Sensorless Control of 5-Degrees of Freedom Controlled Self-Bearing Motor for Pediatric Ventricular Assist Device

Abstract

　A maglev blood pump using an axial flux self-bearing motor has been developed. Sensorless angle and speed control technique is desired to improve mechanical durability and reduce number of wires of drive lines for practical use of the maglev blood pump. In this study, sensorless angle estimation by using back EMF generated in stator winding during impeller rotation was applied to the 5-degrees of freedom (5-DOF) controlled self-bearing motor. This paper proposed a real-time winding inductance estimation to improve the rotating angle estimation accuracy. Non-contact impeller suspension of the maglev blood pump driven with sensorless control was demonstrated. The angle estimation accuracy was deteriorated without radial position control because a symmetrical three-phase back EMF waveform could not be obtained due to whirling of the levitated impeller. In contrast, highly accurate angle estimation was achieved with an error of less than 5 degrees in all pumps driving condition by suppressing the impeller whirling with 5-DOF position control.