Optimization and Calorimetric Analysis of Axial Flux Permanent Magnet Motor for Implantable Blood Pump Assisting the Fontan Circulation

This paper presents a constrained optimization and calorimetric experimental analysis of low torque (2.2 mNm) axial flux permanent magnet motors with small active rotor surface area (1.4 cm
²
) with the aim to drive an implantable blood pump to support patients with a Fontan circulation. Till today, no such treatment option is clinically available, despite the urgent need. For a previously presented implantable blood pump concept, in this paper now the corresponding motors are optimized concerning efficiency and power density, where e.g. the optimal permanent magnet and back-iron height of the rotor or the optimal pole pair number and tooth height of the stator are determined. Afterwards, the different motor prototypes are realized, tested and compared to each other. Besides the implant size also the generated motor losses are very crucial, since the local temperature increase of the blood and surrounding tissue must always be kept below 2 °C. However, as will be shown in this paper, due to the fact that the low torque of the motors cannot be separated from the test-bench bearing friction with conventional torque sensors, a sophisticated calorimetric test bench to accurately measure the motor losses is needed.