Infineon EVAL-IH-R5IPB-A-V1 User manual

UG2019-35
EVAL-IH-R5IPB-A-V1 Evaluation board
User Guide
About this document
Scope and purpose
This application note is a user guide of the evaluation board for IEWS20R5135IPB. It explains the board’s
hardwareandprovidesdetailedinstructionsonhowto use itforaddressingvariousmeasurementtasks. Finally,
practicalexamples demonstratethe benefitsof the IEWS20R5135IPBintherealapplication.
Intended audience
This document is intended for owners and users of the evaluation board. Please read carefully the
recommendationsprovidedinthisdocumentforsafelyoperatingthisboard.
Important Notice
Environmental conditionshave beenconsidered in the design of the Evaluation and Reference Boards provided
byInfineonTechnologies.The designof the Evaluationand Reference Boards istested by Infineon Technologies
only as described in this document. The design is not qualified in terms of safety requirements, manufacturing
andoperationovertheentireoperatingtemperaturerangeorlifetime.
TheEvaluationandReferenceBoardsprovidedbyInfineonTechnologiesaresubject tofunctional testingonly
under typical load conditions. Evaluation and Reference Boards are not subject to the same procedures as
regular products regarding returned material analysis (RMA), process change notification (PCN) and product
discontinuation(PD).
Evaluation and Reference Boards are not commercialized products and are solely intended to be used for
evaluation and testing purposes. They shall not be used for reliability testing or production. Hence, the
Evaluation and Reference Boards may not comply with CE or similar standards (including but not limited to the
EMCDirective2004/EC/108and the EMC Act) and may not fulfill other requirements of the country in which they
are operated by the Customer. The Customer shall ensure that each Evaluation and/or Reference Board will be
handled in a way which is compliant with all relevant requirements and standards in the country in which they
areoperated.
The Evaluation and Reference Boards are addressed only to qualified and skilled technical staff, for
laboratory usage, and shall be used and managed according to the terms and conditions set forth in this
documentand in any other related documentationprovidedwiththerespectiveEvaluationorReferenceBoard.
ItistheresponsibilityoftheCustomer’stechnicalstafftoevaluatethesuitabilityoftheEvaluationandReference
Boards for the intended application and the completeness of the Evaluation and Reference Board information
provided in this document with respect to such application. The Customer accepts that the Evaluation and
Reference Boards are not intended to be used for life-endangering applications such as medical, nuclear,
military, life-critical or other applications, where failure ofthe Evaluation and Reference Boards orany results
fromthe usethereofcan reasonably beexpectedtoresult in personal injury.
ApplicationNote Pleaseread theImportant Noticeand Warningsat theend ofthis document V1.1
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EVAL-IH-R5IPB-A-V1 Evaluation board
User Guide
Safety precautions
Evaluation and ReferenceBoards are provided "AS IS". Infineon Technologies disclaims any and all warranties,
express or implied, including but not limited to warranties of non-compliance with any specification, non-
infringementofthirdpartyrightsandimpliedwarrantiesof fitnessfor any purpose,orformerchantability.
Infineon Technologies shall not be responsible for any damages resulting from the use of the Evaluation and
Reference Boards.Customer isobliged to defend,indemnify and hold Infineon Technologies harmless from and
againstanyclaimsordamagesarisingoutoforresultingfromanyuseoftheEvaluationandReferenceBoards.
Table of contents
About this document....................................................................................................................... 1
Important Notice ............................................................................................................................ 1
Table of contents............................................................................................................................ 2
1Safety precautions ................................................................................................................. 4
2Introduction.......................................................................................................................... 5
2.1 Purposeoftheboard...............................................................................................................................5
2.2 Scopeofdelivery.....................................................................................................................................5
3Hardware.............................................................................................................................. 7
3.1 Scopeofdelivery.....................................................................................................................................7
4Usage...................................................................................................................................10
4.1 Settings..................................................................................................................................................10
4.1.1 ReplacingtheIEWS20R5135IPB.......................................................................................................10
4.1.2 Tuningcollector-emittervoltagesensenetwork............................................................................11
4.1.3 Tuningturn-ondetectionpointoftheIGBT....................................................................................13
4.1.4 Tuningcollector-currentsensenetwork.........................................................................................14
5Experimental results .............................................................................................................15
5.1 Operation...............................................................................................................................................15
5.1.1 Stand-bymode.................................................................................................................................15
5.1.2 Normaloperationandchangeofoutputpower.............................................................................16
5.1.3 Operationincurrentlimitation.......................................................................................................17
5.1.4 Operationincaseofovertemperaturewarningandovertemperatureshutdownconditions.....17
5.2 PerformingEMCtestsontheboard......................................................................................................20
5.2.1 TestduringanACinstantaneoussupplyinterruption....................................................................20
5.2.2 Surgetest..........................................................................................................................................22
6Appendix..............................................................................................................................25
6.1 Resonantinductorspecification...........................................................................................................25
6.2 Schematicdrawing................................................................................................................................26
6.3 Boardlayout..........................................................................................................................................27
6.4 Billofmaterials......................................................................................................................................29
Appendix ......................................................................................................................................32
Revision history.............................................................................................................................33
ListofAbbreviations
•IH:Inductionheating
•SEPR:Single-endedparallelresonant
•E:EmitterpinoftheIEWS20R5135IPB
•C:CollectorpinoftheIEWS20R5135IPB
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•VCC:SupplypinoftheIEWS20R5135IPB
•CS:CurrentsensepinoftheIEWS20R5135IPB
•INN:ControlpinoftheIEWS20R5135IPB
•VDET:VoltagedetectionpinoftheIEWS20R5135IPB
•VCE:Collector-to-emittervoltageoftheIEWS20R5135IPB
•IC:CurrententeringinthecollectorpinoftheIEWS20R5135IPB
•VCS:VoltagebetweenpinCSandE
•VVDET:VoltagebetweenpinVDETandE
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Safety precautions
1Safety precautions
Table 1 Safety Precautions
Warning: The operating potential of this board are up to 600 VRMS. Peak operating
potentials are up to 1350 V. Do NOT touch the board during operation. Even brief
accidentalcontactduring operationmight result in severeinjury or death!
Caution: Only personnel familiar with the high voltage appliances, power
electronics and associated machinery should plan, install, commission and
subsequently service the system. Failure to comply may result in personal injury
and/or equipmentdamage.
Warning: The evaluation or reference board contains DC bus capacitors which may
take time to discharge after removal of the main supply. Before working on the
system, wait up to five minutes for capacitors to discharge to safe voltage levels.
Failure to do so may result in personal injury or death. Darkened display LEDs are
notan indication that capacitors havedischargedto safe voltage levels.
Warning:TheevaluationboardDOESNOTofferproperinsulationtotheuser.DoNOT
connect the board to the grid in any case. When supplying the AC voltage to the
board, USE ISOLATED POWER SUPPLY ONLY, and connect the earth terminal of the
boardto a propergroundedpoint.
Caution: The heat sink and IGBT module surfaces of the evaluation or reference
board may become hot during testing. Hence, necessary precautions are required
whilehandling theboard. Failure tocomply may causeinjury.
Caution:The evaluation or reference board contains parts and assemblies sensitive
toelectrostaticdischarge(ESD).Electrostaticcontrolprecautionsarerequiredwhen
installing, testing, servicing or repairing the assembly. Component damage may
result if ESD control procedures are not followed. If you are not familiar with
electrostatic control procedures, refer to the applicable ESD protection handbooks
andguidelines.
Warning: Remove or disconnect power from the drive before you disconnect or
reconnect wires, or perform maintenance work. Wait up to five minutes after
removingpowertodischargethebuscapacitors.Donotattempttoservicetheboard
until the bus capacitors have discharged to zero. Failure to do so may result in
personalinjury or death.
Caution: Wiring or application errors such as supplying an incorrect or inadequate
AC supply,or excessive ambienttemperatures mayresult in system malfunction.
Caution:The evaluation board may be shipped with packing materials that need to
be removed prior to installation. Check carefully for all the packing materials that
may interfere with the normal operation of the components. Failure to remove all
packing materials that are unnecessary for system installation may result in
overheatingor abnormaloperatingconditions.
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Introduction
2Introduction
The evaluation board EVAL-IH-R5IPB-A-V1 was developed as a test platform for the IEWS20R5135IPB. It
replicates a complete, almost stand-alone, solution for induction heating based on SEPR converter. This
introductory section provides an overview of the potential of the evaluation board and lists the components
includedinthedelivery.
2.1 Purpose of the board
The purpose of the evaluation board shown in Figure 1 is to have one universal test platform for the
IEWS20R5135IPB.Itallowsuserstoevaluatethe advantagesprovided bytheintelligent protectionmechanisms.
Fordetailed informationaboutthe device,refertoApplicationnotes[1].
(a)
(b)
Figure 1 Evaluation board of the IEWS20R5135IPB: (a) top and (b) bottom
The board implements a SEPR converter for induction heating application in order to demonstrate the
functionalities of the IEWS20R5135IPB during the typical operating conditions of an induction heating cooker.
This board also represents a design recommendation. Care has been taken to optimize the layout of the PCB in
orderto guaranteecleansignalsandreproduciblebehaviorofthedevicein all operating conditions.
2.2 Scope of delivery
Theevaluationboardisdeliveredtogetherwithspareparts andcompletedocumentationinanenvironmentally
friendlycarton boxasillustratedinFigure2.Asdepicted,theboxcontains:
•EvaluationboardEVAL-IH-R5IPB-A-V1withasizeof164mmx145mmx83mm(LxWxH).
•10xIEWS20R5135IPB.
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Figure 2 Scope of delivery: evaluation board, spare parts and USB drive with documentation (the
picture is only for illustration purpose)
For guaranteeing safe measurement procedures, testing points have been provided on the board for the key
signals. The following additional accessories/testing equipment may be useful for performing proper
measurements:
•GroundspringPK007-016[3]orprobetiptoPCBadapterPK106-4[4],bothfromTeledyneLeCroy,for
accuratemeasurementsoflowvoltagesignals.
•PEMCWT1ultra-miniRogowskicurrentwaveformtransducerformeasuringthecollectorcurrentof the IGBT
[5].
Inordertoexploitallthebenefitsofthe IEWS20R5135IPB,specific electromagneticcompatibility(EMC) testscan
be performed on the evaluation board (e.g. EFT/bursts, power fail and surge) by means of the following
additionalequipment:
•EmtestCompactNX5,multifunctionaltestgeneratorfortransientsupto5.5kV[6].
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Hardware
3Hardware
Thissectionprovidesashortdescriptionoftheboardhardware.First,itexplainsthepowercircuitry,theauxiliary
powerstage, the controlstage and the connectors. For each of the stages, the main components are presented.
Then,theapplicationoftherecommendedaccessoriesisdiscussed.
3.1 Scope of delivery
The evaluation board implements an induction heating power inverter, with the IEWS20R5135IPB as the main
activedevice.Thepinoutofthedeviceisshownin[1].
Inadditiontothemaindevice,theboardalsofeatures(fromlefttorightinFigure4):
•Aninput filterstage,consistingofapi-filterwithan inductance (L) and two X2 capacitors(C)necessaryfor
attenuationofthehigh-frequencycomponentoftheIGBTpulsecurrent.
•Adiode full-bridgerectifierwithamaximumratedvoltageof1000Vandamaximum rated current of15A.
•AnX2 capacitor of 4.7µF(Cbus)that acts as buscapacitanceforthesubsequentinverterstageallowing
recirculationofthehigh-frequencycurrent.
•Aresonantcapacitanceof270nF(Cres)thatimplementsthe resonantchaintogetherwiththeresonantcoil
(Lres).
•Aresonantcoilwithanominaldiameterof200mmandanominalinductanceof100µH1.
Theresonantcoilmustbeconnectedby means of twoscrew connectors,whichareindicatedonthe board as L1
andL2.Thevalueoftheutilizedinductorwillbeprovidedasareferencefurtheroninthedocument.
Fortheproperimplementation oftheconverter,additional components have beenalso designedin:
•Ametal-oxidevaristoramongtheinputACphasesin order to dissipatepartoftheenergy that is injected
duringasurgetest.
•Acurrent senseresistorwithanominalvalueof10mΩ,in series with the IEWS20R5135IPB,whichisusedfor
sensingthe current ofthe IGBT for over-current protection and output power control. The sense resistor is
placedinserieswiththeemitterpinofIGBTandthebuscapacitance.
•Anauxiliary power supplystagethatprovidesthesupplyvoltagetotheIEWS20R5135IPB,tothefanandto
theMCU.
•Aresonantcapacitanceof270nF(Cres)thatimplementsthe resonantchaintogetherwiththeresonantcoil
(Lres).
Figure 3 Package and pinout of the IEWS20R5135IPB
1Formore detailsof thecoil, seeSection 6.1.
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Figure 4 Overview of the board schematics (a) and components (b)
Forversatility, theevaluation board has been equipped with a control stage that allows the output power of the
convertertobechanged,andthatoffersoptical feedback ofthestatusofthe IEWS20R5135IPBduringoperation.
An Infineon 32-bit XMC™1000 Industrial Microcontroller ARM® Cortex®-M0 has been used as core of the control.
Thecontrolstageisimplementedonaseparate areaoftheevaluationboardinordertoofferasafe,low-voltage
region for controlling the operation of the main converter. The board also comes with a heatsink and fan
arrangement, the size and shape of which provides enough cooling performance required for continuous
operation. The fan speed is regulated by the MCU according to the feedback of the status provided by the
IEWS20R5135IPB.
The experimental analysis of the IEWS20R5135IPB operation requires oscilloscope measurements of the
collector-emittervoltage(VCE),thevoltageatpinINN,andthecollectorcurrent.Thesethreemeasurementsallow
for a complete understanding of the IEWS20R5135IPB operation and status. A more detailed analysis of the
IEWS20R5135IPB behavior could require also the measurement of the voltages at the VDET and CS pins. All the
voltages, except the one at the CS pin, can be measured by connecting the oscilloscope probe to the test points
thatareprovidedontheboard.
•Inordertomeasurethecollector-emittervoltage,ahigh-voltageprobemustbeused,asthepeakvalueof
sucha voltageexceeds thevalue of 1kV also during normal operation, and may even be higher if surge tests
areperformed.
•Forthe measurementof the voltagesattheINNandVDETpins,astandardpassiveprobeincombination
withagroundspringcanbeused,asshowninFigure5a.
(a)
(b)
(c)
Figure 5 Exampleof probe connection for the measurement of: VINN and VVDET (a), IC (b) and VCS
(c)
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•ThebestsolutionformeasuringthecollectorcurrentistouseaRogowskicurrentprobe, and connect it to
theboardasshowninFigure5b.
•ThemeasurementofthevoltageattheCSpinisparticularlytricky,asitsvalueisintherangeofhundredsof
millivolts. Therefore,themeasurementscanbeaffectedbythenoisegeneratedbytheIGBTswitching.In
ordertoperformreasonablemeasurements,a low inductive connectionbetweenCS pin and emitter pin of
theIEWS20R5135IPBhastobemade. A possiblesolutionconsistsof solderingaheaderconnectoranduse
thegroundspring([4])asshowninFigure5c.
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Usage
4Usage
The main purpose of the evaluation board is to show the features provided by the IEWS20R5135IPB in typical
application conditions. While the previous sections explained the basic purpose as well as the hardware of the
board,thissectionprovidesdetailedinstructionsonhowtosetupandoperatetheboard.Section4.1describes
how to replace the active switch and how to modify certain board settings, whilst section 5 deals with the
preparationandexecutionofdifferentexperiments.
4.1 Settings
The evaluation board is intended for testing the IEWS20R5135IPB that comes in a TO-247 6 pin package. Due to
the high number of leads, the assembly and disassembly of the device may pose particular difficulties. The
followingsectionexplainsthebestwaytoreplacetheswitchin ordertoavoiddamage to the PCB.
Attention: Preventpotential exposure to hazardous voltagesby turning off allpower supplies and
discharging the capacitors before undertaking any of the modifications described in the
remainderof this section.
4.1.1 Replacing the IEWS20R5135IPB
A PCB is subject to severe thermomechanical stress when soldering and unsoldering components. As a
consequence,theadhesionbetweenthecopperlayers and the core material getsweakerand eventually copper
pads or traces may lift off and break. Normally, the best way to avoid damage to the PCB is to use press-fit pins
for connecting the TO packages and the PCB. However, such a solution cannot be used in the case of the
IEWS20R5135IPB, as the additional parasitic inductance caused by the pins would dramatically affect the
behavior of the device. As a compromise to ease the assembly and disassembly process of the device, the
mounting holes on the PCB have been deliberately designed bigger than what is normally advised by the
footprint. There are several ways of removing the TO packages from the heatsink and the board. The simplest
approach is to cut the package leads, remove the package body from the heatsink, and unsolder one lead after
anotherfromthepress-fitpins.ThisguaranteesminimumstressonthePCB.TheprocessisshowninFigure6:
1. Putthe board in an uprightpositionso that the devicepackagesfaceupwards(a).
2. Pusha flatscrewdriverbetweenthe clipandthepackagebodyandtwistit to pulltheclipoutofthe
heatsink’sgroove(b).
3. Cutthe6leadsoffthedevice,startingfromthecollectorandproceeduntiltheVDETpin(c).
4. Removetheleftoverpart ofthepinsandcleanthepadsbyusingasolderingironand soldering wick(d).
Itis highlyrecommendedto check thespring aftermounting, as thedisassembly processcould modifyits shape
thuslooseningthepressureforce.In case thishappens,theoriginalshapecanberestoredby meansofpliers.
(a)
(b)
(c)
(d)
Figure 6 Disassembling a device from theheatsink and the PCB
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(a)
(b)
(c)
(d)
Figure 7 Assembling a device onto the heatsink and the PCB
Assemblingprocessiseasierthandisassembling.Figure7presentsapossiblesequenceofsteps:
1. PreparetheTOpackagebycutting the leads to a length of around 5 mm (a).
2. Bend the pins 3 and 5 towards the front of the package in order to provide an offset of roughly 3.5 mm with
respecttheotherpins(a).
3. Put a sufficient amount of thermal grease on the insulator material in order to guarantee a good thermal
contact.
4. Placethepackageontheheatsinkmakingsurethatitlaysperfectlyflatonthesurfaceoftheheatsink(b).
5. Putthespringcliponthepackageandheatsinkgroove,andfastenitusingpliers(c).
6. SolderoneleadaftertheotheronthetopsideofthePCB(d).
4.1.2 Tuning collector-emitter voltage sense network
The IEWS20R5135IPB features an over-voltage protection functionality that prevents the VCE voltage to exceed
defined values. It also prevents the device from turning on if VCE is higher than a determined threshold. The
behavior of the over-voltage protection is determined by the voltage at the VDET pin, and can be adjusted by
modifying this voltage value. The evaluation boards implement a resistor chain to supply the voltage at VDET
pin,asshownin Figure8a.TheresistorRVDET can be replacedin order to change the voltage atVDET. Figure 8b
shows the relation of the resistance RVDET and the corresponding value of the limiting voltage. When the VCE
exceedsthe limitingvoltage, theIEWS20R5135IPB switches to over-voltage shutdown (INN voltage is pulled to 0
V).Inthismode,thedevicecanactivelyclampthevoltageinorderto preventitfromexceedingthemaximumVCE
of the IGBT. The over-voltage shutdown mode is deactivated as soon as VVDET falls below a restart threshold1,
withaminimumblankingtimeof3ms.Figure8aalsoshowsthatasecondresistorchainisderivedfromthemain
resistor dividers. This chain is used to provide theinformation from the VCE to the MCU, so that it can determine
whentheIGBThastobeturnedon.TheusageofasharedchainforsensingVVDETandfortriggeringthetheturn-
on ofthe IGBT isa cheaper andless space-consuming solution compared to a solution with two distinct resistor
dividerchains.
Figure 8c shows a reference of how the VVDET should look in comparison to VCE voltage. As can be seen in the
picture, the voltage at VDET and the voltage VCE show the same behavior except for a small shift in time that is
caused by the capacitance between VDET and GND. In general, the parasitic capacitance that is present at the
package level between the heatsink and VDET pin has to be considered in addition to the external capacitance
showninFigure8a2.
1Fora detailedexplanation ofthe clampingbehavior refer tothe applicationnote ofthe IPD[1].
2Pleasenotethatinthisboardtheheatsinkisconnectedto GND for safety reasons. Inindustrial designs the heatsink is usuallyat the
samepotential asthecollector oftheIGBT. Asaconsequence, theeffectofthe parasiticcapacitancebetween VDETand theheatsink
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(a)
(b)
(c)
Figure 8 (a) Schematic of the collector-voltage sensing network; (b) dependence of the over-voltage
clamping voltageon thevalue of RVDET; (c) experimental waveforms of VVDET (green curve,
700 mV/div) and VCE (cyan curve, 200 V/div), time scale: 5 µs/div.
may produce a different shiftbetween VVDET and VCE that should therefore be compensated by a higher external capacitance between
VDETand GND.
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(a)
(b)
(c)
Figure 9 Collector-current sensing: (a) schematic of sense circuit; (b) dependence of the IGBT peak
current on the resistance RCS; (c) comparison between IGBT collector current measured
by Rogowski coil (yellow curve, 20 A/div) and voltage measured at pin CS (green curve, 60
mV/div), time scale: 10 µs/div.
4.1.3 Tuning turn-on detection point of the IGBT
One of the critical aspects of the SEPR converter is to determine the optimal turn-on point of the IGBT, which is
during the conduction phase of the parallel diode. The evaluation board is already optimized to match the
optimal turn-on point of the IGBT. However, in case the resonant capacitance is replaced with a different value,
theturn-ondetectionpointhastobechanged.Inordertodoso, theresistanceRV-hastobechangedtoadjust
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the turn-on point of the IGBT (as shown in Figure 8a). It is recommended to change the value of the resistance
onlyifthevalueoftheresonantcapacitanceischanged.
4.1.4 Tuning collector-current sense network
The IEWS20R5135IPB forinduction heating also features an overcurrent protection functionality that allows the
IGBT to be switched off as soon as the collector current reaches a selected threshold. Such a functionality
requires avoltagereplica ofthe collectorcurrent, availableat theCS pin.Such avoltage signalhas tobe asclean
aspossibleinordertoavoidunpredictablebehaviorof the IGBT1.
The evaluation board utilized a 10 mΩSMD metal-film resistor as sensing element of the collector current,
followed by a passive low-pass filter, as shown in Figure 9a. The DC gain of the low-pass filter determines the
current at which the IGBT is shut down. By means of the RCS resistance, the gain can be changed, thus changing
the maximum current that can flow in the IGBT. Figure 9b shows the measured dependence of the maximum
collector current onthe value of the resistance RCS.The dependence is not perfectly linear, as at higher RCS the
effectofthecapacitanceinparallelbecomesmoreprominent.
InFigure9c,acomparisonisshownbetweenthecollectorcurrentmeasuredbytheRogowskicoilandthevoltage
measured among CS and emitter pins of the IEWS20R5135IPB. It can be noticed that during the on-time of the
IGBT,where the collector current is almost linearly increasing, the voltage at the CS pin (green curve) replicates
the current measured with the Rogowski coil (yellow curve). During the off-time, the collector current is almost
zero2, but VCS shows similar behavior like the VCE (see Figure 11). This behavior is caused by the parasitic
capacitance of the package that creates a coupling between the collector potential and the CS potential. Such
behavior, however, does not affectthe IEWS20R5135IPB operation, since the coupling is presentonly in the off-
stateoftheIGBT.
1Thethresholdofthecurrentsenselimitationis setto a typical value of-200 mV. The resistor dividerof the low pass filter in Figure 9a is
chosenso thatfor thedesigned peakcurrent, the voltageat CSis equalto -200mV.
2Theoffset ofthe ICinthe off-stateis due tothe ACnature ofthe Rogowskiprobe.
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Experimental results
5Experimental results
5.1 Operation
Once the system has been properly tuned, as explained in the previous sections, the board can be powered up
by connecting it to an AC power supply. The nominal value of the AC voltage is 230 V/50 Hz. If not otherwise
specified,allthe results presentedinthefollowingare obtainedwithsuchasupplyvoltage.
Attention: Priorto starting measurements,ensure thatthe boardsettings are correct.Take special care
thatno physical short circuitsor floating gates are present.
Attention: When supplyingthe AC voltage tothe board,USE ISOLATED POWERSUPPLY ONLY, and
connecttheearth terminalof the boardto a proper groundedpoint.
DANGER:the boardDOESNOT offer proper insulation to the user. Do NOT connect the board to the grid in
any case.
The evaluation board is set up as explained in Section 4.1. Following the recommendations on page 8, current
measurements are made using a Rogowski-coil current sensor, and voltage probes were connected via PCB
adapters.No probehas been connected on the CS pin, as this can be a significant cause of disturbance for some
of the testsexplained below. Figure10 shows the evaluation board and the measurement hardware as the main
partofthesetup– AC powersuppliesandthesurgetestgeneratorarenotshowninthefigure.
The board is provided with a 7-segment display that indicates whether the converteris operating and, in case it
is,whatthetargetoutputpowerlevelis.
Inthenextsection,the typicaloperationofthe boardisshown.
5.1.1 Stand-by mode
Oncethe boardis supplied with the main AC voltage, the board turns on in stand-by mode. In this condition,
thedisplayshowssimplyadot.Theboardreturnstostand-bymode:
•WhentheON/OFFbuttonispressedwhiletheconverterisinoperation.
•Whenthesystemisswitchedon,butnocookingvesselisdetected.
Figure 10 Main parts of the test setup
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Experimental results
5.1.2 Normal operation and change of output power
Table 2 Target output power according to the power setting
Power level setting Target input power level (W)
1 1000
2 1200
3 1400
4 1600
5 1700
6 1900
7 2100
Starting from stand-by mode, by pressing the ON/OFF button once, the system turns on and performs a check
toverifythepresenceofavesselontheresonantinductor.Thedetectionprocessisrepeatedfivetimes,onceper
second. In case a vessel is detected, the output power level is automatically set to ‘5’, as also indicated by the
display,andthesystemstartstheoperation.Inthiscondition,thetarget outputpoweris1700W.Incasethereis
no vessel, the system returns to stand-by mode. While in operation, the output power of the system can be
increased and reduced by means of buttons P+ and P-. Table 2 shows the power levels and the corresponding
targetoutputpower.
DuringnormaloperationconditionstheIEWS20R5135IPBisdrivenbytheINNsignal,asshowninFigure11.When
the INN voltage changes from high to low, the IGBT is turned on, with a typical propagation delay of 700 ns; on
Figure 11 Normal operation of IEWS20R5135IPB: turn-off and turn-on INN-to-IC propagation delay.
IC (yellow curve, 20 A/div), VCE (cyan curve, 200 V/div) and INN (magenta curve, 1V/div),
time scale: 5 µs/div
ApplicationNote 16of 34 V1.1
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EVAL-IH-R5IPB-A-V1 Evaluation board
User Guide
Experimental results
theotherhand,whentheINNvoltagechangesfromlowtohigh,theIGBTisturnedoff,withatypicalpropagation
delay of 2.2 µs. The larger propagation delay at turn-off is due to an increased filtering time to avoid spurious
turn-off events. As a consequence, the turn-off of the current in normal operation occurs with a delay, with
respect to the INN transition, from low to high.During normal operation,the high value of the voltage atpin INN
istypicallyequalto2.5V.Suchavalue correspondsto‘normal’conditionoftheIEWS20R5135IPB.
5.1.3 Operation in current limitation
Depending on the chosen setting of the maximum current, a current limitation can already be reached during
normaloperationmode,especiallyathighpowerlevels. Whenthishappens,the100Hzenvelopeofthecollector
currentchangesasshowninFigure12a.Inthesingleswitchingevent,astrongcurrentlimitationcanbeidentified
if the IGBT current switches off before the INN voltage changes from low to high, as shown in Figure 12b.The
operationin current limitation is still considered a ‘normal’ condition for the IEWS20R5135IPB and therefore no
change in thevalue oftheoff-state INN voltage is produced in this case. Nevertheless,it is important to mention
that when current limitation occurs during the operation, the input current of the overall system changes its
shape according to the envelope shown in Figure 12a. As a consequence, the total harmonic distortion (THD) of
theinputcurrentincreases.For thisreason, thecurrentlimitation featuresshould bemainlyused for protection,
andthelimitationthreshold shouldbeset ina waythat thecurrent isnot limitedduring thenormal operation of
thesystem.
5.1.4 Operation in case of overtemperature warning and overtemperature
shutdown conditions
Incasethetemperatureofthedeviceexceeds75°C,thestatusoftheIEWS20R5135IPBchangesto
‘overtemperaturewarning’mode.Inthiscondition,thehighvalueoftheINNvoltagechangesfrom2.5Vtoa
typicalvalueof4V,asshownin Figure 13a. The MCUcontinuoslymonitors theaveragevalueoftheINNpinand
canthereforedetectthestatusandreactconsequently.Inparticular,in‘overtemperaturewarning’ mode:
•TheLEDOTWontheboardturnson.
•Thespeedofthefanisincreased.
Assoonasthetemperatureofthedevicedropsagainbelow75°C,theOTWLEDswitchesoff,andthespeedofthe
fanisagainreduced.Incaseofsignificantpowerdissipation(e.g.strong hardswitchingturn-on at lower power),
thetemperatureoftheIGBTcanincreaseevenmore,andeventuallyreachthevalueof150°C.Whenthishappens,
theIEWS20R5135IPBenters‘overtemperatureshutdown’mode.Inthiscondition,thedevicestopsoperatingand
keeps the INN voltage constantly at a value that is <0.5 V, as shown in Figure 13b. In this condition, the led OTS
(red) is turned on.The ‘overtemperature shutdown’mode ceases as soon as the temperature ofthe IGBT drops
below 75°C; the OTS LED switches off, and the system restarts automatically, performing the vessel detection.
Thefanspeedis alsoreduced whenthedevice restarts in ‘normal’status. Thecircuitfor detectingthe INNstatus
isshowninFigure13cwhilstitsoperationisexplainedasfollows:
•TheINNsignal is split and fed into a peak-detectorcircuitconsistedofthe SchottkydiodeD3andthe
capacitorC10.ThevoltageacrossthecapacitanceissensedbyanA/DconverteroftheMCU.Bymeansof
thiscircuit,theIEWS20R5135IPBstatusreadcanbeperformedin a relaxed time without the need to be
synchronizedwithPWMdrivingsignal.
•WhentheIEWS20R5135IPBenters overtemperaturewarning mode, the INNvoltageincreases to 4 V during
theoff-state;thecapacitanceisthereforecharged upto3.8V(consideringthevoltagedropacrossD3)
duringroughly100nsbecausethe chargingcurrentismainlylimitedbythemaximum output currentofthe
INNpin.ResistorR22isinsteadusedforallowingthedischargeofthecapacitanceC10whenthe
IEWS20R5135IPBisinshutdownmode,sinceitcan’tbedischargedbytheINNcurrentbecause of the diode
D3.
ApplicationNote 17of 34 V1.1
2019-11-25

EVAL-IH-R5IPB-A-V1 Evaluation board
User Guide
Experimental results
(a)
(b)
Figure 12 Current limitation operation of IEWS20R5135IPB: (a) 100 Hz envelop, 2 ms/div; (b) single-
switching event, 10 µs/div. IC (yellow curve, 20 A/div), VCE (cyan curve, 200 V/div) and INN
(magenta curve, 1V/div)
ApplicationNote 18of34 V 1.1
2019-11-25

EVAL-IH-R5IPB-A-V1 Evaluation board
User Guide
Experimental results
(a)
(b)
ApplicationNote 19of34 V 1.1
2019-11-25

EVAL-IH-R5IPB-A-V1 Evaluation board
User Guide
Experimental results
(c)
Figure 13 INN voltage change: (a) in overtemperature warning (OTW) operation and (b) in
overtemperature shutdown(OTS)(1 V/div– 100 µs/div); (c) schematic of the INN voltage
sense
5.2 Performing EMC tests on the board
The most stressful situations for the SEPR-based induction cooking systems occur when the grid voltage
experiencessudden changes. In fact, this leads to an increase in the bus voltage and finally, due to the voltage
resonantoperation,toasignificantincreaseofthepeak-collectorcurrentandthepeakcollector-emittervoltage
oftheIGBT.Inorderforaninductioncookingsystemtobereliableandusableinthemarket,ithastofulfillthe
electromagneticcompatibility(EMC)requirements,which comprises, among other things,system testingunder
suddenvariationsofthegridvoltage.The IEC 61000-4 norm [8] provides guidelines on how to test the reliability
ofasystemagainstgridtransients.Among the different tests considered, two are of major interest to show how
the IEWS20R5135IPB could improve system reliability: test of instantaneous AC power supply interruption and
surge tests. These tests have been performed by using the test generators presented in section 2.2, and the
resultsareaddressedinthenextsections. Before addressingthe details ofeach test, itis importantto mention
that the system is only properly protected by means of the IEWS20R5135IPB, which is only guaranteed if the
device can sense accurately the collector-emitter voltage and the collector current. The general
recommendation provided in section 4.1 should guarantee the best and most reproducible behavior of the
device.
5.2.1 Test during an AC instantaneous supply interruption
Instantaneousinterruption of the ACsupply (i.e., loss of supply voltage duringa time shorter than 30 cycles)can
occur because of damages to the electrical grid that cannot be immediately compensated by the utility
infrastructure. In the case of an induction cooker that is based on the SEPR topology, the effect of an
instantaneous AC loss can be catastrophic, as it may ultimately lead to the failure of the IGBT. This is because
duringashortinterruptionofthemainsupply,thebuscapacitor,whichfeedstheenergytotheresonantinverter,
is rapidly discharged and then charged again. By the effect of the resonance between the bus capacitance and
theinputfilterinductance,thevoltageonthe buscapacitorcan exceedtheinput voltage,asshownin Figure 14.
ApplicationNote 20 of34 V 1.1
2019-11-25