Experimental Analysis and Full Prediction Model of a 5-DOF Motorized Spindle

Abstract

Abstract:The cost and power consumption of DC power amplifiers are much greater than that of AC power converters. Compared to a motorized spindle supported with DC magnetic bearings, a motorized spindle supported with AC magnetic bearings is inexpensive and more efficient. This paper studies a five-degrees-of-freedom (5-DOF) motorized spindle supported with AC hybrid magnetic bearings (HMBs). Most models of suspension forces, except a "switching model", are quite accurate, but only in a particular operating area and not in regional coverage. If a "switching model" is applied to a 5-DOF motorized spindle, the real-time performance of the control system can be significantly decreased due to the large amount of data processing for both displacement and current. In order to solve this defect, experiments based on the "switching model" are performed, and the resulting data are analyzed. Using the data analysis results, a "full prediction model" based on the operating state is proposed to improve real-time performance and precision. Finally, comparative, verification and stiffness tests are conducted to verify the improvement of the proposed model. Results of the tests indicate that the rotor has excellent characteristics, such as good real-time performance, superior anti-interference performance with load and the accuracy of the model in full zone. The satisfactory experimental results demonstrate the effectiveness of the "full prediction model" applied to the control system under different operating stages. Therefore, the results of the experimental analysis and the proposed full prediction model can provide a control system of a 5-DOF motorized spindle with the most suitable mathematical models of the suspension force.

Loss Estimation and Thermal Analysis of a Magnetic Levitation Reaction Flywheel with PMB and AMB for Satellite Application

“…where i M represents the th i harmonic amplitude of the magnetization of the ro S r  is the distance between the stator and surface ( 3,4)    = , the micro-eleme surface of the inner and outer diameters of the rotor…”

“…Reaction flywheels supported by AMBs and PMBs are very important apparatus in spacecraft attitude adjustment [1,2]. Compared with the traditional reaction flywheel supported by mechanical bearings, the MLRW has the advantages of not making contact, not requiring lubrication, and active vibration suppression [3][4][5]. In essence, it solves the problems of contact friction, lubrication, oil pollution, and vibration of the mechanical bearings, which have negative effects on the precision and life of the satellite platform.…”