Optimal Tuning of Series-Series Tuned Inductive Power Transfer System

The expanding the electric vehicle (EV) market has driven advancements in wireless charging systems, increasing interest in inductive power transfer (IPT) technologies due to rising EV demand. Among these, the series–series tuned IPT (SS-IPT) systems is fundamental for EV charging. Various methods exist for tuning the resonant frequencies of the transmitter (Tx) and receiver (Rx) coils in the SS-IPT system. Tuning these coils can impact the characteristics of the system, including efficiency, output power level, no-load voltage gain, and misalignment tolerance. This study proposes an optimal tuning method for the SS-IPT system, considering five design objectives: coil-to-coil efficiency, inverter efficiency, output power level, no-load voltage gain, and misalignment tolerance. The dependencies of these objectives on the tuning of the Tx and Rx coils are theoretically formulated. The relationship between tuning and system performance is graphically represented. The optimal tuning space is determined by overlaying these maps and identifying an intersecting area that meets all desired objectives. A tuning point within this space was selected and tested through simulation and experimentation. An 11 kVA SAE J2954 compatible setup was constructed. The measured efficiency, power level, no-load voltage gain, and misalignment tolerance closely matched the theoretical predictions, validating the proposed tuning method.