Study on Properties and Utilization in Research on Control Strategy of Permanent Magnet

　　Study on Properties and Utilization in Research on Control Strategy of Permanent Magnet Synchronous Motor High-performance Direct Torque Control
　　Permanent magnet synchronous motors (PMSM) are widely used in high-performance drives such as industrial robots and machine tools thanks to their known advantages as: high power density, high-torque/inertia ratio, and free maintenance. Although the advantages of Direct Torque Control (DTC) over conventional Vector Control (VC) include the simple structure, motor parameter independent and fast torque response, there are many problems such as error in Special shape NdFeB magnets  stator flux, torque ripple. So, study on control strategy for PMSM DTC has great significance.The main contents include:①In this paper, the structure of PMSM , mathematical model and the principle of PMSM DTC are described. The selection and the role of voltage space vector in PMSM DTC are expounded in detail, and that the traditional DTC deficiencies have been discussed.②The traditional PMSM DTC has many problems, such as stator flux error, the existence of DC drift. A new type of cross-compensation flux observer algorithm is presented in this paper, which exchange the sequence of Low-Pass Filter(LPF) and the compensator.
　　Low-Pass Filter is used in the transient. in the steady state, compensation to flux is activated. New flux observer can effectively solve the problems such as DC drift, measuring interference, and improve the accuracy of flux observation. The observer is very simple in structure, robust to motor parameters uncertainty and easy to implement in the industrial http://www.999magnet.com application③None of the available vectors in the conventional DTC system can offer precise torque and flux linkage control. To further improve the performance, a space vector modulation (SVM) method is proposed in this thesis to offer the desired space voltage vector for accurate control of the torque and the stator flux linkage. A space voltage vector used to compensate the error of the torque and stator flux linkage is calculated based on the error vector between the reference and the actual stator flux linkage.④The simulation of new flux observer by Matlab is done in low and high speed. The results of simulation indicate that the new flux observer can estimate accurately the stator flux linkage.