Experimental Loss Separation of Mega-hertz Inverter for WPT System using Calorimetric Power Loss Measurement

This paper discusses a power loss, which occurs in a load-resonant inverter operating at megahertz for wireless power transfer (WPT) systems. A calorimetric method is applied to measure the power losses in the mega-hertz operation accurately. The loss is measured using a single chamber with temperature control of the internal chamber using a Peltier device. The loss can be measured within 10% error when the loss is less than 23 W with a prototype chamber in experiment. A drive circuit loss, conduction loss of GaN devices, and PCB pattern loss are measured using the measurement site. Moreover, the total loss of the inverter with 6.78-MHz operation is measured under the zero voltage switching (ZVS) condition. The losses on the inverter are separated by a combination of each measurement result. As a result, the loss, which is related to the mega-hertz operation under the ZVS condition, is 9.9 W when the output power is 417 W at 6.78-MHz operation.