IEC 61851-1 is an international standard that specifies the general requirements and testing methods for electric vehicle (EV) charging systems. The full title of the standard is “IEC 61851-1 Electric vehicle conductive charging system – Part 1: General requirements.” It’s part of a series of standards developed by the International Electrotechnical Commission (IEC) to ensure interoperability and safety in EV charging infrastructure.
The IEC 61851-1 standard defines the basic requirements for conductive charging systems, covering aspects such as electrical safety and communication between the EV and the charging equipment. It also covers the compatibility of different components within the charging system.
The standard establishes a framework for various charging modes, such as Mode 1, Mode 2, Mode 3, and Mode 4, each specifying different levels of charging power and safety features. As follows, we describe the different modes of the IEC 61851-1 standard in detail.
Mode 1
The first of the four modes is the simplest EV charge method, as shown in Figure 1. People use a standard electrical socket without dedicated control or safety measures to charge the EV. In such cases, the power rating is low for charging an entry-level electric bike or scooter.
The source of power can be either single-phase (250 V) or three-phase (480 V) AC. You can use a standard electrical socket that supports 10 A or 15 A to charge, as the maximum allowable current is 16 A.
Figure 1. Mode 1 charging of an electric vehicle. (Image: Rakesh Kumar, Ph.D.)
Many countries, including the US and England, discourage this type of charging. In this mode, there’s no communication interface between the EV and the electrical grid, so many technologies are difficult to integrate with it.
Mode 2
Figure 2 shows Mode 2, an advanced version of the earlier mode. A dedicated RCD protection is mandatory for charging the EV from the electrical grid, conforming to the IEC 62335 standard for circuit breakers. You can find the protection circuit in the cables, which helps prevent faults and overcurrent conditions. However, charging is slow and is better suited for overnight charging.
Figure 2. Mode 2 charging of an electric vehicle with RCD protection. (Image: Rakesh Kumar, Ph.D.)
Several countries are unconvinced this mode is ideal and limit its use. Mode 2 supports a higher power rating than Mode 1, and a current rating of up to 32 A is supported. You can use single-phase and three-phase AC power supplies in this mode.
Mode 3
All nations welcome Mode 3 for charging EVs, which meets the applicable standard for EV charging. Figure 3, which represents Mode 3, shows that EV charging utilizes dedicated electric vehicle supply equipment, also known as EVSE. The IEC 62196-2 standard also governs EV charging sockets.
Mode 3 enables bidirectional communication between the EV and the electrical grid, a feature necessary for efficient energy management. You can mount the EVSE on the building as a permanent structure or carry it as a mobile EV charger.
Figure 3. Mode 3 charging of an electric vehicle with bidirectional communication and power. (Image: Rakesh Kumar, Ph.D.)
Mode 4
This is the last and most advanced mode of charging an EV. The highest power rating of all the modes is that supported by Mode 4. The EVSE supplies only DC power to the EV for fast charging, with a current rating of 200 A and a voltage rating of 600 V. So, the EVSE in this mode is the most expensive compared to all the EVSEs in the earlier modes. Figure 4 illustrates Mode 4 of EV charging.
It’s interesting to note that the EVSE for Mode 4 is permanently installed and immovable because of the high power involved. Therefore, the ideal locations for the EVSEs are public charging places and commercial parking areas. The IEC 62196-3 standard for electrical sockets, inlets, and connectors is in place to govern Mode 4. Like Mode 3, bidirectional communication is a feature of this mode.
Figure 4. Mode 4 charging of an electric vehicle with direct high-power DC. (Image: Rakesh Kumar, Ph.D.)
Summary
The different charging modes, as discussed in the IEC 61851-1 standard for EV, provide a standardized framework for electric vehicle charging, ensuring compatibility and safety across different manufacturers and charging infrastructure providers. The choice of mode depends on factors such as the available infrastructure, desired charging speed, and safety requirements. We expect these charging standards to evolve as time passes.
References
- EV Charging Definitions, Modes, Levels, Communication Protocols and Applied Standards, ResearchGate
- Review of Electric Vehicle Technologies, Charging Methods, Standards and Optimization Techniques, MDPI
- IEC 61851, Wikipedia
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