800VA Pure Sine Wave Inverter's Reference Design …

1 1 SLAA602A June2013 RevisedAugust2017 SubmitDocumentationFeedbackCopyright 2013 2017,TexasInstrumentsIncorporated800 VAPureSineWaveInverter s ReferenceDesignApplicationReportSLAA602A June2013 RevisedAugust2017800 VAPureSineWaveInverter s ReferenceDesignSanjayDixit,AmbreeshTripa thi,VikasChola,and AnkurVermaABSTRACTT hisapplicationnotedescribesthe designprinciplesand the circuitoperationof the pureSineWaveinverterhas variousapplicationsbecauseof its key advantagessuchas operationwith verylow harmonicdistortionand cleanpowerlike utility-suppliedelectricity,reductionin audibleandelectricalnoisein fans,fluorescentlightsand so on, alongwithfaster,quieterand coolerrunningofInductiveloadslike microwavesand 's the the Design :.. the TestResultsof 800 VASineWaveInverter s ReferenceDesign.

2 193 Comparisonof Low-Frequencyvs. of Figures1 Typesof 600 VAto 3 BridgeConfigurationof InverterModefor 's 's s ,DC Fan,and s the Gatesof the MOSFETsin InverterMode(High-SideA MOSFET sand Low-SideBMOSFET sare Conducting)..1919 FIG 17: Waveformsat the Gatesof the MOSFETsin InverterMode(High-SideB MOSFET sand Low-SideA MOSFET sare Conducting)..2020 TrilevelSwitchingAcrossthe High-SideA MOSFETSS ource(HSA)and High-SideB June2013 RevisedAugust2017 SubmitDocumentationFeedbackCopyright 2013 2017,TexasInstrumentsIncorporated800 VAPureSineWaveInverter s ReferenceDesign(HSB)..2021 TrilevelSwitchingAcrossthe High-SideA MOSFETSS ource(HSA)and High-SideB MOSFETsSource(HSB)..2122 InvertedWaveform(HOA-LOAand HOB-LOB)at the Gatesof the PWMS witchingat No Load(at the inverter s Output)is 88 the PWMS witchingat 400 W (at the inverter s Output)

3 Is Increasedto 98 Percentto MaintainVoltageregulationat the inverter s Outputby Sensingthe Slightclippingof SinusoidalWaveformat the s Outputat No s Outputat High-SideFET is SwitchedOff and BothLower-SideFETstoGroundin the H Bridgeare Switchedat the SameTimeWiththe DutyCycleProportionalto the of TablesTrademarksAll trademarksare the propertyof a devicethat convertselectricalpowerfromDC formto AC is typicalapplicationis to convertbatteryvoltageinto conventionalhouseholdAC voltageallowingyou touse electronicdeviceswhenan AC poweris not basicallythreekindsof Inverteroutof which,the first set of invertersmade,whichare now obsolete,produceda SquareWavesignalat ModifiedSquareWavealso knownas the ModifiedSineWaveInverterproducessquarewa veswithsomedeadspotsbetweenpositiveand negativehalf-cyclesat the cleanestutilitysupplylikepowersourceis providedby presentInvertermarketis goingthroughashift fromtraditionalModifiedSineWaveInvertert o PureSineWaveinvertersbecauseof the Typesof 's Design3 SLAA602A June2013 RevisedAugust2017 SubmitDocumentationFeedbackCopyright 2013 2017,TexasInstrumentsIncorporated800 VAPureSineWaveInverter s ReferenceDesign2 PureSineWaveInverter's BlockDiagramof 600 VAto 3 KVAR esidentialPureSineWaveInvertersThereis a dual modeof operationin a residentialInverter,that is.

4 Mainsmodeand Invertermodesshownin Inverternot only convertsthe DC Voltageof batteryto 220-V/120-VAC Signalsbut also chargetheBatterywhenthe AC mainsis blockdiagramshownaboveis a simpledepictionof the wayan 's June2013 RevisedAugust2017 SubmitDocumentationFeedbackCopyright 2013 2017,TexasInstrumentsIncorporated800 VAPureSineWaveInverter s :The method,in whichthe low voltageDC poweris inverted,is completedin two first step is theconversionof the low voltageDC powerto a high voltageDC source,and the secondstep is theconversionof the high DC sourceto an AC desiredoutcomewouldbe to first convertthe low voltageDC powerto AC, and thenuse atransformerto boostthe voltageto 120 widelyusedmethodin the currentresidentialinverteris the secondone and hencethis referencedesignis basedon this AC inputis sensedthroughisolatedamplifier(AMC1100)a nd the isolatedreplicaof the AC inputisgivento the TI s PicoloLite AC inputis not presentin Validrange(Invertermode)

5 Or AC fails,the relaybetweenMainsAC Inputand the InverterOutputremainopen,themicrocontrol lergeneratesPWMsand sendfour drivesoutputto GateDriver(SM72295). Nowthe GateDriveracceptslow-powerinputsfromthe controllerand producesthe appropriatehigh-currentgatedrivefor the powerMOSFET splacedin Full voltageinto AC usinghigh frequencyPWM(6 kHz to 20 KHz)thus feedingthe 50-HztransformerwhichBoostit to 120V/220 VAC. The outputof transformercontainsacapacitorwhichfilter sit to InverterModeGateDrivesAs seenfromthe BlockDiagram(Figure3), the OutputVoltageis Sensedthroughthe AuxiliarySecondaryWindingand feedsto the Controllertakesthis feedbackand thenWorkon the PWMtogeneratethe regulatedAC currentthat is flowingthroughthe batteryin Invertermodeand the Chargingcurrentduringthe Mainsmodeis measuredusingIntegratedAmplifiersof SM72295and givento the ADCsof 's Design5 SLAA602A June2013 RevisedAugust2017 SubmitDocumentationFeedbackCopyright 2013 2017,TexasInstrumentsIncorporated800 VAPureSineWaveInverter s ReferenceDesignAlsothis referencedesignhas additionalprotectionfor OvercurrentDischarge(OCD)and OverCurrentCharge(OCC)

6 UsingLM339 Comparatorswherethe amplifiedVoltageoutputacrossCurrentsense iscomparedwith a pre determinedValueand the PWMis immediatelyshut downby the controllerif eitherthe OCDor OCClimit is :In the mainsmode,whenthe inputAC is presentand is withinvalidrange,the relaybetweenInputACand the inverteroutputis closedand the inputAC directlygoesto the sameAC is fed totransformer,and the H-bridgeconsistingof MOSFETsor IGBT sare driventhroughmicrocontrollertochargethe bridgeless rectificationprincipleis usedto chargethe batterywherebasicallyboththe high-sideFET is switchedoff and bothlowerside FETsto groundin the H Bridgeare switchedat thesametime with the duty Cycleproportionalto the lowerFETsare turnedON at the sametime,that is, thereis a generationof boostedvoltageacrossthe leakageinductanceof the primaryinductanceconnectedto H Bridgeby the Ldi/dteffectand this energystoredin the LeakageInductanceflow throughthe bodydiodeof the high-sideMOSFETs(Eachhigh-sideMOSFET sbodydiodeconductson AC half cycle)

7 And chargethe chargingcurrentis proportionalto the duty cycleof the PWMswitchingon lowerside understandthe functioningof an inverter ,the usermustunderstandthe switchingrequirementof thefour drivesof the MOSFETsin H Bridgebothin Inverteras well as InverterModeThe SwitchingWaveFormin an Inverteris very simpleto understandand H BridgeConfigurationof MOSFETsOn the A SideMOSFETof the H Bridge,the PWMis generatedby modulatingthe SineWavewith highfrequency(6 KHz to 20 KHz)Squarewavein sucha way that the positivepeakof the SineWaveisrepresentedby maximumduty cycleand the negativepeakby the minimumduty Cycleas 's June2013 RevisedAugust2017 SubmitDocumentationFeedbackCopyright 2013 2017,TexasInstrumentsIncorporated800 VAPureSineWaveInverter s ReferenceDesignFigure5.

8 Modulationof SineWaveWithHigherFrequencyPWMS ignalsNowon the B Side,just phaseshift this SineWaveby 180 degreeand generatethe PWMin a similarWayas followingsimplehardwareimplementationof the PWMgenerationwillmakethe WaveformGenerationin InverterModeA side complementaryor the AM signalis obtainedby just invertingthe A side or AP waveformand thesamegoesfor B Sidecomplementaryor BM 's Design7 SLAA602A June2013 RevisedAugust2017 SubmitDocumentationFeedbackCopyright 2013 2017,TexasInstrumentsIncorporated800 VAPureSineWaveInverter s ReferenceDesignThe differentialsignalseenacrossthe OUTPand OUTN will be a TrilevelPWMS ignalas mentionedinFigure7:Figure7. TrilevelPWMS ignalDuringthe InverterModefor PureSineWaveGeneration2) MainsMode:In the mainsmode,boththe high-sideMOSFETsie A side as well B side is switchedoff and boththelow-sideMOSFET sare switchedwith the similarPWMwaveformwherethe duty cycleof lowersidePWMsignalsdeterminethe 's June2013 RevisedAugust2017 SubmitDocumentationFeedbackCopyright 2013 2017,TexasInstrumentsIncorporated800 VAPureSineWaveInverter s ReferenceDesignFigure8.

9 ChargingModePWMS witchingExplanationWhenthe lowerswitchesare turnedon at the sametime,thereis a boostedvoltage,that appearacrossthe primaryleakageinductanceof transformerconnectedto the H Bridge,by the Ldi/dteffectand thisenergyis use to chargethe batterythroughthe bodydiodesof the thehigh-sideMOSFET s bodydiodewill conductin the eachhalf of the mainsmodeis sensed,firstlyall the MOSFET sare switchedoff and the Relaybetweenthe Acinputand the Inverteroutputis , the LowerFETsare tunedon with PWMof smallduty Cycle(5 to 10 percent)and the high-sideMOSFETSare switchedoff. Nowthe voltageacrossthecurrentsenseis measuredby controllerand if the correspondingcurrentis less or morethanrequiredbychargingalgorithmthant he duty cycleis alteredcorrespondinglyie duty cycleis increasedif morechargingcurrentis requiredand decreasedif the chargingcurrentreductionis the DesignThe schematicis dividedinto two boards:1) MainPower s Board2) Microcontroller s 's Design9 SLAA602A June2013 RevisedAugust2017 SubmitDocumentationFeedbackCopyright 2013 2017,TexasInstrumentsIncorporated800 VAPureSineWaveInverter s ReferenceDesignFigure9.

10 MainBoard's SchematicPureSineWaveInverter's June2013 RevisedAugust2017 SubmitDocumentationFeedbackCopyright 2013 2017,TexasInstrumentsIncorporated800 VAPureSineWaveInverter s 's Design11 SLAA602A June2013 RevisedAugust2017 SubmitDocumentationFeedbackCopyright 2013 2017,TexasInstrumentsIncorporated800 VAPureSineWaveInverter s ReferenceDesignFigure10. Microcontroller's the Design :1) 12-VBatteryInputto :TPS54231buckconverteris usedto convertbatteryvoltage(nominal12 V) to is mainlyusedto powerthe Controllerdaughtercardand 's June2013 RevisedAugust2017 SubmitDocumentationFeedbackCopyright 2013 2017,TexasInstrumentsIncorporated800 VAPureSineWaveInverter s ReferenceDesignThe TPS54231DC-DCconverteris designedto provideup to a 2 A (our requirementis a maximum200 mA) outputfroman inputvoltagesourceof V to 28 V, and this integratesa low-RDSon,high-side the IC can be foundfromthe belowlinks:TPS54231: to 28-VInput,2-A, 570-kHzStep-DownConverterWithEco-Mode.