prEN IEC 63758-5-3:2026

• Status: Not Published
• Publication Date: 23-Feb-2028
• Technical Committee: CLC/TC 100X - Audio, video and multimedia systems and equipment and related sub-systems
• Current Stage: 4020 - Enquiry circulated - Enquiry
• Start Date: 18-Sep-2026
• Completion Date: 18-Sep-2026
• Directive: 2014/53/EU - Directive 2014/53/EU of The European Parliament and of the Council of 16 April 2014 on the harmonisation of the laws of the Member States relating to the making available on the market of radio equipment and repealing Directive 1999/5/EC
• Mandate: M/607 - COMMISSION IMPLEMENTING DECISION of C(2025)1207 on a Standardisation Request M/607 as regards charging interface and charging communication protocol for radio equipment capable of being recharged by means of wireless charging in relation with Article 3(4), sixth subparagraph, of Directive 2014/53/EU of the European Parliament and of the Council.
• Ref Project: oSIST prEN IEC 63758-5-3:2026 - Qi specification - Version 2.3 - Part 5-3: Mpp - Magnetics design (Fast Track)

prEN IEC 63758-5-3:2026 is a CLC/IEC fast-track draft part of the Qi Specification for MPP magnetics design. It defines the system model and requirements for the magnetics used in both Power Transmitter (PTx) and Power Receiver (PRx) products that implement the Magnetic Protocol and the magnetic attach alignment method.

What does prEN IEC 63758-5-3:2026 specify?

prEN IEC 63758-5-3:2026 specifies the magnetics design model for Qi MPP implementations. It sets the reference PTx and PRx coil system models, the mated-condition electrical behavior, and the magnetic boundaries used to judge interoperability.

The document is organized into these main clauses:

• Clause 1 - General: structure of the Qi Specification, scope, compliance language, references, and notation rules.
• Clause 2 - Coil Design: background and how the coil system models are used.
• Clause 3 - PTx Coil System Model: mechanical construction, magnet arrangement, and electrical properties.
• Clause 4 - PRx Coil System Model: mechanical construction, shielding, nearby metal representation, and electrical properties.
• Clause 5 - Properties of Mated Coil System Models: electrical measurement under mated conditions.
• Clause 6 - Coil Specifications: magnetic boundaries and implementation requirements for PRx and PTx.

Clause 1 also explains the document conventions used for numbers, tolerances, data fields, text strings, and shorthand packet notation. That matters in practice because implementers need to read the same values and packet references in the same way during design, verification, and test.

What are the key requirements of prEN IEC 63758-5-3:2026?

Mechanical reference models

prEN IEC 63758-5-3:2026 defines detailed reference constructions for both the PTx and PRx coil system models in Clauses 3 and 4. The PTx model includes a plastic top enclosure, a coil module with ferrite and permanent magnets, and an aluminium bottom enclosure; the PRx model includes a glass bottom enclosure, an aluminium support plate, a coil module with copper and magnetic shielding, and a friendly-metal block.

These models matter because they are the geometric and material baseline for compliance tools and interoperability testing. The document says implementations should follow the coil system models as closely as possible so that practical products stay close to the compliance test tools.

The PTx coil module also includes a cut-out to route coil leads, and the PRx coil module includes a cut-out in the shielding for access to the coil terminals. In practice, those details affect how a real product is packaged and wired without changing the intended magnetic behavior.

Alignment, attraction, and saturation control

prEN IEC 63758-5-3:2026 requires the PTx and PRx coils to align within a 2 mm radius in the magnetic attach sense, as stated in Clauses 6.2.1 and 6.3.1. The PTx is also required to attract the PRx toward the center position and provide enough force both normal to the interface surface and in the plane of the interface surface, per Clause 3.1.8.

This matters because alignment strongly affects charging stability, transfer efficiency, and user experience. If the magnets do not center the receiver well enough, the link can sit near the edge of the valid operating region.

Clause 3.2.2 and Clause 6.3.2 address a second practical risk: the PTx magnets must not saturate the PRx shielding. The document uses a saturation check based on the normalized change of inductance of the TPR#MPP3 test receiver at centered and offset/spaced positions. That is important because shielding saturation can reduce or disturb power transfer.

Free-air and mated electrical behavior

prEN IEC 63758-5-3:2026 gives free-air electrical parameters for the PTx and PRx coil system models in Clauses 3.2.1 and 4.2.1, and it gives mated-condition behavior in Clause 5.1. The mated cases cover a direct-contact condition and a 2 mm air-gap condition, both with the coils aligned.

In practice, these tables let designers and test labs compare real hardware against the reference behavior at the same frequency and position. They also show how the coil pair changes when an accessory or case introduces spacing.

The document uses these mated cases as a guideline for compliant MPP PTx and PRx implementations. The reader is expected to verify coil parameters under both the nominal and the spaced condition, not only in free air.

Magnetic boundaries for interoperability

Clause 6 introduces the MPP magnetic boundary (MPPMB), which is used to increase confidence in certified-device interoperability. The boundary is defined for two frequencies and for two positions, and it is built from parameter sets with different levels of correlation.

This matters because the document does not treat the coil as a single isolated electrical part. It treats the transmitter and receiver pair as a coupled system, so the design must stay inside the acceptable region when mated with other certified devices.

The document also warns that mated coil parameters should not sit too close to the edge of the boundary, because real product tolerances could move them outside the valid region. In practice, that means margin is part of the design target.

Position-specific coil specifications

Clause 6.2.1 requires the PRx coil center to be within a 2 mm radius of the PTx coil center when mating to an MPT. Clause 6.3.1 mirrors that requirement from the transmitter side.

This is the basic placement rule for the magnetic attach system. It tells product teams what the magnetic centering function has to achieve before power transfer can be expected to behave as intended.

Clauses 6.2 and 6.3 then set magnetic boundary cases for aligned, misaligned, and vertically offset positions. The practical effect is that compliance is checked not only at the ideal position, but also at realistic off-center and spaced conditions.

Correlated electrical parameters

Clause 6 groups the relevant electrical parameters into correlated sets, including inductive and resistive parameters and magnetic coupling. That grouping matters because some values move together as the coil pair shifts or spacing changes.

For a designer or buyer, this means the document is not only asking for a nominal coil, but for a coil whose behavior remains inside the expected envelope under multiple operating positions. For a test lab, it defines which values must be checked together.

What terms does prEN IEC 63758-5-3:2026 define?

• Power Transmitter (PTx) - the transmitter-side Qi coil system model defined in Clause 3.
• Power Receiver (PRx) - the receiver-side Qi coil system model defined in Clause 4.
• MPP magnetic boundary (MPPMB) - the interoperability boundary used in Clause 6 to judge whether mated coil parameters stay acceptable.
• TPR#MPP3 - the test receiver configuration used in Clause 3.2.2 to evaluate whether PTx magnets saturate receiver shielding.
• Magnetic Protocol - the Qi magnetic operating mode referenced in the scope for this part.
• magnetic attach alignment method - the Qi alignment method referenced in the scope for this part.
• friendly-metal block - the receiver-side metal structure used in Clause 4.1.6 to represent nearby metallic parts such as a battery or PCB.
• orientation magnet - the extra magnet arrangement used to control angular alignment, not just radial centering.

Who uses prEN IEC 63758-5-3:2026?

prEN IEC 63758-5-3:2026 is used by engineers designing Qi wireless power transmitters and receivers, especially for consumer devices such as flat-surface products, mobile phones, chargers, and accessories. It is also used by mechanical engineers, magnetics specialists, and packaging teams who need to place coils, ferrites, magnets, shields, and nearby metal parts without breaking the Qi magnetic model.

Quality managers and compliance teams use it to verify that a design stays within the specified coil geometry, alignment behavior, and magnetic boundary conditions. Test laboratories use it to compare measured electrical and magnetic behavior against the reference models and mated-condition cases.

Component suppliers can use it to understand the required behavior of ferrite, shielding, magnets, and coil assemblies before product integration. Buyers and product managers can use it to judge whether a proposed design is aimed at the right Qi MPP implementation model.

Which standards are used with prEN IEC 63758-5-3:2026?

The document explicitly relies on ISO/IEC Directives, Part 2 for the rules behind requirement wording such as shall, should, may, and can. That matters because it tells readers how to interpret mandatory and recommended statements.

It also sits inside the wider Qi Specification family named in Clause 1.1. The companion parts and related documents named there are:

• General documents
• Introduction
• Glossary, Acronyms, and Symbols
• Technical System Overview
• Power Profiles
• Mechanical, Thermal, and User Interface
• Power Delivery
• Communications Physical Layer
• Communications Protocol
• Foreign Object Detection
• NFCTag Protection
• Authentication Protocol
• MPP Communications Protocol
• MPP PowerDelivery
• MPP Communications PhysicalLayer
• MPP ForeignObjectDetection
• MPP DesignGuidelines (Informative)
• Magnetic Covers
• Active Alignment System
• Thermal Management Protocol

These named parts provide the broader Qi behavior around packets, communications, power delivery, detection, and system integration that this magnetics part depends on.

What does the prEN IEC 63758-5-3:2026 document contain?

The document contains reference coil-system drawings, exploded views, cross-sections, assembly views, and dimension tables for the PTx and PRx models. It also contains magnetic-field tables for the permanent magnet arrangements, plus figures that show how the field is distributed across the interface surface.

It provides electrical parameter tables for free-air operation and for mated operation at the aligned and offset positions. Those tables are used for design verification and for checking whether a real implementation behaves like the specified reference models.

The document also contains equations and plotted boundary figures for the magnetic boundary cases at the stated frequencies and positions. In practice, those boundary plots are the main tools for certification-style comparison of real coil designs against the Qi MPP interoperability envelope.

SLOVENSKI STANDARD
01-november-2026
Specifikacija Qi - Različica 2.3 - 5-3. del: Mpp - Magnetna zasnova (hitri postopek)
Qi specification - Version 2.3 - Part 5-3: Mpp - Magnetics design (Fast Track)
Ta slovenski standard je istoveten z: prEN IEC 63758-5-3:2026
ICS:
29.240.99 Druga oprema v zvezi z Other equipment related to
omrežji za prenos in power transmission and
distribucijo električne energije distribution networks
33.160.99 Druga avdio, video in Other audio, video and
avdiovizuelna oprema audiovisual equipment
35.200 Vmesniška in povezovalna Interface and interconnection
oprema equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

100/4545/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 63758-5-3 ED1
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2026-09-18 2026-12-11
SUPERSEDES DOCUMENTS:
IEC TC 100 : AUDIO, VIDEO AND MULTIMEDIA SYSTEMS AND EQUIPMENT
SECRETARIAT: SECRETARY:
Japan Ms Mahiru Uehara
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):
TC 106,TC 108
ASPECTS CONCERNED:
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft for
Vote (CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of which they
are aware and to provide supporting documentation.
Recipients of this document are invited to submit, with their comments, notification of any relevant “In Some Countries”
clauses to be included should this proposal proceed. Recipients are reminded that the CDV stage is the final stage for
submitting ISC clauses. (SEE AC/22/2007 OR NEW GUIDANCE DOC).

TITLE:
Qi Specification - Version 2.3 - Part 5-3: MPP - Magnetics design (Fast Track)

PROPOSED STABILITY DATE: 2029
NOTE FROM TC/SC OFFICERS:
As this is a fast-track process offered by WPC, the Word file is not provided.

electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions.
You may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without
permission in writing from IEC.

QiSpecification
MPP–MagneticsDesign
Version2.3
PublishDate:08December2025
DISCLAIMER
Theinformationcontainedhereinisbelievedtobeaccurateasofthedateofpublication,butisprovided“asis”andmay
containerrors.TheWirelessPowerConsortiummakesnowarranty,expressorimplied,withrespecttothisdocument
anditscontents,includinganywarrantyoftitle,ownership,merchantability,orfitnessforaparticularuseorpurpose.
NeithertheWirelessPowerConsortium,noranymemberoftheWirelessPowerConsortiumwillbeliableforerrorsin
thisdocumentorforanydamages,includingindirectorconsequential,fromuseoforrelianceontheaccuracyofthis
document.Foranyfurtherexplanationofthecontentsofthisdocument,orincaseofanyperceivedinconsistencyor
ambiguityofinterpretation,contact:[e-mail].

Contents
1. General 5
1.1 StructureoftheQi Specification 5
1.2 Scope 6
1.3 Compliance 6
1.4 References 6
1.5 Conventions 7
1.5.1 Notationofnumbers 7
1.5.2 Tolerances 7
1.5.3 Fieldsinadatapacket 7
1.5.4 Notationoftextstrings 8
1.5.5 Short-handnotationfordatapackets 8
2. CoilDesign 9
2.1 IntroductionandBackground 9
3. PTxCoilSystemModel 10
3.1 MechanicalConstruction 10
3.1.1 Overview 10
3.1.2 TopEnclosure 10
3.1.3 CoilModule(ACmagnetics) 10
3.1.4 CoilModule(permanentmagnets) 13
3.1.5 Bottomenclosure 17
3.1.6 OverallAssembly 18
3.1.7 PTxOrientationMagnets 19
3.1.8 Permanentmagnetspecifications 21
3.2 ElectricalProperties 22
3.2.1 ElectricalParametersofPTxcoilsystemmodel 22
3.2.2 PreventingSaturationofPRxShielding 22
4. PRxCoilSystemModel 24
4.1 MechanicalConstruction 24
4.1.1 OverallAssembly 24
4.1.2 BottomEnclosure 24
4.1.3 SupportPlate 24
4.1.4 CoilModule 24
4.1.5 CoilModule(permanentmagnets) 28
4.1.6 FriendlyMetalBlock 32
4.1.7 OverallAssembly 32
4.2 ElectricalProperties 32
4.2.1 ElectricalParametersofPRxCoilSystemModel 32
5. PropertiesofMatedCoilSystemModels 34
5.1 Electricalmeasurementundermatedconditions 34
6. CoilSpecifications 36
6.1 MagneticBoundaries 37
6.2 PRxCoilSpecifications 38
6.2.1 PRxCoilSpec1 38
6.2.2 RMBX100-MagneticBoundarywhenAligned 39
6.2.3 RMBX200-MagneticBoundarywhenMisalignedandVerticallyOffset 49
6.2.4 RMBX300-MagneticBoundarywhenAlignedandVerticallyOffset 59
6.3 PTxCoilSpecifications 69
6.3.1 PTxCoilSpec1 69
6.3.2 PTxCoilSpec2 69
6.3.3 TMBX100-MagneticBoundarywhenAligned 70
6.3.4 TMBX200-MagneticBoundarywhenMisalignedandVerticallyOffset 80
6.3.5 TMBX300-MagneticBoundarywhenAligned 90
6.3.6 TMBX400-MagneticBoundarywhenMisalignedandVerticallyOffset 100

1. General
TheWirelessPowerConsortium(WPC)isaworldwideorganizationthataimstodevelopandpromoteglobalstandards
forwirelesspowertransferinvariousapplicationareas.Animportantapplicationareacomprisesflat-surfacedevices
suchasmobilephonesandchargersoperatingatpowerlevelsupto25W.
1.1 StructureoftheQi Specification
Generaldocuments
l
Introduction
l
Glossary,Acronyms,andSymbols
l
TechnicalSystemOverview
l
PowerProfiles
Systemdescriptiondocuments
l
Mechanical,Thermal,andUserInterface
l
PowerDelivery
l
CommunicationsPhysicalLayer
l
CommunicationsProtocol
l
ForeignObjectDetection
l
NFCTagProtection
l
AuthenticationProtocol
l
MPPCommunicationsProtocol
l
MPPMagneticsDesign
l
MPP PowerDelivery
l
MPP CommunicationsPhysicalLayer
l
MPP ForeignObjectDetection
l
MPP DesignGuidelines(Informative)
l
MagneticCovers
l
ActiveAlignmentSystem
l
ThermalManagementProtocol
1.2 Scope
TheQiSpecification,MPPMagneticsDesign(thisdocument)definesthesystemmodelandrequirementsforthe
magneticsusedwithinbothPTxandPRxproductsthatimplementtheMagneticProtocolandthemagneticattach
alignmentmethod.
1.3 Compliance
AllprovisionsintheQiSpecificationaremandatory,unlessspecificallyindicatedasrecommended,optional,note,
example,orinformative.VerbalexpressionofprovisionsinthisSpecificationfollowtherulesprovidedinISO/IEC
Directives,Part2.
Table1-Verbalformsforexpressionsofprovisions
Provision Verbalform
requirement “shall”or“shallnot”
recommendation “should”or“shouldnot”
permission “may”or“maynot”
capability “can”or“cannot”
1.4 References
Forundatedreferences,themostrecentlypublisheddocumentapplies.ThemostrecentWPCpublicationscanbe
downloadedfromhttp://www.wirelesspowerconsortium.com.

1.5 Conventions
1.5.1 Notationofnumbers
l
Realnumbersusethedigits0to9,adecimalpoint,andoptionallyanexponentialpart.
l
Integernumbersindecimalnotationusethedigits0to9.
l
Integernumbersinhexadecimalnotationusethehexadecimaldigits0to9andAtoF,andareprefixedby"0x"
unlessexplicitlyindicatedotherwise.
l
SinglebitvaluesusethewordsZEROandONE.
1.5.2 Tolerances
Unlessindicatedotherwise,allnumericvaluesintheQiSpecificationareexactlyasspecifiedanddonothaveany
impliedtolerance.
1.5.3 Fieldsinadatapacket
Anumericvaluestoredinafieldofadatapacketusesabig-endianformat.Bitsthataremoresignificantarestoredata
lowerbyteoffsetthanbitsthatarelesssignificant.Table2andFigure1provideexamplesoftheinterpretationofsuch
fields.
Table2-Exampleoffieldsinadatapacket(table)
b b b b b b b b
7 6 5 4 3 2 1 0
B (msb)
B 16-bitNumericDataField (lsb)
B OtherField
(msb)
B 16-bitNumericDataField (lsb)
Field
Figure1-Examplesoffieldsinadatapacket

1.5.4 Notationoftextstrings
TextstringsconsistofasequenceofprintableASCIIcharacters(i.e.intherangeof0x20to0x7E)enclosedindouble
quotes(").Textstringsarestoredinfieldsofdatastructureswiththefirstcharacterofthestringatthelowestbyte
offset,andarepaddedwithASCIINUL(0x00)characterstotheendofthefieldwherenecessary.
EXAMPLE: Thetextstring“WPC”isstoredinasix-bytefieldsasthesequenceofcharacters'W','P','C',NUL,NUL,and
NUL.Thetextstring“M:4D3A”isstoredinasix-bytefieldasthesequence'M',':','4','D','3',and'A'.
1.5.5 Short-handnotationfordatapackets
Inmanyinstances,theQiSpecificationreferstoadatapacketusingthefollowingshorthandnotation:
/
Inthisnotation,referstothedatapacket'smnemonicdefinedintheQiSpecification,Communications
Protocol,andreferstoaparticularvalueinafieldofthedatapacket.Thedefinitionsofthedatapacketsin
theQiSpecification,CommunicationsProtocol,listthemeaningsofthemodifiers.
Forexample,EPT/ccreferstoanEndPowerTransferdatapackethavingitsEndPowerTransfercodefieldsetto0x01.

2. CoilDesign
2.1 IntroductionandBackground
ThisbookdescribestheMPPPTxandPRxcoilsystemmodels.
ThecoilsystemmodelsarenominaldesignsfromwhichtheMPPspecificationsarederived.
ItisrecommendedthatMPPPTxorPRximplementationsfollowthesecoilsystemmodelsascloselyaspossibleto
minimizethedifferenceswiththeTPT#MPP1-coilandTPR#MPP1-coilcompliancetesttools.
Eachofthecoilsystemmodelsub-sectionsaresplitintotwosections:
l
Mechanicalspecificationoftheindividualcomponents,fullassembly,andmaterials.
l
Nominalelectricalparametersinfree-airandmatedconditions.
Thefinalsub-sectionspecifiesthecoilrequirementsforPTxandPRximplementations.

3. PTxCoilSystemModel
3.1 MechanicalConstruction
3.1.1 Overview
TheoveralldesignofthePTxcoilsystemmodelisshowninFigure2.
Itconsistsofthreemaincomponents:
l
Topenclosurethatdefinestheinterfacesurface
l
Coilmodule
l
Bottomenclosure
Figure2-ExplodedviewofPTxcoilsystemmodel.
3.1.2 TopEnclosure
Thetopenclosureisconstructedwithplastic.
3.1.3 CoilModule(ACmagnetics)
TheexplodedviewofthecoilmoduleforthePTxcoilsystemmodelisshowninFigure3.Thecoilmoduleconsistsof
fourcomponents:
l
circularwoundcoil
l
ferriteshield
l
magnetring
l
permeablemagnetshunt
ThesideviewofthecoilmoduleisshowninFigure4.
Thecoilis11turnsconstructedwithType-1Litzwirewitheachturnconsistingof65strandsofindividuallyinsulated
80µmdiametercopperwire.
ThemagneticshieldinginthecoilmoduleisconstructedusingDMR95ferrite.
Thepurposeofthemagnetsistoensuretighteralignmentbetweenthetransmitterandreceivercoils.
Practically,acutoutinthePTxferriteisneededtoallowtheexternalroutingofthecoilleads.InFigure5,the
implementationoftheferritecutoutinthesystemmodelisshown.

KeymechanicaldimensionsofthecoilmoduleareinTable3.
Figure3-ExplodedviewoftheCoilModuleforthePTxCoilSystemModel.
Figure4- SideviewofPTxCoilModule.

Figure5- TopviewofPTxferrite.
Table3- MechanicaldimensionsforthecoilmoduleofthePTxcoilsystemmodel.
Description NominalValue
r Innerradiusoftransmittercoil 10.73mm
i
r Outerradiusoftransmittercoil 19.65mm
w Radiusofferritecentrepost 9.58mm
Tx1
w Innerradiusofferriteouterpost 20.33mm
Tx2
w Outerradiusofferriteouterpost 21.20mm
Tx3
d Thicknessofferritebase 1.15mm
h1
d Overallthicknessofferrite 2.15mm
h2
d Thicknessoftransmittercoil 1.03mm
h3
Verticaloffsetofferritecutoutslot 8.20mm
wslt1
Horizontaloffsetofferritecutoutslot 4.18mm
wslt2
Horizontaloffsetofoutsideedgeofferritecutoutslot 7.16mm
wslt3
3.1.4 CoilModule(permanentmagnets)
Themagnetmoduleconsistsofapermeablemagnetshuntandmagnetsarrangedinacirclearoundthecoilmodule.
Detailsofthepermanentmagnetandshuntdimensions(shownintopviewandcross-sectionview)areillustratedin
Figure6,Figure7,andFigure8.
Thedimensionsandorientation(NorthorSouth)ofthefourpolesineachmagnetarrayelementareessentialfor
minimizingtheimpactontheACmagnetics.ForthePTxsystemmodel,theB-fieldaremeasuredinz-andxy-directions
ontheinterfacesurfacealongS1-S8asdefinedinFigure6.ThevaluesofB-fieldthusmeasuredareprovidedinFigure2.
ThemagnetarrayisconstructedusingNdFeBN48Hgrademagnets.ThemagnetarrayhasaNi-Cu-Niplatinglayerof10
um.ThepermeablemagnetshuntisconstructedwithDT4.Thematerialischosenforhighsaturationfluxdensityand
highpermeability.Thekeymagneticparametersofthesematerialsaregivenhere.

Table4-Keymagneticparametersofthematerials
Component Materialparameter Typicalvalues
Magnetarray 1.39T
>1.054x10 A/m
>1.353x10
A/m
3.7x10
T•A/m
Permeableshunt >2.0T
Figure6- MagnetArraytopview.
Figure7-Magnetshunttopview
Figure8- Magnetassembly(Cross-section).

Table5-Magneticfieldspecificationsformagnetarray.
RadialPosition(mm) Bz(T) Bxy(T)
r<19.5 0 0.025
19.5 23 24.5 26 27 r>30 0 0.025
*Thez=0planereferstotheinterfacesurface,andr=0referstothecentreofthemagneticarray.

3.1.5 Bottomenclosure
Thebottomenclosureismadefrom6061gradealuminium.Acut-outisaddedtothebottomenclosure.Thiscutoutis
alignedwiththeferritecutoutshowninFigure5.Thisistoexposethecoilleadsandallowconnectiontoexternal
circuit.ThedimensionofthecutoutisshowninFigure10.
Thecross-sectionalandtopviewofthebottomenclosureisshowninFigure9.
MechanicaldimensionsofthebottomenclosurearespecifiedinTable6.
Figure9- SideviewofBottomEnclosure.
Figure10-Topviewofbottomenclosure

Table6-MechanicaldimensionsforthebottomenclosureofthePTxcoilsystemmodel.
Description NominalValue
d Bottomenclosurethickness 0.7mm
enc1
d Enclosureinnerwallthickness 0.55mm
enc2
d Enclosureouterwallthickness 0.7mm
enc3
d Heightofenclosureouterwall 3.25mm
enc4
d Heightofenclosureinnerwall 3.04mm
enc5
w Innerradiusofenclosureinnerwall 22.12mm
enc1
w Innerradiusofenclosureouterwall 27.48mm
enc2
3.1.6 OverallAssembly
Theassemblyoftheindividualtransmittercomponentsdescribedaboveisoutlinedbelow.Asideviewoftheoverall
assemblyofthereferencetransmitterisshowninFigure11.Thedescriptionandspecificationsofthekeydimensionsof
thereferencetransmitterassemblyisgiveninTable7
Figure11- SideviewofPTxcoilsystemmodelassembly.

Table7-AssemblydimensionsofPTxcoilsystemmodel.
Description NominalValue
d Distancefromtopsurfaceofcoilto 1.20mm
z1
interfacesurface
d Distancefromtopofmagnetsurfaceto 0.95mm
z2
interfacesurface
d Distancefrombottomofferritetointerface 3.4mm
z3
surface
3.1.7 PTxOrientationMagnets
Asdiscussedinpreviouslysections,themagnetarrayinthePTxsystemmodelfollowaringshapearoundthecoil
moduleandthereforeprovidesradialalignmentbetweenthetransmitterandreceivercoilsbutallowsforrotation
aroundthecentreofthemagnetring.ToensurethePTxandPRxonlyalignsinaparticularangulardirection,an
"orientationmagnetarray"isaddedtothesystemmodel.
3.1.7.1 Transmitter-sideOrientationMagnet
Thetopsurfaceofthetransmitterorientationmagnetisin-planewiththemainmagnetarraydiscussedinSection3.1.4,
CoilModule(permanentmagnets).Thepositioningoftheorientationmagnetswithrespecttothemainmagnetarrayis
showninFigure12,whereintheorientationmagnetislabelled"clockingmagnets".Thecentreoftheorientationmagnet
isalignedwiththecentreofthemagnetringofthePTxcoilsystem.Thecross-sectionoftheorientationmagnetis
showninFigure13.TheDCshieldusedintheorientationmagnetshouldusethesamematerialastheDCmagnetshunt
usedinthemainmagnetarray.TheB-fieldstrengthsinz-andxy-directionareshowninTable8.

Figure12- Transmitterorientationmagnets(TopView).
Figure13- TransmitterOrientationMagnetDimensionsandPolarity.

Table8- Fluxdensityat0.85mmfromPTxorientationmagnetsurface.
MaximumX MaximumBz Bxy
x<-5.0mm 0 0.025
-5.0mm -4.5mm -3.0mm -2.0mm -0.5mm 0.5mm 2.0mm 3.0mm 4.0mm x>5.0mm 0 0.025
*Thez=0planereferstotheinterfacesurface,andx=0/y=0referstothecentreofthemagneticarray.
3.1.8 Permanentmagnetspecifications
3.1.8.1 RequirementPTX-MTU-MS-MAG-001
ThePTxshallattractaPRxatthe(0,0)positionwithaforceofatleast400gramsforce,alonganaxisat90°tothe
planeoftheInterfaceSurface.
3.1.8.2 RequirementPTX-MTU-MS-MAG-002
ThePTxshallattractaPRxtowardsthe(0,0)positionwithaforceintheplaneoftheInterfaceSurfacehavingapeak
strengthofatleast200gramsforceataradialoffsetofatleast0.5mm.

3.2 ElectricalProperties
3.2.1 ElectricalParametersofPTxcoilsystemmodel
Whenthemechanicalcomponentsareassembledasspecifiedabove,thePTxcoilsystemmodelhastheelectrical
parametersdescribedinTable9.
Thesevaluesarevalidunderfree-airconditionswherethereisnometallicormagneticobjectpresentinthevicinityof
thePTx.
Table9- ElectricalParametersofthePTxCoilSystemModelinFree-Air.
Nominal
MeasurementFrequency Description
Value
R N/A DCresistancebetweencoilterminalsofthePTxcoilsystem 41mΩ
DC
model
360kHz Self-inductancebetweencoilterminalsofthePTxcoilsystem 7.42μH
model
R 360kHz ACresistancebetweencoilterminalsofthePTxcoilsystem 260mΩ
AC
model
3.2.2 PreventingSaturationofPRxShielding
ThepresenceofmagnetsinanMPPPTxinducesaDCbiasfluxintheShieldingofaPRxunit.
Forproperoperation,themagneticShieldingmustbeoperatedinthenon-saturatedpartoftheirB-Hcurve,awayfrom
theirmagneticsaturationinflectionpoint.
ProperpowerdeliverywillbeimpedediftheShieldingofaPRxisallowedtosaturate.Fortypicalnano-crystalline(NC)
Shieldingmaterials,thesaturationfluxdensityisgreaterthan1T.
TheriskofsaturationisdefinedwithreferencetotheTPR#MPP3,whichisidenticaltoTPR#MPP1inallwaysexcept
thatthenumberofnanocrystalinelayershavebeenreducedto3.
ThismakesTPR#MPP3moresensitivetostrongmagneticfieldsandabettercandidatetoevaluatetheriskofPRx
shieldingsaturationduetothePTxmagnets.
ForMPP,thereisariskofsaturationifeitherofthefollowingaretrue:
Where isthenormalizedchangeofinductanceofTPR#MPP3whenitisplaceddirectlyandinthecentre
ofthePTx(r=0mm,z=0mm).
And isthenormalizedchangeofinductanceofTPR#MPP3whenitisplacedwitharadialoffsetof2mm
fromthecentreofthePTxanda2mmspacerispresentbetweentheTPRandPTx.(r=2mm,z=2mm).

istheminimumvaluewhenmeasuredinallfourdirectionse.g.(x,y,z)=(0,2,2),(0,-2,2),(2,0,2)and
(-2,0,2).
Therationaleofusing∆L'todetectsaturationisasfollows:undernormal,unsaturatedscenarios,∆L'ispositiveasthe
ferromagneticmaterialonPTxhelpstoincreasetheinductanceofPRx.ButifthedcmagnetsaturatesthePRxshielding
(e.g.,nano-crystallineshielding),theniteffectivelyneutralizesthepositiveeffectonPRxinductancebroughtbythe
shieldingmaterialandthus∆L'willreduce.Additionally,themetallicmaterialinPTxwillalsoreduce∆L'throughthe
eddy-currenteffect.Thecompoundeffectwillbring∆L'downtozeroorevennegative.
Since(2,2)positionhasmoreoffsetthan(0,0),itgenerallymayintroducesaturation,that'swhy is
smallerthan .
4. PRxCoilSystemModel
4.1 MechanicalConstruction
4.1.1 OverallAssembly
TheoveralldesignofthePRxcoilsystemmodelisshowninFigure14.Itconsistsoffourmaincomponents:
l
Metalstructureabovethecoilmoduledefinedasa“friendly-metalblock”
l
Coilmoduleforwirelesspowertransfer
l
Metalsupportplate
l
Bottomenclosurethatdefinestheinterfacesurface
InFigure14the“friendly-metalblock”isopaque,todenotethatitisnotintendedtobepartofa"real-world"PRx
design(butitsinclusioninthePRxcoilsystemmodeliscriticalinensuringinteroperability).Moredetailsregardingthe
“friendly-metalblock”areprovidedinSection4.1.6,FriendlyMetalBlock.
Figure14-ExplodedviewofPRxcoilsystemmodel.
4.1.2 BottomEnclosure
Thebottomenclosureisconstructedusingglass.
4.1.3 SupportPlate
ThesupportplateofthePRxSystemModelisconstructedusing6061aluminium.Themechanicaldimensionsofthe
supportplatecanbefoundinTable16.
4.1.4 CoilModule
ThecoilmoduleofthePRxcoilsystemmodelconsistsoffourcomponents:

l
coppershielding
l
magneticshielding
l
coil
l
magnetarray
AnexplodedviewofthereceivercoilmoduleisshowninFigure15.
Across-sectionalviewofthecoilmoduleisshowninFigure16.
ThecoppershieldingaidstodecouplethemagneticparametersofthePRxcoilmodulefromothersystemmodulesthat
maybepresentbehindthecoilmodule.Additionally,italsoaidstominimizecoexistenceissuesbetweentheinductive
chargingsystemandothersystemmodules.
ThemagneticshieldinginthePRxcoilsystemmodelconsistsofabaselayerandacentrepost.Thebaselayeris
constructedbystacking7layersofcircularnano-crystallinesheetsabovethePRxcoil.Thecentrepostisconstructedby
stacking4layersofnano-crystallinesheets.ThespecificationsforthemechanicaldimensionsoftheShieldingcanbe
foundinTable10.
Figure15-ExplodedviewofthecoilmoduleforthePRxcoilsystemmodel.
Figure16-Cross-sectionofthecoilmoduleforthePRxcoilsystemmodel.

Table10- AssemblyspecificationsofcoilmoduleforthePRxcoilsystemmodel.
Description NominalValue
w RadiusofShieldingcentrepost 8.95mm
Rx1
w RadiusofShieldingbaselayer 21.60mm
Rx2
w RadiusofCushield 21.60mm
Rx3
d Centrepostshieldingmaterialthickness 80µm
Rx1
d Baselayershieldingmaterialthickness 179μm
Rx2
d Cushieldingmaterialthickness 30µm
Rx3
Thetopandcross-sectionalviewofthePRxcoilsystemmodelisshowninFigure18andFigure17,respectively.The
receivercoilconsistsofa1-layerofcopperwireswoundin13turns.Tofacilitateaccesstothecoilterminalsinpractical
designs,acut-outexistsintheShieldingtoexposethecoilleads.AsshowninFigure18,oneedgeofthecutoutis
alignedwiththegeometriccentreoftheShielding.ThemechanicaldimensionsofthePRxcoilcanbefoundinTable11.
Thisdiagramshowsoneturnwithmultiplestrandsinparallel.SeeTable11.
Figure17-Cross-sectionalviewofcoilforthePRxcoilsystemmodel.
Figure18- TopviewofPRxcoilsystemmodel.

Figure19-DimensionsofthecutoutinthePRxshielding

Table11- MechanicalspecificationsofthePRxcoilsystemmodel.
Description NominalValue
r OuterradiusofPRxcoil 21.00mm
r InnerradiusofPRxcoil 9.50mm
i
h Heightofshieldingcutout 4.50mm
co2
w Widthofshieldingcutout 4.85mm
co2
d Offsetofshieldingcutoutfromcoilcentre 4.21mm
co2
w DiameterofCuWire 114µm
cl1
w Diameterofwirewithinsulation 131µm
cl2
N Numberofturns 13
N Numberofstrandsinparallelperturn 7
C
(SeeFigure17)
4.1.5 CoilModule(permanentmagnets)
DetailsofthemagnetmoduledimensionsareoutlinedinFigure20,andFigure21.Themagnetmoduleconsistsof
magnetarrayelementsarrangedinacirclearoundthecoilmodule.
Themagneticfieldvalues,asmeasuredattheinterfacesurfaceofthePRxCoilSystemModel,havebeendefinedinTable
13.
InFigure20,anadditionalmagnet(labelled"orientationmagnet")isalsoincludedbelowthecircularmagnetarray.
TheorientationmagnetassemblyconsistsofaN48SHmagnetandathinshieldabovethemagnet.Thecross-sectional
viewofthePRxorientationmagnetisshowninFigure22.
Thechoiceofmaterialsfortheconstructionofthepermanentmagnetmodule(includingthecircularmagnetarrayand
theorientationmagnet)areoutlinedinTable12.

Table12- MagnetpropertiesofthePRxcoilsystemmodel.
Component Materialparameter Typicalvalues
Magnetarray 1.39T
>1.054x10 A/m
>1.671x10
A/m
3.7x10
T•A/m
Permeableshunt >2.0T
Figure20- MagnetofthePRxcoilsystemmodel(topview).

Figure21-MagnetofthePRxcoilsystemmodel(sideview).
Table13-MagneticfieldofthePRxcoilsystemmodel.
RadialPosition(mm) Bz(T) Bxy(T)
r<19.5 0 0.025
19.5 23 24.5 26 27 r>30 -0.025 0.025
*Thez=0planereferstotheinterfacesurface,andr=0referstothecentreofthemagneticarray.
Figure22-OrientationmagnetofthePRxcoilsystemmodel(sideview).

0.00
ARRAY MAGNET
SHOWN FOR REFERENCE
-31.18
E E
( 19.31)
ORIENTATION MAGNET
-50.49
( 6.00 )
Figure23-PowerReceiverorientationmagnetandmagnetarray(topview)
-3.00
0.00
3.00
4.1.6 FriendlyMetalBlock
InapracticalPRximplementation,itislikelythatthecoilmoduleissurroundedbymetalliccomponents(suchas
battery,PCB),hereafterreferredtoas“friendlymetal”.ThefriendlymetalblockshowninFigure14isincludedinthe
PRxcoilsystemmodeltorepresentsuchmetalliccomponents.
InthePRxcoilsystemmodel,thefriendlymetalblockismadefrom316gradestainlesssteel.Thethicknessofthe
friendlymetalblockis4.30mm.
4.1.7 OverallAssembly
TheassemblyoftheindividualcomponentsofthePRxcoilsystemmodelareoutlinedbelow.
AsideviewoftheoverallassemblyofthePRxcoilsystemmodelisshowninFigure24.Descriptionanddimensionsof
theassemblycanbefoundinTable14.
Figure24-Cross-sectionalviewshowingassemblyofPRxcoilsystemmodel.
Table14-AssemblyspecificationsforthePRxcoilsystemmodel.
Description NominalValue
d Distancefrombottomofcoilsurface 0.660mm
z1
toInterfacesurface
d Distancefrombottomofmagnet 0.660mm
z2
surfacetoInterfacesurface
d Distancefrombottomofsupport 0.700mm
z3
platetoInterfacesurface
d Distancefrombottomoffriendly 1.23mm
z4
metalblocktoInterfacesurface
Table15- Mechanicaldimensionsofsupportplate.
Description Nominalvalues
t Thicknessofsupportplate 0.2mm
SP
r Radiusofinnercutoutofsupport 26.73mm
SP
plate
4.2 ElectricalProperties
4.2.1 ElectricalParametersofPRxCoilSystemModel
Withthemechanicalcomponentsassembledasspecifiedabove,thePRxcoilsystemmodelhastheelectricalparameters
describedinTable16.
Thesevaluesarevalidunderfree-airconditions.FortheelectricalparametersofthePTxcoilsystemmodelwhenitis
matedtothePRxcoilsystemmodelrefertoSection5,PropertiesofMatedCoilSystemModels.
Table16-TableElectricalParametersofthePRxCoilSystemModelinFree-Air.
Nominal
MeasurementFrequency Description
Value
R N/A DCresistanceofthereceiver 200mΩ
DC
measuredatthecoilterminals
360kHz Self-inductanceofthereceiver 9.01μH
measuredatthecoilterminals
R 360kHz ACresistanceofthereceiver 751mΩ
AC
measuredatthecoilterminals
5. PropertiesofMatedCoilSystemModels
5.1 Electricalmeasurementundermatedconditions
TheelectricalparametersforthePTxandPRxcoilsystemmodelsundermatedconditionsarepresentedasaguideline
forthedesignofcompliantMPPPTxandPRximplementations.Tothisend,twocasesarepresented:
l
Inthefirstscenario,thePRxcoilsystemmodelisplaceddirectlyonthesurfaceofthePTxcoilsystemmodel.
Thiscase(referredtoas“z=0mm”testcase),representsthenominalusagecasewherethereisnospacing
betweenthetransm
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