A new sensorless control strategy used in direct-drive PMSG wind power system

This paper introduces the operating principle of back-to-back converter in direct-drive variable speed constant frequency (VSCF) wind power system. In system in order to obtain the accurate information of motor speed and angle, and alleviate the shortcomings, a new estimation method of permanent magnet synchronous generator (PMSG) speed and rotor position based on phase-locked loop (PLL) is proposed in this paper. Simulation model and experimental prototype were established. The simulation and experimental results indicate that the sensorless vector control method based on PLL can obtain accurate speed and angle information of PMSG. Then the fast response, good current control effect, and good steady state and dynamic performances, can also be achieved by sensorless vector control of PMSG. Specially, this method is suitable for medium and small scale wind power generation system.