Position sensorless start-up method of surface permanent magnet synchronous motor using nonlinear rotor position observer

A Virtual Impedance-Based Flying Start Considering Transient Characteristics for Permanent Magnet Synchronous Machine Drive Systems

“…Because the transient state caused by the inrush current cannot be predicted and there is a risk of inverter destruction, appropriate control methods are needed to estimate position and speed. Therefore, the initial position/speed estimation method, which is called "flying start", of a rotating machine before FOC has been studied recently [17][18][19][20][21][22][23][24][25][26][27][28].…”

“…One method is to measure the voltage at the rotating stator terminals [17,18]. Position and speed can be determined by measuring the back EMF induced by the rotation of the machine; however, additional voltage sensors are required for this method.…”