| With the innovation of science and technology and the development trend of industry,manufacturing equipment puts forward higher requirements for its driving and transmission devices.The feed system directly driven by linear motor can greatly simplify the overall structure of the equipment,improve the transmission efficiency and control accuracy.However,there are some restrictions on power,cost and reliability of traditional linear motors.Especially in long-distance,large thrust,multi-axis drive and other applications,the high cost of traditional permanent magnet linear motors greatly restricts its application scope.In recent years,a new type of permanent magnet linear motor,switched flux permanent magnet motor,has attracted wide attention.The permanent magnet and armature coil of the motor are placed in the primary stage,and only salient core exists in the secondary stage.The short primary and long secondary structure can greatly reduce the overall cost of the motor,especially for the feeding system with large thrust and long stroke.However,the motor has not been widely used at present.In our previous work,we designed a switched flux linear motor for the feed system of NC machine tools.On this basis,the dynamic characteristics of the motor were studied by combining theoretical analysis,finite element numerical simulation and experimental research.The main work is as follows:Firstly,the electromagnetic field characteristics of a complementary switched flux permanent magnet linear motor designed by the research group are analyzed.According to the determined design parameters of the prototype,the two-dimensional transient electromagnetic field finite element model of the motor is established.The no-load backEMF and winding turn flux of the motor under no-load condition are analyzed.The output thrust,core loss and copper loss of the motor under load condition are analyzed by loading different current densities and given different operating speeds on the model.Then the thermal characteristics of the switched flux permanent magnet linear motor are studied.According to the basic theory of heat transfer,the equivalent thermal circuit model of switched flux permanent magnet linear motor is established,and the loss and temperature rise of each part of the motor are calculated theoretically.Based on ANSYS workbench software platform,the Electromagnetic-Thermal coupling field of the linear motor is simulated by finite element method,and the temperature distribution under different current loads is analyzed.The cooling system of all kinds of motors is studied.On this basis,three cooling modes of switched flux linear motor are designed,and their advantages and disadvantages are compared.The driving control of the switched flux linear motor is analyzed.The mathematic model of the motor is established,and the "id=0" field-oriented control method of the motor is determined.The overall structure of the motor drive system is established,and its servo controller is designed.Feedforward controller is used to improve the response speed,and fuzzy sliding mode control is used to improve the robustness of the system.Combining the finite element model of Maxwell electromagnetic field,Simplorer driving circuit simulation model and Simulink control circuit simulation model,the field-circuit coupling simulation analysis of the whole feed system is carried out.Finally,the dynamic characteristics of switched flux linear motor are experimentally studied.On the basis of the prototype manufactured,the driving control system is built,and the driving response performance of the feed system under different operating speeds and loads is analyzed.The temperature detection system of switched flux linear motor was established to test the temperature rise of the motor under different operating speeds and loads,and the end wind cooling device was set up to test its cooling effect.The results show that the feed system of switched flux permanent magnet linear motor designed by our research group has high power density,fast dynamic response performance and good tracking control accuracy. |
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