Self-Powered Wireless Condition Monitoring for Rotating Machinery

Condition monitoring has played a significant role in reducing downtime and maintenance costs for key rotating machinery. However, traditional methods to power wireless sensor nodes depend highly on capacity-limited batteries or wiring from external source. Although the rotational energy harvesting technologies have been widely considered as a promising self-powered method, the output power under low-frequency occasions fails to supply the usable energy to wireless sensor nodes for condition monitoring. Therefore, a self-powered wireless condition monitoring system for rotating machinery in low-frequency occasions is presented in this article. A variable reluctance energy harvester is designed to convert rotational motion into electrical power. The ring-shaped stator contains magnets and tile silicon steel, while the rotor is composed of teethed silicon steel and coils. Besides, a ring-shaped circuit for low-speed occasions is designed to achieve power management and storage, signal detection and wireless transmission. In addition, an experimental test is carried out to verify the performance of the proposed self-powered wireless condition monitoring system. The results show that the output power of the proposed harvester reaches 336.7-851.8 mW at 200-328 rpm, while the average power after rectification and filtering is 203.3-602.5 mW. Moreover, the power test results show that the broadcasting, connecting, collecting and transmitting, and sleep modes of WiFi consume around 450, 206, 313, and 46 mW, respectively. By properly prolonging sleep mode, the average power consumption of wireless sensor networks can be significantly reduced. Furthermore, the condition monitoring performance of the proposed self-powered system is verified by acceleration detection.