A high-frequency current-output-type inverter aimed for wireless power transmission system

Wireless power transmission (WPT) using magnetic resonance has been attracting increasing attention from power electronics engineers and industry. A number of studies have investigated WPT circuits based on magnetic resonance and have verified the high-efficiency power transmission characteristics of such circuits. However, a 10-MHz-class high-frequency power supply suitable for high-power transmission systems has not been sufficiently investigated. Hence, the authors propose a new circuit topology for high-power and high-frequency inverter systems suitable for high-power wireless power transmission. In this paper, the authors propose a novel high-frequency current-output-type inverter circuit topology using an immittance conversion element, parallel operation of the two proposed inverters and a WPT circuit using magnetic resonance at the parallel resonant frequency. In the prototype tests, a system consisting of a single-unit inverter and the proposed WPT circuit provides an output power in excess of 100 W when the conversion efficiencies of the inverter and the entire system are 85.4% and 80.2%, respectively. In addition, parallel operation of the two proposed inverters with a load RLC circuit yields an output power greater than 290 W, which is twice the output power of a unit of the proposed inverter. Thus, the conversion efficiency of the inverter exceeds 80.4%.