Research on sensorless control system of permanent magnet synchronous motor for CNC machine tool

CNC machine tool is the foundation of modern machinery industry, and plays an important role in the development of national economy and the promotion of national comprehensive national strength. The development of servo drive control technology of CNC machine tool is the key to improve and improve the performance of machine tool in all aspects. Permanent magnet synchronous motor (PMSM) has become the mainstream of modern machine tool AC servo drive control system because of its simple structure, small size, light weight, high efficiency, high power factor, low moment of inertia. Direct torque control (DTC) is a new high-performance variable frequency speed regulation technology after vector control. In PMSM DTC system, the rotor position information is usually needed to realize the commutation operation of the motor, which is difficult to be used in some specific PMSM sensorless control. In this paper, a sensorless direct torque control method for permanent magnet synchronous motor based on low speed pulse high frequency stator flux injection is proposed, and the stator flux estimator is improved to improve the accuracy of traditional stator flux estimator based on current model. Experiments are carried out to verify the effectiveness and feasibility of the proposed strategy.