SDU researchers aim to turn electric vehicles into wireless energy storage systems
A new European research project will make it possible to charge electric vehicles wirelessly and return electricity from their batteries to the grid. SDU will receive approximately DKK 5 million and take responsibility for two of the project’s 15 PhD programmes.
Imagine parking your electric vehicle in an ordinary parking space. Beneath the vehicle is a charging pad that automatically begins transferring electricity – without you having to reach for a cable.
However, the electricity should not only flow from the grid to the vehicle. When the grid needs additional capacity, energy stored in the vehicle’s battery should also be able to flow in the opposite direction.
This is the vision behind the European research project BiWPT, which stands for Bidirectional Wireless Power Transfer. SDU is one of eight universities participating in the project and will receive approximately DKK 5 million for its work.
“When the vehicle is parked above the charging pad, the system should automatically determine how much energy needs to be transferred to the vehicle or returned to the grid. The driver should not have to do anything,” says Amir Babaki, Assistant Professor at the Centre for Industrial Electronics at SDU in Sønderborg.
At the same time, electric vehicle batteries could form part of the solution. Vehicles remain parked for most of the day, and if their batteries are connected to the electricity grid, they could serve as a vast distributed energy storage network.
When large amounts of wind or solar power are available, the vehicles could be charged. When electricity generation falls or demand rises, some of the energy could be returned to the grid. This is known as vehicle-to-grid technology.
The technology already exists with conventional charging cables, but it requires vehicle owners to remember to connect their cars. According to Amir Babaki, wireless charging could make this exchange more automatic and therefore more useful to the organisations responsible for operating the electricity grid.
“If electric vehicles are to provide flexibility to the grid, it is important that the process is reliable and can be controlled automatically. Wireless charging could also make the process more convenient for vehicle owners and, for example, assist people who find it difficult to handle a heavy charging cable,” he says.
Two of the PhD programmes will be based at SDU under the supervision of Amir Babaki. The new researchers are expected to begin in 2027.
The first project will develop the magnetic coupling between the charging pad in the ground and the receiver beneath the vehicle. One challenge is that the two components will rarely be positioned perfectly opposite one another.
If the vehicle is parked off-centre or the distance between the charging pads changes, efficiency decreases. The SDU researchers will therefore develop a solution capable of transferring electricity efficiently across an air gap of approximately 9to 25 centimeters while also tolerating misalignment between the vehicle and the charging pad.
“We need to strengthen the magnetic coupling so that as much energy as possible reaches the vehicle’s battery, even when the vehicle is not positioned completely accurately,” explains Amir Babaki.
The second PhD project concerns the power electronics that control the flow of electricity. Most existing wireless charging systems have been designed to transfer energy in one direction. Allowing electricity to flow in both directions requires new types of converters and control systems.
The aim is to develop a bidirectional converter that can operate efficiently regardless of whether the vehicle is being charged or returning energy to the grid.
The researchers must therefore reduce these losses while balancing them against the benefits offered by the technology.
“There will be a trade-off. Wireless charging results in slightly greater energy losses, but it removes the need for a cable and provides an automatic system that can connect the vehicle to the electricity grid more easily,” he says.
Safety is another central part of the project. Other PhD projects within the network will examine electromagnetic fields, shielding and protection against interference. The technology must comply with international standards before it can be widely adopted.
In the longer term, this could pave the way for dynamic charging, where electric vehicles receive electricity from charging equipment embedded in the road while they are moving.
The technology has already been demonstrated in several parts of the world, but widespread deployment will require greater efficiency, lower costs and common standards.
“The first step is to make stationary, bidirectional wireless charging efficient and automatic. Once we have achieved that, we can continue working towards dynamic solutions that also allow vehicles to charge while moving,” says Amir Babaki.
BiWPT is coordinated by the University of Antwerp. The project involves eight universities and seven companies. The Danish company Converdan is participating as an industrial partner for the two PhD projects at SDU.
However, the electricity should not only flow from the grid to the vehicle. When the grid needs additional capacity, energy stored in the vehicle’s battery should also be able to flow in the opposite direction.
This is the vision behind the European research project BiWPT, which stands for Bidirectional Wireless Power Transfer. SDU is one of eight universities participating in the project and will receive approximately DKK 5 million for its work.
“When the vehicle is parked above the charging pad, the system should automatically determine how much energy needs to be transferred to the vehicle or returned to the grid. The driver should not have to do anything,” says Amir Babaki, Assistant Professor at the Centre for Industrial Electronics at SDU in Sønderborg.
A large battery on four wheels
The number of electric vehicles is increasing, placing additional pressure on the electricity grid. If many vehicles begin charging at the same time, this can create large fluctuations in demand.At the same time, electric vehicle batteries could form part of the solution. Vehicles remain parked for most of the day, and if their batteries are connected to the electricity grid, they could serve as a vast distributed energy storage network.
When large amounts of wind or solar power are available, the vehicles could be charged. When electricity generation falls or demand rises, some of the energy could be returned to the grid. This is known as vehicle-to-grid technology.
The technology already exists with conventional charging cables, but it requires vehicle owners to remember to connect their cars. According to Amir Babaki, wireless charging could make this exchange more automatic and therefore more useful to the organisations responsible for operating the electricity grid.
“If electric vehicles are to provide flexibility to the grid, it is important that the process is reliable and can be controlled automatically. Wireless charging could also make the process more convenient for vehicle owners and, for example, assist people who find it difficult to handle a heavy charging cable,” he says.
Two technical challenges for SDU
BiWPT is a Marie Skłodowska-Curie Doctoral Network funded through Horizon Europe. The network will train 15 PhD researchers and bring together expertise from universities and companies across seven European countries.Two of the PhD programmes will be based at SDU under the supervision of Amir Babaki. The new researchers are expected to begin in 2027.
The first project will develop the magnetic coupling between the charging pad in the ground and the receiver beneath the vehicle. One challenge is that the two components will rarely be positioned perfectly opposite one another.
If the vehicle is parked off-centre or the distance between the charging pads changes, efficiency decreases. The SDU researchers will therefore develop a solution capable of transferring electricity efficiently across an air gap of approximately 9to 25 centimeters while also tolerating misalignment between the vehicle and the charging pad.
“We need to strengthen the magnetic coupling so that as much energy as possible reaches the vehicle’s battery, even when the vehicle is not positioned completely accurately,” explains Amir Babaki.
The second PhD project concerns the power electronics that control the flow of electricity. Most existing wireless charging systems have been designed to transfer energy in one direction. Allowing electricity to flow in both directions requires new types of converters and control systems.
The aim is to develop a bidirectional converter that can operate efficiently regardless of whether the vehicle is being charged or returning energy to the grid.
Convenience comes with a small energy cost
Wireless charging involves slightly greater energy losses than charging via a cable. According to Amir Babaki, the best cable-based chargers can achieve an efficiency of approximately 98 per cent, while wireless systems typically operate at around 96 per cent depending on operation condition.The researchers must therefore reduce these losses while balancing them against the benefits offered by the technology.
“There will be a trade-off. Wireless charging results in slightly greater energy losses, but it removes the need for a cable and provides an automatic system that can connect the vehicle to the electricity grid more easily,” he says.
Safety is another central part of the project. Other PhD projects within the network will examine electromagnetic fields, shielding and protection against interference. The technology must comply with international standards before it can be widely adopted.
In the longer term, the road could charge the vehicle
The project’s primary objective is the wireless charging of parked vehicles. However, one of SDU’s PhD projects will develop a magnetic coupling system that can also tolerate movement and changing alignment.In the longer term, this could pave the way for dynamic charging, where electric vehicles receive electricity from charging equipment embedded in the road while they are moving.
The technology has already been demonstrated in several parts of the world, but widespread deployment will require greater efficiency, lower costs and common standards.
“The first step is to make stationary, bidirectional wireless charging efficient and automatic. Once we have achieved that, we can continue working towards dynamic solutions that also allow vehicles to charge while moving,” says Amir Babaki.
BiWPT is coordinated by the University of Antwerp. The project involves eight universities and seven companies. The Danish company Converdan is participating as an industrial partner for the two PhD projects at SDU.