A new type of contactless transformer in track inductive power transfer system

Many countries around the world advocate to build resource-conserving and environmentally friendly cities. Inductive power transfer (IPT) applied in urban light rail has been regarded as an effective way of ensuring safety and stability of public transportations and also can reduce visual pollution by eliminating the overhead line. Existing researches of track contactless transformer are mainly focusing on how to optimize the secondary side of the transformer to achieve high coupling coefficient. In this paper, a new type of contactless track transformer which can converge the magnetic field is proposed from the perspective of enhancing the magnetic coupling of effective coupling zone. The ability of the figure 8 coil which can converge internal magnetic field and reduce external leakage magnetic field is verified by theoretical analysis, software simulation and experiment. The paper also points out that because of the primary winding structure, the magnetic flux direction changes alternatively. There would exist inductive blind area. Through the simulation the paper also discusses the selection and optimization of the secondary side in order to avoid inductive blind area. An IPT track vehicle charging system was established to verify the new type transformer.