IEC TR 62905:2018

Exposure assessment methods for wireless power transfer systems

IEC/TR 62905:2018(E) is a Technical Report. It describes general exposure assessment methods for wireless power transfer (WPT) at frequency up to 10 MHz considering thermal and stimulus effects. Exposure assessment procedures and experimental results are shown as examples such as electric vehicles (EVs) and mobile devices.
Keywords: Exposure Assessment, Wireless Power Transfer (WPT), Human Exposure

General Information

• Status: Published
• Publication Date: 05-Feb-2018
• ICS: 17.220.20 - Measurement of electrical and magnetic quantities
• Technical Committee: TC 106 - Methods for the assessment of electric, magnetic and electromagnetic fields associated with human exposure
• Current Stage: PPUB - Publication issued
• Start Date: 06-Feb-2018
• Completion Date: 21-Feb-2018

Overview

IEC TR 62905:2018 is a Technical Report that provides guidance on exposure assessment for Wireless Power Transfer (WPT) systems operating at frequencies up to 10 MHz. The report addresses both thermal and stimulus effects and illustrates assessment procedures with experimental and numerical examples - notably for electric vehicles (EVs) and mobile devices. IEC TR 62905 is intended as a practical reference for evaluating human exposure around WPT installations.

Key Topics and Requirements

The report organizes practical assessment methods and supporting material, including:

• Scope and terminology: definitions, symbols and physical quantities relevant to WPT exposure.
• Classification of WPT systems:
  • systems below 100 kHz
  • systems between 100 kHz and 10 MHz
• Basic assessment methods:
  • Procedures for evaluating direct effects (induced fields, SAR, induced E‑field)
  • Procedures for evaluating indirect effects (contact currents, interactions with objects and implants)
  • Flowcharts for assessment decision-making
• Measurement and calculation techniques:
  • Measurement of incident electric and magnetic fields (equipment and method guidance)
  • Coupling factor and generic gradient source models
  • Procedures for induced E‑field and SAR estimation (measurement and numerical calculation)
  • Contact current measurement equipment and methods
• Informative annexes with worked examples:
  • Case studies for EV charging pads and mobile-device chargers
  • Numerical and experimental studies, coupling-factor evaluations
  • Considerations for medical implants and implant enhancement factors
• Reference to international exposure guidelines (Annex B), including ICNIRP and IEEE guidance.

Practical Applications and Who Uses This Standard

IEC TR 62905 is useful for professionals involved with the design, testing and safety evaluation of WPT systems:

• WPT system designers and RF engineers (EV charging infrastructure, consumer wireless chargers)
• Compliance and test laboratories performing human exposure measurements
• Health & safety officers and regulatory bodies assessing compliance with exposure limits
• Researchers conducting numerical modelling and experimental exposure studies
• Manufacturers preparing technical documentation for product certification

The report helps these users determine when field measurements, numerical modelling or contact-current testing are required, and provides example procedures for realistic exposure scenarios.

Related Standards

• ICNIRP exposure guidelines and IEEE exposure standards (summarized in Annex B)
• IEC measurement-related standards referenced in the normative clauses (see TR for full list)

IEC TR 62905:2018 is a practical, example-rich resource for assessing human exposure from WPT systems and supports harmonized, safety-focused deployment of wireless power technologies.

Standards Content (Sample)

IEC TR 62905 ®
Edition 1.0 2018-02
TECHNICAL
REPORT
colour
inside
Exposure assessment methods for wireless power transfer systems
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IEC TR 62905 ®
Edition 1.0 2018-02
TECHNICAL
REPORT
colour
inside
Exposure assessment methods for wireless power transfer systems

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 17.220.20 ISBN 978-2-8322-5350-2

– 2 – IEC TR 62905:2018 © IEC 2018
CONTENTS
FOREWORD . 7
INTRODUCTION . 9
1 Scope . 10
2 Normative references . 10
3 Terms and definitions . 10
4 Symbols and abbreviations . 12
4.1 Physical quantities . 12
4.2 Constants . 12
4.3 Abbreviations . 12
5 Overview of WPT systems . 13
5.1 General . 13
5.2 WPT systems whose frequency range is less than 100 kHz . 13
5.3 WPT systems whose frequency range is from 100 kHz to 10 MHz . 17
6 Basic assessment methods . 20
6.1 General . 20
6.2 Basic assessment methods considering direct effect . 20
6.2.1 General . 20
6.2.2 Evaluation based on transmit power or current . 21
6.2.3 Evaluation of incident fields against reference levels . 21
6.2.4 Evaluation of incident fields against basic restrictions . 21
6.2.5 Evaluation of induced E-field and SAR against basic restrictions . 22
6.2.6 Assessment procedure . 23
6.3 Basic assessment method considering indirect effect . 23
Annex A (informative) WPT systems whose frequency range is over 10 MHz . 25
Annex B (informative) International exposure guidelines . 27
B.1 ICNIRP guidelines. 27
B.2 IEEE standards . 30
Annex C (informative) Assessment methods . 33
C.1 Exclusion based on transmit power or current . 33
C.2 Measurement of incident electromagnetic fields . 34
C.2.1 Equipment for electric field measurement . 34
C.2.2 Equipment for magnetic field measurement . 34
C.2.3 Measurement method . 35
C.3 Coupling factor . 36
C.4 Generic gradient source model . 37
C.5 Induced E-field or SAR . 40
C.5.1 Measurement . 40
C.5.2 Calculation . 41
C.6 Contact current . 43
C.6.1 Equipment . 43
C.6.2 Measurements . 45
Annex D (informative) Case studies . 46
D.1 WPT system for EV . 46
D.1.1 General . 46
D.1.2 Assessment procedures for WPT system for EV . 47
D.2 Experimental assessment results for EV . 58

D.2.1 General . 58
D.2.2 Electromagnetic field measurement results . 58
D.2.3 Contact current measurement . 60
D.3 WPT system for mobile devices . 61
D.3.1 General . 61
D.3.2 Assessment procedures for WPT system for mobile . 62
Annex E (informative) Numerical and experimental studies . 64
E.1 Exposure evaluation of WPT for EV . 64
E.1.1 Research in Japan . 64
E.1.2 Research in Korea . 68
E.2 Exposure evaluation of WPT for mobile device. 72
E.2.1 WPT system in 140 kHz band . 72
E.2.2 WPT systems in MHz band . 74
E.3 Coupling factor . 79
E.3.1 WPT system for EV . 79
E.3.2 WPT system for mobile device . 82
E.3.3 Evaluation example of CF and GGSM using a cylinder model . 83
E.4 SAR measurement . 87
E.5 Contact current . 89
E.5.1 WPT system for EV . 89
E.5.2 WPT systems for mobile (MHz) . 90
Annex F (informative) Medical implants . 92
F.1 Background. 92
F.2 Medical implant enhancement factor . 92
F.3 Numerical evaluation of medical implant enhancement factor . 97
F.3.1 General . 97
F.3.2 Numerical setup . 97
Bibliography . 99

Figure 1 – Wireless power kitchen appliances [1] . 13
(WPT kitchen island of apartment) . 14
Figure 2 – Use cases of the LCD and semiconductor product lines and kitchen WPT
systems [1] . 14
Figure 3 – Example of a WPT system for EV/PHEV [1] . 15
Figure 4 – Example of an online electric vehicle [1] . 16
Figure 5 – Technical characteristics of an online electric vehicle [1] . 16
Figure 6 – Example magnetic induction WPT system block diagram [1] . 18
Figure 7 – Example magnetic resonance WPT system block diagram [1] . 18
Figure 8 – Capacitive coupling WPT system block diagram [1] . 19
Figure 9 – Typical structure of the capacitive coupling system [1] . 19
Figure 10 – Flowchart of assessment procedure considering the direct effect . 23
Figure 11 – Two exposure situations for ungrounded and grounded metal objects . 24
Figure 12 – Flowchart of assessment procedures for indirect effects . 24
Figure C.1 – Frequency characteristics of impedance of adult male and IEC equivalent
circuit . 44
Figure C.2 – IEC equivalent circuit . 44
Figure C.3 – Example of contact current measurement equipment . 44

– 4 – IEC TR 62905:2018 © IEC 2018
Figure D.1 – Example for areas of protection, for ground mounted systems [37] . 47
Figure D.2 – Area 3 measurement position [37] . 48
Figure D.3 – Area 4 measurement position [37] . 48
Figure D.4 – Assessment flow of Part 1 . 51
Figure D.5 – Assessment flow of Part 2 . 55
Figure D.6 – Assessment flow of Part 3 . 56
Figure D.7 – Example measurement layout for Area 3 surrounding area of vehicle . 59
Figure D.8 – Example measurement layout for Area 4 car interior . 60
Figure D.9 – Contact current meters used in the measurement . 60
Figure D.10 – Measurement of contact current . 61
Figure E.1 – Geometry of vehicle model . 64
Figure E.2 – Measured and simulated magnetic field strength leaked from wireless
power system in an electric vehicle [46] . 65
Figure E.3 – Distance dependence of peak induced electric field strength in human
body model . 65
Figure E.4 – Analysis of induced electric field strength in the human body for different
human positions relative to the vehicle [41] . 66
Figure E.5 – Relationship between the maximum induced electric field in the human
body and the magnetic field strength [41] . 67
Figure E.6 – The induced electric field distributions in a human body model lying on
the ground with his right arm stretched [48] . 68
Figure E.7 – EMF human exposure condition from the power line and pickup coils of
OLEV system . 69
Figure E.8 – The model in the field generated by OLEV . 70
Figure E.9 – The calculated magnetic field distributions at each distance from OLEV . 71
Figure E.10 – Photograph of magnetic field measurement for transmitting and receiving
pads of wireless charging system. 72
Figure E.11 – Measurement results of magnetic field value for two cases of low voltage
output (case 1) and high voltage output (case 2) . 72
Figure E.12 – Transmitting and receiving coils, and magnetic sheet . 73
Figure E.13 – Simulated magnetic field strength distribution (Charging (a) xy plane,
(b) yz plane; Standby model (c) xy plane, (d) yz plane) and measured value (Charging
(e) xy plane, (f) yz plane; Standby mode (g) xy plane, (h) yz plane) . 73
Figure E.14 – Position of human body and coil (left), exposure point in chest (right) . 74
Figure E.15 – Realistic human body model and system position. 75
Figure E.16 – Position of the human body model: (a) the human body is moved in the
horizontal direction, (b) the coils are moved in vertical direction. 76
Figure E.17 – Peak of 10 g average SAR moved in (a) horizontal direction, (b) vertical
direction . 76
Figure E.18 – Peaks of 10 g average SAR . 77
Figure E.19 – Wireless power transfer system configurations . 78
Figure E.20 – Electric field and magnetic field distributions around the coil when an
input power is 1 W . 78
Figure E.21 – Exposure conditions for WPT system . 78
Figure E.22 – Top and bird’s-eye views of (a) solenoid type and (b) circular spiral type
coupling coils, and (c) geometry of electric vehicle with a wireless power transfer
system [13] . 81
Figure E.23 – A numerical model of dielectric cylinder used in the calculation. 83

Figure E.24 – Distribution of induced electric field strength inside the cylinder in the
vicinity of a one-turn loop with 1 A current . 85
Figure E.25 – A two-line current model . 85
Figure E.26 – Decay profile of incident magnetic field for each component . 86
Figure E.27 – Profile of incident magnetic field for G = 13 (left) and 80 (right) . 86
n
Figure E.28 – Distribution of induced electric field for x-, y-, and z-components of the
incident magnetic field profiles generated by GGSM . 86
Figure E.29 – Solenoid-type WPT system (left) and flat-spiral-type WPT system (right)
used for SAR measurement . 88
Figure E.30 – SAR distribution in a liquid phantom, calculated by MoM (above) and
measured by the developed measurement system (below) . 88
Figure E.31 – Two conditions of contact current measurement . 89
Figure E.32 – Contact currents with ungrounded condition . 90
Figure E.33 – Contact currents with grounded condition. 90
Figure E.34 – Contact current with ungrounded metal . 91
Figure E.35 – Contact current with grounded metal . 91
Figure F.1 – Model of the insulated perfectly conducting wire with non-insulated bare
tips used as generic implantable medical device . 94
Figure F.2 – pSAR (W/kg) at the lead tip as a function of frequency in the range
0,1g
100 kHz to 10 MHz for each lead length (100 mm, 200 mm, 500 mm and 800 mm) . 96
Figure F.3 – Induced E-field tangential to the implant, embedded in the homogeneous
tissue, in the absence of the implant, to reach ICNIRP2010 BRs in the frequency range
10 kHz to 10 MHz and as a function of the lead length, when the implant is present . 97

Table 1 – Summary of application, technology and specification of WPT systems
whose frequency range is less than 100 kHz. 17
Table 2 – WPT systems whose frequency range is from 100 kHz to 10 MHz . 20
Table A.1 – Classification of WPT applications . 26
Table A.2 – Characteristics of beam WPT applications . 26
Table B.1 – Basic restrictions up to 10 GHz of ICNIRP1998 . 27
Table B.2 – Basic restrictions of ICNIRP2010 . 28
Table B.3 – Reference levels for electric and magnetic fields (unperturbed rms values)
of ICNIRP1998 . 29
Table B.4 – Reference levels for electric and magnetic fields (unperturbed rms values)
of ICNIRP2010 . 29
Table B.5 – Reference levels for contact currents of ICNIRP1998 and ICNIRP2010 . 30
Table B.6 – Basic restrictions up to 5 MHz of IEEE C95.6 and IEEE C95.1 . 30
Table B.7 – Basic restrictions between 100 kHz and 3 GHz of IEEE C95.1 . 31
Table B.8 – Magnetic field MPE up to 5 MHz of IEEE C95.1 and IEEE C95.6. 31
Table B.9 – Electric field MPE for whole-body exposure up to 100 kHz of IEEE C95.1
and IEEE C95.6 . 31
Table B.10 – MPE for electric and magnetic field over 100 kHz for whole-body
exposure of IEEE C95.1 and IEEE C95.6 . 32
Table B.11 – Contact current MPE of IEEE C95.1 and IEEE C95.6 . 32
Table C.1 – Basic restrictions regarding SAR (unit is W/kg) . 33
Table C.2 – Possible exclusion power level regarding local SAR. 34

– 6 – IEC TR 62905:2018 © IEC 2018
Table C.3 – Coupling transformation matrix to estimate induced E-field for compliance
with ICNIRP 2010 . 38
Table C.4 – Coupling transformation matrix to estimate induced current density for
compliance with ICNIRP 1998 . 38
Table C.5 – Coupling transformation matrix to estimate induced E-field for compliance
with IEEE 2005 . 39
Table C.6 – Coupling transformation matrix to estimate SAR (pSAR and wbSAR)
10g
for compliance with ICNIRP 1998 and IEEE 2005 . 39
Table C.7 – Dielectric properties of the tissue equivalent liquid defined in IEC 62209-2 . 40
Table C.8 – Dielectric properties of the tissue equivalent NaCl solution . 40
Table C.9 – Human models and source models . 42
Table C.10 – Computational methods . 43
Table C.11 – SAR evaluation method based on numerical simulation. 43
Table D.1 – Uncertainty of H-field measurements for WPT systems in Area 3 . 52
Table D.2 – Numerical uncertainty of the exposure of anatomical human models to
WPT systems for EV . 53
Table D.3 – Uncertainty of EMF measurements for WPT systems in Area 4 . 54
Table D.4 – Uncertainty of contact current measurements . 57
Table D.5 – ICNIRP2010 guideline at 85 kHz . 58
Table D.6 – Specification of DUT . 58
Table D.7 – Measured incident H-fields and E-fields of Area 3 . 59
Table D.8 – Measured incident H-fields and E-fields of Area 4 . 59
Table D.9 – Measurement results of contact current [mA] . 61
Table E.1 – Estimated permissible power for WPT system for EV . 68
Table E.2 – Local SAR and induced electric field in in a human body on the chest surface . 74
Table E.3 – Simulated result of local SAR and whole-body average SAR by Nagoya
Institute of Technology (NITech) / NTT DOCOMO and NICT (input power is 40 W) . 79
Table E.4 – Dimensions of WPT systems for electric vehicles considered by different
groups [13] . 81
Table E.5 – Coupling factor for internal electric field of WPT systems for EV [13] . 82
Table E.6 – Coupling factor for peak 10 g SAR for WPT systems at 6,78 MHz
(implemented on the desk) [13] . 83
Table E.7 – Coupling factor for internal electric field for WPT systems at 6,78 MHz
(implemented on the desk) [13] . 83
Table E.8 – NICT and IT’IS results of induced electric field and local peak 10 g
average SAR in the dielectric cylinder using GGSM . 87
Table E.9 – Experimental and numerical results of spatial peak 10 g average SAR
(input power = 10 W) . 88
Table F.1 – Preliminary medical implant enhancement factors for nerve stimulation up
to 10 MHz . 93
Table F.2 – Preliminary medical implant enhancement factors for tissue heating up to
10 MHz (∆T) . 93
Table F.3 – Dielectric and thermal properties assigned to the muscle tissue and to the
generic implants . 94
Table F.4 – Induced E-field in the homogeneous tissue without the implant to reach J-
BR of ICNIRP 1998 . 95
Table F.5 – Induced E-field in the homogeneous tissue without the implant to reach
SAR-BR of ICNIRP 1998 and IEEE 2005 for f ≥ 100 kHz . 95

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
EXPOSURE ASSESSMENT METHODS FOR
WIRELESS POWER TRANSFER SYSTEMS

FOREWORD
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The main task of IEC technical committees is to prepare International Standards. However, a
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example "state of the art".
IEC TR 62905, which is a Technical Report, has been prepared by IEC technical committee
106: Methods for the assessment of electric, magnetic and electromagnetic fields associated
with human exposure.
The text of this Technical Report is based on the following documents:
Enquiry draft Report on voting
106/416/DTR 106/424A/RVDTR
Full information on the voting for the approval of this Technical Report 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 TR 62905:2018 © IEC 2018
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INTRODUCTION
IEC TC 106 has the scope to prepare International Standards on measurement and
calculation methods used to assess human exposure to electric, magnetic and
electromagnetic fields. Wireless power transfer (WPT) systems have been developed and
gradually become popular over the world. WPT basically utilize similar wireless technologies
to provide power to mobile phones, tablet PCs, electric vehicles (EVs) and so on without
cables; but the used frequency range, i.e., tens of kHz to tens of MHz, has not been often
used and paid attention to. Both stimulation-based effects (< 10 MHz, for example) and
heat-based effects (> 100 kHz, for example) should be considered in this frequency range.
ITU-R published a report (ITU-R SM. 2303-1) related to WPT in June 2015 which also
mentions RF exposure assessment methodologies. However, no concrete assessment method
has been introduced. Only IEC TC 69 has addressed exposure assessment method of WPT
for EV in IEC 61980-1:2015. There is no product standard related to WPT other than that
standard. Considering that WPT products might be spread in the near future, IEC TC 106
needs to be aware of this issue and established a working group to address methods for
assessment of WPT related to human exposures to electric, magnetic and electromagnetic
fields.
Based on these backgrounds IEC TC 106 prepared this document consisting of an overview of
WPT, basic exposure assessment methods for direct and indirect effects by WPT, case
studies, and relevant research. Frequency up to 10 MHz is mainly focused on because both
stimulation and heat effects need to be considered but have not been addressed so far. This
document also mentions enhancement of internal fields by medical implant devices.
It is hoped that this document will be useful and helpful to develop International Standards for
WPT exposure assessment.
– 10 – IEC TR 62905:2018 © IEC 2018
EXPOSURE ASSESSMENT METHODS FOR
WIRELESS POWER TRANSFER SYSTEMS

1 Scope
This document describes general exposure assessment methods for wireless power transfer
(WPT) at frequency up to 10 MHz considering thermal and stimulus effects. Exposure
assessment procedures and experimental results are shown as examples such as electric
vehicles (EVs) and mobile devices.
2 Normative references
There are no normative references in this document.
3 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
basic restriction
BR
restriction on exposure to time-varying electric, magnetic and electromagnetic fields that is
based on established biological effects
3.2
contact current
current flowing into the body resulting from contact with a conductive object in an
electromagnetic field
Note 1 to entry: This is the localized current flow into the body (usually the hand, for a light brushing contact).
3.3
current density
current per unit cross-sectional area flowing inside the human body as a result of exposure to
electromagnetic fields
3.4
device under test
DUT
device that is tested according to the procedures specified in this document
3.5
dielectric constant
real part of the complex relative permittivity of the lossy material

3.6
direct effect
biological effect resulting from direct interaction of electromagnetic field with biological
structures
3.7
electric field strength
magnitude of a field vector at a point that represents the force (F) on an infinitely small
charge (q) divided by the charge
3.8
exposure
situation that occurs wherever a person is subjected to electric, magnetic or electromagnetic
fields
3.9
incident field
electric and magnetic fields incident upon the human body
Note 1 to entry: This document focuses on the WPT operating close to the human body at frequency below
10 MHz. Electric and magnetic fields need to be separately evaluated in this region.
3.10
induced current
current induced inside the body as a result of exposure to electromagnetic fields
3.11
indirect effect
biological effect resulting from indirect interaction of electromagnetic field with biological
structure
3.12
magnetic field strength
magnitude of vector quantity obtained at a given point by subtracting the magnetization M
from the magnetic flux density B divided by the magnetic constant μ
3.13
peak spatial-average SAR
maximum average SAR within a local region based on a specific averaging volume or mass,
e.g. any 1 g or 10 g of tissue in the shape of a cube
3.14
phantom
physical model similar in appearance to the human anatomy and comprised of material with
electrical properties similar to the corresponding tissues
Note 1 to entry: A phantom representing the human head could be a simple spherical model or a more complex
multi-tissue anthropomorphic model.
3.15
reference level
field level derived from the basic restrictions under worst case assumptions (e.g. exposure to
homogeneous field)
3.16
specific absorption rate
SAR
SAR in the tissue-equivalent liquid can be determined by E-field or the rate of temperature
increase, according to:
– 12 – IEC TR 62905:2018 © IEC 2018
σ E
SAR=
ρ
dT
SAR= C
h
dt
t=0
where
SAR is the specific absorption rate in W/kg;
E is the rms value of the electric field strength in the tissue medium in V/m;

σ is the electrical conductivity of the tissue medium in S/m;
ρ is the mass density of the tissue medium in kg/m ;
C is the specific heat capacity of the tissue medium in J/(kg K);
h
dT
is the initial time derivative of temperature in the tissue medium in K/s.
dt
t=0
4 Symbols and abbreviations
4.1 Physical quantities
The internationally accepted SI units are used throughout this document.
Symbol Quantity Unit Dimensions
C Specific heat capacity joule per kilogram per kelvin J/(kg K)
h
E Electric field strength volt per metre V/m
f Frequency hertz Hz
J Current density ampere per square metre A/m
P Average (temporal) absorbed power watt W
T
Temperature kelvin K
ε Permittivity farad per metre F/m
Wavelength metre m
λ
Electric conductivity siemens per metre S/m
σ
NOTE In this document, temperature is quantified in degrees Celsius, as defined by: T (°C) = T (K) – 273,15.
4.2 Constants
Symbol Physical constant Magnitude
η Intrinsic impedance of free space 120π Ω or 377 Ω
–12
ε Permittivity of free space 8,854 × 10 F/m
–7
μ Permeability of free space
4π × 10 H/m
4.3 Abbreviations
BR basic restriction
DUT device under test
RF radio frequency
rms root mean square
RSS root sum square
CW continuous wave
SAR specific absorption rate
psSAR peak spatial-average SAR
WPT wireless power transfer
EV electric vehicle
5 Overview of WPT systems
5.1 General
Clause 5 describes an overview of WPT systems, which include WPT technologies,
applications and frequency ranges reported by ITU-R [1] . WPT systems using frequency
range over 10 MHz are described in Annex A.
5.2 WPT systems whose frequency range is less than 100 kHz
a) Magnetic induction WPT systems for home appliances
Inductive power sources (transmitters) may stand alone or be integrated into the kitchen
counter tops or dining tables. These transmitters could combine the WPT to an appliance
with conventional inductive heating.
For the home appliance application, the power level is usually up to several kilowatts, and
the load may be motor-driven or heating type (Figure 1). Future products will support more
than 2 kW power and some new design proposal for cordless kitchen appliances is being
investigated.
Considering the high power usage in the home, frequencies in the order of tens of kHz are
preferred to restrict electromagnetic exposure to human bodies. And high reliable devices
such as Insulated Gate Bipolar Transistors (IGBTs) are usually used and these devices
are working in the 10 kHz to 100 kHz frequency range.
The product applied in the kitchen needs to meet the safety and electromagnetic field
(EMF) requirements and it is a key issue that transmitter should be the light and small size
to fit the kitchen in addition to being low cost. The distance between the transmitter and
the receiver is intended to be less than 10 cm.
The following pictures show examples of wireless power kitchen appliances that will come
to the market soon.
IEC
Figure 1 – Wireless power kitchen appliances [1]
WPT systems have already integrated into the product lines of semiconductor and LCD
panel; the following pictures show examples (Figure 2).
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Numbers in square brackets refer to the Bibliography.

– 14 – IEC TR 62905:2018 © IEC 2018

IEC
(WPT kitchen island of apartment)
Figure 2 – Use cases of the LCD and semiconductor product lines and
kitchen WPT systems [1]
b) Magnetic induction WPT systems for electric vehicles
Magnetic field wireless power transmission (MF-WPT) is one of the focus points in
standardization discussion such as IEC PT 61980 and SAE J2954TF regarding WPT for
EV including plug-in hybrid EV (PHEV) though there are several types of WPT methods.
MF-WPT for EV and PHEV contains both inductive type and magnetic resonance type.
Electric power can be transmitted from the primary coil to the secondary coil efficiently via
magnetic field by using resonance between the coil and the capacitor.
Expected passenger vehicle ap
...