Research On Layered Multi-objective Optimization Method Of Permanent Magnet Torque Motor

Permanent magnet torque motors are widely used in aerospace,machine tools,industrial robots and other fields with many advantages such as high torque density,strong overload capacity,and low torque ripple.With the transformation and upgrading of my country’s industrial manufacturing,the requirements for the performance of torque motors have become more stringent.At present,how to achieve high output torque and low torque ripple has become a research hotspot of torque motors.This paper takes the permanent magnet torque motor applied to the robot joint as the research object,and the torque performance of the motor is improved by optimizing the design parameter size of the motor.This paper starts with the optimization design of the torque performance of the slotless torque motor with fewer parameters,and the principle and process of the multi-objective optimization design of the motor are analyzed.The support vector machine(SVM)is used to complete the fitting of the functional relationship between the average torque and back-EMF harmonic distortion rate and the seven design parameters.The surrogate models of the optimization objectives are obtained,and the accuracy of the surrogate model is verified.Based on the above two surrogate models,a multi-objective optimization model is obtained,and the improved asynchronous time-varying particle swarm algorithm is used to search the model to obtain the pareto front surface.The appropriate design parameter combination is selected,which can prove that SVM and PSO feasibility in the field of motor optimization.It is also proved that the optimization of the back-EMF distortion rate is beneficial to reduce the torque ripple of the motor.and prepares for the design and optimization of the slotted torque motor.This prepares for the design and optimization of the slotted torque motor.For the characteristics of many design parameters for slotted torque motors,in the above optimization method,the design parameter stratification is added.According to the relevant theory and experience of motor design,the initial design of the motor structure and parameters is completed.Orthogonal experiment and range analysis are used to analyze the sensitivity between the design parameters and the optimization objective,and the design parameters are classified according to the different sensitivity.The design parameters and the optimization objectives are decoupled to a certain extent.The optimization of the motor output torque,back-EMF harmonics and cogging torque are completed by layering.The simulation results prove that the torque performance is improved and the actual demand of the motor is met.For the temperature rise problem caused by the large current density of the torque motor,the selection and design of the cooling system water channel are completed according to the structure and loss of the motor.The temperature field of the motor working in the rated state and the overload state is carried out.The simulation shows that the maximum temperature under the two working conditions does not exceed the temperature rise limit,which verifies the rationality of the cooling system.In order to verify the rationality of the designed motor and cooling system design,the prototype of the slotted torque motor is completed and the prototype performance test platform is built.By no-load experiment,load experiment and temperature rise test on the prototype,measuring and recording the back-EMF amplitude of the motor and the output torque of the motor respectively.Due to friction in the experiment and machining errors in the prototype,the actual results and simulation have certain errors.The result meets the requirements of technical indicators,which proves the rationality of the prototype design.