IEC TR 62905:2018

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 .
...