CAREER: Direct Drive E-Field Motors for Sustainable Power Conversion

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

Electric motors and generators, or more generally "electric machines," are a fundamental building block of modern society. Over 99% of all the electricity on the planet originates from an electric generator regardless of how it is spun (wind, coal, nuclear, etc.) and roughly 2/3 of that energy goes on to power electric motors. There is a worldwide market of $73.2 billion annually for electric machines. As electric energy consumption steadily increases annually, these ubiquitous workhorses continue to be mass-produced for performing the pumping, heating, cooling, drilling, pressing, cutting, grinding, and moving that occurs every minute of every day. Traditional electric motors rely on magnetism to function, and are made of steel, copper wire windings, and permanent magnets. These materials are mostly sourced from abroad, especially copper for the windings and rare earth elements for the magnets. These elements are expensive and have a volatile market. This project focuses on overcoming technical barriers in order to create motors that use electric fields, rather than magnetism, to operate. Electric fields would allow other materials, e.g. aluminum and plastic, to be used which are lighter weight and lower cost than materials for magnetism based motors. These materials could be domestically sourced, in addition to being more easily recycled. The educational aspects of the project are focused on increasing the scientific and engineering literacy of pre-college and college students as well as the general public. Hands-on science and engineering demonstrations for pre-college students will stimulate STEM education and entice students to pursue STEM fields in their careers. College courses will be reworked to allow students to gain skills as effective researchers. Science Cafés held for the general public will serve as grass roots discussions on relevant energy science and engineering topics to increase science literacy in the general public. Motors utilizing an electric field as the torque-producing mechanism (E-field Motors) can have significant materials, manufacturing, and operational advantages over their magnetic counterparts. To realize the potential of E-field machines the project will develop analytical E-field machine models encompassing electrostatics, fluid mechanics, and dielectric materials to form a multiphysics analytical model/methodology for E-field machine development. These models will be applied to reduce the mechanical gap between rotors and stators of the E-field motor via hydrodynamic bearing action with a dielectric fluid. The gap reduction will drive up the operational electric field and electrostatic shear stress simultaneously. This approach will be validated by multiphysics finite element simulations, bench scale experiments and E-field machine prototypes based on the multiphysics analytical design. Performance of the prototypes will be compared to traditional magnetism based motor designs. By exceeding the performance of magnetic motors, the project will transform the life cycle of electric motors by making them more recyclable through reducing the raw materials they require. Since E-field systems use electric fields to produce torque, rare earth magnets and silicon steel would no longer be required, and copper could be be replaced with aluminum.