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Analysis of Electromagnetic Compatibility Requirements and Test Methods for Conductive Charging of Electric Vehicles
Release time:
2023-06-05 15:25
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From the 1970 s to the early 1980 s, at the beginning of the emergence of electric vehicles, EMC problems attracted people's attention. At that time, some countries and regions began to introduce technical standards and specifications for electric vehicles EMC. With the continuous expansion of the electric vehicle market, EMC has gradually become the focus of attention. Governments are beginning to develop stringent EMC regulations for electric vehicles and are working with automakers and technical bodies to develop, improve and refine EMC standards. In 2011, UNR10.04 included the EMC performance of vehicle charging into the scope of standard investigation for the first time. In 2019, UNR10.06 improved the details of vehicle charging status.
In 2001, the first domestic electromagnetic compatibility standard for electric vehicles GB/T18387 was promulgated, and in 2021, the first domestic electromagnetic compatibility standard for automobile charging was officially released, namely GB/T40428-2021 "Electromagnetic Compatibility Requirements and Test Methods for Conductive Charging of Electric Vehicles". The standard is applicable to electric vehicles that can be charged externally, as well as to systems composed of vehicles and power supply equipment.
1 Introduction
New energy vehicles need to be connected to the power grid when charging, and the power grid will inevitably carry some by-products, such as harmonics and indirect lightning, which not only easily lead to the interruption of electric vehicle charging, but also can even damage the vehicle's charging system in severe cases. GB/T40428 introduces the EMC test items and specific test methods for electric vehicles in the charging state.
2 Terms and definitions
The following terms need to be involved in the analysis of test methods, so they are explained in this article from other standards and regulations.
- Charging mode of electric vehicle
The method of connecting electric vehicles to the grid (power supply) to supply power to electric vehicles is called charging style.
Different brands and types of pure electric vehicles not only have different cruising ranges, but also have different charging methods, so when we buy electric vehicles, we should pay attention to asking whether they can only be charged by charging piles. In addition to charging piles, what other charging methods are there?
According to GB/T 18487.1-2015 electric vehicle charging mode is divided into four kinds:
Figure 1
Mode 1(MODE1)
The electric vehicle is directly passively connected to an AC household power supply with a maximum output voltage of 250V single-phase or 480V 3-phase. Use a portable charging cable without a control protocol for low-speed (charging current is up to 16 amps, usually 10 amps) charging.
There is no control box on the charging gun. When the car is charging, it is directly plugged into the household AC socket through the cable of the charging gun for charging. Communication with the vehicle cannot be established, and the maximum current intensity, voltage, temperature, etc. cannot be confirmed during charging. The charging method of mode 1 has been basically eliminated because of poor safety.
Figure 2
Mode 2(MODE2)
Electric vehicles are directly semi-actively connected to AC household or commercial power sources with a maximum output voltage of 250V single-phase or 480V 3-phase. Use a portable charging cable with an in-cable control box (ICCB) for low-speed (charging current up to 16 amps, usually 10 amps) or high-speed (charging current up to 32 amps) charging.
Currently on the market the main charging mode of portable charging gun. The difference from mode 1 is that a protection device, that is, an adapter, is added. At the same time, communication is established with the vehicle through the control wire, and charging parameters can be exchanged between the vehicle and the charger. This mode is generally used for vehicle charging, and the charging current is relatively small., Generally 8-16A.
Figure 3
Mode 3(MODE3)
The electric vehicle is actively connected to a fixed electric vehicle supply equipment (EVSE) with a maximum output voltage of 250V single phase or 480V 3 phase. For example, a wall-mounted charging box or a public charging station. Use the portable charging cable or stripline charging cable with the control circuit built into the EVSE for high-speed (charging current up to 32 amps) charging.
The difference between mode 3 and mode 1 and mode 2 is that the charging gun is not connected to the household AC power grid, but is connected to a dedicated AC power supply device, that is, an AC charging pile. At this time, the charging gun can be without an adapter, because the AC charging pile itself plays a protective role. Mode 3 can not only ensure the safety of charging, but also improve the charging speed to a certain extent (10/13/32/63A). AC charging pile and wall-mounted charging box are MODE 3.
Figure 4
Mode 4(MODE4)
The electric vehicle is actively connected to a stationary EVSE with a maximum output voltage of 1000 volts DC. In an EVSE, AC mains power is rectified to DC charging power. Fast (up to 400 A charging current) charging using the wired charging cable with control circuitry built into the EVSE.
Mode 4 is the DC charging mode, which charges electric vehicles in a short time. It has high-power and high-voltage working conditions. For example, Tesla Super Charging Station is generally not a household, but is specially set at a fast charging station. The charging current of mode 4 is large, and the current is generally 80/125/200/250A or even higher DC, so the natural charging speed is also the fastest. However, DC charging has very high installation requirements and costs, and long-term DC charging will affect the life of the battery.
- Charging connection mode
The method of connecting electric vehicles to the grid (power supply) using cables and connectors is called the connection method.
The standard GB/T 1847.1-2015 for electric vehicle conductive charging system defines three charging connection modes.
Connection mode A
The charging gun/or plug is permanently connected to the electric vehicle (the charging cable assembly is part of the electric vehicle)
Figure 5
Connection mode B
Both ends of the charging cable assembly can be unplugged (the charging cable assembly is neither an electric vehicle nor a charging pile).
Figure 6
Connection mode C
The charging gun/or plug is permanently connected to the charging pile (the charging cable assembly is part of the charging pile)
Figure 7
- Vehicle charging interface
In 2006, China issued the General Requirements for plugs, sockets, vehicle couplers and vehicle jacks for conductive charging of electric vehicles (GB/T20234-2006). This national standard specifies the connection classification method of charging current 16A, 32A, 250A AC and 400A DC in detail. Mainly drawing on the standards put forward by the International Electrotechnical Commission (IEC) IEC) in 2003, China issued the recommended standard GB/T20234-2011 in 2011, replacing some of the contents in GB/T20234-2006, stipulating that the rated AC voltage should not exceed 690V, the frequency should be 50Hz and the rated current should not exceed 250 A. The rated DC voltage does not exceed 1000V and the rated current does not exceed 400A.
Figure 8
Figure 9
Figure 10
The vast majority of electric vehicles on sale in China use these two interfaces. Imported electric vehicles are not such interfaces, and interface converters can be used.
After introducing the charging mode, charging connection mode and charging interface of electric vehicles, we will look at the electromagnetic compatibility test items applicable to electric vehicles under different types of charging modes.
3 General requirements
According to the power supply mode and charging connection mode, the test items to be met by electric vehicles are as follows:
Figure 11
4 Technical requirements
The test method of the vehicle alone is also called the simulation method, that is, the power supply of the charging pile is simulated. According to GB/T18487.1, the charging equipment needs to provide L, N, PE and CP to link with the vehicle, and ensure the normal charging of the vehicle according to certain control procedures and protocols. Usually L, N and PE are powered by LISN, and the CP signal is PWM signal (pet width modulation), which needs to be provided by the laboratory.
Technical requirements for 4.1 emission
Before the test, the state of charge of the vehicle rechargeable energy storage system shall be between 20% and 80%. The charging current for AC charging shall not be less than 20% of the maximum continuous charging current of the vehicle. The charging current for DC charging shall not be less than 20A or 20% of the maximum continuous charging current of the vehicle, whichever is greater.
During the test, the vehicle shall be stationary and the engine (if any) shall be turned off. All equipment that is not related to the test function and can be turned off by the driver or passenger shall be turned off. If necessary, the insulation detection system of the charging circuit of the DC charging vehicle can be turned off. If it is closed, other safety precautions should be considered.
Technical requirements for 4.2 immunity
Before the test, the state of charge of the vehicle rechargeable energy storage system shall be between 20% and 80%. The charging current of AC charging shall not be less than 80% of the continuous maximum charging current value of the vehicle. The charging current for DC charging shall not be less than 20A or 20% of the maximum continuous charging current of the vehicle, whichever is greater. Unless otherwise specified.
Before the immunity test, the vehicle should be operated to keep the vehicle drive system in different working states, and the charging function should be verified under all possible states. The state that can be charged normally and has a higher priority is selected as the vehicle immunity test state. The vehicle test state selection is shown in the figure below.
Figure 12
During the immunity test, the parking brake system of the vehicle shall meet the following requirements:
a) If the parking brake system of the vehicle can be released manually or automatically, the parking brake system shall be in the non-parking state;
B) If the vehicle parking system cannot be released manually or automatically, the parking brake system can be in the parking state.
5 Requirements for analog power supply equipment
- AC analog power supply equipment
The charging mode shall be Mode 3, the connection mode shall be B or C, and the vehicle plug and/or power supply interface shall comply with GB/T 20234.2.
The guiding circuit and control principle shall meet the relevant requirements of Annex A of GB/T 18487.1-2015.
If the simulated AC charging pile is placed in the test site, the electromagnetic emission level of the simulated AC charging pile shall be at least 6dB below the specified limit.
- DC analog power supply equipment
The charging mode shall be Mode 4, the connection mode shall be Mode C, and the vehicle plug and/or power supply interface shall comply with GB/T 20234.3.
The guiding circuit and control principle shall conform to Annex B of GB/T 18487.1-2015, the communication protocol shall conform to GB/T 27930-2015, the voltage of the low-voltage auxiliary power supply circuit shall be 12.0±0.6V, the current shall be 10 A, and PE and A- shall be electrically isolated.
If the simulated off-board charger is placed in the test site, the electromagnetic emission level of the simulated off-board charger shall be at least 6dB below the specified limit.
A charging cable to be shielded shall be used between the analog off-board charger and the DC manual power supply network.
A shielded twisted pair communication line should be used between the simulated off-board charger and the vehicle.
6 Test method
6.1 Radiated Emission
- Limits Requirements
The radiation emission test can be tested by 10m method or 3m method, and the limit requirements are as follows:
Figure 13
- Layout requirements
The simulated AC charging pile or the simulated off-board charger may be located in the test site or outside the test site.
The antenna is aligned with the center position of the longitudinal dimension of the outer contour of the measured object. The effective lobe width of the antenna should be able to cover the test object, if not, the measurement position should be increased.
See the following figure for layout distance requirements, cable placement and length requirements:
Figure 14
Figure 15
6.2 AC power line harmonic current
- Limits Requirements
1) When the test object is a vehicle or a system, and the continuous maximum current of each phase is less than or equal to 16A, the test shall be carried out in accordance with the CLASS A limit requirements of GB/T 17625.1;
2) When the test object is a vehicle or a system, and the continuous maximum current of each phase is> 16A and ≤ 75A
a) The test shall be carried out in accordance with the CLASS A limit requirements of GB/T 17625.1 when the vehicle current of the test object is ≥ 12.8A and ≤ 16A;
B) The test shall be carried out when the system current of the subject is ≤ 16A according to the CLASS A limit of GB/T 17625.1;
c) The test shall be carried out in accordance with the standard limit requirements of GB/T 17625.8 when the vehicle or system current of the subject is> 16A and ≤ 75A;
3) When the actual input current of each phase of the system is greater than 75A, no harmonic emission test is required.
- Layout requirements
The total length of the charging cable from the vehicle plug to the measuring device shall not be greater than 10m. The excess length of cable is folded into a "Z" shape. The charging cable of the vehicle shall be dropped vertically at a distance of 1 000 200mm from the vehicle body. Cables shall be placed on insulating support material with a height of 100mm ± 25mm.
The test arrangement when charging the vehicle or system is shown in the figure below.
Figure 16
6.3 AC power line voltage variations, voltage fluctuations, and flicker
- Limits Requirements
1) When the test object is a vehicle or a system, and the continuous maximum current of each phase is ≤ 16A, the test shall be carried out in accordance with the requirements of GB/T 17625.2;
2) When the test object is a vehicle or a system, and the continuous maximum current of each phase is> 16A and ≤ 75A
a) The test shall be carried out in accordance with the requirements of GB/T 17625.2 when the vehicle current of the test object is ≥ 12.8A and ≤ 16A;
B) The test shall be carried out in accordance with the requirements of GB/T 17625.2 when the system current of the test object is ≤ 16A;
c) The test shall be carried out in accordance with the requirements of GB/T 17625.7 when the vehicle or system current of the test object is> 16A and ≤ 75A;
3) When the actual input current of each phase of the system is greater than 75A, there is no need to test voltage change, voltage fluctuation and flicker.
- Layout requirements
The total length of the charging cable from the vehicle plug to the measuring device shall not be greater than 10m. The excess length of cable is folded into a "Z" shape. The charging cable of the vehicle shall be dropped vertically at a distance of 1 000 200mm from the vehicle body. Cables shall be placed on insulating support material with a height of 100mm ± 25mm.
The test arrangement when charging the vehicle or system is shown in the figure below.
Figure 17
6.4 AC power line conducted emission
- Limits Requirements
The conduction emission limit of AC power line refers to the limit requirements of group 1 class B equipment power terminal disturbance wire in GB 4824 standard.
When it can only be connected to the industrial environment power grid (non-household or residential power supply network), the conducted emission limit shall refer to the limit requirements for the disturbance wire of group 1 class A equipment power terminal of GB 4824 standard.
- Layout requirements
The test shall be carried out according to the floor type equipment specified in GB/T 6113.201.
When the test object can work under single-phase and/or three-phase AC power supply conditions, the test shall be carried out separately under all possible power supply conditions.
The test arrangement for vehicle and system charging is as follows:
Figure 18
Figure 19
6.5 radiated immunity
We use a simple diagram to understand the radiated immunity test method for electric vehicles.
Figure 20
Note: The UNR10.06 criterion requires only whether the vehicle is moving (parking failure), and there is no performance requirement for the charging function.
The simulated AC charging pile or the simulated off-board charger may be located in the test site or outside the test site.
The antenna is aligned with the reference point of the measured object. Measuring distance ≥ 2m.
See the following figure for layout distance requirements, cable placement and length requirements:
Figure 21
Figure 22
6.6 AC power line electrical fast transient burst immunity
We use a simple diagram to understand the electric vehicle electric fast transient burst test method.
Figure 23
Note: The UNR10.06 criterion requires only whether the vehicle is moving (parking failure), and there is no performance requirement for the charging function.
The test shall be carried out in accordance with GB/T 17626.4.
When the test object can work under single-phase and/or three-phase AC power supply conditions, the test shall be carried out separately under all possible power supply conditions.
The vehicle is directly placed on the metal grounding plate, which shall be larger than the vertical projection size of the vehicle body, and the horizontal distance between the edge of the plate and the vehicle body shall not be less than 20cm.
The vehicle test arrangement method is as follows:
Figure 24
6.7 AC power line surge
We use a simple diagram to understand the electric vehicle surge test method.
Figure 25
Note: The UNR10.06 criterion requires only whether the vehicle is moving (parking failure), and there is no performance requirement for the charging function.
The test shall be carried out in accordance with GB/T 17626.5.
When the test object can work under single-phase and/or three-phase AC power supply conditions, the test shall be carried out separately under all possible power supply conditions.
The vehicle is directly placed on the metal grounding plate, which shall be larger than the vertical projection size of the vehicle body, and the horizontal distance between the edge of the plate and the vehicle body shall not be less than 20cm.
The vehicle test arrangement method is as follows:
Figure 26