Sliding transformers for linear contactless power delivery

Contactless power delivery systems for mobile loads use transformers comprised of a core with a secondary winding sliding along an extended primary winding. The sliding transformer is identified as the most limiting component in the system and is analyzed by representing it as a special, multiturn power transmission line. Two performance parameters, namely the transmission line efficiency and system penalty 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.