Magnetization of speed sensorless squirrel-cage induction generator for wind power application using a phase-locked loop

The paper proposes a new method for magnetizing speed sensorless squirrel-cage induction generators used in wind power applications. These generators are magnetized at non-zero speeds, and for this reason, their successful magnetization is difficult to achieve. If the generator speed is not known, the required converter output frequency is also unknown and it is impossible to control the magnetization process by using the existing voltage-based flux estimation methods. This paper proposes a magnetization method which is based on a phase-locked loop (PLL) and ensures successful magnetization of the generator when voltage-based flux estimation methods are used. The proposed method is implemented in a digital control system and verified on a laboratory model using two different voltage-based flux estimation methods. The experimental tests carried out on a 560 kW squirrel-cage induction generator show the effectiveness of the proposed method.