In this paper we explore the concept of transmitting
and receiving power wirelessly at multiple frequencies. This
proposed frequency multiplex is achieved by using multiresonant tanks at the transmitter and receiver to amplify and
extract power at multiple frequencies. Frequency multiplexed
IPT system is a new concept that has numerous advantages over
the state of the art: (1) low switching frequency converters can be
used to drive high-frequency IPT systems, (2) emission standards
may become easier to meet by spreading the power transfer over
a spectrum of frequencies, (3) single-frequency receivers tuned to
different frequencies can be charged simultaneously even though
their coils are at close proximity and mutually coupled, etc.. In
this paper we develop the theory of source and receiver resonant
tank design, and present the complete methodology for
determining the system quality factor, effective resistance and
power transfer at each frequency. We present a case study of a
system that transfers equal amounts of power at 25 kHz and 75
kHz through simulations and experiments.