A Magnetic Flux Collection Enhanced Arc-Shaped Core and Its Optimal Coil Turn Design Method of Free-Standing Magnetic Field Energy Harvester

Due to the flexible and reliable advantages of the free-standing magnetic field energy harvester (FSMFEH), it is suitable for powering the sensor on the cable. However, the existing cores based on the long straight structure have limited magnetic flux gathering ability on the cable, resulting in low-output power of the FSMFEH. To address this issue, a novel arc-shaped core is proposed in this work. The designed arc-shaped core fits the surface of the cable, which can effectively enhance the magnetic field intensity of the area where the FSMFEH is located. Besides, based on theoretical analysis, the optimal coil turns design method of the FSMFEH with the arc-shaped core is proposed and verified by experiments: when the core lamination size is 1 cm, that is, less than the critical size of 1.3 cm, the coil turns are required to be fully wound to maximize the output power; when the core lamination size is 2 cm or 3 cm, that is, greater than the critical size of 1.3 cm, there is a fixed optimal turn to maximize the output power regardless of the core lamination size. The experimental results also show that when the cable current is 100 A, and the core lamination size is 1 cm, the output power of the FSMFEH with an arc-shaped core can reach 22.8 mW, which is 8.84 times that of the FSMFEH with an H-shaped core.

I. Introduction

As The main carrier of electric energy transmission in urban transmission and distribution networks, the cable plays a key role, as shown in Fig. 1(a). To ensure the reliable and safe operation of the cable, it is necessary to monitor the temperature, voltage, current, and other information of the cable by using wireless sensors. At present, wireless sensors are powered mainly by batteries. However, batteries are required to be replaced frequently due to capacity and life limitations. Thus, it is urgent to develop a novel power supply method to achieve a self-sustainable monitoring system. Fig. 1.

Cable in urban transmission and distribution network. (a) MFEHs are placed on the cable. (b) Magnetic field distribution of the cable.