Permanent Magnet Synchronous Motor Direct Torque Control Improvements

With the development of motor manufacture technology, electrical and electronics technology and computer control technology, Servo systems are used in industrial controllers and household appliances. Digital controlled AC servo systems will be the trend, which uses Permanent Magnet Synchronous Motors (PMSM) as power units and Direct Torque Control strategy, based on DSP. So it is necessary to research high performance AC servo systemsIn this paper, the author does some research and amelioration on Direct Torque Control system of Permanent Magnet Synchronous Motors. Direct Torque Control (DTC) is a novel technology of frequency conversion timing after Field Oriented Control (FOC) in the field of AC drive systems. The principle is analyzed and the characteristics are presented. DTC has very fast response of torque dynamic performance. But, only one space voltage vector applied in each sampling period in PMSM DTC servo system results in large ripples of torque and stator flux linkage. Because DTC has weakness, a novel direct torque control of PMSM based on observing error of stator flux linkage is proposed. It can realize continuous voltage vector modulation and decrease the torque ripple and enhance the performance of AC drive systems.The simulating models of DTC and DTC-SVM are built, and experiments are carried out. The results of simulation and experiments show: The control strategy of DTC-SVM is validated.