A 3D printed fluid filled variable elastance electrostatic machine optimized with conformal mapping

Abstract

Recently, fluid filled electrostatic machines have demonstrated specific and volumetric torque density that hold promise to be competitive with electromagnetic machines in niche applications. These demonstrations of variable elastance (dual of reluctance) machines were non-optimized from an electrostatics perspective as their geometry was heavily constrained due to manufacturability. Higher performance electromechanical power conversion for electrostatics requires optimal geometric design. This paper proposes a semi-analytical method incorporating conformal mapping techniques with finite element (FE) analysis to optimize a variable elastance electrostatic machine in a low speed direct drive applications. As a proof of concept, an optimized geometry was built using additive manufacturing, specifically stereolithographic 3D printing, to circumvent geometry constraints. By building the machine from plastic plated with conductor, it is lightweight with improved torque density. This manufacturing approach suggests that a machine can be injected molded or cast in a single step. Experimental results support both the design and manufacturing approaches and the resulting machine is benchmarked against previous work.