Solution to problem of heating of metallic foreign objects during inductive charging of electric vehicles
The invention provides a simple solution to the "foreign object problem”, i.e., the heating of electrically conductive foreign objects in the magnetic field during inductive charging of electric vehicles.This solution presented enables an uninterrupted charging process.
There are no wireless charging stations available on the market, and so far, inductive charging of electric vehicle accumulators has only been implemented in prototypes at best. One of the challenges of inductive charging is to ensure that there are no electrically conductive foreign objects in the alternating magnetic field between the primary coil and the secondary coil, as these foreign objects can be heated by induced eddy currents and cause fires. Approaches to solving the so-called foreign object problem include using suitable detection devices for detecting foreign objects in the transmission path. If necessary, power transfer could then be interrupted. Examples are camera monitoring, light barriers, temperature monitoring, measurement of weight force and monitoring of electrical variables of the primary coil. However, camera and light systems quickly become dirty; other methods can be disturbed by weather or are not accurate enough, especially when it comes to detecting small objects. In any case, the energy transfer is interrupted upon detection of the foreign object, so the vehicle's accumulator is not charged until the object is removed.
- Cost-effective implementation without additional sensors required
- Fewer interruptions of the charging proces
Fields of application
Inductive charging infrastructure for electric vehicles
M. Böttigheimer: Methodischer Entwurf von Systemen zur Gefahrenreduktion von metallischen Fremdkörpern beim induktiven Laden von Elektrofahrzeugen [Methodical design of systems for hazard reduction of metallic foreign objects during inductive charging of electric vehicles]