Research On Fractional Order Identification And Fractional Order Control Of AC Servo Motor

With the discovery of new permanent magnet materials and the continuous improvement of Motor manufacturing process,constructing of AC servo system with PMSM has become the mainstream of high-performance areas.At present,the AC servo system generally uses the traditional integer order object model and integer order controller.However,in most cases,fractional order phenomenon exists in physical systems,and using only the integer order calculus equation cannot fully picture the characteristics of AC servo system,but also limit its performance to a certain extent.Therefore,this paper will identify PMSM fractional model to obtain a more accurate object model and design the fractional order controller base on fractional model,in order to achieve the performance of the servo system.Firstly,the integer order dynamic model of PMSM is extended to fractional dynamic model by fractional theory,and it is divided into two parts,which respectively is electromagnetic links and mechanical links.For the characteristics of two object links,the identification experiment method of fractional model is designed respectively,and the time domain identification algorithm is designed based on the output error method.Furthermore,in order to get a more accurate fractional model of PMSM,this paper uses DSP and FPGA to build the AC servo control system experimental platform.At the beginning,the fractional identification experiments are carried out on this two parts respectively,and then the fractional and the integer model can be obtained by the system identification algorithm.Then,the controller of the fractional and integer model is designed under the same constraint condition,and the two sets of controllers are simulated in the MATLAB / Simulink,and the experiment is carried out on the experimental platform.Finally,the simulation results are compared with the experimental’ results based on certain indexes,which can find that the fractional model can describe the characteristics of the PMSM system more accurately.Last but not the least,for further improving the performance of the servo system,this paper uses the above-mentioned fractional model to design the controller.The fractional PIλDμ controller and integer PID controller is designed respectively using the same criteria,being used both in simulation and experiment.Through comparing simulation with the experimental results,it is shown that the fractional order controller has better control effect,which can improve the fastness,stability and immunity of the system,and improve the performance of the servo system.