Study On Magnetic Motor Spindle Control System For NC Machine Tools

Now the development of NC machine tools is forward high speed, high precision, high efficiency and supermatic. The speed-up of spindle system is the main symbol of high-speed machining of NC machine tools, and spindle bearing technology is one of its key technologies. Compared to traditional bearing, the magnetic bearing system is finding more and more application because it can offer a non-contact, non-friction, high precision, and reliable method of suspending a rotor.The principle of magnetic bearing and its basic composition are introduced briefly in the thesis. Based on the analyse of magnetic field and magnetic force of magnetic bearing, mathematic models of axial 1 -DOF and radial 4-DOF are established, which lay the theoretical foundation for the control system design of magnetic levitation bearings.The controller is a key composition of magnetic bearing system. The accurate mathematic model of magnetic bearing cannot be obtained because of the nonlinearity and parameters uncertainty. Ideal controlling effect usually cannot be obtained by using traditional PID controller. The application of BP (Back Propagation) neural network in magnetic bearing was studied, and the control algorithm and control structure which is based on the traditional PID control algorithm and BP neural network was established in the thesis.In this thesis many issues related to DSP (Digital Signal Processing) peripheral components and software implementation of control algorithm are considered. Furthermore, the main program module and flow chart of software design were given.Finally, the process of parameter design for magnetic bearing radial and axial bearing was elaborated. Taking radial bearing as an example, at the ensure of the maximum carrying capacity, the structural parameters of radial bearing are determined by taking minimum gross weight of stator...