Reduction of commutation torque ripples in brushless direct current motors

In this thesis, it is aimed to reduce the torque ripples occurring during commutation of phase currents of brushless direct current motors (BLDCM) operating at both low and high speeds by using direct current (DC) link voltage control technique. This technique is achieved by placing a DC-DC converter in front of the inverter to obtain the voltage level required to equalize the slopes of the incoming and outgoing phase currents during commutation at the maximum level. A mode selector circuit is designed for this operation. The mode selective circuit was used in the commutation times. Except for commutation time was used the normal source voltage of the BLDCM. The simulation studies carried out under different load and different speed conditions. When the simulation results are compared with those of the traditional BLDCM, it was observed that the torque ripples occurring in commutation decreased considerably.