Study On The Speed Sensorless Vector Control Of PMSM

The mechanical sensors not only hinder the development of motors to high-speed andminiaturization, but also reduce system reliability easily and deteriorate environmentaladaptability in traditional permanent magnet synchronous motor control system. In orderto overcome the various defects of the sensors bring, speed sensorless control technologyhas been a hot topic in the field of motor control and achieved fruitful research in recentyears. This thesis deals with the speed estimation for PMSM in the full speed range.This thesis designs a speed identification system based on a speed-adaptive observerbased on the dual-loop speed control system of PMSM. The dynamics of the system areanalyzed by linearizing the observer in full speed and load range when the observer gain isselected to different design methods. The simulation results of the speed identificationsystem in both open-loop and closed-loop show that the system has a good dynamic, staticperformance and anti-load disturbance in high, medium and low speed range.This thesis also studys the parameter sensitivity of the system in the electric mode atlow speeds due to the adaptive observer model is closely related to motor parameters. Theproblem of system instability caused by the motor saliency effects is analysised. Thesimulation results for the stator resistance and inductance time varying show that thesystem has a poor ability in anti-interference and stability at low speeds.To solve the estimated performance at low speeds, the observer augmented with asignal injection technique is researched. The simulation results show that the method iseffective to enhance the system parameter robustness and speed observation precision,improve low-speed performance of the speed-sensorless vector control system.