The efficiency of inductive power links driven by Class-E amplifiers may deteriorate due to variation in the coupling coefficient when the relative position of the radio frequency (RF) coils changes. To solve this problem

a new design methodology of power links is presented in this paper. The aim of the new design is to use the feedback signal

which is a phase difference between the driving signal and the output current of the Class-E amplifier

to adjust the duty cycle and angular frequency of the driving signal to maintain the optimum state of the inductive power link

and to adjust the supply voltage to keep the output power constant when the coupling coefficient of the RF coils changes. The parameter adjustments with respect to the coupling coefficient and the feedback signal are derived from the design equation of the inductive power link. To validate the feedback control rules

a prototype of the inductive power link was constructed

and its performance validated with the coupling coefficient set at 0.2 and a duty cycle of 0.5. The experimental results showed that

by adjusting the duty cycle

the angular frequency

and the supply voltage

the power link can be kept in optimal operation with a constant output power when the coupling coefficient changes from 0.2 to 0.1 to 0.25.