Abstract: 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. Two types of qualitative behavior, delimited by a codimension-two bifurcation, are distinguished. The investigation is extended to a Class-E oscillator at 13.56 MHz, analyzed with a new harmonic balance (HB) method that provides the family of locked-solution curves in a single simulation. Very good agreement is obtained with the measurement results.

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