Flying Start of Sensorless Synchronous Machines with Reactive Power Injection

In this work, a flying start of sensorless synchronous machines based on the reactive power injection is proposed to identify the initial rotor position and angular speed under non-stationary conditions. This is realized with a novel control structure designed in the stator current reference frame such that it produces negligible braking torque and has minimal disturbances on the load. The proposed method benefits from a simple structure, low reliance on the motor model and is applicable to the family of synchronous machines. Moreover, the paper provides guidelines for gain selection based on the nominal nameplate parameters and discusses sensitivity analysis to errors in stator resistance. The proposed method is validated in simulation on a 5.5 kW permanent magnet-assisted synchronous reluctance (PM-SyR) machine.