Characteristic Analysis And Mover Optimization Of Two-Degrees-of-Freedom Direct Drive Induction Motor

With the rapid advancement of industrialization,the traditional single-degree-of-freedom motor is difficult to meet the needs of industrial field,such as precision machine tools and robotic arms that require multi-degree-of-freedom motion drive systems.The traditional multi-degree-of-freedom motion field requires multiple linear or rotary motors to achieve,with a large number of parts and difficult maintenance.The two-degrees-of-freedom motor which can integrate linear,rotary and spiral motion is a new development trend.In this paper,a new type of two-degrees-of-freedom direct drive induction motor is taken as the object,and its topological structure and working mechanism analysis,electromagnetic design,equivalent circuit modeling and characteristic analysis,three-dimensional global temperature field analysis,multi-objective optimization and other aspects are studied.The main research contents are as follows:1.Determine the electromagnetic parameters of the two-degrees-of-freedom direct drive induction motor.According to the rated parameters of the motor,the main dimensions of the motor are designed firstly,and then the key technical parameters such as the thickness of the air gap,the stator slot type of the rotating part and the linear part,the winding and wire gauge,and the length of the mover are designed.2.Adopt the penetration depth method and the multilayer theory method to establish the motor equivalent circuit model and calculate the motor characteristics.The equivalent circuit model of the two-degrees-of-freedom direct drive induction motor is established.Two analytical methods-penetration depth method and multilayer theory method are used to solve the motor equivalent circuit model parameters,and the electromagnetic characteristics of the motor are further calculated.Finally,a three-dimensional finite element model of the motor is established,and the analytical calculation results of the equivalent circuit model are compared with the finite element simulation results to verify the correctness of the analytical calculation model.3.The electromagnetic field-temperature field coupling analysis method is adopted to establish the three-dimensional global temperature field model of the direct-drive induction motor with two degrees of freedom.The temperature rise of the motor has a very important impact on the performance of the motor.First,the heat source density is calculated according to the loss of each component of the motor under rated conditions,and then the heat dissipation coefficient and air gap convective heat transfer coefficient of each component of the motor are calculated.Finally,starting from a single degree of freedom,the temperature distribution of each component of the motor under rated conditions of rotation and linear motion is analyzed.At the same time,the temperature distribution of the motor under different slip conditions and the influence of ambient temperature on the temperature rise of the motor are analyzed.4.Taguchi method and multi-objective grasshopper optimization algorithm were used to optimize the two-degrees-of-freedom direct drive induction motor with slot with copper cast mover structure.In order to improve the output characteristics of the solid mover structure,a slot with copper cast mover structure is introduced.The magnetic field and eddy current analysis and finite element results show that the structure can effectively improve the performance of the motor.To improve the torque,efficiency,power factor,torque-to-current ratio,and reduce torque fluctuations as the optimization goals,select the slot depth,slot width and circumferential slot number of the slot with copper cast mover as the optimization variables,using Taguchi method and the multi-objective grasshopper optimization algorithm obtains the optimal combination of structural parameters,which further improves the electromagnetic characteristics of the motor.