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This paper presents a design procedure of high-frequency loosely inductive coupled wireless power transfer (LIC-WPT) system based on class-E^2 dc-dc converter, taking into account the power loss reduction of inverter, coupling part, and rectifier simultaneously. Analytical expressions including the dc-to-dc efficiency of the WPT system are derived and the efficiency deterioration mechanism is explained by the circuit model. Through the analytical expressions, the design procedure for satisfying both the class-E switching conditions and power loss reductions at the coupling part is proposed from the circuit-theory viewpoint. The class-E^2 WPT system designed by the proposed design procedure achieves high dc-to-dc efficiency at low coupling coefficient, in particular, compared with those designed by the previous design strategies. The validity and effectiveness of the proposed design procedure were confirmed by PSpice simulations and circuit experiments. [ABSTRACT FROM PUBLISHER]

This paper presents analytical expressions for the class-EM power amplifier, taking into account the fundamental-frequency and harmonic components of output currents in the main and auxiliary circuits. By using the proposed expressions, design values for satisfying not only the class-EM ZVS/ZDVS/ZCS/ZDCS conditions of the main circuit, but also the ZVS condition of the auxiliary circuit can be achieved without applying any tuning process. The analytical predictions agreed with experimental and PSpice-simulation results quantitatively, which showed the validity of analytical expressions given in this paper. [ABSTRACT FROM AUTHOR]

This paper presents the class-EM oscillator with the second-harmonic injection current, along with its design procedure, design curves, and design example. In the proposed oscillator, the output frequency of the proposed oscillator is locked with the input frequency of the injection circuit. Additionally, the switch-voltage and switch-current waveforms in the main circuit achieve the class-EM zero-voltage switching, zero-voltage-derivative switching, zero-current switching, and zero-current-derivative switching (ZVS/ZVDS/ZCS/ZCDS) conditions and the switch voltage waveform in the injection circuit satisfied the class-E ZVS/ZDS conditions. In the laboratory experiment, the oscillator achieved 92.0% power-conversion efficiency at 34.8 W output power and 1 MHz operating frequency. The experimental results agreed with the numerical predictions quantitatively, which denotes the validity of the design procedure. [ABSTRACT FROM AUTHOR]

This paper introduces a push-pull class-EM power amplifier for achieving low harmonic contents and high output power. By applying the push-pull configuration of the class-EM power amplifier, the proposed amplifier achieves an extremely lower total harmonic distortion (THD) and about four times higher output power than the conventional single class-EM power amplifier. Design curves of the proposed amplifiers for satisfying the class-EM ZVS/ZDVS/ZCS/ZDCS conditions are given. A design example is shown along with the PSpice-simulation and experimental waveforms for 1-MHz amplifier, considering the MOSFET drain-to-source nonlinear parasitic capacitances, MOSFET switch-on resistances, and equivalent series resistance of the inductors. The waveforms from the PSpice simulation and circuit experiment satisfied all the switching conditions, which has shown the accuracy of the design curves given in this paper and validated the effectiveness of the push-pull class-EM power amplifier. [ABSTRACT FROM PUBLISHER]