Design Of Direct-drive Permanent Magnet Synchronous Motor For New Energy Low-speed Electric Rail Locomotive

In view of the current situation of increasingly tight energy supply,it has become a trend for locomotives in industrial and mining plants to adopt high-efficiency and energy conservation drive systems.As an electromagnetic device with low speed,high power density,low speed and high torque permanent magnet synchronous motor has a very wide range of application prospects in industrial and mining fields.Due to the high power density of the low-speed and high-torque permanent magnet synchronous motor,it will produce abundant heat during operation,and the limited installation space makes it difficult to dissipate heat.Excessive temperature rise may cause safety hazards to the motor operation.Therefore,reasonable design of motor parameters,accurate calculation of motor losses,and study of motor temperature distribution are very important tasks.In this paper,a direct drive permanent magnet synchronous motor for rail locomotives was designed and its performance was analyzed.First,according to the performance indicators and technical requirements of low-speed and direct-drive permanent magnet synchronous motors for railway locomotives,electromagnetic design of a 160 k W,160 rpm low-speed direct-drive permanent magnet synchronous motor mostly contained the design of the main dimensions of the motor,the selection of the number of pole slots,the stator slot type and the rotor structure,design of stator slot size and permanent magnet size,and selection of various materials.Finally,the rationality of the design data was verified through preliminary calculations,and the preliminary design data was confirmed.Second,after initially determining the design data of the motor,based on the relevant theories of the electromagnetic field,a two-dimensional finite element model of the electromagnetic field was established to analyze the motor's no-load and load performance,focusing on the no-load and load transient magnetic field of the motor.Finally,the stator and rotor core loss,winding copper loss,and permanent magnet eddy current loss were analyzed in detail,which was the basis of the following analysis of the temperature field.Third,On the basis of the analysis of the electromagnetic field and the calculation of the loss,it was analyzed and calculated that the temperature field of the motor.In order to improve the calculation accuracy of the temperature field of the motor,the two-way coupling between Maxwell and the thermal analysis module was realized in ANSYS Workbench,and the temperature distribution cloud diagram under the rated load of the motor was received.Through the analysis,it was found that the motor's temperature distribution is appropriate,and the temperature of each part is within the maximum allowable temperature,indicating that the design is appropriate.Finally,through sensitivity analysis,the influencing factors that affect the motor efficiency and cogging torque are obtained,and the trend of the influence of the slot width,air gap length and permanent magnet size of the motor on the efficiency and cogging torque was parametrically analyzed,and the value of the influencing factor was obtained.On this basis,the response surface optimization method was used for multi-objective optimization.According to the optimization results,the magnetic thermal performance of the motor was simulated and verified,and the performance of the motor was found to be significantly improved after analysis.The successful implementation of this research provides a reference technical solution for the electromagnetic heating design of low-speed direct-drive permanent magnet synchronous motors for rail locomotives.