Optimising sliding transformers for contactless power transmission systems

Contactless power delivery systems for mobile loads use transformers comprised of a core with a secondary winding sliding along an extended primary winding. The transformer, the most limiting component in the system, is analyzed by representing it as a special power transmission line. Two performance parameters, namely the transmission line efficiency and system quality factor, are introduced. It is shown that fundamental restrictions may limit the attainable performance of the system. The inductance of the primary winding is identified as a parameter which can be optimized to improve the system performance. Experimental results for a short and a long stroke transformer are presented