The world's leading international standard for electric vehicles ISO 15118

The official name of ISO 15118 is "Road vehicles - Communication interface between vehicles and the power grid". ISO 15118 is one of the most important and future oriented standards available today.

The built-in intelligent charging mechanism in ISO 15118 makes it possible to perfectly match the power grid capacity with the energy needs of an increasing number of electric vehicles connected to the grid. ISO 15118 also supports bidirectional energy transfer to achieve vehicle to grid applications by feeding energy back from the EV when needed. ISO 15118 allows for more grid friendly, safe, and convenient charging of electric vehicles.

Vehicle to grid - integrating electric vehicles into the power grid

ISO 15118 supports the integration of electric vehicles into the smart grid (also known as vehicle 2 grid or vehicle to grid). A smart grid is a type of power grid that connects energy producers, consumers, and transformers through information and communication technology, as shown in the following figure.

ISO 15118 allows for the dynamic exchange of information between EVs and charging stations, based on which an appropriate charging schedule can be (re) negotiated. It is crucial to ensure that electric vehicles operate in a grid friendly manner. In this case, 'grid friendly' means that the device supports charging multiple vehicles simultaneously while preventing grid overload. The intelligent charging application will calculate a separate charging schedule for each electric vehicle using available information about the state of the power grid, the energy needs of each electric vehicle, and the mobility needs (departure time and mileage) of each driver.

In this way, every charging will perfectly match the grid capacity with the electricity demand for charging electric vehicles simultaneously. Charging when renewable energy is highly available and/or when overall electricity consumption is low is one of the main use cases that ISO 15118 can achieve.

The power grid is a critical infrastructure that needs to defend against potential attacks and charge drivers appropriate fees for the energy provided to EVs. If there is no secure communication between the EV and the charging station, malicious third parties can intercept and modify messages and tamper with billing information. This is why ISO 15118 has a feature called plug and play. Plug&Charge deploys multiple encryption mechanisms to protect this communication and ensure the confidentiality, integrity, and authenticity of all exchanged data.

The plug and play function of ISO 15118 also enables the EV to automatically identify itself to the charging station and obtain authorization to access the energy required to charge the battery. All of this is based on the digital certificate and public key infrastructure provided through plug and play functionality. The best part is to insert the charging cable into the vehicle and charging station (during wired charging) or park it above the ground mat (during wireless charging), and the driver does not need to perform any actions. Using this technology, the behavior of inputting credit cards, opening applications to scan QR codes, or searching for easily lost RFID cards has become a thing of the past.

Due to three key factors, ISO 15118 will significantly affect the future of global electric vehicle charging:

1.Plug and Play brings convenience to customers

The encryption mechanism defined in ISO 15118 brings enhanced data security

2.Grid friendly intelligent charging

Considering these basic elements, let's delve deeper into the specific details of the standard.

3.ISO 15118 file family

The standard itself is called "Road Vehicles - Vehicle to Grid Communication Interface" and consists of eight parts. Hyphens or Em dash and numbers indicate the corresponding parts. ISO 15118-1 refers to the first part and so on.

In the following figure, you can see how each part of ISO 15118 is related to one or more layers of the seven layers of communication that define information processing in telecommunications networks. When the EV is inserted into the charging station, the communication controller (referred to as EVCC) of the EV and the communication controller (SECC) of the charging station establish a communication network. The goal of this network is to exchange messages and initiate billing sessions. Both EVCC and SECC must provide these seven functional layers (as described in the comprehensive ISO/OSI communication stack) to handle the information they send and receive. Each layer is built on top of the functionality provided at the bottom, starting from the top application layer and continuing all the way to the physical layer.