Consideration of contactless power station with selective excitation to moving robot

A new method of contactless energy transmission to a moving machine is proposed. This system is useful for application with moving robots, including electric vehicles such as an electric wheelchair, an automatic guided vehicle, and so on. A moving robot was used as a model experimental system with these loads. The primary coils, an arrangement of spiral coils used with the selective excitation system, are located on the floor. A secondary spiral coil is attached to the bottom of the robot. The robot receives the magnetic flux radiating from the primary coils, which serves as the power source for the robot. In terms of electric power, in this experimental system the robot needs at least 2 W to start moving. As the robot moves, the excitation follows its movement. We have studied the characteristics of power transmission when the robot moves from one primary coil to another. This selective excitation system was found to be very effective for the overall efficiency of electric power transmission. We also examined the efficiency of the coil system used herein. Based on a comparison of the closed magnetic loop circuit and the open magnetic loop circuit, the efficiency of the former determined to be 70 [%] and that of the latter was determined to be 9 [%]. A monitoring system was constructed to ascertain which coil was excited. Based on our results, it would be possible to apply this contactless power transmission system to larger systems.