Four Electric Vehicle Charging Modes in the IEC 61851 Standard

January 14, 2022

Latest company news about Four Electric Vehicle Charging Modes in the IEC 61851 Standard

The charging system provides energy supply for the operation of electric vehicles, which is an important basic support system for electric vehicles and an important link in the process of commercialization and industrialization of electric vehicles. With the rapid development of the electric vehicle industry, charging technology has become one of the key factors restricting the development of the industry, and intelligent and fast charging methods have become the development trend of electric vehicle charging technology.


There are different ways to classify electric vehicle charging devices. In general, it can be divided into on-board charging devices and off-board charging devices. According to the different ways of energy replacement when charging the electric vehicle battery, the charging device can be divided into contact type and induction type. Electric vehicles can be divided into slow charging, fast charging, battery swapping, wireless charging, mobile charging and other methods according to different charging methods. In this article, we will introduce the different electric vehicle charging modes specified by the International Electrotechnical Commission (IEC).


International standards are being developed to meet the needs of the electric vehicle market. The global adoption of electric vehicles depends on well-established international standards that address safety, reliability, and interoperability in the electric vehicle market.


In this article, we will examine the different EV charging modes specified by the International Electrotechnical Commission (IEC). These modes are specified in the IEC 61851 standard dealing with conductive charging systems for electric vehicles. The standard describes four different charging modes - Mode 1, Mode 2, Mode 3 and Mode 4.


IEC has also developed other standards for electric vehicle charging technology. For example, IEC 62196 discusses plugs, sockets, vehicle connectors and vehicle inlets, while IEC 61980 discusses wireless power transfer (WPT) systems for electric vehicles.



Different types of cable connections


IEC 61851-1 describes three different connection methods, as shown in the following figure:

The Case A cable is permanently connected to the electric vehicle, but the EVSE is detachable at the charging station (also called EVSE - electric vehicle supply equipment). Case B specifies a cable that is detachable at both ends, and Case C is a cable that is permanently attached to the EVSE.

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Charging Mode 1

In this mode, the electric car is connected directly to a household outlet. The maximum current of this mode is 16A, the single-phase does not exceed 250V, and the three-phase does not exceed 480V.

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Mode 1 is the simplest charging mode and does not support any communication between the EV and the charging point. This charging model is prohibited or restricted in many countries.



Charging Mode 2

Household outlets do not always supply power to the actual standard. Additionally, receptacles and plugs designed for domestic applications may not withstand the continuous current at the maximum ratings.


That's why having an EV socket connected for extended periods of time without controls and safety features increases the risk of electric shock. To solve this problem, experts developed Charging Mode 2, which uses a special type of charging cable and is equipped with an in-cable control and protection device (IC-CPD).


The IC-CPD performs the required control and safety functions. The maximum current of this mode is 32A, the maximum voltage does not exceed 250V for single-phase and 480v for three-phase. Mode 2 can be used for both domestic and industrial sockets.


The safety function of this mode can detect and monitor the protective earth. Mode 2 also supports overcurrent and overtemperature protection. In addition, EVSE can switch functions while detecting the connection to the EV and analyzing its charging power demand.


The charging mode 2 and the supporting cable are shown in the figure below:

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While Mode 2 can be used for private charges, public use is also restricted in many countries.



Charging Mode 3

This model uses a dedicated EVSE and EV onboard charger. AC current from the charging station is applied to the onboard circuitry to charge the battery. Multiple control and protection functions to ensure public safety. These include verifying the protective earth and the connection between the EVSE and the EV.


Additionally, this mode adjusts the charging current to the maximum current capability of the cable assembly. This charging mode has a maximum current of 250A and can be configured with a 250V 1-phase or 480V 3-phase network. It also supports a mode of operation compatible with Mode 2, in which the maximum current for both single-phase and three-phase is limited to less than 32A.


Any of the three possible connections (case A, case B, and case C) can be used in this mode. Scenario B and Scenario C are shown below.

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Let's see how this pattern defines the communication between the charging station and the electric vehicle. The control pilot circuit of mode 3 is shown in the figure below.

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Depending on the state of switches S1, S2 and S3, different voltage levels will appear on the "pilot contacts". “This can be used to represent different charging phases. An electric vehicle can start a charging cycle as follows:


Before plugging in the charging cable, switches S2 and S3 are disconnected and S1 is connected to a 12v DC power supply. In this case, the EVSE measures 12v DC at the pilot contact (the EVSE realizes that the EV is not connected).


After the charging cable is connected to the EV and EVSE, the controller on the EV side can turn on S3, reducing the voltage at the driver's contact to about 9v. Notify EVSE that the cable is connected to both EV and EVSE. Additionally, a DC 9v signal at the pilot junction will tell the EV that the EVSE is not ready.


When the EVSE is ready to charge the EV, it connects S1 to the oscillator. The PWM signal at the pilot contact tells the EV that the electric vehicle power supply is ready.


The EV then turns on S2, producing about 6v at the pilot contact, which indicates it's ready as well. The voltage generated at this stage depends on the R3 resistor value. The value of this resistor specifies whether ventilation is required for this charging area. R3 = 1.3 kΩ, the driver's contact voltage is 6 V. This is equivalent to a charging area that does not require air circulation. If required, R3 = 270Ω and a touch voltage of 3 V.


S2 can be turned off when the vehicle is charging or wants to stop charging for any reason. This will change the positive voltage level of the PWM to 9v and inform EVSE that the EV is not ready to recharge.



Charging Mode 4

This is the only charging mode that includes an external charger with a DC output. DC power is delivered directly to the battery, and the on-board charger is bypassed. This mode can provide 600v DC with a maximum current of 400A. The high-power levels involved in this mode require higher levels of communication and stricter security features.


Mode 4 only allows connection to case C, with the charging cable permanently connected to the charging station.

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Two New Charging Methods


Wireless Charging

The wireless charging mode does not need to transmit energy through cables, and uses electromagnetic induction, electric field coupling, magnetic resonance and radio waves to transmit energy. To use the wireless charging mode, you first need to install a car inductive charger in the car. There is no mechanical link between the power receiving part and the power supply part of the vehicle, but the connection between the power receiving body and the power supply body is required to be more accurate.


Subject to the limitations of technology maturity and basic equipment, electric experts believe that wireless charging technology cannot be mass-produced for the time being. The mainstream wireless charging technology in the industry mainly uses electromagnetic induction and magnetic resonance to transfer electric energy, but the magnetic resonance method has higher charging efficiency and lower electromagnetic radiation intensity, which is smaller than that of mobile phone calls. The coils don't need to be perfectly aligned, which is beyond the reach of electromagnetic induction.


The future application prospect of wireless charging mode is immeasurable. In the future, it will be able to charge while walking. The electric energy may come from the power supply system of the road pavement, or from the electromagnetic wave energy received by the car.

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Mobile Charging

The ideal situation for EV batteries is charging while the car is cruising on the road, so-called mobile charging (MAC). In this way, electric vehicle users do not have to search for charging stations, park their vehicles and spend time charging. The MAC system is buried under a section of road, namely the charging area, and does not require additional space.


Both contact and inductive MAC systems can be implemented. For the contact-type MAC system, a contact arch needs to be installed at the bottom of the vehicle body, and the contact arch can obtain instantaneous high current by contacting the charging element embedded in the road surface. When the electric vehicle cruises through the MAC area, its charging process is pulse charging. For inductive MAC systems, the on-board contact arches are replaced by inductive coils, and the charging elements embedded in the road surface are replaced by high-current windings that generate strong magnetic fields. Obviously, due to the influence of factors such as mechanical loss and the installation location of the contact arch, the contact type MAC is not very attractive to people.

in conclusion


In summary, the IEC 61851 standard deals with electrically conductive charging systems for electric vehicles. These standards describe four different charging modes.


The first three modes provide AC power to the EV onboard charger; however, Mode 4 delivers DC power directly to the battery and bypasses the onboard charger. Mode 3 employs a variety of control and protection functions, targeting public safety.

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