Research And Implementation Of PMSM Direct Torque Control System Based On DSP

Direct torque control (DTC) theory has attracted wide attention since it was proposed. Unlike vector control, the flux and torque are calculated by the parameters of motors with the help of space vector theory. However, there are still many problems to be solved in conventional DTC and scholars have proposed many valuable ideas and methods.In this paper, PMSM is set as the research object. The development of PMSM DTC is described by reading many relevant literatures. To improve the shortcomings of conventional DTC, this paper will achieve it from two aspects:First, from the aspect of optimizing switching table of conventional DTC, In order to improve the asymmetry of the flux and torque, six sectors division of the stator flux in conventional DTC has been changed into eighteen sectors. Zero vectors are also used to stabilize and maintain the torque. The simulation results show that eighteen-sector division of stator flux combined with zero vectors in DTC can improve the flux asymmetry and reduce the torque ripple effectively.Second, from the aspect of abandoning speed sensor in conventional DTC, the speed estimation algorithms based on adaptive control are used in the paper. Speed estimation formulas are deduced according to the basic principle of stability theory. Then, the speed and rotor position of the motor can be estimated by detecting the parameters of PMSM. The complexity of the circuit is simplified. The simulation results show that the speed estimated by adaptive control has high accuracy and response speed.Finally, the method of improving switching table in DTC has been accomplished in CCS development platform. The algorithms are eventually implemented based on DSP TMS320F2812. The experiment results verified the validity of the algorithms.