Patent ID: 7977910

Claim:
A method of controlling startup of a synchronous motor having a brushless direct current exciter, comprising: applying, by a variable frequency drive controller, a magnetizing current to a motor stator and a predetermined field current to the exciter such that the motor is operated as an induction motor during a first time period; applying, by the variable frequency drive controller, a torque current to the motor stator to rotate a rotor; monitoring, at a phase lock loop operably connected to the variable frequency drive controller, current feedback and voltage feedback from the motor; reducing the magnetizing current applied to the motor stator and regulating the field current applied to the exciter after a certain transition speed such that the motor is operated as a synchronous motor during a second time period; and receiving, at a motor model controller operably connected to the phase lock loop, the current feedback and voltage feedback and providing a motor control component with motor speed and motor flux values during the second time period.