Heretofore BLDC motors are widely used in many applications. High power density, low cost, low losses due to the absence of magnetizing currents are some of the advantageous of these kinds of machines that has increased their application. PMSMs have the most torque density and instantaneous rotor position information is not needed for controlling them. One of the most important reasons limited BLDC motors applications is their high torque ripple, specifically commutation torque ripple. in this thesis, the purpose is to hire a proper method to eliminate the mentioned disadvantage and reduce torque ripple in BLDC motors. Till now, a lot of approaches have been proposed to solve this restriction. Recently, a new method based on supplying currents considering all harmonics of Back EMFs is proposed which is known as petal wave current supply method. this method is employed in this thesis for three phase current conduction. High torque ripple caused by Back EMF harmonics are removed. More ever, the advantage of high torque density is retained. By checking currents and torque ripple in different speeds, a disadvantage of the applied method is detected. The disadvantage belongs to controlling currents. Since in high speed remarkable torque ripples are detected, an adaptive notch filter based on SOGI (Second Order Generalized Integrator) model to extract harmonic components and two different rotor frame to control currents are applied. While the latter is used for the fundamental component of currents, the former is used for harmonic components. It is notable that the second rotor frame is chosen based on the major harmonic component. Keywords: PMSM, BLDC, torque ripple, commutation, harmonic components, SOGI, notch filter.
