Research On Servo Drive Used On MW Wind Turbine Pitch Syetem

Wind turbine pitch system is important in the control of the windpower and the safe operation of the wind turbine, played a great role in thesafe, efficient, stable operation of the wind turbine.Electric servo system in the pitch consists of the pitch master, servodrives, backup power and PMSM. Each of the servos drives a paddle inelectric pitch system by the PMSM individually, to achieve independentcontrol of the pitch angle.This paper provided an overview of the structure and classification ofpermanent magnet synchronous motor, established the mathematicalmodels of PMSM in different coordinate systems, analysis and comparisonof different control methods of PMSM, vector control method and itsimplementation was studied.This paper analyzed the advantages and disadvantages of differentmethods of observation of PMSM rotor position. The PMSM rotor positionobserver using a high-frequency voltage injection method was studied.Rotor polarity identification cannot be achieved by the high frequencyvoltage injection method; the method has been improved using theunsaturated effect of the inductance of the stator winding of the PMSM byprocessing the high-frequency currents of the d-axis to identify the polarityof the rotor. The proposed improved method has been theoreticallyanalyzed.The pitch servo drives hardware system, software system has beendesigned, built a pitch servo drive experimental platform. Experimentshowed that the servo drive has a good dynamic response performance;observer of the PMSM rotor position has been verified by experiment, theresults showed that the observer can achieve accurate position observe of the rotor and the polarity identification of rotor.