Before electric cars can become a means of transport for everyone, a charging infrastructure needs to be introduced that can serve the mass market. The engineering company Finepower is developing a charging system that can charge the batteries in all vehicle types wirelessly, regardless of their manufacturer, as it is done inductively. The special circuitry provides a high level of efficiency – with no need to painstakingly position the system with millimetric accuracy.
Inductive charging systems are currently a hot topic for developers in the field of electromobility. It not only concerns the charging infrastructure for electric cars but also the contactless charging of industrial trucks. What makes it challenging is that certain parameters which are important for wireless energy transmission (vehicle ground clearance, coil geometry, positioning method) differ from one manufacturer to the next. Charging systems must therefore be able to connect as wide a range of vehicle types as possible, comprising heterogenous receiver coils and battery systems, to the charging infrastructure. This kind of technology is very important for the future of electromobility. Politicians are also very interested in this technology and are supporting its development as part of the UnIndCha (Universal Inductive Charging) research project.
The project’s goal is no small matter. It involves achieving a constantly high level of efficiency for vehicles in very different positions relative to the inductive charger, while, at the same time, not exceeding the maximum permissible EMC values. To meet these conditions, the variable vehicle position must be compensated for using an electronic circuit. To this end, the capacity of the primary coil circuit needs to be made adjustable.
The scenario for using this charging technology envisages also being able to temporarily charge vehicle batteries at rest stops, supermarkets or even at traffic lights – situations in which it would be too time-consuming to position the vehicle with millimetric precision in relation to the inductor coil of the charging infrastructure. The aim is for the charging process to be started as quickly and simply as possible, even with a large number of different vehicle types and with minimal communication between the infrastructure and the vehicle.
So far on the project, Finepower has created a prototype for an inductive charging system with adaptive compensation. Comparative measurements involving systems without such compensation have shown that the Finepower system can achieve greater efficiency; where the vehicle and charging station are extremely misaligned, it is only the Finepower system that makes the operation possible in the first place. In the next stages of the development project, Finepower will continue to improve and optimise the adaptive compensation circuitry.
In doing so, Finepower is playing a key role in enabling electric cars to be recharged with a wireless, inductive system at many points of the road traffic network – public car parks, train stations, airports or supermarkets – potentially in the not-too-distant future. The concept presented is meanwhile not limited to the field of automobility, but can also be used to great advantage in many industrial sectors, for example in the manufacturing industry.
EPCOS AG is involved in the project as a manufacturer of transmitter and receiver coils for inductive charging systems, and is particularly focused on the electromagnetic compatibility (EMC) of universal systems. The project is further supported by the Department of Energy Conversion Technology at the Technical University of Munich (TUM) and the Technology Network Allgäu (TNA) of Kempten University of Applied Sciences, both of which are carrying out fundamental research.