Abstract
Siemens, along with its partner BMW, recently concluded a feasibility study that focused on inductive charging of passenger electric vehicles. The objective of the study was to verify that automatic wireless charging could be accomplished with a comparable level of efficiency to today’s conductive solutions and without impact to human or vehicle safety. In its first phase, the study began with testing of a non-vehicle integrated solution. After verification of KPIs, the second phase of the study proceeded to integrate the technology into two BMW ActiveE electric vehicles. The study specifically measured power transfer efficiency with varying levels of coil to coil air gaps and misalignments between the road side and in-car coils while observing the most influential factors. Key findings of the study were that two areas merited further focus - the design of the coil system and the necessity for air gap observation. It is clear that as the automotive OEM community continues to seek inductive solutions that are smaller, lighter, more efficient, and less costly, these areas along with positioning guidance technology will be critical topics of further research. Siemens is using the results of the study to enhance their 2nd generation prototype which seeks to significantly reduce the size and weight of the inductive coils while adding in compliances and certifications to in-car safety and quality standards.