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Brushless DC (BLDC) motors are widely used in various low-power drive applications owing to their several advantages over conventional motors. This study describes a fuzzy logic-based improved loss minimisation technique for the BLDC motor drive system. The proposed algorithm uses selective harmonic elimination-based pulse-width modulation to optimise both the converter switching losses along with machine core and copper losses based on a speed-and load-dependent fuzzy rule matrix. The optimum switching angles eliminating lower-order harmonics are calculated offline and stored in microcontroller memory for online application. The suitability of the proposed control is well demonstrated through simulation and experimental results on a practical 350 W BLDC machine.

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Permanent magnet brushless dc (BLDC) motor drives are widely used in high performance applications where torque smoothness is essential. In this paper, the reduction in commutation torque ripple due to phase commutation of brushless dc motor is described. In a conventional three-phase BLDC machine with two-phase 120 0 electrical conduction, commutation torque ripple, which occurs at every 60 0 electrical degrees changing over of load current from one phase to another. The torque ripple increases at higher speeds due to increase in commutation time. On the other hand for 180 0 switching mode of phase currents, the torque ripple reduces at higher speeds but shows substantial increase at lower speeds. In this paper a hybrid switching characteristics is proposed at lower and higher speeds for satisfactory operation. Computer simulation and suitable experiments has been shown to validate the concept.