Direct Control of Radial Displacement for Bearingless Permanent-Magnet-Type Synchronous Motors

In recent years, research has been focused on bearingless motors to suspend the rotor stably by controlling rotor radial displacement. Without studying the relationship between the radial suspension force and radial displacement, the traditional control method for rotor radial displacement has some drawbacks such as the complexity of computation and time-consuming tuning. In order to overcome these drawbacks, a novel approach to control the rotor radial displacement was proposed based on the relationship between the radial displacement and radial suspension force. The rotor flux orientation is adopted to decouple the electromagnetic torque and radial suspension force. This approach directly controls the rotor radial displacement of bearingless permanent-magnet-type synchronous motors. In addition, a control system was designed by applying this approach. The simulation and experimental results show that the proposed control strategy is effective in realizing stable operation in rotor radial position control.