Direct Torque Control System Of PMSM Based On Model Predictive Control

Permanent magnet synchronous motors have many advantages,such as small size, high efficiency, simple structure and so on. With the rapid development of permanent magnetic materials and the reduction of cost, PMSM control systems have a high value on research and development in many areas.Direct torque control is a high performance speed control method and has novel idea, simple structure and fast response, it regards the torque as control object directly.In recent years, direct torque control has become a hot topic. But in traditional direct torque control system, the speed and torque ripple are terrible.In order to overcome these shortcomings, a new direct torque control system of permanent magnet synchronous motor based on model predictive control is proposed.Firstly, several control strategies of PMSM were analyzed, and the current research of direct torque control system were summarized. Then, three kinds of mathematical models of permanent magnet synchronous motor in three kinds of common used coordinate and transformation relation were deduced. And the theory of direct torque control were analysed in detail.The actual model and the reference model equations of permanent magnet synchronous motor were established.The control rate was derived reversely with the error vector, and then the backstepping control model was established. The stability of the system is proved by using Lyapunov stability theorem and then the stator flux and torque values were predicted.At the same time, due to the uncertainty of the motor model, so the Control volume by using backstepping model need to optimize. Through the specifically designed evaluation function for backstepping model to consider d-q axis voltage and current constraints,the optimal input voltage vector is selected and the stator flux and torque errors are kept to a minimum.By using Matlab/Simulink simulation tool the simulation model is constructed based on above theory.Through the analysis of simulation results, the direct torque control system of permanent magnet synchronous motor based on backstepping model predictive enables the waveform speed and torque improved. And the control strategy is running at low speed can be achieved at high speed with an approximate control results.Finally, using the TMS320F2812 DSP control chip designed hardware system and software system of the permanent magnet synchronous motor control system.