Wireless power transfer via magnetic resonance
coupling method has opened a new possibility to the electric
vehicle system. It allows the wireless charging system of moving
vehicles, using charging lanes. However, although the efficiency of
power transmission is relatively high, the efficiency still depends
on displacement of coils. There have been several researches on
methods to maintain power transmission at the highest efficiency.
However, in such systems, the information on system parameter
especially coupling coefficients is needed, and in the charging lane
system, such information is unlikely to be obtainable without a
communication system. Therefore, it has come to attention that
parameter estimation is a crucial factor to implement a charging
lane system. This paper presents derivations of equations for estimating coupling coefficients in several configurations of wireless
power transfer system, using information from only one side,
either the transmitting side or the receiving side, of the system.
The presented equations are both applicable to the case of single
receiving coil and are also generalized for the case of multiple
receiving coils. Each equation is verified by both simulations and
experiments. An experimental system of the coupling coefficient
estimation system is constructed for estimation from the receiving
side using a dc/dc converter.