Guest commentary: Building EV charging infrastructure will need coordinated effort

Electric vehicles are becoming more commonplace around the world. This is driving demand for a charging infrastructure that can support this turning point in transportation.

The individual cost may still be a challenge, but the move to EVs is inevitable. This is change driven by need, rather than the whim of suppliers.

The charging infrastructure supporting e-mobility is less coordinated. This can be viewed positively for those looking to enter the market. Public money is in good supply, and private investment is also high. The underlying technology is not particularly complex, which means the barriers to entry are low.

But it isn't quite as simple as putting a socket in a public location and calling it a charge point. Those that are putting equipment into service are referred to as charge point operators, and they must work with the electric vehicle supply equipment manufacturers to develop a strategy that will support the charging infrastructure as demand continues to increase.

Not all EVs charge at the same rate, and not all charge points deliver the same amount of power. This creates a multitiered landscape of both public and private charging. As most cars are parked for most of the time, private chargers work at a slower rate. But drivers on a longer journey will want to charge as quickly as their vehicle allows. This means public fast DC charging will be in higher demand in service areas, while slower AC charging will be common in places where people spend more time, such as shopping malls.

Installing a fast DC charger in a public area requires more power from the grid. The design of the charge point will also be more complex and potentially more expensive. It will need a DC-to-DC converter rated for continuous operation, and the safety aspects of working with higher power will also impose design constraints.

Standards are still being developed for the EV charging infrastructure but one of the most important is ISO 15118. This defines how road vehicles communicate to the grid. With the recent release of Part 20, the standard now mandates the use of transport layer security. It also makes it easier to implement multiple contracts securely. This means a vehicle can use charge points owned by different operators more easily.

Another important aspect to consider is what happens when all the charge points in one location are used at the same time.

The grid will need to support this demand, and each charge point will be designed to supply the most power possible. But there may not be local grid capacity to support this instantaneous demand.

The solution is to impose some sort of load balancing. In practice, the policies are still in development, but it will require the vehicle to share information. This may extend beyond its current battery capacity; it may also include details of the onward journey.

Load balancing can take various forms. Charge points may be supplied from up to three phases of AC from the grid, so balancing by phase is one option.

Another would be to use time, by giving each vehicle an equal amount of time to charge at their highest possible rate. A more collaborative approach would be to charge each vehicle in turn to a defined level, giving priority to the first vehicle to arrive.

All these scenarios can be managed through secure negotiation with the equipment (if supplied by different vendors), the vehicles and the grid.

This adds complexity to the control system. It will likely require connectivity to a cloud platform where negotiations take place.

Given the location of the charge points, the communication will most likely use cellular networks. Pre-certified cellular modules could be used, potentially even providing local Wi-Fi access to the customer.

The EV charging infrastructure is growing at an astonishing rate, all around the world.

Technically, electric vehicle supply equipment is more complex than a wall socket, and that complexity is increasing as the industry needs to consider critical issues including security and load balancing. These demands draw on existing solutions from the electronics industry, with new innovations on the way.