Adaptive Input-output feedback linearization control of Brushless DC Motor with arbitrary current reference using Voltage Source Inverter

Torque ripple reduction of Brushless DC Motors (BLDCs) with concentrated winding is an attractive subject in variable speed AC drives. In ideal BLDC with trapezoidal back-EMF torque ripple elimination can be achieved using rectangular stator current, while in motors with non-ideal back-EMF, feeding the rectangular current leads to more torque ripple. In this paper at first, a mathematical expression for torque ripple harmonics is done. Then for a non-ideal BLDC motor with known harmonic contents of back-EMF, calculation of desired reference current amplitudes, which are required to eliminate some selected harmonics of torque ripple, is reviewed. In order to inject the reference currents to the motor windings, an adaptive input-output feedback linearization control is proposed, which generates the reference voltages for three phases Voltage Source Inverter (VSI). Also, this method is robust against the motor parameter variations like as stator's resistance and leakage inductance. The effectiveness of the proposed method is evaluated with simulation in the two harmonic selection methods.