A novel transformer for contactless energy transmission systems

Coupling coefficient k of a transformer is a key parameter affecting the efficiency of a contactless energy transmission systems (CETS). Aiming to obtain higher k, smaller size and lighter weight for the contactless transformer, techniques for the improvement of core structure and coil arrangement are proposed in this paper. A new magnetic reluctance circuit is also proposed for the transformer. Based on magnetic flux coupling, magnetic reluctances are found for the calculation of k. A novel contactless transformer is fabricated for a 60 W CETS. The k calculated is verified with experimental measurement to be very accurate. A contactless transformer with k of 0.6 and weight of 60 g is achieved. Compared with our previous transformer having k of 0.53 and weight of 122 g, the new transformer offers about 2.5% improvement in the maximum efficiency.