Will induction charging solve EV range anxiety?
Peter Els | April 24, 2024
Editor's note: This article is part of the specialty theme, E-mobility meets the road, by Boyd theme, hosted by GlobalSpec News & Analysis.
In 2023 electric vehicle (EV) sales in the U.S. showed signs of a slowdown. Many early sales forecasts pegged the number of sales to total between 1.3 and 1.7 million vehicles. The most optimistic of those sources claims a high of 1.3 million EVs sold. Nonetheless, total year-over-year sales was another record, just not as high as one anticipated.
There were several reasons for this. Among those listed by Fortune, price and charging infrastructure are key challenges to EV buyer appeal.
To address these consumer concerns, manufacturers are looking for novel answers to old challenges - at least in terms of infrastructure.
While almost all EVs have relied on wired charging solutions, in which drivers plug in a cable to recharge the car’s battery, wireless charging has the potential to make EV ownership more convenient, cost-effective and appealing to drivers and fleet operators.
Scaling up inductive solutions
Wireless EV charging operates on the principle of resonant electromagnetic induction, a method that facilitates the transfer of electrical current wirelessly. This process involves two magnetic coils: one embedded in the charging station and the other fixed to the vehicle's underside. The charging event is initiated when these coils align, enabling the seamless transmission of power from the charger to the vehicle. If there is no coil connection, power is not transmitted and little is wasted.
By mirroring the technology behind wireless phone charging, if applied to EVs, the features of inductive charging offer manufacturers a unique pathway to overcoming several longstanding hurdles impeding the mass adoption of EVs.
In a January 2024 report, McKinsey and Company establish that for EVs to gain widespread consumer support, an almost exponential increase in the public and private chargers is needed. In the U.S., about 2.6 million ports were available in 2022; but with the number of EVs increasing every year, the country will need approximately 9.5 million by 2025 and 28 million by 2030.
If the growth in EV-charging infrastructure fails to keep pace with demand, consumers will be reluctant to move on from their internal combustion engine vehicles. Other charging issues, including consumers’ lingering concerns about being able to charge as conveniently as they can fuel up today, could also slow the widespread adoption of EVs.
Let's face it: Current wired EV charging systems are clumsy at best and dangerous at worst. To recharge an EV, the task is to connect a high voltage cable to the vehicle interconnect. When connecting to high-power DC chargers there is also the safety of the operator to consider. Then they must wait hours, perhaps even 12 hours depending on charging system and vehicle, before the vehicle is fully recharged.
And this is assuming ready access to a charger, good weather and the driver can wait that long. And that the driver has even remembered to recharge. And local power service is stable. Finally, in many cases owners can't wait for a full recharge, and thus begins a game of partial recharges and a slow decline of available battery potential.
And with it, the EV driver begins to dread every detour or delay, as the peril of being stranded without reliable transportation inches near. This is called range anxiety. Here is another similarity between EVs and smartphones, as battery anxiety is sometimes experienced by users of smartphones, who fear idle moments without their devices.
Inductive charging can simplify many of the complexities of normal EV charging. Users can pull into an equipped parking space, get a dashboard alert to notify them charging has started, and walk away without a second thought. Wireless systems can perform alignment, authentication, verification and initiate charging within a few seconds of the vehicle arriving at the charger.
Contrary to popular belief, wireless EV chargers operate at similar power transfer efficiencies as their cable counterparts. Recently, U.S. Oak Ridge National Laboratory (ORNL) researchers wirelessly charged a light-duty passenger EV at 100 kW with 96% efficiency using polyphase electromagnetic coupling coils with rotating magnetic fields.
There are other benefits to inductive charging that are less obvious. The U.S. Access Board, an independent federal agency, promotes equality for people with disabilities under the auspices of the Americans with Disabilities Act. Wireless charging can help less capable people easily top up their vehicle's range.
Consider that the vast majority of vehicles owners will not have private driveways in which to park their cars for long periods. Level 1 and 2 EV chargers that use cables will be impractical in many car-dense and urban areas. Instead, inductive chargers that are embedded into pavement or asphalt will prevent cable loops from cluttering sidewalks, and also reduce damage to roadside chargers.
Finally, inductive charging may also help with ADAS and autonomous vehicle adoption, due to ample electrical supply and networks that will permit cars to quickly find open spaces.
Wireless charging: On to go
Taking inductive EV charging to the next level, several research projects are currently underway exploring the feasibility of dynamic wireless charging, where vehicles can be charged while on the move, through coils embedded in roadways.
Dynamic wireless charging allows electric cars and trucks to continuously charge on the go, while driving on the road. To achieve this, the U.S. Department of Energy (DOE) and ORNL are working to advance dynamic wireless EV charging at highway speeds to make EVs more convenient and cost-effective for consumers.
The researchers have already achieved several milestones, including high-level cost and feasibility studies, identifying a suitable architecture for 200 kW dynamic wireless power transfer (DWPT) couplers, and analyzing the feasibility of large-scale deployment on Atlanta's primary roadways. Researchers are also reviewing the operational challenges of vehicle misalignment, power density and efficiency, as well as the safety of the electromagnetic field, resulting from the high current (approximately 750 A), high voltage (approx. 4 kV), and high frequency (approx. 85 kHz) required by these systems. The ORNL-developed dynamic wireless EV charging technology, including the polyphase electromagnetic coil and converter, has been licensed to Brooklyn-based HEVO. Under the agreement, ORNL and HEVO will work together to advance the technology for commercial manufacturing.
Also, perhaps it's not surprising that the Motor City is on the cutting edge of something like this. In November 2023, Detroit became the first city in the U.S. to install a public wireless charging system for EVs. The Michigan Transportation Department (MDOT) and the City of Detroit commissioned the system on a quarter-mile stretch of 14th Street, near Michigan Central Station. This experimental area is of particular significance to Ford Motor Co. because of its proximity to the company’s electric and autonomous vehicle campus. The road has been fitted with inductive-charging coils provided by Electreon Wireless Ltd. and aims to evaluate the effectiveness of the technology while exploring its potential applications in public transportation.
Trials such as this play a crucial role in developing the technology to overcome the challenges currently impeding the commercial rollout of dynamic wireless charging. For example, misalignment of the receiving coil versus the transmitting coil impacts the efficiency and reliability of wireless charging. Maintaining this alignment in a moving vehicle in a roadway is a significant challenge. There are also many risks for signal interference - everything from litter to leaves can degrade recharging.
Induction EV systems also add power supply and systems complexity. This equipment can be bulky, and thereby further reduce EV range. There are also many lessons to be learned for retrofitting dynamic wireless charging into existing infrastructure.
If wireless EV charging technology can be perfected and implemented the widespread use of dynamic inductive power transfer holds many potential advantages for EVs. Continuous EV battery charging can alleviate range and charge anxieties because vehicles can automatically charge as they move. Ongoing charging allows for a smaller EV battery with reduced weight, which helps to decrease the cost of EVs, conserve materials and improve safety. Dynamic charging is more convenient than using a gas station or stationary EV charging station because it saves time, helping to boost the appeal of EVs. If wireless EV charging technology becomes widely used, it could accelerate the transition to cleaner energy sources and help mitigate climate change. Effective dynamic charging solutions reduce the need for plug-in charging stations, saving valuable real estate.
Summary
Wireless EV charging technology stands at the cusp of revolutionizing the electric vehicle ecosystem. The technology promises solutions to range anxiety which is a significant barrier to EV adoption.
Through advances in resonant electromagnetic induction and the development of superfast wireless charging systems, this technology promises not only convenience and safety but also high efficiency. The exploration and implementation of wireless charging, from static setups in homes and offices to dynamic charging on the move, paves the way for a more sustainable and hassle-free electric mobility future.