Flying start and sensorless control of permanent magnet wind power generator using induced voltage measurement and phase-locked loop

This paper proposes a new method for the estimation of the rotor angle of interior permanent magnet generators used in wind power applications. The proposed method provides the flying restart and the continuous operation of permanent magnet generators. The paper addresses the problem of switching on the converter (start of the pulse-width modulation) when the generator rotates and the occurrence of inrush current if the converter is not synchronized with the generator. The proposed method is based on the induced voltage measured at generator terminals before switching on the generator converter and on a phase-locked loop with a proportional-integral position controller, which ensures the decoupled sensorless control of the permanent magnet generator. The simulation results show a comparison between the performances of the proposed method and the method based on the back-EMF. The proposed method is implemented in a digital control system and verified on a laboratory model. The experimental tests carried out on a 375 kW interior permanent magnet generator show the effectiveness of the proposed method.