Two-dimensional ferrite core-based transmitting coil for wireless power transfer in novel capsule robots

Multi-dimensional wireless power transmission is a critical element in the development of capsule robots. To solve the problem caused by the increasing number of functions of new capsule robots and the fact that the traditional three-dimensional receiving coil occupies excessive inner space, a two-dimensional square transmitting coil with an embedded ferrite core is proposed. The proposed transmitting coil consists of two pairs of rectangular solenoid coils distributed radially along the human body. By changing the direction of the current flow, it can generate a two-dimensional magnetic field covering the whole central plane. This paper presents a theoretical model and conducts finite element simulations to analyze the magnetic flux density in the center plane. To evaluate the effectiveness of the proposed system, two prototypes of transmitting coils with and without ferrite cores are created, tested and compared to assess the performance improvements. Results indicate that the transmitting coil with a ferrite core increases the power transfer efficiency from 5.07% to 6.11%. In addition, attitude experiments reveal that the receiving coil efficiently captures sufficient energy at various angles when operated in the center plane.