| The two-degree-of-freedom direct motor,which capable of rotary,linear and helical motion without the traditional intermediate transmission,is widely used in mechanical manufacturing,robot arms,multi-coordinate machine,etc.In recent years,it becomes the research hotspot of domestic and foreign motor exports and researchers with the advantages of small volume,high integration,high control precision and so on.The two-degree-of-freedom direct drive induction motor(2DoFDDIM)researched in this paper,which consists of two arc-stators with equal inner and external diameter and a solid mover shared by the stators,has high application and research value.The coupling-magnetic field,magnetic-coupling effect and mover design of 2DoFDDIM,which lay a foundation for the future research and application of 2DoFDDIM,are studied in this paper.The main research results of this paper are as follows:1.The distribution of rotary part coupling-magnetic field of 2DoFDDIM and its variation rule are calculated and analyzed respectively.Due to the cut-off structure and the installation mode of rotary and linear stator,the air-gap magnetic field,which consists of effective,coupling and invalid leakage magnetic field,will be produced when the motor works.The coupling-magnetic field is the magnetic field produced by the rotary or linear part which coupling the relative part.Analyzing the characteristics of the coupling-magnetic field has significance value for researching on the magnetic field and coupling effect of 2DoFDDIM.This paper calculates the distribution of the rotary part coupling-magnetic field and establishes its finite element model.Then the distribution of the rotary part coupling-magnetic field and its variation with air-gap thickness and rotary speed are analyzed.The finite element model is validated by coupling prototype in the last.The research of the distribution and variation of the coupling-magnetic field lays a foundation for the study of magnetic-coupling effect of 2DoFDDIM.2.The magnetic-coupling effect of 2DoFDDIM,including static and dynamic magnetic-coupling effect,are analyzed.Due to the structure and the installation mode of the stators,there are complex magnetic-coupling effects including the static and dynamic magnetic-coupling effects exist in 2DoFDDIM.The static magnetic-coupling effect indicates the phenomenon of the dynamic part(energized part)produce induced voltages and currents in the static part(unenergized part)by coupling-magnetic field.The dynamic magnetic-coupling effect indicates the motor performance changes in helical motion contrast to that in linear or rotary motion due to coupling-magnetic field.According to the results,the static magnetic-coupling effect will produce three-phase asymmetric induced voltages and currents in the relative windings and the magnetic-coupling strength increase with source frequency and rotary speed.The dynamic magnetic-coupling effect will result in the decrease of the torque(or force)and speed apart from the increase of the fluctuation compared with rotary or linear motion.Finally,the existence of magnetic-coupling effect and the validity of 2DoFDDIM 3D finite element model are verified by prototype experiment.3.The speed coupling coefficients,which indicate the influence on the motor speeds by coupling-magnetic fields,are proposed and the difference of rotary and linear speed coupling coefficient is analyzed in detail.According to the simulation results,the rotary speed coupling coefficient increases with rotary speed but the linear coupling coefficient has little changes with linear speed,which in accordance with the variation of magnetic-coupling strength with motor speeds.These results also confirms that the influence of magnetic-coupling effect on the motor performance enhances with the magnetic-coupling strength.4.A novel slot with copper cast mover structure suitable for 2DoFDDIM is proposed,and the influence of mover structure on the motor performances are analyzed.A novel slot with copper cast mover(SWCCM),which is slotted along the axial and circumferential direction on a smooth solid mover and copper is cast in the slot,is proposed to overcome the disadvantages of the initial solid with copper layer mover(SWCLM).The distribution of magnetic field and eddy current field are improved by the difference of permeability and conductivity of slots and teeth,and the performance of the motor is improved.The research results show that the novel mover can reduce the mover loss,increase the output force,weaken the fluctuation and improve the motor performance.This research,which provides a new path for the optimization of 2DoF induction motor,verifies the feasibility of improving the performance of 2DoF induction motor by changing the mover structure. |
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