Fundamental Study of Leakage Field Cancellation Coil Characteristics of Contactless Power-Feeding Coil for Power Feeding during Running

Recently, automated guided vehicles (AGVs) have been deployed in factories to improve work efficiency and address labor shortages. However, current power supply systems, such as AGV shift systems and battery replacement systems, cannot fully utilize the advantages of AGVs owing to their inactivity time. Therefore, to improve work efficiency, an in-transit noncontact power supply system was adopted that can supply power while work is in progress and the machine is moving. There are several noncontact power supply methods. In this study, the most widely used one, the electromagnetic induction method, was used. Compared with conventional noncontact power transfer, a stable power supply and reduction of the magnetic leakage field are more important for noncontact power transfer while traveling because power is transferred over a long section of track. Therefore, the characteristics of a cancellation coil with enhanced effectiveness based on an 8-shaped coil that reduces the leakage of magnetic fields were investigated using electromagnetic field analysis simulations. Then, a feeding coil was fabricated, and its effectiveness was verified through measurements. It was confirmed that the cancellation coil has superior magnetic field leakage reduction performance to that of the ordinary 8-shaped coil. Finally, the current characteristics of the cancellation coil in the transmission section without ferrite tiles were studied.