Sensorless Field Oriented Control of BLDC motor based on Sliding Mode Observer

This paper presents the sensorless field oriented control of a brushless direct current motor (BLDC). A sliding mode observer is used to estimate the phase currents, after the current observer, a back-EMF observer is proposed to estimate the electrical position and speed of the rotor. The back-EMF sensorless operation is intended for medium to high speed. A comparison with a conventional observer and the proposed observer is carried out. Numerical simulations are presented to validate the proposed sliding mode observer for the sensorless field oriented control of a BLDC motor.