RESONANCE-TYPE POWER TRANSFER COIL
FIG3 is a view illustrating an equivalent circuit of the power transmitting coil illustrated in FIG2  FIG4 is a cross-sectional view illustrating a configuration example of the power transmitting coil according to the first embodiment of the present invention
In this case, as illustrated in FIG3, parasitic capacitance (C1 to C4 in FIG3) is generated between the conductor 31 of the first layer L1 and the conductor 31 of the second layer L2. Voltages (VC1 to VC4 in FIG3) in the parasitic capacitance generated when a current flows through the conductor 31 gradually become small with increasing distance from an input end (input voltage V1) (VC1 > VC2 > VC3 > VC4). Note that, the parasitic capacitance is generated not only between the layers of the conductor 31 but also between portions adjacent to each other in the same layer of conductor 31, but since there is substantially no potential difference in parasitic capacitance between these portions, this may be neglected.  Since the parasitic capacitance is generated between the layers of the conductor 31 in this manner, in the power transmitting coil 3 according to the first embodiment, as illustrated in FIG4, an insulating member 32 is provided between the layers of the conductor 31. In FIG4, the insulating member 32 is formed to have a uniform thickness. The insulating member 32 is formed of a material having a low dielectric constant, for example, a material such as acrylic, glass epoxy, carbon fiber reinforced plastic (CFRP), polyimide, or resin.
cross-sectional view, view
31
conductor
3
power transmitting coil
4
power receiving coil
32
insulating member
['1. A resonance-type power transfer coil comprising: a conductor wound into a multiple-layered helical shape; and an insulating member provided between layers of the conductor.']