Development of Miniature Bearingless Motors for RVAD and Fontan Circulation Assist Devices

This paper presents the development of a miniature bearingless motor for pediatric blood pump applications. Three bearingless machine topologies are investigated: the traditional bearingless homopolar motor (BHPM), the bearingless consequent-pole motor (BCPM), and the hybrid version of these two (BHCPM). A multi-objective optimization framework is implemented to minimize the stack length while achieving required torque and force performance. To enable rapid and accurate evaluation of these machines, a novel evaluation algorithm is developed for the optimization study that utilizes parallel 3D finite element analysis (FEA) solves. The results show that the BHCPM is able to meet the proposed blood pump requirements with an axial length that is up to 60% shorter than the BHPM. The role of the field coil magnetomotive force (MMF) is examined and it is found that adding homopolar flux to create a BHCPM can further reduce the stack length, but tends to increase torque ripple and force vector error, highlighting a critical trade-off in the design of compact and stable bearingless machines.