Sensorless Direct Torque Control Of PMSM Using Unsected Kalman Filter

With the advantages of high-power density and high efficiency, PMSM has beenwidely used in the current field of AC speed regulation. Compared with the traditionalvector control, the complicated vector transform is not needed for direct torquecontrol,and the place of VC is gradually replaced by DTC in motor field. In thetraditional motor-controlled system, the mechanical sensor is mainly used, however themechanical sensor reduces reliability by the environment and increases the cost of theoperation.So the sensor-less technique becomes the focus of the research in theapplication of the permanent magnet synchronous motor control.In the field of sensor-less technology, many methods for detection have been putforward by experts and scholars, but most of them have the disadvantages of lowrobustness,low speed,low precision and over-dependence on motor parameters.However among these methods, EKF is the mostly widely used, but there are largedifferences and difficult realization of high-order system when the EKF algorithmsolves the linear filtering problem. Therefore some scholars proposed one kind ofimproved algorithm which is based on UKF,namely UDUT UKF. the algorithmdoesn’t need to calculate the square root and has high stability. It has been widely usedin the application of navigation and positioning, but still not in the field of AC motordrive control.This paper will get the value of the electromagnetic torque through the accuratelyestimation of the stator flux,rotor speed and rotor-potion which is based on the improvedalgorithm.thereby a controlled system of sensor-less permanent magnet synchronousmotor direct torque is established. Compared with the simulation results of the EKFalgorithm, the algorithm of UKUTUKF has higher accuracy and stability.