy: Reviews, 58, 1395–1410, 2016. 3. Aamir,M;Mekhilef,S;“OnlineTransformer-lessUninterruptiblePowerSupply (UPS) system with reduced battery bank for low power applications” IEEE Transaction on Power Electronics vol. 32, no. 1, pp. 233–247, Jan. 2017. 4. Aamir, M; Mekhilef, S; Ahmed. K, “Proportional-Resonant and Slide Mode Control for Single Phase UPS Inverter,” Electric Power Components and Systems, Vol 45, no.10, Taylor and Franscis 2017. ix
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