Choosing the best Wireless Technologies for your EV Charging Station

As a highly efficient process, the refueling of an internal combustion engine is a hard act for EV charging to follow. Right now, EVSE manufacturers may be focused on geographical coverage but very soon we can expect to see a wide range of value-added services, enabled by wireless connectivity, enhancing the user experience.?

In this blog post I outline how wireless communication technologies are transforming the EV charging experience and highlight how key technology choices can help the EVSE manufacturer to differentiate their infrastructure in an increasingly competitive market.?

An Overview of EV charging?

Let’s look quickly at the challenges and opportunities surrounding EV charging. Two wired charging technologies currently dominate the market – AC charging and DC charging - although wireless, or inductive charging, is emerging with the promise of? significantly increased convenience . With most charging taking place while the EV is at home or in the workplace car park, slow AC charging offers a simple solution, requiring only an AC power socket. The availability of a 32A outlet supports faster AC charging but, since these are not standard in homes, this faster AC charging is generally only available at commercial charging points. Offering even faster charging times, DC charging is rapidly gaining ground, requiring more complex infrastructure but improving driver convenience with reduced charge times and, consequently practical vehicle range.?

But the EV charging process is about more than simply topping up a battery. The high-capacity batteries of the growing EV fleet represent a significant power source, with the potential of supplementing local power grids. With careful management this decentralized power bank can be used to store energy when supply exceeds demand and also to supplement demand at peak times. Integration with the power grid is therefore an important consideration in the design of any modern EV charging system.

Wireless Connectivity in the EV Charging System

A truly integrated EV charging process requires communication across a range of entities and, due to its simplicity, wireless connectivity is establishing itself as the natural enabler of these paths. Wi-Fi is already widely used for back-end communications in home and building environments, for example, while cellular technologies are common for communication to third-party, cloud-based services. Figure 1 shows the EV charging Ecosystem, indicating the principal communication flows.?

These flows are split into back-end communication, between the charging station and third-party cloud services, and front-end communication, between the charging station and the EV. Back-end communication carries information such as charging process status, battery levels and trip details and front-end communication primarily controls and monitors the charging process. The specifics of these flows are dictated by the charging environment; in domestic and commercial buildings charging could be integrated with local energy management systems, managing loads such as solar energy systems and heat pumps. For public charging systems, communication is mainly between the charging station and third-party operators.

As with any technology, open standards are critical to ensure interoperability across the EVSE eco-system, and a number of open and proprietary protocols have been developed for both front and back-end communications. The main standards for back-end include IEC 63110, IEEE 2030.5, EEBUS, OpenADR, and OCPPand, for front-end communication, we have CHAdeMO (IEC 61851-24) and ISO 11518.

Technology Choices

The u-blox range of wireless connectivity modules are specifically aimed at the EVSE market but our services go far beyond the provision of these devices. Through many years of collaboration with our customers we have developed an in-house solutions capability which enables us to ensure that you optimize the design of your charging station for cost, functionality, and futureproofing.?

As the only wireless technology included in the ISO 15118 standard, Wi-Fi is the natural choice for front end communication but which version should you integrate? Cost considerations and data volumes may seem to justify Wi-Fi 4, but Wi-Fi 6 may enable more flexibility and create a platform which supports future services and opportunities. Also, with Bluetooth increasingly used for charging station setup, does it make sense to use a multi-radio module?

At the back end, which is the best cellular standard to go with? Although 2G and 3G remain good for certain markets (outside of the NA Maket), we see a strong trend towards LTE-M and LTE Cat 1 in new deployments of EV terminals. Perhaps your system will be deployed in an underground area, in which case LTE-M may be the best option, or you may need the larger bandwidth of LTE Cat 1 if the station will require regular FOTA updates?

Other important considerations include choice of host module. For charging stations with large displays and advanced graphical user interfaces host-based Wi-Fi or multi-radio modules may be the only option. On the other hand, cost -optimization may drive the decision towards stand-alone modules? for simpler charging stations, such as domestic charging points.?

These are just some of the decisions which will influence the outcome of the charging station design. At u-blox we have the skills and knowledge and are ready to work with you to select the best options.