2018 年 74 巻 5 号 p. 109-116
TDK is developing a wireless power transfer technology for electric vehicles (EV) that is based on two coils: one built into roads, parking spaces, or garages and the other fitted to the underbody of the car. One of these coils is the power transmission coil, and the other is the receiving coil. The receiving coil receives the magnetic field generated by the power transmission coil. Furthermore, the rectifier rectifies the alternating current to direct current. A coil case with magnetic and conductive properties produces an eddy current and decreases the power efficiency. Therefore, non-magnetic and non-conductive materials must be adopted in the design of the coil case. Furthermore, the coil case must protect the coil, ferrite cores, and the electronic component array. According to the Underwriters Laboratories Inc. (UL) standard, a vehicle overdrive test must be performed on the power transmission coil such that even if a vehicle rides on the power transmission coil case, it should not be damaged. In addition, a prototype of the power transmission coil case made of glassfiber-reinforced plastic was created. During the glass-fiber-reinforced plastic molding process, the glass fiber bundle slipped and air gaps were formed. We decided to consider the scale of three patterns: micro, macro, and mesoscale. After considering the three scales, the experimental results and calculated results matched with high accuracy.