Research On Torque Performance Improvement Method Of Model Predictive Control For Induction Motors

Induction motors are widely used in the field of electric AC drive systems owing to simple structure,reliable operation and low price.Model predictive control,as an emerging nonlinear control strategy,has received widespread attention in recent years.Compared with traditional control strategies including field oriented control and direct torque control,model predictive control has the advantages of intuitive concept,flexible control and straightforward handling of nonlinearities and constraints.It also provides an important breakthrough for domestic and foreign scholars in the theoretical research of control methods.In order to improve the torque performance of the model predictive control system for induction motors,a model predictive control method based on sliding mode control(SMC)for induction motors is researched.Firstly,the mathematical modeling of induction motor in different coordinate systems is introduced.The basic implementation steps of the model predictive torque control method are deduced.The effect of motor parameter mismatches in model predictive control system is analyzed in detail.Moreover,in order to improve the torque performance of control system,the SMC controller is used as the speed outer loop of induction motor model predictive control system.The main principles and characteristics of SMC are introduced and the SMC controller is designed.Comparisons of SMC controller and PI controller are elaborated.In order to reduce the inherent chattering problem,a load torque observer is introduced as the feed-forward compensation of the model predictive control system speed outer loop.The basic principles and design method of load torque observer are explained.Stability analysis of the load torque observer is performed.Finally,the model predictive control method based on torque performance improvement for induction motors is verified by Matlab2010/Simulink,and the experimental platform is established using TI DSP TMS320F28335 as the core chip.The correctness and effectiveness of the proposed method are confirmed by different kinds of experiments.The simulation and experimental results reveal that the proposed SMC method not only effectively improves the system’s ability to resist load disturbances,but also has stronger robustness against motor parameter mismatches.