This paper proposes the frequency-modulation (FM) controlled load-independent class-E inverter, which has robustness against simultaneous variations of the load and the components in the output resonant filter. The main idea is to apply the FM control of the output-voltage regulation to the loadindependent class-E inverter. By applying that, the proposed inverter can keep the phase shift between the driving signal and the output voltage constant without using any time information. As a result, the proposed inverter can maintain the constant output voltage and high power-conversion efficiency operation at high frequencies despite the load variations and the component tolerances in the output resonant filter. We give analytical expressions of the proposed inverter and quantitative evaluations. Additionally, an experimental prototype of the proposed inverter was implemented. The theoretical and experimental results showed the validity and effectiveness of the proposed inverter. The implemented inverter achieved 95% efficiency with the 5.7 W output and 1-MHz operating frequency at the rated operation.

No abstract

This paper analyzes the gate noise performance using simulation and experimental test focused on parasitic inductances of power semiconductor devices' terminals. The gate noise which is over the threshold voltage makes non-active FETs turn on and leads the FETs to a breakdown. Next generation devices which have very high speed switching characteristic are difficult to be dealt with due to the false turn-on problem. The false turn-on mechanism in conventional theory is related to parasitic capacitors and a gate resistor and false turn-on occurs by the current flowing through a reverse transfer capacitor. However, the novel mechanism we proposed is mainly linked to parasitic inductors and recovery current and a non-active FET is switched on due to the oscillation which the energy charged by the current flowing from the source to the gate makes. We verified our theory by experiments, simulations and simplistic circuit equations.

This paper proposes a wireless power transfer (WPT) system using the loadindependent inverse class-E oscillator. The proposed system realizes autonomous operation without using external driving circuits. Therefore, it is easier to design the power-transmission inverter at high frequencies, in particular. Moreover, the proposed WPT system has loadindependent characteristics. It maintains constant output voltage and zero current switching (ZCS) of the MOSFET without applying any controls for load variations. We conducted the circuit analysis and the experimental verifications for the proposed system. In the experiment, the proposed system achieved 76.5 % power-delivery efficiency with 20 W output power and 1 MHz operating frequency at the rated state.

No abstract