This paper presents wireless power transfer
(WPT) characteristics according to load variation in multidevice WPT systems using capacitive impedance matching
networks (IMNs). Two basis IMNs of using series–parallel
(SP) capacitors and parallel–series (PS) capacitors are
used. Four combinations of capacitive IMNs are considered, i.e., SP in a transmitting side and SP in a receiving
(Rx) side (SP-SP), SP-PS, PS-SP, and PS-PS. The optimum
capacitance values for each IMN are also derived by circuit
analysis. For verification, three cases based on the number
of Rx coils are considered, and the calculated results are
compared with the simulated and measured results for
each case. A WPT system for only a single device has
identical power transfer efficiency for four combinations
of the IMNs. Multidevice WPT systems with the PS IMN
in Rx sides are found to transfer more power toward the
Rx coil with lower load impedance according to the load
variation. On the other hand, using the SP IMN in Rx sides
is less sensitive to load variation than using the PS IMN. In
addition, a WPT system using the PS-PS IMN combination
is less responsive to the cross coupling between Rx coils
than that using the SP-SP IMN combination.