Papers by Keyword: Bearingless Motor

Abstract: In this paper, the high speed motor hybrids with a radial-axial 3 degree of freedom hybrid magnetic bearing unit and BPMSM unit is proposed. The radial suspension force and magnetic field distributions with different magnetized mode are calculated. The losses are calculated and compared using time-stepping finite element method. The research results have shown that the high-speed BPMSM with Halbach array permanent magnet rotor has sinusoidal air-gap magnetic field, minimum losses.

Abstract: A dynamic coupling model of the bearingless motor is established. This test does some simulations of motor displacement, no load speed and tracking accuracy under certain performance indicators. Analysis and simulation results show that the system has a control strategy of high precision as well as good dynamic and static performance.

Abstract: The bearingless motor combined technical characteristics of motor and magnetic bearings. It can simultaneously implemented electromagnet torque control and suspension control all in the motor .Since there are two sets of windings wound on the stator of bearingless motor, two sets of power circuit hardware and controller are required. In the case of most conventional structures, each terminal controller calculate references by themselves and transmits a torque/positon interactively. However, the latency issues of data delivery latency affecting the decoupling between the air-gap flux.The paper proposed the structure for a torque/positon hybrid control through network, torque/positon is transmitted from each terminal controller to a central controller. Then the central controller calculates references that are feedback to the terminal. The delay time is eliminated. In the paper, the hybrid control of bearingless induction motor is realized with the digital system based on the TMS320F2812.

Abstract: It is important to clarify the rotor eddy current losses in bearingless permanent magnet synchronous (BPMSM) for temperature rising to induce irreversible demagnetization. In this paper, the torque and radial suspension force producing mechanisms of BPMSM are introduced. The relative motion relationships among radial suspension force, rotor magnetic field and suspension winding magnetic field are analyzed. The necessary conditions of producing stable controllable radial suspension force in single direction are concluded. The rotor eddy current losses in BPMSM with PB=PM+1 and PB=PM-1 are calculated and compared using 2D time-steeping finite element method. The research results have shown that the BPMSM with PB=PM+1 is the most suitable for high speed operation with the minimum eddy current losses in rotor.

Abstract: Radial weight and rotary torque load often demand large winding current in a bearingless switched reluctance motor (BSRM). This will tend to cause magnetic saturation. But traditional mathematic model can not fit for this saturated working state, which has formatted a sever limitation. With a BSRM model in Maxwell, its magnetic saturation characteristics were analyzed, and a critical criterion was computed. Then a novel mathematic model was established with Maxwell tensor method and confirmed by Finite element computing results. It could fit for both unsaturated and saturated working state, and also satisfy reversibility condition. These were both very useful for nonlinear decoupling with state feedback method and wide application in industry process. This proposed modeling and analyzing method could also provide useful references for motor’s optimization design and control algorithm research.

Abstract: In this paper, a novel speed-sensorless suspension decoupling control strategy for bearingless motor was proposed based on linear Extended State Observer (ESO). In the proposed control strategy, a second-order and a third-order linear-ESO algorithm were added respectively into torque d-q axis current-loop and suspension system x-y direction displacement-loop. A product of electrical angular speed and torque system d-q axis current and a product of torque q axis flux and suspension system d-q axis current were defined as disturbances in order to use the linear-ESO algorithm to estimate the defined disturbances. By obtaining speed information and compensation for disturbance force, the motor can work on speed-sensorless condition and traditional decoupling algorithm can be simplified. The simulation results show that the proposed control strategy can realize accurate speed estimation and guarantee stable suspension under the rated speed.