Design And Implementation Of The Speed Sensorless Vector Control System Of Permanent Magnet Synchronous Motor

Permanent magnetic synchronous motor(PMSM) is widely used in medium- and lowscale motion control systems and high performance required application fields for its outstanding characteristics such as compact size, high efficiency, high power density and wide speed range. Photoelectric encoders or resolvers are commonly used to measure the speed of the shaft in PMSM control systems, however, several drawbacks are introduced by these speed sensors, such as increment of motor size and price, degradation of robustness of the whole system. As a result, sensorless control of PMSM has become a hotspot in recent years.In this thesis, theoretical analyses and physical implementation are carried out on the focus of sensorless control techniques of PMSM and their related problems.Field oriented control theory of PMSM is introduced, furthermore, two detection methods of initial position of the rotor are proposed. On basis of the magnetic saturation effect,the voltage pulses injection method utilizes approaching based angle searching algorithms where identification precision can be improved by increasing approaching iterations. On the other hand, high frequency signal injection takes advantage of the saliency of the motor, by selecting the pulsating voltage signals, this identification method is independent of the model and parameters of the motor, consequently high precision can be achieved. A new method with separated estimation algorithms on high and low speed ranges respectively is proposed,which can be operated in the full speed range. The high frequency signal injection method and the voltage model based method are used for low speed range, high- and medium-speed ranges correspondingly, during transition, linear switching between each other is applied.High frequency signal injection is independent of motor parameters and operation environments, where rotor position can be extracted effectively in zero and low frequency based on the saliency of the motor. Whereas the voltage model based method bases on the fundamental excitation function of the motor, which has good dynamic performance. The combination of the two methods improves performance of the PMSM control system greatly, including steady and dynamic performance, behavior in low frequency and anti-disturbance.Control software is designed and implemented on the TMS320F28062 microchip, on which field oriented sensorless control of PMSM is carried out. Validity and effectiveness of the two proposed initial position detection methods and the two speed estimation methods,as well as their values in engineering applications, are verified via experiment results.