Magnetic Suspension Performance and Energy Consumption Characteristics of a Maglev Pediatric VAD Using an Ultra-Compact Axial Gap Type Self-Bearing Motor with Different Number of Actively Controlled Axes

An ultra-compact ventricular assist device with an axial gap type self-bearing motor has been developed for use in pediatric circulatory support. The developed self-bearing motor has double stator structure to actively control five degrees of freedom (DOF) of levitated impeller postures and to enhance motor torque capacity with small device size which is 22 mm in outer diameter and 33.6 mm in total height, respectively. This study investigated magnetic suspension stability and energy consumption characteristics during pump operation with 3-DOF (z, θx, θy) control and 5-DOF (x, y, z, θx, θy) control. The axial position and inclination angles were sufficiently stabilized independently with the radial position control. The radial position control can be effective to suppress the radial whirling oscillation at resonance, however power consumption increased by up to 0.4-0.9 W compared to in the case of the motor utilizing 3-DOF control.