E^2ÆD-E³üdÍ`VXeÌÁ«är <Abstract> The class-D and the class-E inverter can be achieved the high-power conversion efficiency at high frequencies. Therefore, the class-D-E and the class-E^2 wireless power transfer (WPT) systems, which consist of the class-D inverter and the class-E rectifier and the class-E inverter and the class-E rectifier, respectively, can be also achieved high-power conversion efficiency. These systems, however, have the different characteristic, such as maximum switch voltage and power conversion efficiency at coupling distance and load variations. It is important to understand the system characteristics against these variations analytically. This paper presents analytical expressions of the class-D-E and the class-E^2 WPT system outside nominal conditions. By using the analytical expressions, the characteristics of these systems outside nominal conditions can be compared and discussed. Experimental result showed the validity of the analytical expressions. |