Impeller posture control evaluation in 3-pole magnetic bearing for implantable pediatric ventricular assist device

A maglev motor with 3-pole magnetic bearing has been developed for use in implanted pediatric ventricular assist devices (VAD). Maglev motors for implanted pediatric VAD require compact size, high magnetic suspension performance, and low power consumption due to low heat generation. However, it is difficult to achieve both high performance and efficiency in compact size maglev motors. In this paper, we developed two control methods for 3-pole magnetic bearing which are Axial position and 2-tilt angle control method and Axial position and 3-tilt angle control method. And conducted to investigate magnetic suspension performance for impeller and power consumption of the 3-pole magnetic bearing. In the result, maximum oscillation amplitudes of the impeller axial position and inclination are 0.020 mm and 0.22 deg with magnetic beating power consumption of 0.4-1.4 W and motor power consumption of 0.5-4.8 W in Axial position and 2-tilt angle control, 0.018 mm and 0.23 deg with magnetic beating power consumption of 0.4-0.6 W and motor power consumption of 0.4-1.3 W in Axial position and 3-tilt angle control. Axial position and tilt angle amplitude was sufficiently small for the axial clearance range of ±0.3 mm and the tilt angle clearance range of ±1.5 deg, resulting in equivalent magnetic support performance. Axial position and 2-tilt angle control consumed more power in motor and magnetic bearing than axial position and 3-tilt angle control. This is thought to be due to an imbalance in the motor and magnetic bearing axial attractive force. Therefore, in the future, we will create a simulation model to optimize the control and introduce zero-power control to clarify the effect of the control method on the performance of the magnetic bearings.