Low Loss on a Litz Aluminum Wire Coil Using Magnetic Tape for Automotive Wireless Power Transmission

Litz copper wire (LCW) coils are used in wireless power-transmission systems in electric vehicles, which require minimal low loss and weight to reduce heat generation and improve fuel economy. In this study, we investigated magnetic tapes for low-loss and lightweight Litz aluminum wire (LAW) coils. The direct current resistance of the aluminum coil was higher than that of the copper coil; however, at 84 kHz, the alternative-current resistance was suppressed by the magnetic tape, and the weight of the LAW coil with a magnetic tape, which could reduce the resistance, was smaller than that of the LCW coil. The effectiveness of the magnetic tape in temperature reduction was clarified by the power-transmission experiment at 84 kHz. The transmission efficiency of the LAW coil with magnetic tape was improved and the temperature rise was reduced compared to the LCW coil.