Third Harmonic Operation of Current Fed Resonant Inverters for Inductive Power Transfer Systems

Abstract

This paper presents Third Harmonic Operation (THO) of Current Fed Parallel Resonant Push-pull Inverter (CFPRPI) for Inductive Power Transfer (IPT) systems. THO is proposed for CFPRPI to achieve higher voltage ratio with lower switching frequency, which is essential for low input voltage IPT systems. The IPT system is considered based on PS compensation method, i.e. parallel compensation for the primary side and series compensation for the secondary side. Moreover, a phase-shift control method is presented based self-oscillating tuning loop for output voltage or power regulations. The tuning loop and IPT system are modeled and formulated in THO mode. To verify the validity of the proposed method, a laboratory prototype with resonant frequency of about 120 kHz and maximum output power of about 50 W has been implemented.