Design and optimization of a tunable magnetoelectric and electromagnetic hybrid vibration-based generator for wireless sensor networks

Wireless Sensor Networks (WSNs) have undergone rapid advancement over the past few decades. Typically, batteries power these wireless sensors. However, in many cases, battery life is preventing the WSNs from being widely applied. The power supply bottlenecks of WSNs would be solved by the self-powering sensors completely. As vibration energy is ubiquitous, energy harvesting from environment vibration to generate electric power has been a hot research topic at present. There are four well-known transduction mechanisms: electrostatic, piezoelectric, magnetoelectric (ME) and electromagnetic (EM). Each mechanism has its pros and cons ^{[1, 2]}. The electromagnetic vibration-based generators (EMVG) have the advantages of high output current and power, but also have the disadvantage of low voltage. Accordingly, the magnetoelectric vibration-based generators (MEVG) have the virtues of high output voltage, but also have the drawback of low current. Nevertheless, in order to make a wireless sensor do a better job, the VGs should have the advantages of high output voltage, current and power simultaneously ^{[3, 4]}. To solve this key problem and improve power density of VG, a tunable ME and EM hybrid vibration-based generator (HVG) has been proposed in this paper (Fig. 1). The electric output performance of the proposed HVG has been investigated. Compared to traditional single MEVG or EMVG, the proposed HVG obtain a remarkably enhanced output performance. It is found that appropriate turns number N of coil is propitious to the electric output characteristics. When N is 750, the five-phase ME transducer provides high voltage of 118 V, the coil provides large current of 124.14 mA. The optimum output power of the HVG achieves 40.84 mW for an acceleration of 0.75 g at frequency of 25.7 Hz (Fig. 2). Remarkably, the proposed HVG has great potential for its application in WSNs.