Study On Sensorless Control Of PMSM Based On The Theory Of Nonlinear Estimation

Permanent magnet synchronous motor (PMSM) is attractive candidates for high performance drive systems because of its high efficiency and suitability for wide speed ranges of constant power operation. The demand of inexpensive and reliable drive now pushes applied research toward the elimination of mechanical sensors. Recently, sensorless position control of motor is a challenge. There have been numerous publications on methods to eliminate the position sensor on motors in the last several years. Most of these techniques are based on tracking back EMF, which limit the low speed operation of the machine, and is sensitive to the estimation of machine parameters, such as stator inductance and resistance. High performance position control at low speed and zero speed is possible using anisotropic effect being not considered in the fundamental-frequency. At very low speed, several high-frequency signal injection methods have been proposed for estimation rotor position in addition to the fundamental machine driving signals. The main common practical problem in the high frequency signal injection approach is how to process response due to the injected high frequency signal and how to estimate properly rotor position through response processing.Based on the theory of nonlinear estimation, we researched on the sensorless control of PMSM. The PMSM vector control system is first studied by simulation to verify the validity of the PMSM model built. Then for sensorless vector control, the nonlinear estimation technology as extended Kalman filter (EKF) is adopted for estimating the rotor speed and position. To overcome this limitation of EKF algorithm, the interpolation filtering and unscented Kalman filtering are adopted as new nonlinear estimation methods in sensorless PMSM vector control system. Simulations of the systems designed above are carried out to validate the performances. With the dSPACE system, experimental researches on sensorless vector control are given which show the effectiveness of the system and the methods.