This paper presents a novel design procedure for Class E amplifiers without using waveform equations. By the proposed design procedure, Class E amplifiers can be designed regardless of the Q factor of resonant circuit, existence of the switch on resistor, and so on. The proposed design procedure requires only circuit equations and design specifications. All design procedures reported until now require deriving waveform equations which requires a lot of work. The benefits of the proposed design procedure is that it is to deriving waveform equations is no longer necessary. When the circuit equations are obtained, the other procedures for computation of design values are carried out with aid of computer. Therefore, we can design Class E amplifier more easily than the conventional design procedure. The authors design Class E amplifiers by using the proposed design procedures and carry out the circuit experiments, and find that the experimental results agree with calculation results, and show the validity of the proposed design procedure.

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.

This paper presents expressions for the waveforms and design equations to satisfy the ZVS/ZDS conditions in the class-E power amplifier, taking into account the MOSFET gate-to-drain linear parasitic capacitance and the drain-to-source nonlinear parasitic capacitance. Expressions are given for power output capability and power conversion efficiency. Design examples are presented along with the PSpice-simulation and experimental waveforms at 2.3 W output power and 4 MHz operating frequency. It is shown from the expressions that the slope of the voltage across the MOSFET gate-to-drain parasitic capacitance during the switch-off state affects the switch-voltage waveform. Therefore, it is necessary to consider the MOSFET gate-to-drain capacitance for achieving the class-E ZVS/ZDS conditions. As a result, the power output capability and the power conversion efficiency are also affected by the MOSFET gate-to-drain capacitance. The waveforms obtained from PSpice simulations and circuit experiments showed the quantitative agreements with the theoretical predictions, which verify the expressions given in this paper.

There are no well-established criteria for selecting the core for the design of resonant inductors. This paper presents new expressions of the area product for resonant inductors. By using proposed expressions, the area-product value can be calculated from loaded-quality factor of a resonant circuit, output power, and operating frequency assuming the window utilization factor and the maximum flax density. The area-product value expressed in terms of the loaded-quality factor is a good criterion for selecting the core. The design examples are given for single-wire winding and multiple-strand winding with a gapped core taking into account skin, proximity, and fringing effects.

This paper presents novel design procedures for class E switching circuits allowing implicit circuit equations. Because of the allowance, circuit simulators can be used in the proposed design procedures. Moreover, the proposed design procedures also allow any conditions considered until now. The proposed design algorithms are implemented by using PSpice and OPTIMUS. This paper shows the design examples of two kinds of class E switching circuits. In particular, the design example of the class E oscillator shows the benefit of the proposed design procedure eminently, i.e., it is unnecessary to make an equivalent model of the semiconductor devices for the design. These design examples show the validity and effectiveness of the proposed design procedures.

This paper presents a design procedure for wireless power transfer (WPT) systems with the load-independent class-E inverter family. The design procedure guarantees that the WPT system will achieve constant output and soft switching in response to load variations without particular control, which can apply not only single-hop single-output but multi-hop multi-output WPT system designs. It is analytically explained that a WPT-system output type is determined by properly selecting inverter, rectifier, and coupling resonant structure. As a concrete design example, we designed the three-hop three-output WPT system for installation into a robot arm. Experimental results exemplified the validity and usefulness of the established procedure.