Self-Driven Current-Doubler Synchronous Rectifier and Design Tuning for Maximizing Efficiency in IPT Systems

A novel driving circuit for a current doubler synchronous rectifier to inductive power transfer (IPT) applications is proposed in this paper using only auxiliary windings in the existent rectifier output filter inductors to drive the active switches. The proposed synchronous rectifier (SR) overcomes the limitations of the traditional driving schemes because it does not require any processing, analog circuits, gate drivers circuits or current measurement, normally used in the conventional SR applied to IPT systems. The proposed configuration presents a simple and robust operation considering usual parametric variation in IPT systems, such as coupling factor, misalignment, load variation and component tolerances. Moreover, the same size and weight of the conventional diode rectifier board is maintained due to the simplicity of the self-driven circuit. The proposed configuration allows increasing the global efficiency by reducing the conduction losses of the output rectifier and previous stages. A resonant circuit design procedure using an iterative process to find the maximum efficiency point considering the self-driven SR is proposed to maximize the global system efficiency. A 100 W resonant series-parallel IPT prototype is developed to validate the performance of the proposed self-driven SR circuit presenting a maximum global efficiency equal to 94.8%.