Study On Chaotic Characteristics Of PMSM Under Time-Delay Nonlinear Contro

Permanent magnet synchronous motor(PMSM)has the characteristics of light weight,high reliability,and high output efficiency,so it is popularly used in power transmission,aerospace,and other fields.The mathematical model of the PMSM system proves that it has chaos phenomenon and it is a nonlinear system with multivariate and strong coupling characteristics.The PMSM can generate chaos in a certain parameter range and under certain operating conditions,when the phase diagram of the system state variables will show complex nonlinear chaotic characteristics or limit cycles phenomena.One of the important causes of PMSM system instability or oscillation is the chaos phenomenon generated by the system,which may lead to the degradation of the system’s operation performance and even damage the motor.Chaotic phenomena are an important part of the nonlinear field and a leading edge of scientific research,which are both prevalent and extremely complex.And the time delay phenomenon exists in almost all control systems,therefore,it is meaningful to study the chaotic characteristics when PMSM time lag nonlinear control.First of all,the mathematical model of PMSM in the two-phase rotating coordinate system of d-q axis is obtained by the method of coordinate transformation,and the chaos model of PMSM is derived by using two methods of linear affine transformation and time scale transformation,respectively.The stability analysis of the bifurcation behavior of the system at the equilibrium point is performed for two different external input cases of the system,and the corresponding system eigenvalues are solved for the two different cases.Then,the parameter values of the system are adjusted and some numerical simulations are performed for example analysis,and the results illustrate the limit cycle or chaotic behavior that the time domain and trajectory phase diagrams of the system state variables can exhibit.A small change is made to the initial value of the system as a way to investigate the high sensitivity of the system to the initial value.After that,the subsequent validation experimental part of the thesis is prepared,and the sliding mode variable structure control strategy is selected by understanding the time delay phenomenon present in the motor.A sliding mode speed controller is designed based on the power reaching law,and its stability is verified by applying Lyapunov stability theory.Finally,the designed sliding mode speed controller is applied in the simulation and physical experimental platform and compared with the conventional PI controller,and chaos verification experiments with different stable speeds are performed and the chaos phenomenon is observed.The system model in this thesis is built in a Matlab/Simulink simulation environment,and the chaos phenomenon is verified on a physical experimental platform with TMS320F28335 as the control core.Acquisition of relevant data for simulation and experiment,time domain and trajectory phase diagrams of the system’s state variables are plotted by data processing software.The simulation and experimental results show that the trajectory curves of the state variables are all moving irregularly within a bounded range,which not only verifies the correctness of the theoretical analysis,but also proves the existence of the chaos phenomenon in the actual motor.Comparison of experimental results and screenshots obtained from the oscilloscope show that the sliding mode variable structure control has better control over the chaos phenomenon of the motor.