Inductive power transfer (IPT) is a non-radiative type of energy transmission based on inductive coupling. An inductive coupling is basically a K-inverter circuit whose K parameter describes how strength the coupling is. Another interesting property about the inductive coupling and any other K-inverters is that they output a load-independent constant current when driven by a constant voltage and they outputs a constant voltage when driven by a constant current. Because a cascade connection of any two K-inverters outputs a constant voltage from a voltage source, a K-inverter circuit (comprised of inductors and capacitors) is usually added to the transmitter or the receiver to provide constant voltage and guarantee stable charging for the load. This research further utilizes the property of K-inverter to realize practical multiple-receiver IPT systems. Novelties of this research are as follows.
1. In multiple-receiver IPT system using single frequency, we propose using multiple K-inverters to stabilize the load voltages and adjusting the K-parameters properly so that the load voltages reach the rated values required by the users.
2. In cooperative IPT where a nearby user receives power and simultaneously cooperates in relaying the signal toward a distant user, because the distant user is already connected to the transmitter via two K-inverters, we propose adding only one man-made K-invert to the cooperative user so that all the loads are connected transmitter via two K-inverters and obtained constant voltages.
3. In multiple receiver IPT using multiple frequencies, we propose novel K-inverter designs to mitigate out-of-band interference.