| This study aimed at establishing the mathematical model for determining the dynamic regime torque and at emphasizing constructive aspects which influence its magnitude and variation. Brushless direct current motors are very present and there have been carried out researches regarding their design and optimum construction. The technology evolution in several areas has caused an increase in production of permanent-magnet BLDC motors, which has good technical-economic performances for a large range of controlled-speed applications. The study carried out, by the simulations we presented, shows that these motors have high torque oscillations in a complete rotation. There are identified the slots which create high torques, respectively low torques, in a complete rotation, thus justifying the oscillations. In this paper there is emphasized that the optimum variant of maximum torque involves a supply by six pulses per period in direct direction, also indicating the value of the control angle. The most unfavourable variant occurs at brushless direct current motor supplied by three pulses per period and reverse succession of phases, where the average value of the torque decreases by 56.7% over the optimum machine. A complete elimination of oscillations in this type of motor is not possible, but an optimal design can reduce them considerably |
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