Design And Research On Compound Magnetic Field Control System Of Aluminum Alloy Low Frequency Electromagnetic Semi-continuous Casting

Aluminum alloy is the widely used non-ferrous metal alloy, improving product quality, reducing production costs is of great significance.This research is a part work of solidification of Al alloy under outer fields,which comes from the project of Improvement of the Quality of Aluminum Products supported by the Major State Fundamental Research Projects of China(973).By a low frequency electromagnetic field applied out of the mould, the fine equiaxedas-cast structures are obtained and surface quality is remarkably improved.So the compound magnetic field control system is important for application of the low frequency electromagnetic semi-continuous casting.The thesis analyses the functional mechanism of low frequency electromagnetic semi-continuous casting and the forming principle of compound magnetic field. In order to match the requirements, the variable frequency converter which is a double PWM converter is adopted in the system. and three-level inverter is used to reduce harmonie content.To match the requirements, a new main circuit structure is brought up, and the design principle is discussed.Ethernet and DeviceNet is used in this system,PLC and touch screen composed Host Computer,the new DSP controler-TMS320F2809 is control core, some modules are emphasized in the paper, such as PWM module,human-machine interface module,watch dog module,current and voltage Detection module.Aiming at the system real-time commanding, the embedded real-time operating systemμC/OS- II is imported.μC/OS- II is transplanted to TMS320F2809 DSP according to its characteristics. The interrupt management,multitask based on management and message exchanging,μC/OS- II are realized. The flow chart of main tasks is also presented. The thesis applies self-adaptive fuzzy controller, Simulation results show that self-adaptive fuzzy control arithmetic can effectively improve dynamic performance of control system and get better control effect than routine PID.Finally, this thesis makes some conclusions, and presents some issues for future research.