oSIST prEN IEC 63758-5-3:2026

• Status: Not Published
• Public Enquiry End Date: 29-Nov-2026
• ICS: 29.240.99 - Other equipment related to power transmission and distribution networks
• ICS: 33.160.99 - Other audio, video and audiovisual equipment
• ICS: 35.200 - Interface and interconnection equipment
• Technical Committee: AVM - Audio, video and multimedia systems and equipment
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 28-Sep-2026
• Due Date: 15-Feb-2027
• 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: prEN IEC 63758-5-3:2026 - Qi specification - Version 2.3 - Part 5-3: Mpp - Magnetics design (Fast Track)

oSIST prEN IEC 63758-5-3:2026 is the Slovenian adoption of the Qi Specification, Version 2.3, Part 5-3 from IEC. It specifies the magnetics design model for Qi MPP power transmitters (PTx) and power receivers (PRx) that use the Magnetic Protocol and the magnetic attach alignment method. In practice, it gives the nominal coil, magnet, shielding and assembly details, plus the electrical and magnetic boundary values used to design and check interoperable products.

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

oSIST prEN IEC 63758-5-3:2026 specifies the system model and requirements for the magnetics used in both PTx and PRx products that implement the Magnetic Protocol and the magnetic attach alignment method. The document is focused on coil-system design, not on the rest of the Qi stack such as power delivery or communications.

The document is organized into six main clauses:

• General
• Coil Design
• PTx Coil System Model
• PRx Coil System Model
• Properties of Mated Coil System Models
• Coil Specifications

Clause 2 explains that the PTx and PRx coil system models are nominal designs from which the MPP specifications are derived. Clause 6 then turns those models into coil specifications and magnetic boundaries for aligned and offset cases.

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

oSIST prEN IEC 63758-5-3:2026 combines construction rules, alignment rules, electrical targets and magnetic boundary limits. The key point for implementers is that the standard defines both the physical coil stack-up and the performance envelope that products must stay within.

General rules and conventions

Clause 1.3 states that the provisions are mandatory unless they are explicitly marked as recommended, optional, note, example or informative. That matters because the document uses the usual IEC wording - “shall”, “should”, “may” and “can” - to separate hard requirements from guidance.

Clause 1.5 fixes the way the specification is read. Numeric values are exact unless a tolerance is stated, and fields in data packets use big-endian byte order. For engineers, that means there is no assumed margin on a stated value and no ambiguity in how packet fields are encoded.

Nominal coil-system models

Clause 2 says the document describes the MPP PTx and PRx coil system models and recommends that implementations follow them as closely as possible. The practical reason is interoperability - the closer a product is to the model, the easier it is to stay aligned with the TPT#MPP1-coil and TPR#MPP1-coil compliance test tools.

Clause 3 gives the PTx model and Clause 4 gives the PRx model. Both are broken into mechanical construction and electrical properties, so a designer can work from the physical stack-up through to the expected terminal behavior.

PTx construction and magnetic behavior

Clause 3 defines the PTx as a plastic top enclosure, a coil module and a 6061 aluminium bottom enclosure. The coil module uses an 11-turn circular coil with Type-1 Litz wire, DMR95 ferrite, a magnet ring and a permeable magnet shunt. In practice, this tells a designer what materials and geometry the transmitter model assumes.

Clause 3 also adds PTx orientation magnets so the transmitter and receiver only align in a particular angular direction. That matters because the ring magnets alone provide radial alignment, but not clocking.

Clause 3.1.8 contains two direct magnet-force requirements: the PTx shall attract a PRx at the centre position along the normal axis, and it shall also pull a PRx toward centre in the plane of the interface surface at a radial offset. These requirements matter because they describe the self-alignment force that a user experiences when placing a device on the charger.

PRx construction and nearby-metal model

Clause 4 defines the PRx model with a glass bottom enclosure, a 6061 aluminium support plate, a coil module, a magnet array and a “friendly-metal block”. The friendly-metal block represents nearby metallic parts such as a battery or PCB, and its inclusion is important because real products often have metal close to the receiver coil.

The PRx coil module uses copper shielding, magnetic shielding made from layered nano-crystalline sheets, a 13-turn coil, and a permanent magnet module with an orientation magnet. In practice, this clause tells a receiver designer how much shielding and nearby metal the model assumes, so the product can be tested in realistic conditions.

Free-air and mated electrical properties

Clauses 3.2 and 4.2 give nominal electrical parameters at the coil terminals in free air. The tables cover DC resistance, self-inductance and AC resistance for both PTx and PRx at the stated measurement frequency. For design work, these values are the baseline coil characteristics before the transmitter and receiver are brought together.

Clause 5 then defines electrical measurement under mated conditions for two cases: direct contact at z = 0 mm and a 2 mm air gap at z = 2 mm, both with radial alignment. It gives the aligned-coupled electrical behavior of the pair, including self-inductance, AC resistance, magnetic coupling and resistive coupling. This is the practical check for how the coils behave when the product is actually charging.

Magnetic boundaries and saturation protection

Clause 6 defines the MPP Magnetic Boundary (MPPMB). The boundary is built from correlated parameter pairs and low-correlation limits, and it is defined at 128 kHz and 360 kHz for both aligned and offset positions. For implementers, this is the design envelope that product-to-product mated coil parameters must stay inside to support interoperability with certified transmitters and receivers.

Clause 6.2 gives PRx coil specifications, including center alignment within a 2 mm radius of the PTx coil center. Clause 6.3 gives the matching PTx requirements and adds a requirement that the PTx shall not saturate the magnetic shielding of the TPR#MPP3 test receiver. That matters because shielding saturation can reduce power transfer and change the inductive behavior of the receiver.

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

oSIST prEN IEC 63758-5-3:2026 uses several system-model terms that are central to the specification.

• PTx - the power transmitter, meaning the Qi transmitting side covered by the PTx Coil System Model.
• PRx - the power receiver, meaning the Qi receiving side covered by the PRx Coil System Model.
• MPR - the power receiver system model used in Clause 6 for magnetic boundary checks.
• MPT#1 - the power transmitter system model described in Clause 3.
• MPT#2 - the transmitter system model used in the alternate boundary cases in Clause 6.
• MPP Magnetic Boundary (MPPMB) - the boundary that defines the acceptable mated magnetic and electrical parameter region.
• Friendly-metal block - a modeled block of nearby metal in the PRx that represents real product metal parts.
• TPR#MPP3 - the test receiver used to check whether transmitter magnets risk saturating receiver shielding.

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

oSIST prEN IEC 63758-5-3:2026 is used by engineers who design Qi wireless charging hardware, especially coil, magnet and enclosure designers. It is also used by compliance labs that need a reference model for alignment, coupling and saturation checks.

Quality teams use it to compare production designs against the nominal model and the magnetic boundary. Buyers and sourcing teams can use it to understand whether a supplier’s design is based on the Qi MPP magnetics model, especially for flat-surface devices such as mobile phones and chargers that the Qi specification notes as a key application area.

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

This part sits inside the wider Qi Specification and is intended to be read with the other Qi system documents named in Clause 1.1. The most relevant companion parts named in the document are:

• Communications Protocol - used because Clause 1.5.5 refers to its data-packet mnemonics and shorthand notation.
• MPP Communications Protocol - the companion MPP communications part listed in the Qi structure.
• MPP Power Delivery - the power-delivery companion part for MPP products.
• MPP Communications Physical Layer - the physical-layer companion part for MPP communications.
• MPP Foreign Object Detection - the companion part for MPP foreign-object detection.
• MPP Design Guidelines (Informative) - the design-guidance companion part listed as informative.

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

The document contains the nominal PTx and PRx mechanical drawings, cross-sections and assembly descriptions needed to build the coil system models. It also contains tables of dimensions, materials and electrical parameters for free-air operation and for mated operation.

It further provides magnetic-field profiles, alignment conditions, and boundary equations at 128 kHz and 360 kHz for aligned and offset cases. For verification work, the document includes the force requirements, saturation check logic, and the plots and equations used to define the MPP Magnetic Boundary.

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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