One of the significant challenges with widespread electric car adoption is related to vehicle charging. Many potential EV drivers have range anxiety or don’t want to spend much time charging an EV battery on long trips. Although wireless charging of electric vehicles may seem like something out of a science fiction movie, it could be a viable way to overcome electric vehicle charging issues. These wireless power transfer systems work while the vehicle is in motion, providing numerous benefits.
As EVs grow in popularity and are used in a variety of applications, such as delivery vehicles, corporate fleets, and personal trips, it will be critical to keep EV batteries charged without hindering vehicle range. Although the capacity and driving range of EV batteries has expanded significantly in recent years, charging solutions can also make EVs more viable for widespread use. Therefore, it is helpful for EV professionals to understand industry developments to help implement innovative approaches in creating a carbon-neutral world.
What Is Wireless Charging of Electric Vehicles?
Unlike static charging, dynamic wireless charging of electric vehicles or in-motion charging allows electric cars and trucks to continuously charge on the go, so they do not need to stop to refuel or recharge. Instead, they receive a constant stream of energy across an air gap while the vehicle is in motion. In these systems, a high-frequency inverter is used to generate the alternating magnetic field necessary for transferring electrical energy wirelessly to the vehicle using the principle of electromagnetic induction. In other words, public infrastructure is used for advanced battery charging for EVs.
However, inductive charging or inductive power transfer is not a new phenomenon, and you may already use this technology in your home with an electric toothbrush or wireless cell phone charger. Magnetic resonance wireless power transfer (WPT) uses induction charging with a pad on the ground and a receiver on the vehicle that is tuned to the same frequency. The advantage is the modules don’t need to be perfectly aligned to transfer power if they are on the same operating frequency.
“Opening up new parts of the transportation sector to electrification is a key benefit of this technology,” said Burak Ozpineci, section head for Vehicle and Mobility Systems Research at the U.S. Department of Energy's (DOE) Oak Ridge National Laboratory (ORNL). “It’s not just about charging your vehicle really fast. It’s also about being able to convert to electricity long-haul trucks, which burn a significant portion of the vehicle fuel used in this country.”
Despite challenges, momentum is building, with companies coalescing around standardized technology and automakers and municipalities exploring use cases. Even Tesla has shown interest in wireless charging technology. Pilot projects are currently underway, with trials focusing on both passenger and commercial vehicles. Standardization efforts by SAE International are also underway, which could further boost dynamic wireless charging adoption.
What Research Has Been Done For Dynamic Wireless EV Charging?
The DOE and ORNL are working to advance dynamic wireless EV charging to make EV use more convenient, cost-effective for consumers, and viable at highway speeds. The goal is to integrate high-efficiency wireless charging technology with the nation’s power grid and maintain charging power for high-speed applications.
Collaborators include the Idaho National Laboratory, the National Renewable Energy Laboratory, the Hyundai Motor Group, the American Center for Mobility, and the Virginia Tech Transportation Institute. This work is also supported by the DOE Office of Energy Efficiency and Renewable Energy’s Vehicle Technologies Office.
Researchers have already achieved numerous technical accomplishments, 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. Some researchers are investigating vehicle misalignment, electromagnetic field safety, and power density and efficiency challenges due to high current (~750A), high voltage (~4kV), and high frequency (~85 kHz) operation.
The ORNL has developed dynamic wireless EV charging technology and has licensed it to Brooklyn-based HEVO. The license includes ORNL’s unique polyphase electromagnetic coil and the Oak Ridge Converter. Under the agreement, ORNL and HEVO will work together to prepare the technology for commercial manufacturing.
“We are excited to see another one of our technologies move into the private sector where it can create new green jobs and support the nation’s clean energy goals,” said Xin Sun, associate laboratory director for energy science and technology at ORNL.
“EV charging must be simple, seamless and safe in order to accelerate mass adoption and prepare for an autonomous future,” said Jeremy McCool, HEVO founder and CEO. “Our collaboration with ORNL utilizes HEVO’s strength in designing, developing and commercializing wireless charging technology and software as the first and only company in the world that is compliant with both SAE and UL safety and performance standards.”
Advantages & Disadvantages Of Wireless EV Charging
Although wireless electric vehicle charging technology has many benefits, making it commercially viable requires overcoming some challenges, and more research and evaluation are needed.
Potential Advantages of Dynamic Charging
If wireless EV charging technology can be perfected and implemented in infrastructure, the widespread use of dynamic inductive power transfer has many potential advantages.
Continuous electric vehicle battery charging can alleviate range anxiety because vehicles can charge as they move, potentially boosting their market share.
Effective dynamic charging solutions reduce the need for plug-in charging stations, saving space.
Ongoing charging allows for a smaller EV battery size with reduced weight, helping to decrease the cost of EVs and conserving materials.
Dynamic charging is more convenient than using a gas station or stationary EV charging stations because it saves time, helping to boost the popularity and 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.
Increases the potential uses for electric vehicles, including long-haul trucks.
Disadvantages of Wireless EV Charging
Although dynamic wireless charging is promising, it does have challenges requiring further research and funding.
More research is needed to boost the power levels and efficiency of the existing technology. For example, misalignments or deviations of the receiving coil's position from the optimal position above the transmitting coil can impact the efficiency and reliability of wireless dynamic charging systems.
Finding the space for the wireless charging pad and equipment on the underside of an existing vehicle can be challenging.
Overcoming technological challenges related to vehicle body interference with power transfer efficiency.
Retrofitting infrastructure and integrating dynamic wireless charging capabilities into existing construction for widespread implementation would be costly.
Dynamic Wireless Charging Projects
Several EV charging road projects have been implemented worldwide, showcasing innovative approaches to charging infrastructure.
Detroit Has the First Wireless EV Charging Road
The Motor City boasts the first public wireless charging roadway for electric vehicles in the U.S. on a quarter-mile stretch of road in Corktown. In November 2023, the Michigan Transportation Department (MDOT) and the City of Detroit unveiled a new section on 14th Street, stretching between Marantette and Dalzelle streets near Michigan Central Station.
“Developing electrified roadways may be the catalyst to accelerate interest and acceptance of EVs for all consumers,” said MDOT Director, Bradley C. Wieferich. “Making it easier for EV users to find a reliable charging source without disrupting their commute supports both fleet operations and passenger travel. We’re proud to collaborate with private industry partners and the City of Detroit to support these important initiatives leading us toward a more sustainable future with fewer emissions.”
This experimental area is significant as Ford Motor Co. is actively constructing an electric and autonomous vehicle campus. The road has been fitted with inductive-charging coils provided by Electreon Wireless Ltd., an Israel-based company. This wireless EV charging installation aims to evaluate the effectiveness of the technology and explore its potential applications in public transportation. However, only electric vehicles equipped with a specialized wireless charging receiver can utilize this EV charging infrastructure.
"We're excited to spearhead the development and deployment of America's first wireless charging road," said Dr. Stefan Tongur, Electreon’s vice president of business development. "This milestone stands as a testament to our collaborative efforts with the State of Michigan and MDOT, City of Detroit, Michigan Central, Ford, Jacobs, Next Energy, DTE and others. Alongside Michigan's automotive expertise, we'll demonstrate how wireless charging unlocks widespread EV adoption, addressing limited range, grid limitations, and battery size and costs. This project paves the way for a zero-emission mobility future, where EVs are the norm, not the exception."
EV Charging Road For Buses In Norway
In Trondheim, a stretch of road near a bus depot has been equipped with inductive charging technology for electric buses. This project is part of an effort to enhance the efficiency and sustainability of public transportation. The inductive charging system allows buses to be charged wirelessly while they are parked or moving slowly, eliminating the need for physical connectors and reducing downtime for charging. The project aims to demonstrate the viability of inductive charging in real-world conditions and pave the way for broader adoption in public transit systems.
Like the pilot project in Detroit, the dynamic wireless charging technology for this project was developed by Electreon. Electreon’s system uses embedded coils in the road surface that transfer energy to receivers installed on the buses, enabling efficient and seamless dynamic wireless power transfer without disrupting regular operations.
Wireless Bus Charging in Israel
Electreon has implemented a pilot project in Tel Aviv to charge electric buses wirelessly. This dynamic inductive charging project involves embedding coils under a section of the road, allowing buses to charge while moving. This dynamic wireless charging initiative aims to reduce greenhouse emissions and improve the efficiency of public transportation in urban areas.
Smart Road for Trucks and Buses in Scotland
Electreon has developed a 1.6-kilometer electrified road on the Swedish island of Gotland. This project focuses on dynamic wireless charging for electric trucks and buses. It includes a demonstration of a long-distance electric truck capable of charging while driving, showcasing the potential for reducing reliance on large battery packs and improving the sustainability of freight transport.
What EV Models Are Equipped With Dynamic Wireless Charging Capabilities?
At present, the only electric vehicle available in the United States with wireless charging as a built-in feature is the BMW 530e hybrid sedan. WiTricity, a wireless charging provider that secured a $25 million investment from Siemens in 2022, is actively working on licensing agreements. These agreements, which have caught the attention of General Motors, are part of WiTricity's ongoing efforts to advance wireless charging technology.
Is There Strong Interest in Wireless EV Charging?
According to WiTricity, there is strong consumer demand for dynamic wireless charging. WiTricity surveyed 1,000 people in the U.S. who either own or are considering an electric vehicle, and discovered that 81% of them are highly interested in EVs that come with wireless charging capability.
Legislation Supporting Dynamic Charging of Electric Cars
Representative Haley Stevens of Michigan introduced the Wireless Electric Vehicle Charging Grant Program Act of 2023. This legislation aims to establish a grant initiative within the U.S. Department of Transportation (DOT) to support dynamic wireless charging of electric vehicles. Inspired by a pilot program in Michigan, the dynamic wireless charging bill seeks to position the United States at the forefront of this technology.
“Dynamic wireless charging has tremendous potential in revolutionizing how EVs charge and can enable widespread adoption of EVs by addressing some of the biggest challenges associated with electrification,” said Congresswoman Stevens.
“Michigan is innovating our EV future, and making charging easier for consumers is the next step. Investing in new electric vehicle technologies is crucial to enhancing America’s global competitiveness. Wireless charging can reduce battery size and cost, extend driving range, reduce pressure on the electric grid, and enable the electrification of autonomous vehicles.”
Dynamic Charging of Electric Vehicles Could Help Adoption Rates
As EVs gain market share in the automotive industry and help reduce vehicle emissions, fossil fuel energy consumption, and environmental pollution, convenient battery charging solutions are becoming increasingly critical. Wireless charging of electric cars has the potential to advance vehicle electrification and widespread adoption.
Due to their amazing potential, significant research is being conducted on high-power wireless charging systems. While wireless EV charging research is promising, it’s a long way from being implemented at scale with greater availability.
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