Torque ripple reduction in brushless DC motors by employing three-phase conduction mode drive

In this article, this study aims to reduce torque ripple in a brushless direct current motor by employing a three-phase active mode voltage source inverter, and the torque ripple caused by commutation has been studied in detail. In this study, brushless direct current motors with two different pole numbers and central phase windings, which are frequently used in printing machines, were used. Nowadays, six-step two-phase winding active drives are used as brushless direct current motor (BLDC) drives. In conventional two-phase active mode drives, two phases are connected in series at any time, and the voltage at the ends of the phase windings is half that of the direct current source. In this proposed drive, the phase windings are connected in three different ways, creating a stepped-sinusoidal voltage across the phase windings. This voltage across the phase windings ensures that the current flowing through the phase windings is very close to a sinusoidal current. The closer the current flowing through the phase windings is to a sinusoidal current, the lower the torque ripple. Although the phase windings of the BLDC motors used in the study were centered type phase windings, phase currents were close to sinusoidal. The results from this experimental study showed that the torque ripple of the three-phase active mode drive was significantly reduced. In this work, the torque ripple was found to be 12% in two-phase conduction mode, while it was found to be 7% in three-phase conduction mode.