Article ID: 2024GCP0004
A load voltage estimation and regulation system for wireless power transfer circuits exploiting only primary-side control is proposed. The proposed system provides regulated load voltage independent of load and coupling conditions, using neither a secondary-side controller nor an external coil for intercommunication, as required in conventional systems. Adaptive frequency control based on a phase-locked loop technique enables the estimation of load voltage using only the electric parameters measurable on the primary side. Some formulas for voltage estimation and for designing a two-port matching circuit on the secondary side to maximize power transfer efficiency are derived. The versatile and explicit design formulas allow designers to easily determine circuit parameters to theoretically maximize efficiency corresponding to the specifications of each application. It is confirmed that a prototype system implemented on an one-coin-sized printed circuit board regulates the load voltage for several values of load and coupling coefficient.
