外文翻译-基于单片机的单相电压自动调节器

英文原文Microcontroller-BasedSingle-PhaseAutomaticVoltageRegulatorNangKaythiHlaingHardwareTechnologyDepartmentComputerUniversity(Myanmar)Abstract:Thispaperproposesthedesignandimplementationofamicrocontroller-basedsingle-phaseautomaticvoltageregulator(AVR).ThebasicbuildingblocksforthisdesignincludeaPIC16f628microcontroller,atriac,astep-uptransformer,azerocrossingcircuitryandaloadvoltagesensingcircuitry.Thisdesignisbasedontheprincipleofphasecontrolofacvoltageusingatriac.Thetriggerpulseforthetriacisdelayedbythemicrocontrollertoprovidethedesiredregulatorterminalvoltage.Thisvoltageisalwayssensedandfedbacktothemicrocontrollerviaameasuringunittogetacontinuouscontrolsystem.OneoftheintensionstodevelopthisAVRistouseitindomesticheatingandlightingcontrols.Itcanalsobeusedasanadjustablevoltagesourcebyadjustingavariableresistorinthevoltagesensingcircuitry.ItisalsointendedtointroduceacompactAVRandtodemonstratetheusefulnessofthePICmicrocontrollerinpowercontrolfield.Keywords:voltageregulator(AVR);PICmicrocontroller;autotransformer;phasecontrol;triacI.INTRODUCTIONTheautomaticvoltageregulatororAVR,asthenameimplies,isadeviceintendedtoregulatevoltageautomatically:thatistotakeavaryingvoltagelevelandturnitintoaconstantvoltagelevel4.Automaticvoltageregulatorsarewidelyusedinelectricalpowerfieldtoobtainthestabilityandgoodregulationoftheelectricsystem.IntypicalAVRs,switchingisdonebyelectromagneticrelays,orservomotor,orelectronicdevice,whichautomaticallyselectedtapsinthetransformertogettherequiredvoltagetoboost(add)orbuck(subtract)theinputvoltage.Relaytapchangershavetheproblemssuchaspowerlostmomentarilyduringrelaychangeover,unstableoutputandrelaycontactdamages.Servomotortypesgavethedisadvantagesthattheyhavelowlifeofthecontactpointsoftherelays5.SolidstateelectronicdeviceusedAVRscanovercomemostoftheaboveproblemsastheydonotuseanymovingpartandtheoutputvoltagecanvaryfromcycletocycle13.Formicrocontrollers,theyhavebeenproventheirabilitiestoperformwellinawiderangeofapplications26.Nowadays,manymicrocontroller-basedAVRcanbeavailableinmarkets.OneofthemisSollatekAVR7.Inthispaper,itisaimedtoimplementPICmicrocontrollerbasedsolidsateswitchingautomaticvoltageregulator.II.OVERVIEWOFTHEPROPOSEDDESIGNThebasicbuildingblocksforthisdesignincludeaPICl6f628microcontroller,atriac,a400Vautotransformer,azerocrossingcircuitry,andaloadvoltagesensingcircuitry.Thisdesignisbasedontheprincipleofphasecontrolofacvoltageusingatriac,wheretriggering(firing)delayisdeterminedbythePICmicrocontroller.Fig.1showstheimportantcomonentsofourAVR.Figure1.Blockdiagramofmicrocontroller-basedautomaticvoltageregulatorIII.HARDWAREIMPLEMENTATIONANDOPERATIONOFTHESYSTEMCOMPONENTSThegeneraloperationofthecomponentsgoeslikethis:linevoltageissteppedupto400Vusinganautotransformer.ZerocrossingdetectioncircuitprovidesapulsetothePICwheneverthelinevoltagereachesOV.Aftergettingthezerocrosspulse,thePICdeterminesthedelaytosendagatetriggerpulseforthetriacinaccordancewiththeoutputoftheregulatorterminalvoltage.Triac,here,isusedtocontrolthephaseofthelinevoltage.TheregulatorterminalvoltageisalwayssensedandfedbacktothePICviaameasuringunit.AControlorRegulatingUnitIncontrolunit,PICl6f628formstheheartoftheunitwhereBTAl6(600C)triacisusedasanacswitch.ItisdrivenbyPC817optocouplerandistriggeredwithapulsesentfromthePICbytakingsomedelayaftereveryzerocrossingofeachacmaincycle.Theswitchisopenifnotriggerpulseisgiventothegate.Itisclosedifpulsesaregivencontinuouslytwiceeveryacwave.Inourdesign,a16amperetriacisusedtoinsureanadequatemarginofsafety.Thetriacismountedtoaheatsinkwhichislargeenoughtoremovetheheatcausedbybidirectionalcurrentflowofthetriac.Tosuppressvoltagetransientsa100resistoranda0.1uFcapacitorisusedasasnubbernetworkacrossthetriac.Thepresenceofthisnetworkcanimprovetheturn-onperformanceofthetriac.InthiscontrolunitPIC16f628plusPC817isusedasatriacgatefiringcircuit,whichisdesignedwithcaretoensurethatunwantedconduction,i.e.,lossofcontrol,doesnotoccurwhentriggeringlaststoolong.Thegate-cathoderesistorprotectsthedevicefromfalsetriggeringduetonoise.Fig.2showstheinterfaceofPIC16f628withothercomponentscontainedinourAVR.Figure2.MicrocontrollerinterfaceBMeasuringorFeedbackUnitThismeasuringorfeedbackunitcontainsLM358,thewindowcomparator.TheregulatorterminalvoltageisalwayssensedandfedbacktothePICviathecircuitshowninFig.3.Figure3.SchematiccircuitformeasuringorfeedbackunitTheoutputvoltagefromtheAVRissteppeddownto9Vandthenrectifiedthroughthebridgerectifier.A220uF,12Vcapacitoranda100resistor,whichareconnectedinseries,performasanintegrator.ThevaluesofthesecapacitorandresistorarechosensothattheRCvaluemustbegreaterthan10ms,whichishalfoftheperiodoftheaclinevoltage.ThefeedbackvoltageisappliedtopotVR1andthevoltagedropatitscenterpinisfedasasensorvoltagetopin2and5ofLM358.Thissensorvoltagevariesproportionallyinaccordancewiththevariationoffeedbackvoltage.TheupperandlowerthresholdsaresetbyadjustingthePOTs,VR2andVR3,showninFigure3,whichareconnectedinseriestomakeensurethattheupperthresholdvoltagewillalwaysbehigherthanthelower.A3Vzenerdiode,connectedinreversebiaswiththepowersupply,operatesasareferenceforthePOTs.Here,thezenervoltagemustbelowerthanthePICpowersupply.Butitwillgointoconductionwhenthevoltagereachesorexceedsitsrating.Inthiscircuittheupperandlowerthresholdsaresetatl.5Vand1.38V,respectively.Aslongasthesensorvoltageiswithinthesetwolimits,theAVRterminalvoltagewillbeconstantat220V,andnoneofthetwooutputpinsofLM358willsaturate.Asaconsequence,thePICwilldetectnohighstatusatitstwoinputpins.So,itdoesnothavetochangethedelaytotriggerthetriacwhichhasbeenpreviouslydeterminedtoprovidethenormal220V.Asaresulttheregulatorretainsitspreviousnormalvoltage.CZerocrossDetectionCircuitryDetectionofzerocrosspointisnecessaryforthemicrocontrollertosynchronizetherunningofitssoftwareprogramtothemainswave-form.ThiszerocrossdetectionunitshowninFig.4includesabridgerectifier,anoptocoupler(PC817)andatransistor(C945).Thiscircuitacceptsacvoltagesignalsandinterfacesthemtologic-levelsignals.Utilizingabridgerectifierenablestosenseeitheracordcvoltage.InPC817,theinputsideistheLEDandtheoutputsideisthetransistor,whicharedrivenbydifferent.Figure4.SchematicdiagramforzerocrossdetectioncircuitryTheinputsideisconnectedtotherectified400VaclinewhiletheoutputsideisconnectedtothePIC.AdiodeconnectedininverseparalleltotheLEDontheinputsideofPC817protectstheLEDfromdamageduetoover-voltageconditions.DStep-UpAutotransformerA400Vstep-upautotransformerhavingacoresizeof(1.5x1.4)squareinchesisusedtohandleupto500wattload.For0-400V,21SWGwireisused,andfor12-0-12Vusedfortriacfiringcircuit,23SWGwireisused.IV.SOFTWAREIMPLEMENTATIONFORTHECONTROLUNITThefirmwareprogramforthemicrocontrolleriscompiledwiththePICCCompilerToolsuiteversion8.02fromHI-TECHSoftware.ThesourcecodeiswrittenintheMPLABIDEversion6.60fromMicrochipCorporation.Theflowoftheprogram,Fig.5,goeslikethis:Afterinitializingtheregisters,thePICwaitstillthezerocrossingofaccyclereachedinordertosynchronizethetimingoftheprogramtotheacmains.AssoonasthePICacceptsazerocrosspulsefromthezerocrossdetectioncircuit,itchecksthestatusofthetwoinputs,RAOandRA1(pin17and18).Thesetwopinsareconfiguredasoverandundervoltageindicatorsforregulatorterminalvoltage.ThePICacceptsthetwooutputstatusofthemeasuringunit,whichsensestheregulatorterminalvoltageandfeedsbackittothePIC.InourAVRitisdesiredthatthenormalregulatorterminalvoltagetobe220V.Since,aclinevoltageistypicallyunder220V,itisfirstlysteppedupto400Vtoprovidethedesiredregulatorterminalvoltage.So,thetriachastobetriggerednearlyathalfofeachacmaincycletoprovidethedesired220V.AstheTMROoverflowinterruptisusedtogettherequireddelayforthetriggerpulse,128isputasaninitialcount.Ifpin17,over-voltageindicator,ishigh,thatis,theoutputvoltageisgreaterthan220V;thePIChastoreducethatover-voltageto220V.ThusthePIChastotakemoredelaytosendagate-triggerpulseforthetriacthanthattakentogivethedesired220V.DelayistakenbydecreasingthevalueofTrigger,whichisthenputintotheTMRO.WhentheTMROoverflows,thePICsendsthetriggerpulseforthetriac.Thereisanunder-voltageconditionifpin18,undervoltageindicator,ishigh;itmeansregulatorterminalvoltageislessthan220V.AtthisconditionthePIChastostepupthatvoltagetonormal220V.Soithasadutytosendthetriggerpulsebytakinglessdelaythanthattakentogetnormalvoltage.ThisstepisaccomplishedbyincreasingtheTriggervalue.Aftersendingthetriggerpulseforhalfacycleofacmains,thePICagainwaitszerocrossingforthenexthalfcycleandfollowstheflowoftheprogramasshowninFig.5.Figure5.SoftwareflowdiagramforthecontrolunitV.DISCUSSIONONTHERESULTSForourAVR,theinputvoltagevariationortheoperationalrangeisfrom170to240V.Thismeansthatthetriacmaintainingtheoutputvoltageconstantwouldbetriggeredonlywhentheinputvoltageiswithin170and240V.Inourexperiments,theinputvoltagevariationisdonemanuallyusingavariableautotransformercalledavariac.Usingthemeasurementsobtained,regulationISdeterminedbyuseof(1)1(%)fnVregulatioLdThevoltageregulationinpercentagerelatedtotheinputvoltagevariationispresentedinTable1.TABLEI.EFFECTOFLOADSONVOLTAGEREGULATIONThemputrangeIScalculatedfrom(2)10PIrange(%).mxmaxNMiputAnd(3)Ir().iintTheoutputaccuracyisdeterminedusing(4)10PO)acury(.xmaxNotpand(5)r(%.mininMtWherevoltageipuPI.axmninvoltagenrmNMupPO.xavltetiminTherelationshipbetweentheinputvoltagevariationandtheAVRoutputonvariousloadscanbeseeninFig.6.Figure6.InputvoltagevsoutputvoltageonvariousloadFromtheresultsobtained,thefeaturesofourAVRcanbesummarizedasfollows:Thewideinputrangeof-22%to+9%isanidealandessentialforsomeplaceswherethevoltageisextremelyerratic.Moreover,theoutputaccuracyof-1%to+2.3%issufficientforheatingandlightingapplications.Nevertheless,theoutputvoltagefluctuationofourAVRiswithinanacceptablerange.VI.CONCLUSIONANDFUTUREWORKThispaperhascoveredthedesignandimplementationofmicrocontroller-basedAVR.ItisjustanattempttointroducesuchanAVRofhavingdifferentdesignandoperationincomparingcurrentlyavailableAVRs.Asthisdesignisconcernedwithhighvoltage,carehasbeentakeninchoosingsuitabletriactowithstandthishighvoltage.Theuniquenessofourdesignisthatnomovingpartispresentandasaresult,nomaintenanceisrequired.Moreover,lackofmechanicaldevicesenablesourAVRnottobeencounteredwithdisadvantagessuchaswearandtearofrelaycontactpoints,fatigueofthetransfonnertaps,etc.,which,but,canbefoundinsometypicalAVRs.OurAVR,inreal,cannotofferasmoothregulation.Thismaybeduetoeitherawiderangebetweenthethresholdsofthecomparator,orthecoresaturationoftheautotransfonnerfortheinputvoltagegreaterthan230V.Usinganautotransfonnerwithlargercoresizemaybearemedytosolvethiscoresaturationproblem.Moreover,abetterregulationwillalsobepossiblewithsomeotherperipheralmodulescontainedinthePICmicrocontroller.AlthoughthisAVRisnotaperfectone,itishopedthatthispaper,atleast,enablesonetohavebetterunderstandingontheusefulnessofaPICmicrocontrollerinpowercontrolfield.REFERENCES1A.Ahmed,PowerElectronicsforTechnology,Prentice-HallInternational,1999.2J.B.Peatmann,DesignwithPICMicrocontrollers,Prentice-Hall,1998.3J.M.Jacob,PowerElectronics:PrinciplesandApplications,VikasPublishingHouse,2002.4M.C.Sharma,VoltageStabilizersandAutomaticCutouts,1987.5P.C.Sen,PowerElectronics,TataMcGraw-HillPublishingCompanyLimited,NewDelhi,1987.6R.A.Penfold,AnIntroductiontoPICMicrocontrollers,BernardBabaniPublishing,1997.7Sollatek(UK),AutomaticVoltageRegulator.中文译文基于单片机的单相电压自动调节器NangKaythiHlaing硬件技术专业计算机大学(缅甸)摘要：本文提出的基于微控制器的单相自动电压调节器(AVR)的设计和实施。这个设计的基本构建块包括一个PIC16F628单片机，可控硅，升压变压器，过零电路和负载电压检测电路。这种设计是基于使用可控硅交流电压的相位控制的原则。由单片机提供所需的稳压器端电压的可控硅的触发延迟脉冲。发展这个自动电压调节器的意义之一，是用它在国内的取暖和照明控制使用。它也可以通过调节可变电阻被用来作为一个可调电压源的电压检测电路。还打算引进一个小巧的自动电压调节器和表明PIC单片机在电力控制领域的实用性。关键词：自动电压调节器(AVR)；PIC单片机；自耦变压器；相位控制可控硅I引言自动电压调节器一个电压调节器，顾名思义，是可以自动调节电压的装置；即采取了不同的电压等级，让它变成一个恒定的电压水平4。自动电压调节器被广泛应用在电力领域，使得电力系统的稳定和良好的调节。典型的自动电压调节器，是通过电磁继电器，或伺服电机，电子设备，它会自动选择在变压器的抽头，以获得所需的电压提高(加)或降压(减)输入电压开关。继电器存在的问题，如电力暂时失去了在对继电器变化，不稳定的输出和继电器触点损坏。伺服电机类型给他们有继电器的接触点，寿命低的缺点5。固态电子设备使用的单相电压调节器可以克服上述问题，因为他们不使用任何移动部件和输出电压可随着循环周期的变化而变化13。微控制器，他们已经证明自己的能力并且得到了广泛的应用26。如今，许多基于单片机的的电压调节器在市场得到广泛应用。其中之一是Sollatek的电压调节器7。在本文中，它的目的是实现单片机为基础的固态开关自动电压调节器。II所提出的设计概述这个设计的基本构建块包括一个PICl6f628单片机，可控硅，一个400V的自耦变压器，零路口电路，负载电压检测电路。基于这种设计的原则，使用可控硅的三相交流电压的控制，其中触发(射击)延迟是由PIC单片机的决定。图1显示了我们的自动电压调节器的重要步骤。交流升压自耦变压器过零电路开关(可控硅)PIC16f28稳定的输出计量单元调节单元图1基于单片机的自动电压调节器框图III硬件实施和运行系统组件该组件的一般操作是这样的；线电压通过自耦变压器上升至400V。每当线路电压达到过压时过零检测电路就会提供了一个脉冲到PIC。零交叉脉冲过后，PIC决定按照输出调节端电压为可控硅门极触发脉冲延迟发送。双向可控硅，在这里，是用来控制线电压的相位。调节端电压始终检测并通过测量单位反馈到PIC。A控制或调节单元在控制单元，PICl6f628表格，在BTA的L6(600C)可控硅交流开关使用单位的中心。它是由PC817光耦从PIC发送到每个交流的主要周期过零后，延迟脉冲触发。如果没有触发脉冲开关不被打开。它是封闭的，如果脉冲连续两次是交流波。在我们的设计中，使用一个16A的可控硅，以确保足够的安全。可控硅被安装一个散热片，这是为了足以消除由双向可控硅的电流流动所造成的热量。为了抑制电压瞬变一个100的电阻和10uF电容作为缓冲网络对面的可控硅使用。这个网络的存在可以提高可控硅导通的性能。在此控制单元的PIC16F628加PC机817使用三端双向可控硅门发射电路，这是谨慎的设计，以确保无用的传导，即触发时间过长不会失控。门阴极电阻因噪声而误触发的保护装置。图2PIC16F628与我们的自动电压调节器中的其他组件的接口。Vc(+5)过零电路(RBO/INT)(A2)可控硅14PIC16f85(A)78R1计量单元30pF4MHz图2单片机的接口B测量或反馈单元这种测量或反馈单位包含的LM358，窗口比较器。调节端电压始终检测，并反馈到PIC通过在图3所示的电路。图3测量或反馈装置的电路原理输出电压为通过自动电压调节器下降至9V，然后通过整流桥整流。一个220uF，12V电容和1100的电阻，串联，履行作为一个积分。这些电容和电阻值的选择，使RC值必须大于10毫秒，这是交流线电压时期的一半。反馈电压的应用于电阻VR1和在它的中心引脚的电压降，送入电压传感器LM358的管脚2和5。这种传感器电压变化比例根据反馈电压的变化而变化。通过调节电阻VR2和VR3设置上限和下限，如图3所示，这是串联，以确保上限阈值电压总是会比下限高。一个3V的齐纳二极管，在逆向偏压与电源相连，运作时以为POTS基准。在这里，齐纳电压必须低于PIC电源。但当电压达到或超过其额定值它会进入导通。在这个电路的上限和下限分别设置在l.5V和1.38V。只要的电压传感器在这两个范围之内，AVR端电压是恒定在220V并且LM358的两个输出引脚都不会饱和。因此，PIC对两个输入引脚检测没有大的影响。因此，它在改变延迟触发可控硅之前已决定提供正常的220V。因此稳压器保留其以前的正常电压。C过零检测电路检测零交叉点的微控制器电源波形的同步运行的软件程序是必要的。如图这零交叉检测单位图4包括一个整流桥，光耦(PC机817)和(945)晶体管。接受此电路的交流电压信号和接口逻辑电平信号。利用桥式整流器可以检测到无论是交流或直流电压。在PC817，它是由不同的是LED驱动输入端和输出端的晶体管。图4过零检测电路示意图输入端连接到400VAC整流线而输出端连接到PIC。反并联二极管连接到PC817的LED输入端的，以保护在过电压的条件下而损坏的LED。D升压自耦变压器一个400V升压自耦变压器，一平方英寸(1.5x1.4)的核心大小是用来处理高达500瓦load.For0-400至五，21SWG线使用，并为12-0-12V使用可控硅点火电路，用于23SWG导线。IV控制单元的的软件实现单片机的固件程序编译与PIC的C语言编译器工具套件版本从HI-TECH软件8.02。源代码是写在由Microchip公司制造的MPLABIDE版本6.60。程序流5是这样的：初始化寄存器后，PIC等待到的定时时间到是为了同步的交流电交流周期过零。尽快让PIC接受从零交叉检测电路的零交叉脉冲，它会检查，RAO和RA1(引脚17和18)的两个输入端的状态。这两个引脚被配置为电压调节端电压指标之下。PIC的接受计量单位的两个输出感应的调节端电压的状态，并反馈到PIC。我们的AVR所需的正常调节端电压是220V。由于交流线电压通常是220V下，首先上升至400V，以提供稳压器所需的端电压。因此，几乎在每