Multiple Harmonics Analysis for Variable Frequency Variable Duty-Cycle Controlled Inductive Power Transfer Systems

Variable frequency variable duty-cycle (VFVDC) control is a widely adopted control scheme in inductive power transfer (IPT). One characteristic of variable frequency variable duty-cycle controlled IPT systems is that they could contain multiple harmonics. Conventional first harmonics approximation (FHA) analysis method only considers the fundamental harmonic signals. Hence, a new analytical technique is needed. In this paper, a new analytical technique called multiple harmonics analysis (MHA) is developed to analyze IPT systems operating at variable frequency and variable duty-cycle mode. The MHA technique can predict behaviors of harmonics and give insights into IPT systems. It is also shown that MHA is more accurate than FHA by both calculation and measurements.