Mid Sweden University

Rotating components are found in a majority of modern industrial applications.As key parts for machinery operations, rotating components need tobe monitored in order to detect and prevent machine failures. This requiresvarious sensor devices, which are electronic systems that detect and respondto physical quantities obtained from rotating components or their surroundingenvironments.

With the rapid development of semiconductor technology, sensor deviceshave low power consumption, enabling energy harvesting to remove the dependenceon battery or wired power solutions and thus leading to self-poweredsensing applications. The kinetic energy of rotating components provides aubiquitous and stable energy source that can be exploited, resulting in rotationalenergy harvesting as a promising solution to produce electrical powerfor sensor devices.

The research in this thesis focuses on the rotational energy harvesting bymeans of variable reluctance (VR) principle. In the literature, despite VR energyharvesting being a suitable candidate for the conversion of rotary kineticmotion, a comprehensive study on this energy harvesting system is still lacking.Moreover, low rotational speeds lead to a low level of extracted energyand negative mechanical effects on the rotary host which makes the deploymentof a VR energy harvesting to achieve a self-powered sensing applicationin rotating environment challenging, requiring a closer investigation onthe design and implementation. Based on theoretical analyses and numericalsimulations, combined with experimental validations, this research expandson the study of VR energy harvesting by exploring various structural designs,introducing a systematical optimization, demonstrating a sensing application,and investigating different circuits for AC/DC energy conversion to minimizethe circuit losses. The results of this research provide a guideline for enhancingthe performance of VR energy harvesting in low-speed rotational applications,which expands the research field on energy harvesting for realizingself-powered wireless sensing systems used in rotating environments.