Through innovation, Belgian research centre Flanders’ DRIVE wants to play a leading role in the transformation of the vehicle industry in Flanders towards green and smart mobility. It works with companies and other research institutes at application-oriented research and develops technological solutions that contribute to a strong Flemish manufacturing industry, as Linda Corstjens discovers.
Flanders’ DRIVE sets up research projects together with leading Flemish companies, SMEs and other research institutes, with financial support from the Flemish government. It recently presented the results of the project Inductive Charging, a feasibility study into the wireless charging of electric vehicles.
Renilde Craps, Director Flanders’ DRIVE, explains: “Over the past two and a half years, we co-operated closely with nine Flemish companies and two universities, focusing on stationary and dynamic charging of buses and stationary charging of cars. Wireless charging appears perfectly feasible and can be done safely and efficiently, both stationary and while driving. All this using, among other things. expertise and technology gained and developed in Flanders, the northern part of Belgium.”
In this research project, Flanders’ DRIVE focused on technological aspects such as systems efficiency and the impact on both energy supply and non-technological issues such as safety and social acceptance. “We studied the applications on a traffic lane of the N769 in Lommel, which served as test track, and in the Flanders’ Drive research facilities,” she adds.
Inductive power transfer is done using the operating principle of a transformer consisting of magnetically connected coils. When transmitting a variable current through one of the coils, called the primary coil, this will generate tension in the secondary coil. In an inductive charging system for vehicles, these two coils are not physically connected to one another as in a conventional transformer: one is suspended below the vehicle whereas the other is installed in the road surface. The main challenge is to control the magnetic field that isgenerated upon the transfer of energy in the free space in between both coils.
Stationary and dynamic wireless charging for electric buses
Craps explains: “The basis for the system studied by us is the charging technology originally developed by our project partner Bombardier for trams. In the autumn of 2010 we started with the integration of this system in a Van Hool bus. Parallel to this, we worked on the integration of primary coils in the road surface of the test track. We installed connected segments in asphalt and concrete surfaces.”
Craps says that the centre studied the efficiency of the energy transfer in proportion to the speed of the bus and the lateral and vertical positioning of the secondary coil above the primary one. Here, results show a horizontal positioning tolerance of 40cm upon a vertical distance between both coils of 10cm.
“We’ve also gained knowledge about how to measure the magnetic field during the energy transfer. The first charging system prototype of 100 kW that we used in the research didn’t yet meet the ICNIRP safety standards, but Bombardier applies a system meeting these standards. We also studied which impact the characteristics of a dynamic inductive energy transfer have on the charging of batteries.”
Static wireless charging for electric cars
In the spring of 2011, Flanders’ DRIVE widened its research efforts to a car, using as a test vehicle the first Volvo C30 Electric that was available in Belgium. Craps explains that tests that were conducted with the vehicle included work with a 3.6kW static inductive charging system developed by Inverto, a company with more than 10 years of experience with inductive power transfer for industrial applications. This system charges the car, with a battery of 24kWh, in seven hours.
“Subsequently, we also studied a 22kW charger from Bombardier, which was developed using the expertise gained with the bus and which charges the battery in just one hour. As for the integration of the receiver in the car,” she continues, “we’ve chosen an add-on architecture and focused on energy management and control. To limit the size and weight of the secondary coil, we incorporated as many functions as possible in the primary coil.”
As for the positioning of the secondary coil in the car above the primary one in the road surface, Craps’ test results show a lateral deviation tolerance of 30cm upon a vertical distance of 10cm. The research also shows that inductive systems of 3.6 to 22 kW are possible.
These systems meet the expectations indicated by consumers and experts in a survey for charging electric cars at home. EMF tests show that the construction of the car protects passengers during the energy transfer against the electromagnetic field according to the ICNIRP standards. Also outside the vehicle, these standards are respected. The charging system is automatically activated upon disconnecting the motor. A user interface developed by Flanders’ DRIVE informs the driver on the status of the battery and the remaining time needed for charging it.
Wireless charging of electric vehicles is feasible, safe and user-friendly. Says Craps: “The study shows that wireless charging using an inductive charging system can be done almost as efficiently as charging with a cable. The average efficiency of the charging systems used in the study exceeds 90% (compared to 94% with a standard conductive charger typically used at home) for both for stationary and dynamic charging at speeds up to 70km/h.”
On the road
It also appears that the integration of charging technology in asphalt and concrete is equivalent as to quality but that prefabricated modules can offer a higher uniformity and that their implementation can be done more efficiently. At present, the test track is again open for normal traffic and the effects on the road surface are still being monitored.
The possibility of charging electric vehicles using a simple, wireless system represents a major step towards improved social acceptance of electric vehicles.
The achievements of Flanders’ DRIVE and its Flemish partners will doubtless generate lots of possibilities. They represent a solid basis for further applications. For instance, in early 2014 in the Flemish Living Lab for Electric Vehicles, wireless charging of electric buses will be tested in real everyday conditions.
The project results also provide the Flemish project partners with interesting perspectives on how to reap the rewards of their technological expertise on an international level. Bombardier, for instance, has been able to successfully apply wireless charging technology developed in this project on cars and buses and is now ready for commercial exploitation. The other partners also extended their expertise in view of further commercial developments in electric driving. For Flanders’ DRIVE, the project is part of a wider programme aimed at evolving towards autonomous vehicles.
First commercial applications for electric cars and public transport buses
“The first commercial applications for cars can be expected as from 2015, possibly as optional feature, with home and work as main charging stations,” says Renilde Craps. “Many drivers of plug-in hybrid cars appear to plug in their car only rarely or not at all. Here as well, wireless charging may offer a solution.
“For public transport buses, we consider static charging at one or more stops on their route as a first step. This may be combined with short inductive strips on steep inclines, with the absorbed energy being immediately deployed for driving the vehicle. From an economic point of view, it would obviously be interesting to install charging points at stops where several bus lines come together.”
Broad range of local and international activities
Flanders’ DRIVE also supports individual companies in their innovations. For instance, in the innovation project “E-Truck”, supported financially by the Flemish government through IWT, E-trucks Europe developed a modular electric powertrain for trucks up to 22 tons with Flanders’ DRIVE and Triphase. The electric powertrain can be integrated in both existing as well as new trucks from different brands. This kind of electric truck can produce a significant contribution to the evolution towards green transport of goods in city centres.
Flanders’ DRIVE encourages and assists both Flemish major players and SMEs to innovate, in order to support them to become or to remain global players in their domain. On an international level, Flanders’ DRIVE collaborates among others with the research centres of car manufacturers and participates in European research projects.