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GB/T 38775.4-2020 PDF in English


GB/T 38775.4-2020 (GB/T38775.4-2020, GBT 38775.4-2020, GBT38775.4-2020)
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GB/T 38775.4-2020: PDF in English (GBT 38775.4-2020)

GB/T 38775.4-2020
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 43.040.99
K 81
Electric Vehicle Wireless Power Transfer - Part 4:
Limits and Test Methods of Electromagnetic
Environment
ISSUED ON: APRIL 28, 2020
IMPLEMENTED ON: NOVEMBER 1, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3 
Introduction ... 4 
1 Scope ... 5 
2 Normative References ... 5 
3 Terms and Definitions ... 5 
4 Overview ... 7 
5 Limits ... 8 
6 Test Methods ... 11 
7 Evaluation of Test Result ... 20 
Appendix A (informative) Test Record Form ... 22 
Bibliography ... 26 
Electric Vehicle Wireless Power Transfer - Part 4:
Limits and Test Methods of Electromagnetic
Environment
1 Scope
This Part of GB/T 38775 specifies limits and test methods of electromagnetic
environment inside and outside electric vehicles during wireless power transfer.
This Part is applicable to stationary magnetic coupling wireless power transfer system
of electric vehicles, with the maximum rated voltage of power supply of 1,000 V (AC)
or 1,500 V (DC); the maximum rated output voltage of 1,000 V (AC) or 1,500 V (DC);
primary devices shall adopt the mode of buried installation or above-ground installation.
2 Normative References
The following documents are indispensable to the application of this document. In
terms of references with a specified date, only versions with a specified date are
applicable to this document. In terms of references without a specified date, the latest
version (including all the modifications) is applicable to this document.
GB/T 2900.60-2002 Electrotechnical Terminology - Electromagnetism
GB/T 12113-2003 Methods of Measurement of Touch Current and Protective
Conductor Current
GB/T 38775.1-2020 Electric Vehicle Wireless Power Transfer - Part 1: General
Requirements
GB/T 38775.3-2020 Electric Vehicle Wireless Power Transfer - Part 3: Specific
Requirements
3 Terms and Definitions
What is defined in GB/T 2900.60-2002 and GB/T 38775.1-2020, and the following
terms and definitions are applicable to this document.
3.1 Occupational Exposure
Occupational exposure refers to all electromagnetic field exposure that individuals are
subject to due to the engagement in fixed or designated occupational activities. Under
the conditions of receiving appropriate instructions and trainings, workers are already
informed, and voluntarily experience the effects of the electromagnetic fields.
3.2 Public Exposure
Public exposure refers to all electromagnetic field exposure to the public, excluding
occupational exposure and medical exposure. Under general circumstances, the
public is exposed to the electromagnetic fields without knowing it.
3.3 Medical Exposure
Medical exposure refers to electromagnetic field exposure to patients undergoing
medical diagnosis or approved medical treatment, or volunteers in medical researches.
3.4 Active Implantable Medical Device
Active implantable medical device refers to active medical devices implanted in the
human body. Through surgical or medical methods, active medical devices are partly
or wholly implanted into the human body. Or, through medical invasive means, active
medical devices enter the natural cavity and remain in the body after the surgery.
NOTE 1: in this Part, it refers to implantable cardiac pacemakers, implantable cardioverter
defibrillators and cardiac resynchronization devices.
NOTE 2: Definition 3.3 of GB 16174.1-2015 is modified.
3.5 Touch Current
Touch current refers to the current flowing through the human body or animal when
they touch one of more accessible parts of devices or equipment.
[GB/T 12113-2003, Definition 3.1]
3.6 Basic Restriction
Basic restriction refers to a limit determined for human tissue that may cause harmful
health effects. It strictly conforms to all the already-known biophysical interaction
mechanisms and is usually difficult to measure. As long as the basic restriction is not
exceeded, it can be confirmed that no known acute harmful health effects will occur.
3.7 Reference Level
Reference level refers to a physical quantity introduced for the convenience of actual
exposure assessment that are convenient for actual measurement. It is used to
determine whether the basic restriction is exceeded. Exceeding the reference level
does not signify that the basic restriction is definitely exceeded, but it is necessary to
determine whether the basic restriction is met.
6 Test Methods
6.1 Test Conditions
6.1.1 Temperature, humidity and atmospheric pressure
The environmental requirements of the laboratory are as follows: °C
---Ambient temperature: 15 °C ~ 35 °C;
---Relative humidity: 45% ~ 75%;
---Atmospheric pressure: 86 kPa ~ 106 kPa.
Outdoor environmental requirements are as follows:
---Ambient temperature: -20 °C ~ + 50 °C;
---Relative humidity: 5% ~ 95%.
6.1.2 Test point
Within a 1.5 m horizontal range around the test point, there shall be no objects that
would affect the test. Primary devices shall be placed on non-metallic ground.
The environmental background value shall be not higher than 5% of the limit value in
Chapter 5.
6.2 Test Instruments
6.2.1 Test instruments of magnetic field
A three-axis isotropic low-frequency field strength probe shall be used. In addition, the
circular sensor area shall be not more than 100 cm2. The probe shall use peak
detection.
The scope of application of the test instrument shall cover the frequency range
corresponding to the limits in Chapter 5, including the operating frequency of the
wireless power transfer system.
Before the test, the probe shall be calibrated and scaled for the operating frequency of
the wireless power transfer system.
When using a test instrument with frequency analysis function, the resolution
bandwidth shall be not lower than he requirements in Table 5.
U1---voltage value of both ends of RB;
U2---voltage value of both ends of C1.
Figure 2 -- Schematic Diagram of Perceptual or Reactive Current Test
Impedance Network
6.2.2.3 Test electrodes
Unless it is otherwise specified in the test instrument standard, the test electrodes shall
be one of the following two modes:
---Test clip;
---10 cm  20 cm metal foil representing the human hand; the adhesive used to
bond the metal foil shall be conductive.
Test electrodes shall be connected to measuring terminal A and B of the test network.
6.3 Test State of Wireless Power Transfer System
During wireless power transfer, the electric vehicle is in a stationary state; the vehicle’s
wireless power transfer system shall be normally operating. Other electrical appliances
shall be normally turned off, except to ensure that the wireless power transfer system
is normally operating.
The wireless power transfer system shall be operating at the rated power, and the
primary devices shall be installed on the vehicle.
In accordance with the requirements of GB/T 38775.3-2020, and the offset range and
mechanical air gap / ground clearance range provided in the manufacturer’s operation
manual, the offset range and mechanical air gap / ground clearance of the primary
devices and secondary devices of the wireless power transfer system shall be tested.
The relative offset position, mechanical air gap / ground clearance and operating
efficiency of the primary devices and secondary devices shall be recorded.
6.4 Test Method of Magnetic Field
6.4.1 Test range
Conduct electromagnetic field test for Protection Area 3, Protection Area 4 and off-
board power components.
6.4.2 Test point of Protection Area 3
The electromagnetic test shall be conducted in four test areas: the front, the rear, the
left and the right of the vehicle.
6.4.4 Test points of off-board power components
Merely select the surface of off-board power components that may be touched by the
human body for the electromagnetic field test.
The test points are at a vertical distance of 20 cm above the component surface, and
at the maximum reading scanned by the mobile test instrument parallel to the
component surface.
6.4.5 Test procedure
The test procedure of electromagnetic field is as follows:
a) Set the initial offset and mechanical air gap / ground clearance to be the
maximum value;
b) In accordance with 6.4.2 and 6.4.4, set the test points of Protection Area 3
and off-board power components;
c) Conduct electric field strength test on the various test points; record the test
value and mark the maximum value being measured;
d) Conduct magnetic induction or magnetic field strength test on the various test
points; record the test value and mark the maximum value being measured;
e) In accordance with 6.4.3, set the test points of Protection Area 4;
f) Conduct electric field strength test on the various test points; record the test
value and mark the maximum value being measured;
g) Conduct magnetic induction or magnetic field strength test on the various test
points; record the test value and mark the maximum value being measured;
h) Set other offsets or mechanical air gaps / ground clearances;
i) Repeat b) ~ h).
The electromagnetic field test record form is shown in Appendix A. Table A.3 is the
smallest combination of offset and mechanical air gap / ground clearance. If the test
data is higher than 50% of the limit, then, increase the combination of offset and
mechanical air gap / ground clearance; repeat b) ~ h) to conduct the test.
6.5 Test Method of Contact Current
6.5.1 Test layout
If the electric vehicle wireless power transfer system is connected to a three-phase
power system, the specific wiring form is shown in GB/T 12113-2003. In accordance
with the actual power supply, the wiring form may be selected.
 If the former is higher than the limits in Table 3, then, the magnetic field
does not comply with the requirements of this Part; in accordance with
Step c), evaluate the electric field result.
c) Divide the final maximum value of electric and / or magnetic field by 1.414,
then, compare it with the reference levels in Table 2:
 If the former is lower than or equals to the reference levels in Table 2,
then, it complies with the requirements of this Part;
 If the former is higher than the reference levels in Table 2, then, adopt an
appropriate method to further determine whether the former complies with
the basic limits of electromagnetic field in Table 1; if it is lower than or
equals to the basic limits, then, it complies with the requirements of this
Part.
NOTE: methods of determining whether it complies with the basic limits of
electromagnetic field are still under study.
7.2 Contact Current Test Result Evaluation
The evaluation procedure for contact current test result is as follows:
a) Take the maximum value of U2 peak value obtained in accordance with the
different offset, mechanical air gap / ground clearance combinations in 6.5 as
the final test result of U2 peak value.
b) Divide the final U2 peak value test result by 500  resistance value to obtain
the maximum value of the perceptual or reactive current.
c) Divide the maximum value of this current by 1.414, then, compare it with the
contact current limits in Table 4:
 If the former is lower than or equals to the limits in Table 4, then, it
complies with the requirements of this Part;
 If the former is higher than the limits in Table 4, then, it does not comply
with the requirements of this Part.
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.