Nonlinear Analysis of an Injection-Locked Oscillator Coupled to an External Resonator

This work investigates an injection-locked power oscillator inductively coupled to an external resonator for wireless power transfer. The system allows a high transfer efficiency, while ensuring a constant oscillation frequency versus the coupling factor, unlike free-running implementations. An analytical formulation provides insight into the impact of the coupling factor on the locked-operation ranges, and two types of qualitative behavior, delimited by a codimension 2 bifurcation, are distinguished. The analysis principles have been extended to a new harmonic balance (HB) method that directly provides the family of locked-solution curves in a single simulation. It has been successfully applied to a Class–E oscillator at 13.56 MHz.