A Slightly Detuned Inductive Power Transfer System with High-misalignment Tolerance via Simple Modulation

Physical misalignment between the transmitter coil and receiver coil is inevitable in inductive power transfer (IPT) systems, which will lower the coupling coefficient and then mutual inductance, causing a reduction in transmission power and efficiency to some extent. In this paper, a slightly detuned compensated IPT system in series-series topology is proposed to realize stable output power over a wide misalignment range by simple frequency and voltage modulation. Unlike other methods, there are no extra voltage control modules, closed-loop feedback, and complex coupler design in this detuned IPT system. The transmission performance of the system has been deduced using the fundamental harmonic approximation (FHA) method. Then the anti-misalignment ability is also obtained through theoretical analysis and numerical simulation. Meanwhile, current detection at the primary side provides a trigger for the controller to generate corresponding PWM signals with different shift angles, realizing frequency and voltage modulation. Finally, simulation and experiment results of a 100 W detuned IPT prototype are presented to validate the proposed slightly detuned IPT system, where the maximum output power fluctuation is only 3.89% when the coupling coefficient changes by 71.4% from 0.35 to 0.1.