IEC 63028:2017

Wireless power transfer - Airfuel Alliance resonant baseline system specification (BSS)

IEC 63028:2017 defines technical requirements, behaviors and interfaces used for ensuring interoperability for flexibly coupled wireless power transfer (WPT) systems for AirFuel Resonant WPT. This document is based on AirFuel Wireless Power Transfer System Baseline System Specification (BSS) v1.3.

Transfert d'énergie sans fil - Spécification du système de référence (BSS) pour le système résonant d'AirFuel Alliance

L'IEC 63028:2017 définit les exigences techniques, les comportements ainsi que les interfaces utilisées pour assurer l'interopérabilité des systèmes de transfert d'énergie sans fil (WPT) à couplage flexible avec le système WPT résonant AirFuel. Ce document repose sur la Spécification du système de référence (BSS) du système de transfert d'énergie sans fil AirFuel v1.3.

General Information

• Status: Published
• Publication Date: 18-Jun-2017
• 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: TA 15 - Wireless Power Transfer
• Drafting Committee: WG 1 - TC 100/TA 15/WG 1
• Current Stage: PPUB - Publication issued
• Start Date: 30-Jun-2017
• Completion Date: 19-Jun-2017

Standards Content (Sample)

IEC 63028 ®
Edition 1.0 2017-06
INTERNATIONAL
STANDARD
colour
inside
Wireless power transfer – Airfuel alliance resonant baseline system specification
(BSS)
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IEC 63028 ®
Edition 1.0 2017-06
INTERNATIONAL
STANDARD
colour
inside
Wireless power transfer – Airfuel alliance resonant baseline system specification

(BSS)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.240.99; 33.160.99; 35.200 ISBN 978-2-8322-4429-6

– 2 – IEC 63028:2017  IEC:2017
CONTENTS
FOREWORD . 7
INTRODUCTION . 9
1 Scope . 10
2 Normative references . 10
3 Terms, definitions, symbols and abbreviated terms . 10
3.1 Terms and definitions . 10
3.2 Symbols and abbreviated terms . 13
3.2.1 Symbols . 13
3.2.2 Abbreviated terms . 17
4 System description . 17
5 Conformance and backwards compatibility . 18
6 Device types . 19
6.1 PTU classification . 19
6.2 PRU category . 20
7 Power transfer specifications . 20
7.1 System equivalent circuit and reference parameters . 20
7.2 General system requirements . 21
7.2.1 Operating frequency . 21
7.2.2 Z relationship to R . 21
TX_IN RECT
7.2.3 Power stability . 21
7.2.4 PTU co-location protection. 21
7.2.5 PRU self-protection (informative) . 21
7.3 Resonator requirements . 21
7.3.1 Resonator coupling efficiency (RCE) . 21
7.3.2 PTU resonator requirements . 22
7.3.3 PRU resonator requirements . 24
7.4 Load parameters . 25
7.4.1 Load parameters introduction . 25
7.4.2 Minimum load resistance . 26
7.4.3 Maximum allowable dynamic load . 26
7.4.4 Maximum load capacitance . 26
8 Power control specifications . 26
8.1 Control objectives . 26
8.2 PTU specifications . 26
8.2.1 PTU state . 26
8.2.2 General state requirements . 27
8.2.3 PTU power save state. 28
8.2.4 PTU Low Power state . 30
8.2.5 PTU Power Transfer state . 31
8.2.6 PTU Configuration state . 33
8.2.7 PTU Local Fault state . 34
8.2.8 PTU latching fault state . 34
8.2.9 PTU state transitions . 35
8.2.10 PTU Test Mode. 38
8.3 PRU specifications . 38
8.3.1 PRU general requirements . 38

8.3.2 PRU state model . 41
8.3.3 Null state . 42
8.3.4 PRU boot . 42
8.3.5 PRU On state . 42
8.3.6 PRU System Error state . 43
8.3.7 PRU state transitions . 44
9 Signaling specifications . 45
9.1 Architecture and state diagrams . 45
9.1.1 Architecture . 45
9.1.2 Overall charge process . 46
9.2 Charge procedure and requirements . 48
9.2.1 Removing PRU from WPT network . 48
9.2.2 Power Sharing mode . 48
9.3 Bluetooth low energy requirements . 49
9.3.1 Bluetooth low energy requirements introduction . 49
9.3.2 Bluetooth low energy objectives . 49
9.3.3 PTU hardware requirement . 49
9.3.4 PRU hardware requirement . 49
9.3.5 Basic network structure . 49
9.3.6 RF requirements . 49
9.3.7 Timing and sequencing requirements . 50
9.3.8 Profile structure . 53
9.4 BLE profile definition . 53
9.4.1 GATT sub-procedure . 53
9.4.2 Configuration . 53
9.4.3 PRU requirements . 54
9.4.4 PTU requirements . 55
9.4.5 Connection establishment . 55
9.4.6 Security considerations . 57
9.4.7 Charge completion . 57
9.5 WPT service characteristics . 58
9.5.1 WPT service characteristics introduction. 58
9.5.2 PRU advertising payload . 58
9.5.3 WPT service . 60
9.5.4 PRU control . 62
9.5.5 PTU static parameter . 64
9.5.6 PRU static parameter characteristic . 69
9.5.7 PRU dynamic parameter characteristic . 72
9.5.8 PRU alert characteristic . 76
9.6 Cross connection algorithm . 78
9.6.1 Cross connection algorithm introduction . 78
9.6.2 Definitions . 78
9.6.3 Acceptance of advertisement . 78
9.6.4 Impedance shift sensing . 78
9.6.5 Reboot bit handling . 79
9.6.6 Time set handling . 79
9.7 Mode transition . 80
9.7.1 Mode transition introduction . 80
9.7.2 Mode transition procedure . 80

– 4 – IEC 63028:2017  IEC:2017
9.7.3 BLE reconnection procedure . 81
10 PTU resonators . 83
10.1 PTU resonators introduction . 83
10.2 Class n design template . 83
10.2.1 Class n design template introduction. 83
10.2.2 Table of specifications . 83
10.2.3 PTU resonator structure . 83
10.3 Approved PTU resonators . 83
Annex A (informative) Reference PRU for PTU acceptance testing . 84
A.1 Category 1 . 84
A.2 Category 2 . 84
A.3 Category 3 . 84
A.3.1 PRU design 3-1 . 84
A.3.2 Geometry. 84
A.4 Category 4 . 87
A.5 Category 5 . 87
Annex B (informative) Lost power . 88
B.1 Overview. 88
B.2 General . 88
B.3 Cross connection issues . 88
B.4 Handoff issues . 88
B.5 Power noise issues . 89
B.6 PTU lost power calculation . 89
B.6.1 Lost power detection threshold . 89
B.6.2 Lost power detection speed . 89
B.6.3 PTU lost power calculation . 89
B.6.4 PTU power transmission detection accuracy . 89
B.6.5 PRU lost power reports . 89
B.6.6 Accuracy of reported power . 90
B.6.7 Other PRU lost power reports . 90
Annex C (normative) User experience requirements . 91
C.1 General . 91
C.2 User indication . 91
C.2.1 PRU user indication . 91
C.2.2 PTU user indication . 91
Annex D (informative) RCE calculations . 92
D.1 RCE calculation (using S-parameters) . 92
D.2 RCE calculation (using Z-parameters) . 93
D.2.1 Series tuned case . 94
D.2.2 Other RCE calculations. 94
D.3 Conversion between S-parameters and Z-parameters . 94

Figure 1 – Wireless power transfer system . 18
Figure 2 – PTU-PRU resonator P . 19
TX_IN
Figure 3 – PTU-PRU resonator P . 20
RX_OUT
Figure 4 – Equivalent circuit and system parameters . 20
Figure 5 – PTU resonator-load considerations . 24

Figure 6 – PTU state model . 27
Figure 7 – Beacon sequences . 29
Figure 8 – Load variation detection . 29
Figure 9 – Discovery . 30
Figure 10 – PTU I transition responses. 31
TX
Figure 11 – PRU state model . 41
Figure 12 – V operating regions . 42
RECT
Figure 13 – Basic architecture of WPT system . 45
Figure 14 – Basic state procedure (informative) . 47
Figure 15 – Registration period timeline example (informative) . 52
Figure 16 – PTU/PRU services/characteristics communication . 54
Figure 17 – PRU mode transition – Device Address field set to a non-zero value . 81
Figure 18 – PRU mode transition – Device Address field set to all zeros . 82
Figure A.1 – PRU design 3 block diagram . 84
Figure A.2 – Front view . 85
Figure A.3 – Back view . 85
Figure A.4 – Side view . 86
Figure A.5 – Front view, coil only . 86
Figure A.6 – Side view, coil only . 86

Table 1 – PTU classification. 19
Table 2 – PRU category . 20
Table 3 – Minimum RCE (percent and dB) between PRU and PTU. 22
Table 4 – Maximum load capacitance . 26
Table 5 – Time requirement to enter PTU Power Transfer state . 28
Table 6 – Sub-state of PTU Power Transfer . 32
Table 7 – PTU latching faults . 37
Table 8 – Example of accuracy of reported current . 41
Table 9 – PRU system errors . 45
Table 10 – RF budget (informative) . 50
Table 11 – Timing constraints . 52
Table 12 – BLE profile characteristics . 53
Table 13 – GATT sub-procedure . 53
Table 14 – PRU advertising payload . 58
Table 15 – Impedance shift bit . 60
Table 16 – WPT service UUID . 60
Table 17 – WPT service . 61
Table 18 – GAP service . 62
Table 19 – GATT service . 62
Table 20 – PRU Control Characteristic . 63
Table 21 – Detail: bit field for enables . 63
Table 22 – Detail: bit field for permission . 64
Table 23 – Detail: bit field for time set . 64

– 6 – IEC 63028:2017  IEC:2017
Table 24 – PTU reporting static values to PRU . 65
Table 25 – Detail: bit field for optional fields validity . 65
Table 26 – PTU power . 66
Table 27 – Max source impedance . 67
Table 28 – Max load resistance . 68
Table 29 – AirFuel protocol revision field . 69
Table 30 – PTU number of devices . 69
Table 31 – PRU reporting static values to the PTU . 70
Table 32 – Detail: bit field for optional fields validity . 70
Table 33 – Detail: bit field for PRU information . 71
Table 34 – PRU dynamic parameter characteristic . 73
Table 35 – Detail: bit field for optional fields validity . 73
Table 36 – Detail: bit field for PRU alert . 75
Table 37 – Detail: bit field for PRU alert . 76
Table 38 – Test mode commands . 76
Table 39 – PRU alert fields . 77
Table 40 – Detail: bit field for PRU alert notification . 77
Table 41 – Mode transition . 78
Table A.1 – PRU table of specifications . 84

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
WIRELESS POWER TRANSFER – AIRFUEL ALLIANCE RESONANT
BASELINE SYSTEM SPECIFICATION (BSS)

FOREWORD
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International Standard IEC 63028 has been prepared by technical area 15: Wireless power
transfer, of IEC technical committee 100: Audio, video and multimedia systems and
equipment.
The text of this International Standard is based on the following documents:
FDIS Report on voting
100/2901/FDIS 100/2941/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 8 – IEC 63028:2017  IEC:2017
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
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INTRODUCTION
In today’s world, mainstream consumer mobile devices are ubiquitously supported by wireless
technologies for data communication and connectivity functions while charging function is
primarily supported by wired technologies. The development of wireless power transfer
technologies offers increased user convenience for charging mobile devices; technologies
include inductive, resonant, uncoupled (RF, ultrasonic, laser) methods.
IEC 63028 defines a specific wireless charging approach based on resonant technology and
TM
specifies technical requirements for the AirFuel resonant wireless power transfer (WPT)
systems.
___________
TM
AirFuel is the trade name of a product supplied by AirFuel Alliance. This information is given for the
convenience of users of this document and does not constitute an endorsement by IEC of the product named.

– 10 – IEC 63028:2017  IEC:2017
WIRELESS POWER TRANSFER – AIRFUEL ALLIANCE RESONANT
BASELINE SYSTEM SPECIFICATION (BSS)

1 Scope
This document defines technical requirements, behaviors and interfaces used for ensuring
interoperability for flexibly coupled wireless power transfer (WPT) systems for AirFuel
Resonant WPT. This document is based on AirFuel Wireless Power Transfer System Baseline
System Specification (BSS) v1.3.
Products implementing this document are expected to follow applicable regulations and global
standards.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
AirFuel Wireless Power Transfer System Baseline System Specification (BSS) v1.3 [viewed
2017-03-13]. Available at: http://www.airfuel.org/technologies/specification-download
AirFuel Wireless Power Transfer System Baseline System Specification (BSS) v1.2.1 [viewed
2017-03-13]. Available at: http://www.airfuel.org/technologies/specification-download
Bluetooth core specification v4.0, or later versions as they are available [viewed 2017-03-13].
Available at: https://www.bluetooth.org/docman/handlers/downloaddoc.ashx?doc_id=229737
CSA4, or later versions as they are available [viewed 2017-03-13]. Available at:
https://www.bluetooth.org/docman/handlers/DownloadDoc.ashx?doc_id=269452
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
advertisement
connectable, undirected advertising event where the device transmits three WPT service
specific ADV_IND packets and accepts both scan requests and connect requests
Note 1 to entry: There is one ADV_IND packet transmitted on each of the advertising channels.
Note 2 to entry: Receipt of an advertisement is defined to be receipt of one of the three advertisement packets.

3.1.2
category
type of power receiving unit (PRU)
Note 1 to entry: Refer also to the definition of power receiving unit (3.1.17).
3.1.3
charge area
region of maximum overlap between the PTU charge area
and the PRU resonator
Note 1 to entry: The charge area is provided by the vendor, the PRU is the entire device, and the test area is the
charge area in tests.
3.1.4
charge area
region of maximum overlap between the PTU charge area
and the PRU
Note 1 to entry: The charge area is provided by the vendor, and the test area is the charge area in tests.
Note 2 to entry: This does not preclude the PRU resonator being larger than the PTU resonator.
Note 3 to entry: Additionally, "within the charge area" is equated to mean "within the test area".
Note 4 to entry: The charge area includes the specification of the Z heights intended for the final product, from
the surface of resonator coil.
3.1.5
class
type of power transmitting unit (PTU)
Note 1 to entry: Refer also to the definition of power transmitting unit (3.1.18).
3.1.6
concurrent multiple charging
transmission of power from one transmitting resonator to multiple receiving resonators
Note 1 to entry: Magnetic resonant coupling can occur among one transmitting resonator and many receiving
resonators, while tight coupling is restricted to only one transmitting coil and one receiving coil. Thus, tightly
coupled technology only allows one-to-one power transmission.
3.1.7
delta R1
change in a PTU resonator’s measured resistance when a PRU is placed at the center of
PTU’s charge area as compared to the resistance when no objects are in the charge area
Note 1 to entry: This measurement refers to the use of a PRU with an open-circuit resonator.
3.1.8
device registry
list of active PRU’s maintained by the PTU
3.1.9
dominant PRU
PRU consuming the highest percentage of its rated output power (V x I / P )
RECT RECT RECT_MAX
3.1.10
flexibly coupled wireless power transfer
power transfer system that provides power through magnetic induction between a transmitter
coil and a receiver coil, where the coupling factor (k) between the coils can be within a range
between large and very small (e.g., less than 0,025)

– 12 – IEC 63028:2017  IEC:2017
Note 1 to entry: Also, in a flexibly coupled system, the transmitter (i.e., the primary) coil can be of the same size,
or much larger than the receiver (i.e., secondary) coil. The allowable difference in coil size enables concurrent
charging of multiple devices as well as more flexible placement of receiver coils within the charge area.
3.1.11
high voltage region
PRU region in which V levels result in high power dissipation without damaging the PRU
RECT
3.1.12
keep-out volume
volume outside of the charge area in which no testing is performed
Note 1 to entry: This parameter is defined by the PTU vendor.
3.1.13
low voltage region
V voltages below the operational range
RECT
3.1.14
normal operation
range of all specified WPT states other than PRU System Error state for over-voltage
3.1.15
over-voltage
V voltages greater than V
RECT RECT_MAX
Note 1 to entry: Over-voltage can permanently damage PRU components if the PRU does not correct the
condition (see 8.3.6).
3.1.16
OVP switch
switch in the PRU that opens or closes to protect the PRU
3.1.17
power receiving unit
unit receiving electrical power wirelessly from a power transmitting unit
3.1.18
power transmitting unit
unit transferring electrical power wirelessly to each power receiving unit
3.1.19
rectifier efficiency
ratio of rectified power to PRU received power (P / P )
RECT RX_OUT
3.1.20
resonance
condition of a body or system when it is subjected to a periodic disturbance of the same
frequency as the natural frequency of the body or system
Note 1 to entry: At this frequency, the system displays an enhanced oscillation or vibration.
3.1.21
resonator
magnetic field generator that satisfies the resonance condition for efficiently transferring
electrical power from a PTU to a PRU
Note 1 to entry: Both a coil and an electrical conducting wire are examples of a resonator.

3.1.22
wireless power transfer
processes and methods that take place in any system where electrical power is transmitted
from a power source to an electrical load without interconnecting wires
3.2 Symbols and abbreviated terms
3.2.1 Symbols
For the purposes of this document, the following symbols for variable parameters apply.
3.2.1.1
η
RECT
rectifier efficiency (P / P )
RECT RX_OUT
3.2.1.2
I
RECT
DC current out of the PRU’s rectifier
3.2.1.3
I
RECT_REPORT
I value reported by a PRU to a PTU
RECT
3.2.1.4
I
RX_IN
RMS current out of the resonator/into the rectifier, while in the PRU on state
3.2.1.5
I
TX
RMS current into the PTU resonator coil
3.2.1.6
I
TX_LONG_BEACON
RMS current into the PTU resonator during the long beacon period in the PTU power save
state
Note 1 to entry: This current is used to provide minimum power for waking up a PRU signaling module and MCU,
and to initiate communication.
3.2.1.7
I
TX_SHORT_BEACON
RMS current into the PTU resonator while in the PTU power save state
Note 1 to entry: This current is used to detect the PTU impedance change caused by the placement of an object
in the charge area.
3.2.1.8
I
TX_START
RMS current into the PTU resonator that provides minimum power for waking up a PRU
signaling module and MCU
Note 1 to entry: This current is also used to initiate communication and registration.
3.2.1.9
P
IN
DC power into the PTU
3.2.1.10
P
TX_IN
input power to the PTU resonator

– 14 – IEC 63028:2017  IEC:2017
3.2.1.11
P
TX_IN_MAX
maximum input power to the PTU resonator
3.2.1.12
P
RECT
average power out of the PRU’s rectifier AVG (V x I )
RECT RECT
3.2.1.13
P
RECT_BOOT
maximum average power out of the PRU’s rectifier as declared by the vendor
Note 1 to entry: The rectifier power is measured over a 1 ms interval.
3.2.1.14
P
RECT_IN
average power into the PRU rectifier
3.2.1.15
P
RX_REPORTED
product of reported rectified voltage and current (V x I )
RECT_REPORT RECT_REPORT
3.2.1.16
P
RX_OUT
power out of the PRU resonator
3.2.1.17
R
RECT
effective load resistance at the output of the PRU’s rectifier
3.2.1.18
R
RECT_MP
maximum power point resistance
3.2.1.19
R
RX_IN
parasitic resistance of the PRU resonator
3.2.1.20
V
PAa
DC input voltage to the PTU’s power amplifier
3.2.1.21
V
RECT
DC voltage at the output of a PRU’s rectifier
3.2.1.22
V
RECT_REPORT
V value which a PRU reports to a PTU
RECT
3.2.1.23
Z
RX_IN
input impedance of the PRU resonator and matching network
For the purposes of this document, the following symbols for PTU/PRU design dependent
variable parameters apply.
3.2.1.24
ADV_PWR_MIN
minimum BLE advertisement power as seen at the PTU BLE antenna
3.2.1.25
I
TX_ABS_MAX
absolute maximum PTU current
3.2.1.26
I
TX_LONG_BEACON_MIN
minimum allowed current during PTU long beacon
3.2.1.27
I
TX_SHORT_BEACON_MIN
minimum allowed current during PTU short beacon
3.2.1.28
I
TX_MAX
operational maximum PTU current
3.2.1.29
I
TX_MIN
operational minimum PTU current
3.2.1.30
I
TX_NOMINAL
nominal PTU resonator current driving all PRUs to operate in the optimum voltage region
3.2.1.31
P
RECT_MAX
PRU’s maximum rated P power
RECT
3.2.1.32
P
RECT_MIN
PRU’s minimum rated P power
RECT
3.2.1.33
P
RX_OUT_MAX
maximum output power of the PRU resonator
3.2.1.34
R
RX_MIN
minimum resistance presented to the PRU resonator terminals during normal operation
3.2.1.35
R
RECT_MP
R resistance that achieves maximum P power
RECT RECT
3.2.1.36
R
TX_IN
real part of Z
TX_IN
3.2.1.37
V
RECT_BOOT
boot V voltage
RECT
Note 1 to entry: Below this level, the PRU cannot enter the PRU boot state.

– 16 – IEC 63028:2017  IEC:2017
3.2.1.38
V
RECT_HIGH
maximum operat
...

IEC 63028 ®
Edition 1.0 2017-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
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Wireless power transfer – AirFuel Alliance resonant baseline system specification
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Transfert d'énergie sans fil – Spécification du système de référence (BSS) pour le
système résonant d'AirFuel Alliance

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IEC 63028 ®
Edition 1.0 2017-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Wireless power transfer – AirFuel Alliance resonant baseline system specification

(BSS)
Transfert d'énergie sans fil – Spécification du système de référence (BSS) pour le

système résonant d'AirFuel Alliance

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.240.99; 33.160.99; 35.200 ISBN 978-2-8322-8732-3

– 2 – IEC 63028:2017  IEC 2017
CONTENTS
FOREWORD . 7
INTRODUCTION . 9
1 Scope . 10
2 Normative references . 10
3 Terms, definitions, symbols and abbreviated terms . 10
3.1 Terms and definitions . 10
3.2 Symbols and abbreviated terms . 13
3.2.1 Symbols . 13
3.2.2 Abbreviated terms . 17
4 System description . 17
5 Conformance and backwards compatibility . 18
6 Device types . 19
6.1 PTU classification . 19
6.2 PRU category . 20
7 Power transfer specifications . 21
7.1 System equivalent circuit and reference parameters . 21
7.2 General system requirements . 21
7.2.1 Operating frequency . 21
7.2.2 Z relationship to R . 21
TX_IN RECT
7.2.3 Power stability . 21
7.2.4 PTU co-location protection. 21
7.2.5 PRU self-protection (informative) . 21
7.3 Resonator requirements . 22
7.3.1 Resonator coupling efficiency (RCE) . 22
7.3.2 PTU resonator requirements . 22
7.3.3 PRU resonator requirements . 24
7.4 Load parameters . 26
7.4.1 Load parameters introduction . 26
7.4.2 Minimum load resistance . 26
7.4.3 Maximum allowable dynamic load . 26
7.4.4 Maximum load capacitance . 26
8 Power control specifications . 27
8.1 Control objectives . 27
8.2 PTU specifications . 27
8.2.1 PTU state . 27
8.2.2 General state requirements . 27
8.2.3 PTU power save state. 29
8.2.4 PTU Low Power state . 31
8.2.5 PTU Power Transfer state . 31
8.2.6 PTU Configuration state . 34
8.2.7 PTU Local Fault state . 35
8.2.8 PTU latching fault state . 35
8.2.9 PTU state transitions . 36
8.2.10 PTU Test Mode. 39
8.3 PRU specifications . 39
8.3.1 PRU general requirements . 39

8.3.2 PRU state model . 42
8.3.3 Null state . 43
8.3.4 PRU boot . 43
8.3.5 PRU On state . 44
8.3.6 PRU System Error state . 44
8.3.7 PRU state transitions . 45
9 Signaling specifications . 46
9.1 Architecture and state diagrams . 46
9.1.1 Architecture . 46
9.1.2 Overall charge process . 47
9.2 Charge procedure and requirements . 49
9.2.1 Removing PRU from WPT network . 49
9.2.2 Power Sharing mode . 49
9.3 Bluetooth low energy requirements . 50
9.3.1 Bluetooth low energy requirements introduction . 50
9.3.2 Bluetooth low energy objectives . 50
9.3.3 PTU hardware requirement . 50
9.3.4 PRU hardware requirement . 50
9.3.5 Basic network structure . 50
9.3.6 RF requirements . 50
9.3.7 Timing and sequencing requirements . 51
9.3.8 Profile structure . 54
9.4 BLE profile definition . 54
9.4.1 GATT sub-procedure . 54
9.4.2 Configuration . 54
9.4.3 PRU requirements . 55
9.4.4 PTU requirements . 56
9.4.5 Connection establishment . 56
9.4.6 Security considerations . 58
9.4.7 Charge completion . 58
9.5 WPT service characteristics . 59
9.5.1 WPT service characteristics introduction. 59
9.5.2 PRU advertising payload . 59
9.5.3 WPT service . 61
9.5.4 PRU control . 63
9.5.5 PTU static parameter . 65
9.5.6 PRU static parameter characteristic . 70
9.5.7 PRU dynamic parameter characteristic . 73
9.5.8 PRU alert characteristic . 77
9.6 Cross connection algorithm . 79
9.6.1 Cross connection algorithm introduction . 79
9.6.2 Definitions . 79
9.6.3 Acceptance of advertisement . 79
9.6.4 Impedance shift sensing . 79
9.6.5 Reboot bit handling . 80
9.6.6 Time set handling . 80
9.7 Mode transition . 81
9.7.1 Mode transition introduction . 81
9.7.2 Mode transition procedure . 81

– 4 – IEC 63028:2017  IEC 2017
9.7.3 BLE reconnection procedure . 81
10 PTU resonators . 84
10.1 PTU resonators introduction . 84
10.2 Class n design template . 84
10.2.1 Class n design template introduction. 84
10.2.2 Table of specifications . 84
10.2.3 PTU resonator structure . 84
10.3 Approved PTU resonators . 84
Annex A (informative) Reference PRU for PTU acceptance testing . 85
A.1 Category 1 . 85
A.2 Category 2 . 85
A.3 Category 3 . 85
A.3.1 PRU design 3-1 . 85
A.3.2 Geometry. 85
A.4 Category 4 . 88
A.5 Category 5 . 88
Annex B (informative) Lost power . 89
B.1 Overview. 89
B.2 General . 89
B.3 Cross connection issues . 89
B.4 Handoff issues . 89
B.5 Power noise issues . 90
B.6 PTU lost power calculation . 90
B.6.1 Lost power detection threshold . 90
B.6.2 Lost power detection speed . 90
B.6.3 PTU lost power calculation . 90
B.6.4 PTU power transmission detection accuracy . 90
B.6.5 PRU lost power reports . 91
B.6.6 Accuracy of reported power . 91
B.6.7 Other PRU lost power reports . 91
Annex C (normative) User experience requirements . 92
C.1 General . 92
C.2 User indication . 92
C.2.1 PRU user indication . 92
C.2.2 PTU user indication . 92
Annex D (informative) RCE calculations . 93
D.1 RCE calculation (using S-parameters) . 93
D.2 RCE calculation (using Z-parameters) . 94
D.2.1 Series tuned case . 95
D.2.2 Other RCE calculations. 95
D.3 Conversion between S-parameters and Z-parameters . 95

Figure 1 – Wireless power transfer system . 18
Figure 2 – PTU-PRU resonator P . 19
TX_IN
Figure 3 – PTU-PRU resonator P . 20
RX_OUT
Figure 4 – Equivalent circuit and system parameters . 21
Figure 5 – PTU resonator-load considerations . 24

Figure 6 – PTU state model . 27
Figure 7 – Beacon sequences . 29
Figure 8 – Load variation detection . 30
Figure 9 – Discovery . 31
Figure 10 – PTU I transition responses. 32
TX
Figure 11 – PRU state model . 42
Figure 12 – V operating regions . 43
RECT
Figure 13 – Basic architecture of WPT system . 47
Figure 14 – Basic state procedure (informative) . 48
Figure 15 – Registration period timeline example (informative) . 53
Figure 16 – PTU/PRU services/characteristics communication . 55
Figure 17 – PRU mode transition – Device Address field set to a non-zero value . 82
Figure 18 – PRU mode transition – Device Address field set to all zeros . 83
Figure A.1 – PRU design 3 block diagram . 85
Figure A.2 – Front view . 86
Figure A.3 – Back view . 86
Figure A.4 – Side view . 87
Figure A.5 – Front view, coil only . 87
Figure A.6 – Side view, coil only . 87

Table 1 – PTU classification. 20
Table 2 – PRU category . 20
Table 3 – Minimum RCE (percent and dB) between PRU and PTU. 22
Table 4 – Maximum load capacitance . 26
Table 5 – Time requirement to enter PTU Power Transfer state . 28
Table 6 – Sub-state of PTU Power Transfer . 32
Table 7 – PTU latching faults . 38
Table 8 – Example of accuracy of reported current . 42
Table 9 – PRU system errors . 46
Table 10 – RF budget (informative) . 51
Table 11 – Timing constraints . 53
Table 12 – BLE profile characteristics . 54
Table 13 – GATT sub-procedure . 54
Table 14 – PRU advertising payload . 59
Table 15 – Impedance shift bit . 61
Table 16 – WPT service UUID . 61
Table 17 – WPT service . 62
Table 18 – GAP service . 63
Table 19 – GATT service . 63
Table 20 – PRU Control Characteristic . 64
Table 21 – Detail: bit field for enables . 64
Table 22 – Detail: bit field for permission . 65
Table 23 – Detail: bit field for time set . 65

– 6 – IEC 63028:2017  IEC 2017
Table 24 – PTU reporting static values to PRU . 66
Table 25 – Detail: bit field for optional fields validity . 66
Table 26 – PTU power . 67
Table 27 – Max source impedance . 68
Table 28 – Max load resistance . 69
Table 29 – AirFuel protocol revision field . 70
Table 30 – PTU number of devices . 70
Table 31 – PRU reporting static values to the PTU . 71
Table 32 – Detail: bit field for optional fields validity . 71
Table 33 – Detail: bit field for PRU information . 72
Table 34 – PRU dynamic parameter characteristic . 74
Table 35 – Detail: bit field for optional fields validity . 74
Table 36 – Detail: bit field for PRU alert . 76
Table 37 – Detail: bit field for PRU alert . 77
Table 38 – Test mode commands . 77
Table 39 – PRU alert fields . 78
Table 40 – Detail: bit field for PRU alert notification . 78
Table 41 – Mode transition . 79
Table A.1 – PRU table of specifications . 85

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
WIRELESS POWER TRANSFER – AIRFUEL ALLIANCE RESONANT
BASELINE SYSTEM SPECIFICATION (BSS)

FOREWORD
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rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 63028 has been prepared by technical area 15: Wireless power
transfer, of IEC technical committee 100: Audio, video and multimedia systems and equipment.
The text of this International Standard is based on the following documents:
FDIS Report on voting
100/2901/FDIS 100/2941/RVD
Full information on the voting for the approval of this International Standard can be found in the
report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 8 – IEC 63028:2017  IEC 2017
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

INTRODUCTION
In today’s world, mainstream consumer mobile devices are ubiquitously supported by wireless
technologies for data communication and connectivity functions while charging function is
primarily supported by wired technologies. The development of wireless power transfer
technologies offers increased user convenience for charging mobile devices; technologies
include inductive, resonant, uncoupled (RF, ultrasonic, laser) methods.
IEC 63028 defines a specific wireless charging approach based on resonant technology and
TM
specifies technical requirements for the AirFuel resonant wireless power transfer (WPT)
systems.
___________
TM
AirFuel is the trade name of a product supplied by AirFuel Alliance. This information is given for the
convenience of users of this document and does not constitute an endorsement by IEC of the product named.

– 10 – IEC 63028:2017  IEC 2017
WIRELESS POWER TRANSFER – AIRFUEL ALLIANCE RESONANT
BASELINE SYSTEM SPECIFICATION (BSS)

1 Scope
This document defines technical requirements, behaviors and interfaces used for ensuring
interoperability for flexibly coupled wireless power transfer (WPT) systems for AirFuel Resonant
WPT. This document is based on AirFuel Wireless Power Transfer System Baseline System
Specification (BSS) v1.3.
Products implementing this document are expected to follow applicable regulations and global
standards.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
AirFuel Wireless Power Transfer System Baseline System Specification (BSS) v1.3 [viewed
2017-03-13]. Available at: http://www.airfuel.org/technologies/specification-download
AirFuel Wireless Power Transfer System Baseline System Specification (BSS) v1.2.1 [viewed
2017-03-13]. Available at: http://www.airfuel.org/technologies/specification-download
Bluetooth core specification v4.0, or later versions as they are available [viewed 2017-03-13].
Available at: https://www.bluetooth.org/docman/handlers/downloaddoc.ashx?doc_id=229737
CSA4, or later versions as they are available [viewed 2017-03-13]. Available at:
https://www.bluetooth.org/docman/handlers/DownloadDoc.ashx?doc_id=269452
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
advertisement
connectable, undirected advertising event where the device transmits three WPT service
specific ADV_IND packets and accepts both scan requests and connect requests
Note 1 to entry: There is one ADV_IND packet transmitted on each of the advertising channels.
Note 2 to entry: Receipt of an advertisement is defined to be receipt of one of the three advertisement packets.

3.1.2
category
type of power receiving unit (PRU)
Note 1 to entry: Refer also to the definition of power receiving unit (3.1.17).
3.1.3
charge area
region of maximum overlap between the PTU charge area and
the PRU resonator
Note 1 to entry: The charge area is provided by the vendor, the PRU is the entire device, and the test area is the
charge area in tests.
3.1.4
charge area
region of maximum overlap between the PTU charge area
and the PRU
Note 1 to entry: The charge area is provided by the vendor, and the test area is the charge area in tests.
Note 2 to entry: This does not preclude the PRU resonator being larger than the PTU resonator.
Note 3 to entry: Additionally, "within the charge area" is equated to mean "within the test area".
Note 4 to entry: The charge area includes the specification of the Z heights intended for the final product, from the
surface of resonator coil.
3.1.5
class
type of power transmitting unit (PTU)
Note 1 to entry: Refer also to the definition of power transmitting unit (3.1.18).
3.1.6
concurrent multiple charging
transmission of power from one transmitting resonator to multiple receiving resonators
Note 1 to entry: Magnetic resonant coupling can occur among one transmitting resonator and many receiving
resonators, while tight coupling is restricted to only one transmitting coil and one receiving coil. Thus, tightly coupled
technology only allows one-to-one power transmission.
3.1.7
delta R1
change in a PTU resonator’s measured resistance when a PRU is placed at the center of PTU’s
charge area as compared to the resistance when no objects are in the charge area
Note 1 to entry: This measurement refers to the use of a PRU with an open-circuit resonator.
3.1.8
device registry
list of active PRU’s maintained by the PTU
3.1.9
dominant PRU
PRU consuming the highest percentage of its rated output power (V x I / P )
RECT RECT RECT_MAX
3.1.10
flexibly coupled wireless power transfer
power transfer system that provides power through magnetic induction between a transmitter
coil and a receiver coil, where the coupling factor (k) between the coils can be within a range
between large and very small (e.g., less than 0,025)

– 12 – IEC 63028:2017  IEC 2017
Note 1 to entry: Also, in a flexibly coupled system, the transmitter (i.e., the primary) coil can be of the same size,
or much larger than the receiver (i.e., secondary) coil. The allowable difference in coil size enables concurrent
charging of multiple devices as well as more flexible placement of receiver coils within the charge area.
3.1.11
high voltage region
PRU region in which V levels result in high power dissipation without damaging the PRU
RECT
3.1.12
keep-out volume
volume outside of the charge area in which no testing is performed
Note 1 to entry: This parameter is defined by the PTU vendor.
3.1.13
low voltage region
V voltages below the operational range
RECT
3.1.14
normal operation
range of all specified WPT states other than PRU System Error state for over-voltage
3.1.15
over-voltage
V voltages greater than V
RECT RECT_MAX
Note 1 to entry: Over-voltage can permanently damage PRU components if the PRU does not correct the condition
(see 8.3.6).
3.1.16
OVP switch
switch in the PRU that opens or closes to protect the PRU
3.1.17
power receiving unit
unit receiving electrical power wirelessly from a power transmitting unit
3.1.18
power transmitting unit
unit transferring electrical power wirelessly to each power receiving unit
3.1.19
rectifier efficiency
ratio of rectified power to PRU received power (P / P )
RECT RX_OUT
3.1.20
resonance
condition of a body or system when it is subjected to a periodic disturbance of the same
frequency as the natural frequency of the body or system
Note 1 to entry: At this frequency, the system displays an enhanced oscillation or vibration.
3.1.21
resonator
magnetic field generator that satisfies the resonance condition for efficiently transferring
electrical power from a PTU to a PRU
Note 1 to entry: Both a coil and an electrical conducting wire are examples of a resonator.

3.1.22
wireless power transfer
processes and methods that take place in any system where electrical power is transmitted
from a power source to an electrical load without interconnecting wires
3.2 Symbols and abbreviated terms
3.2.1 Symbols
For the purposes of this document, the following symbols for variable parameters apply.
3.2.1.1
η
RECT
rectifier efficiency (P / P )
RECT RX_OUT
3.2.1.2
I
RECT
DC current out of the PRU’s rectifier
3.2.1.3
I
RECT_REPORT
I value reported by a PRU to a PTU
RECT
3.2.1.4
I
RX_IN
RMS current out of the resonator/into the rectifier, while in the PRU on state
3.2.1.5
I
TX
RMS current into the PTU resonator coil
3.2.1.6
I
TX_LONG_BEACON
RMS current into the PTU resonator during the long beacon period in the PTU power save state
Note 1 to entry: This current is used to provide minimum power for waking up a PRU signaling module and MCU,
and to initiate communication.
3.2.1.7
I
TX_SHORT_BEACON
RMS current into the PTU resonator while in the PTU power save state
Note 1 to entry: This current is used to detect the PTU impedance change caused by the placement of an object in
the charge area.
3.2.1.8
I
TX_START
RMS current into the PTU resonator that provides minimum power for waking up a PRU
signaling module and MCU
Note 1 to entry: This current is also used to initiate communication and registration.
3.2.1.9
P
IN
DC power into the PTU
– 14 – IEC 63028:20
...