High Efficient Contact-less Power Transmission System for the High Speed Trains

Historically the contact type power delivery system has been employed for the trains, the advantages of which might be the high reliability and the low cost, however the metal contact essentially results in the abrasion, which in turn inevitable causes the frequent maintenance, the audible noise generation and the contamination to the environment. This paper proposes a contact-less power transmission system with a wide air gap transformer for the high speed trains. We describe the proposed basic concept, problems and our approach for the proposed wire-less system. The magnetic coupling is influenced by the structure of the transformer. Since the wide gap type transformer results in the less coupling between the primary and secondary windings, the analysis on the magnetic coupling and power delivery efficiency are performed based on the magnetic circuit. Then, the best structure is investigated by the magnetic flux computer calculations. The small power experiment verification is performed about in the 40 W power range, in which 75.4% efficiency was demonstrated at 10 kHz frequency. After we analyzed the loss breakdown of the experiments, we made a case study of the possible contact-less power delivery system for the Shinkansen. As a conclusion, it is technically possible that the simple C-core type wide air gap transformer with the proposed special location of the windings wirelessly delivers 1000 kW power with the 1 cm air gap and high efficiency