Communication network for electric vehicle charging

Introduction

As the number of EVs on the road grows, the need for reliable and scalable charging infrastructure becomes paramount. For Electric Vehicle (EV) charging systems to be effective, it is vital to have fast and reliable communications between the EVs and their charging systems. Vehicular communication solutions enable information exchange for charge scheduling, routing, coordination, authentication, and billing. The communication network is essential to ensure the EV charging infrastructure runs effectively. This article will look at the importance of communication networks for EV charging, outcomes in the sector, and future concerns.

Benefits of a communication network for electric vehicle charging

A. Real-time data monitoring and management: Charging station operators and utility providers can monitor charging activity in real-time according to a communication network. This information can be used to optimise charging schedules, identify potential problems, and boost overall system efficiency. Operators may regulate charging stations remotely, change charging costs, and guarantee that charge is distributed somewhat over the network.

B. Optimised charging infrastructure utilisation: The charging infrastructure could be better managed to satisfy EV customers' dynamic demands with a communication network. The network can forecast peak charging times by analysing historical data and charging patterns to distribute resources accordingly. This leads to higher charging station utilisation, shorter wait times, and a better user charging experience.

C. Enhanced user experience and convenience: Mobile apps, web portals, and real-time charging status information are all possible with a strong communication network. EV drivers can find charging stations, reserve slots, and be notified when their vehicle is fully charged. Furthermore, seamless payment processing and interoperability between multiple charging networks improve user convenience.

D. Integration with renewable energy sources: One of the primary benefits of EVs is their ability to use clean energy from renewable sources. A communication network can aid EV charging integration with solar, wind, and other renewable energy sources. The network can lower the carbon footprint of EV charging operations by proactively controlling charging based on the availability of renewable energy.

Figure 1: Overview of EV charging solutions within a smart city infrastructure

Components of a communication network for electric vehicle charging

A. Charging stations with communication capabilities: Modern charging stations include communication modules that enable them to communicate with the central control system. Stations can use these communication features to communicate essential details such as charging status, power usage, and payment data.

B. Centralised control and monitoring system: The central control system is the communication network's brain. It collects data from individual charging stations, runs analytics, and controls the charging infrastructure. The system can connect with EV vehicles and utility companies to ensure a seamless and effective charging process.

C. Communication protocols and standards: Industry-standard communication protocols are required to provide compatibility and easy communication between network components. The following are some of the critical methods for vehicle-grid integration.

• ISO/IEC 15118 facilitates communication between the EV and the EVSE easier. It delivers charging parameters based on the user's demands and the CPO's charging profiles. The most recent upgrade provides bidirectional charging procedures.
• CHAdeMO is a Japanese protocol with its own CHAdeMO connector and allows physical bidirectional DC charging.
• IEC 61850 is a set of standards that defines communication protocols for intelligent electronic devices in power plants. It is an essential requirement for smart grids.
• The Open Charge Point Protocol (OCPP) communicates smart charging elements like grid capacity, energy costs, local, sustainable energy sources, and user preferences. It is currently included in IEC 63110 to provide a consistent international technical standard.
• The Open Charge Point Interface (OCPI) allows electric mobility service providers and CPOs to connect, allowing EV consumers to access different charging sites and expedite payments across jurisdictional borders. This promotes EV adoption through roaming. OCPI supports the most functionalities, including smart charging, among the several roaming protocols. It's widespread throughout the European Union.
• Open Automated Demand Response (OpenADR) exchanges price and event messages between the utility and linked distributed energy resources to control demand. It emphasises information exchange, whereas OCPP concentrates on control. OpenADR has widespread acceptance around the globe.
• IEEE 2030.5 allows utilities to manage distributed energy resources like electric vehicles through demand response, load control, and time-of-day pricing. It's ubiquitous in California.
• The Open Smart Charging Protocol (OSCP) conveys to charging station owners estimations of locally available capacity. The latest version includes use cases that employ more generic terminology to enable the integration of solar PVs, batteries, and other devices. However, the use of OSCP remains limited.

Communication network architecture for electric vehicle charging

According to the above demand analysis of the electric vehicle energy network communication system, the three-layer communication network architecture supports dynamic access and switch, as indicated in the figure below. The network architecture will support cross-regional information transmission by connecting the headquarters operation service center, provincial operation service centers, municipal operation service centers, and station monitoring centers. The first-level network is the backbone communications network connecting operation service headquarters and subordinate operation service centers. The first-level network uses a private network for power communication. However, installing a private power communication network that relies on power transmission line paths has not yet covered some motorways and provincial highways. Current communications networks involving optical fiber cable, microwave, Power Line Carrier (PLC), and satellite have fully covered headquarters, regional, and municipal companies. As a result, the communication system of the electric car energy service network can further extend the current enterprise network to tackle the wide-area coverage problem.

The transmission network connects subordinate operation service centers and station-level facilities on the second level. The second-level network is mainly based on the provincial power communication private network. The public network can be hired if the private network is unavailable. Access networks can use WSN, Optical Fibre Composite Low-voltage Cable (OPLC), 3G/GPRS/4G/TD_LTE, and 3G/GPRS/4G/TD_LTE to implement information exchange between charging-swap devices, vehicle automatic identification equipment, and monitoring equipment, as well as information interaction between inner equipment inside charging-swap stations, electric vehicles, battery packs and information access to geographically distributed charging piles. For low-voltage side distribution networks, communication network coverage is generally limited. For various scenarios, we can use wired communications (optical fiber communications, for example), IoT communication technologies, and public wireless communications (GPRS/3G/4G) to aggregate a variety of perception data, such as battery status information, identity information, electric vehicle status information, location information, smart electric card identity information and charging-swap environment information. The aggregation gateway will upload the aggregated data to the second-level network layer.

Meanwhile, charging-swap devices and other intelligent terminals receive control instructions. V2G communication technology enables bidirectional communication between EVs and the power grid. This allows EVs to not only receive power from the grid but also to supply excess energy to the grid during peak demand or emergencies. V2G integration improves grid stability and supports a more sustainable energy ecosystem.

Figure 2: Three-layer communication network architecture

Challenges and considerations in implementing a communication network for electric vehicle charging

EV charging systems rely on smooth and consistent communication to collect information for optimised EV charging efficiency. When an electric vehicle (EV) is hooked into an EV charging station, the EV charging station, the grid, and the Energy Storage System (ESS) communicate information such as battery charging status, power capacity, and energy usage through a wireless or wired network. The data is also supplied to the control centre for processing, allowing operators to understand how much power wattage is necessary at any given time. As a result, enough power is always available to meet charging requirements.

Knowing how to activate connectivity for your EV charging equipment is a prerequisite for reliable communication. When enabling dependable connectivity for their EV charging systems, operators confront two significant communication problems.

Transmission limitation of CAN communication protocols

Automotives have embraced the CAN bus as their communication bus, and their internal batteries do as well. Because many EVs and EV charging stations communicate via CAN, EV charging systems must be capable of connecting to CAN devices used in EV charging stations. However, as mentioned in the ISO 11898 standard, baud rates limit the transmission distance of a CAN system. The greater the baud rate, the shorter the maximum transmission distance. In other words, a CAN system's maximum transmission length for a given baud rate cannot be increased. To circumvent this distance limitation and deploy EV charging stations more flexibly, there is a requirement for a networking solution to solve this issue and deliver the expected baud rates over extended communication distances.

Find the suitable communication interfaces

Some EV charging stations that are maintained by the same company may be located widely apart, making it impossible to link them. EV charging stations, for example, can be put individually between buildings or in the suburbs, necessitating a networking system capable of long-distance connectivity. Some EV charging stations use wireless communication to share or send battery/electricity data amongst themselves, minimising wiring deployment costs. However, many EV charger manufacturers and system integrators frequently report wireless signal coverage that falls short of expectations or signal loss due to environmental constraints. As a result, they prefer wired data connections for enhanced stability and a better user experience. Fibre optic cables instead of copper lines provide isolation and protection from electromagnetic interferences and carry data across great distances.

Conclusion

As the popularity of electric vehicles grows, an effective communication network for EV charging becomes critical. This technical paper explored the advantages of such a network, such as real-time data monitoring, optimised infrastructure utilisation, improved user experience, and integration with renewable energy sources. It also looked at the communication network's components, several architecture possibilities, and the problems and concerns involved in implementation. While there will be challenges, the potential benefits of sustainability, convenience, and total energy management make investing in a robust communication network for electric vehicle charging essential for a greener and brighter transportation future.