In this paper, a method of impedance matching for
wireless power transfer (WPT) to multiple receivers is presented
considering cross coupling effects between non-adjacent coils. For
maximizing power transfer efficiency, design of a source coil and
optimal load impedance are achieved based on circuit analysis
and mutual inductance calculation. For verification, a WPT
system of a transmitter and three receivers is fabricated. The
fabricated WPT system can obtain reflection coefficient of under
-11 dB for the maximum three receivers at once by using a
circular single loop coil without capacitance compensation or
additional impedance matching circuit. The simulated results
show that the WPT system using the proposed method has more
than 85% efficiency regardless of the number of receivers while
efficiency for the conventional method is severely changed
according to the number of the receivers. Measured results of the
proposed method are consistent with calculation results.