Modeling air-core permanent-magnet linear generators in free-rotating devices

This paper details modeling to support the design of an air-core permanent-magnet-based energy-harvest system for use within an in-pipe mobile water-quality sensor. A challenge presented by this system is that the electrical and mechanical dynamics of the device are strongly coupled. Recently, a rigorous electrical/mechanical model was established to address this challenge in order to determine expected energy harvest, given the geometric/material parameters and electrical/mechanical inputs. An initial focus herein is the development of parameter measurement techniques for purposes of model validation. Subsequently, based upon hardware results, an alternative friction model is derived and utilized to explore the effect of friction on expected energy harvest.