Initial Rotor Position Estimation For PMSM

PMSMs are widely used in many industry applications for their high efficiency, high power density and good control performance. Initial rotor position of PMSM is exactly required for successful start-up. An initial position error will cause very large current or reverse rotating. The situation is even more serious with a heavy load. The initial rotor position estimation for PMSM is studied in this paper.The forced alignment of the rotor is a conventional method to estimate initial position. The principles of the method and the accuracy factors are analyzed and the implement issues are designed. A method is proposed to eliminate the errors caused by friction. The effectiveness of the proposed method is verified by the experimental results under no load.A method to estimate initial rotor position under load condition is proposed in this paper based on the analysis of the relationship among current vectors, electrical magnetic torque and initial rotor position error. It is successful to avoid the effect of the limit rotor position by the method combined with rotor forced alignment. The effectiveness of the proposed method is verified by the experimental results under condition of load.The method based on the magnetic saturation saliency is able to estimate initial position without rotor rotating. Saturated saliency effect of PMSM is analysis. Initial position estimation is implemented by injecting voltage vectors and detecting the response of current vectors. The accuracy of the method is improved by using voltage vector optimization and current vector process. The method is effective under load condition.Finally, high frequency signal injection is studied to estimate initial rotor position error. The principle is analyzed. The simulation results show that the method is able to estimate the initial position under load condition without rotor rotating.