Modeling and Analysis of Radial Suspension Force in 3-DOF Active Suspension Electromagnetic System for Maglev Pump

A magnetically levitated (maglev) pump is a bearingless component of fluid power systems. Unlike traditional centrifugal pumps, maglev pumps require a passive reluctance force to compensate for the hydraulic forces in the axial direction. Active magnetic support was previously reported as a technical solution to provide constraints in the axial direction; however, this affects the distribution of the radial air-gap flux density and suspension force. In this study, the radial force of a three degrees-of-freedom (DOF) active suspension system coupled with multiple magnetic fields was modeled and analyzed. The accurate radial electromagnetic force under eccentricity were theoretically derived by the Maxwell stress tensor method. The effects of the variable excitation flux on the controllable suspension force were also analyzed. The factors affecting the controllable force were verified through simulations and experiments. After analyzing the stability of the dynamic model of the electromagnetic system, the displacements of both radial DOF were accurately controlled using the proposed suspension force control model. When the rotor was suspended and driven with multiple DOF, the system exhibited excellent stability.