Enhancement of piezoelectric vibration energy harvester output power level for powering of wireless sensor node in large rotary machine diagnostic system

The paper presents results of experimental and theoretical studies on small-size piezoelectric generators, in which energy of machine mechanical vibrations is harvested and converted to electric energy. These piezoelectric generators were proposed, as an alternative to a battery-based solution, for powering of sensor nodes in condition monitoring systems of large rotary machines such as turbogenerators in power plants. Initial studies conducted for three bending-beam piezogenerators were focused on maximization of generated electric power by matching load impedance to piezoelectric element output impedance and designing suitable weighting mass for mechanical resonance. As a performance of the piezoelectric element and the weighting mass setup turned out to be unsatisfactory when tested in real conditions on a turbogenerator, Synchronized Switch Harvesting on Inductor technique has been recently applied for an enhancement of generated power levels. A test interface circuit is described. The obtained laboratory results confirm possible usefulness of this solution and are a basis for a future work on power-processing blocks operating with piezoelectric generators.