Document Type : Research Paper

Authors

Electrical Engineering Dept., University of Technology-Iraq, Alsina’a Street, 10066 Baghdad, Iraq.

Abstract

The bearingless BLDC motor gathers all advantages of the BLDC motor and bearingless machine, and this motor is extensively used in blood and artificial heart pumps. In a bearingless BLDC motor, there are two sets of windings, the main winding, responsible for producing the motor torque, and the suspension winding, which keeps the rotor in the center without any contact with the stator. Generally, the suspension system is responsible for the generation of the suspension forces to cancel the pull-out forces (radial forces), which strongly depends on the accurate evaluation of radial forces distribution at different operating conditions. In this paper, a mathematical model based on the finite element method is used to calculate and analyze the radial force of a bearingless blood pump BLDC motor using Ansys/Maxwell. Based on Maxwell equations, the normal and tangential components of the airgap flux density is determined and used to calculate the radial force, magnitude, and direction. In addition, different cases of rotor displacement under eccentricity conditions are covered. The relation between the rotor displacement and radial force is analyzed, accounting for the displacement direction. Finally, the results are analyzed and discussed.

Graphical Abstract

Highlights

  • The magnetostatic analysis is used to evaluate the effect of the permanent magnet.
  •  The transient analysis evaluates the effect of both the magnet and the armature current.
  •  The lowest value of the radial force exists when the rotor is at the center position.
  •  The radial force increases directly with the rotor displacement.
  •  The radial force is variable because the air gap reluctance varies with rotor angle.

Keywords

[1] C. Xia, Mathematical Model and Characteristics Analysis of the BLDC Motor, Permanent Magnet Brushless DC Motor Drives and Controls, (2012) 25-40.
[2] C.-l. Xia, Permanent magnet brushless DC motor drives and controls: John Wiley & Sons, (2012).
[3] M. Ooshima and M. Rahman, Control strategy of magnetic suspension and performances of a bearingless BLDC motor, in 2011 IEEE International Electric Machines & Drives Conference (IEMDC), (2011) 71-76.
[4] Y. Qin and H. Zhu, Optimal design of a multi-phase double-stator bearingless brushless direct current motor, Advances in Mechanical Engineering, 9 (2017) 1687814017705112.
[5] R. S. Raheem, M. Y. Hassan, and S. K. Kadhim, Simulation Design of Blood-pump Intelligent Controller Based on PID-like fuzzy logic Technique, Engineering and Technology Journal, 38 (2020) 1200-1213.
[6] N.-W. Liu, K.-Y. Hung, S.-C. Yang, F.-C. Lee, and C.-J. Liu, Design of High-Speed Permanent Magnet Motor Considering Rotor Radial Force and Motor Losses, Energies, 13 (2020) 5872.
[7] X. Tu, W. Bu, and Q. Zeng, Research on the Modelling of a Single-winding Bearingless Permanent Magnet Brushless DC Motor, in Journal of Physics: Conference Series, (2021) 012049.
[8] A. Chiba, T. Fukao, O. Ichikawa, M. Oshima, M. Takemoto, and D. G. Dorrell, Magnetic bearings and bearingless drives: Elsevier, (2005).
[9] J. Pyrhonen, T. Jokinen, and V. Hrabovcova, Design of rotating electrical machines: John Wiley & Sons, (2013).
[10] R. Islam and I. Husain, Analytical model for predicting noise and vibration in permanent-magnet synchronous motors, IEEE Transactions on industry applications, 46 (2010) 2346-2354.
[11] W. Zhu, S. Pekarek, B. Fahimi, and B. J. Deken, Investigation of force generation in a permanent magnet synchronous machine, IEEE Transactions on Energy Conversion, 22 (2007) 557-565.
[12] L. Zhou and D. L. Trumper, Reluctance force magnetic suspension characteristics and control for cylindrical rotor bearingless motors, Journal of Dynamic Systems, Measurement, and Control, 139 (2017).
[13] M. Y. Bdewi, A. M. Mohammed, and M. M. Ezzaldean, Design and Performance Analysis of Permanent Magnet Synchronous Motor for Electric Vehicles Application, Engineering and Technology Journal, 39 (2021) 394-406.
[14] H. Dogan, F. Wurtz, A. Foggia, and L. Garbuio, Analysis of slot-pole combination of fractional-slots pmsm for embedded applications, in International Aegean Conference on Electrical Machines and Power Electronics and Electromotion, Joint Conference, (2011) 611-615.
[15] F. Wang, Y. Zhu, H. Wang, and D. Zhao, Design and analysis of a bearingless permanent-magnet motor for axial blood pump applications, IEEE Access, 8 (2019) 7622-7627.