An Active Torque Control Strategy for Cost Effective BLDC Motor Drive

Brushless DC motor(BLDC), under the category of special electrical machines, portrays an important role in the industrial and manufacturing applications because of their improved characteristics and better controllability unlike induction machines which are difficult to control. Therefore, BLDC motors have become one of the most favorable choice for applications where efficiency, compactness, and cost-effectiveness is of prime importance. The electrolytic capacitor in a typical BLDC motor drive is bulkier in size and weight and also depends on operating temperature. Elimination of this capacitor will pave way for many advantages to the drive. It improves the reliability and helps to minimize the cost of the drive as a whole and in addition will reduce the area of the printed circuit board and hence the volume of the whole enclosure. But all these happen at the expense of torque ripples, which are inevitable. The proposed compensation technique makes use of a small capacitor on the DC link to energize the motor on demand. Benefits of employing such a small capacitor on the DC link with the switch overcome the disadvantages caused by the absence of the DC link capacitor.