A ZVS Pulsewidth Modulation Scheme for Active Class-E Rectifier Based IPT Systems

In inductive power transfer (IPT) systems, it is usually desirable to have an adjustable output voltage. This paper proposes a pulsewidth modulation scheme for active class-E rectifier based IPT systems. The output voltage is regulated by the duty cycle of the active rectifier. Utilizing the proposed modulation scheme, the active MOSFET is turned on at the zero crossing point of its drain-source voltage. Thus, the power MOSFET of the rectifier is achieved with zero-voltage-switching (ZVS) condition over a wide output range. Detailed circuit analysis, modeling and parameters design are presented. The experimental results match well with the circuit modeling and validate the soft-switching operation and the output voltage regulation capabilities. The efficiencies of overall system and rectifier reach 90.22 % and 95.45 % at 120 W output respectively.