Design and Optimization of a Novel Double-Layer Helmholtz Coil for Wirelessly Powering a Capsule Robot
Jinyang Gao, Siyu Tian, Changshun Yuan, Ziyu Ma, Chen Gao, Guozheng Yan, Ruiqin Li, Qiulin Tan, Li Zhang
Abstract
Inductively coupled wireless power transfer (IWPT) is promising to power a freely moving capsule robot (CR) continuously. The existing IWPT system for this application normally adopts a single-layer Helmholtz coil (SHC), which can generate a uniform alternating magnetic field (AMF) to cover the CR workspace but leads to low power transfer efficiency (PTE). To improve the PTE, this article proposes a novel double-layer Helmholtz coil (DHC). The DHC is composed of two in-parallel connected SHCs that have identical coil turns and winding directions but different diameters. To design and optimize the DHC, a dedicated analytical model is built and verified. A comparison between the DHC and SHC is also conducted, which shows that the DHC can not only generate a uniform AMF to cover a larger region, but its power consumption is lower when the generated AMF is identical, thus improving the PTE. Finally, the DHC is used to power a 3-D receiving coil, and the achieved PTE is in a range of 7.58%–17.41%, higher than that when using the SHC, which is in a range of 6.74%–14.92%.