Since the torque characteristic of the 40mm roter radius BLDC is investigated with the fixed 30mm length of the magnet,lm,the height and width of magnet was varied from 8mm to 14mm and 1mm to 7mm respectively due to their limited space avilable in the rotor slot. For more clear view, the dimension of the magnet structure and its position in the rotor is shown in Figure 6,table II shows the overall dimension for the various sizes of the magnet which used in the investigation of the torque behavior according to the modification of the magnet structure.