As Electric Vehicles (EVs) become a more prevalent mode of transportation, discussions about different electric charging options are increasing. Wireless charging is one option that received a great deal of interest in the past few years. Proponents see wireless charging as a simpler, more convenient way to charge EVs because it eliminates the hassle of handling charging cables. Also, they envision charging vehicles at rest or in motion through charging pads built into roadways. A number of companies are actively testing systems—and even offering kits to retrofit EVs—for wireless charging. But, is wireless charging a viable option for EVs?
The principle behind wireless charging is the same as the one used to wirelessly charge low-power devices such as cell phones and electric toothbrushes. A primary coil built into the charging location creates a magnetic field when it is powered up. This magnetic field induces a current in a secondary coil attached to the battery of the device being charged. Wireless charging works best when the primary and secondary coils are at an optimum distance from one another.
There are two types of wireless charging:
In a typical EV wireless charging configuration, the primary coil is in a pad that sits under the car and plugs into the AC power. The secondary coil is located in the car. When parked, the coils properly align.
A number of companies are developing wireless EV charging technologies. These include:
Though wireless charging holds great promise, wireless charging is not ready for prime time. Current barriers to widespread adoption include:
Christopher Michelbacher, EV Charging & Infrastructure Manager for Audi, sees the current challenges to wide adoption of wireless charging in this way. “The technology is not fully mature, and there are a number of cost and operational tradeoffs. At the present time, the best application may be for EV fleets rather than personally owned EVs. Some fleet operators are actually looking at that. In the case of vehicles that normally park at loading docks, alignment is not so much of a problem because the vehicle’s location is defined by the loading dock. The back of the vehicle touching the loading dock is the alignment mechanism. Also, some fleets have a scheduled route that allows you to know how much energy they will use between charges and how much time they need to charge. You also don’t have to worry about proprietary systems on different vehicles, because the same trucks will always be pulling up to the loading dock. It might work for some battery electric buses in a transit system where they run fixed routes, and they've got known stops or known break times where they can recharge in order to complete their route throughout the day.”
Wireless charging is still evolving, but the possibilities are worth the effort. Technologies such as movable primary coils and new materials that make secondary coils lighter with lower wire resistance can make wireless charging solutions that are more efficient and work at higher power outputs. If wireless charging succeeds in becoming truly cost-effective, it would completely transform the way EVs are charged and even how they are used.
David Talbott is an IT and Technology Analyst with Mighty Guides who focuses on emerging technologies including deep learning, cloud and edge computing, and ubiquitous connectivity, and how these technologies converge to create powerful self-learning systems.