Research On Sensorless Control Of Permanent Magnet Synchronous Wind Motor

With the aggravation of the energy crisis and environmental problem, the development and utilization of new energy received more and more attention all around the world. Direct-driven permanent magnet synchronous motor(PMSM) has been widely used in the large wind power generation system since it features simple structure, high-energy efficiency, reliable operation, and high power density. The information of rotor speed and position are necessary in PMSM control system. Since the use of position sensor is not only increasing the system cost but also not conducive to be protected and repaired, the research on sensorless control of PMSM drive has become one of most important considered problems of wind power control system.In this paper, improved speed control and estimation method are proposed respectively. The sensorless control system of PMSM below rated wind speed is systematically studied. The major research and innovative achievements can be illustrated as follows:1. To solve the weak robustness of extended Kalman filtering(EKF) to the permanent magnet synchronous motor without position sensor, a rotor speed estimator based on H∞ filtering algorithm is proposed. Moreover, the amount of calculation is decreased by using reduced-order model of PMSM,in which only rotor speed and position are estimated. The stronger robustness against non-Gaussian noises of H∞ filter can be shown in simulation results comparing with the EKF method.2. To satisfy the high performance control demand for speed tracking problem, a nonlinear predictive controller for a permanent magnet synchronous motor is designed based on optimal control theory. The load torque is considered as an unknown perturbation. Both rotor speed and load torque are estimated through H∞ filter. Combining the controller and H∞ filter, an integrated system of sensorless PMSM can be obtained. The influences of load torque changes are overcame through utilizing estimated value. Finally, quick accurate speed tracking performance can be shown in the simulation results.