Electromagnetic energy harvester based on a single pendulum structure for smart wind turbine bearing

Abstract Bearings are the key basic components of industrial equipment, and the failures of mechanical equipment are often related to bearings. For wind turbines in the field, condition monitoring of bearings is particularly important. The installation of sensors inside hollow rollers enables condition sensing of both the rollers and the bearings. To solve the power supply problem of the sensors inside the hollow rollers, an electromagnetic energy harvester based on a single pendulum structure (SPEH) is proposed. The harvester mainly contains a multi-pole magnetic ring, the coils, a rotating platform, and a single pendulum structure. The rotating platform is connected to the inner wall of the roller and the coils, and the single pendulum ensures that the magnetic ring is stationary relative to the ground. To not affect the load-carrying capacity of the roller, the finite element simulation analysis is performed to determine the hollow ratio of the roller. The single pendulum structure of the harvester is designed and the magnetic field is simulated to ensure the relative rotation exists between the coils and the multi-pole magnetic ring. The experiments demonstrate that the SPEH has a high power output, with a voltage of 1.25 V, an output power of 12.40 mW, and a power volume density of 592.59 μW/cm 3 at a rotation speed of 6 Hz. Application experiments on smart rollers containing SPEH have been carried out, demonstrating that condition monitoring and wireless signal transmission of multiple physical information can be achieved.