Analysis of Losses in Brushless Direct Current Motors and Their Influence upon Operation Characteristics


Researches regarding the optimum design and construction of brushless direct current motors are very present, owing to their use in small-dimension vehicles (elec-trical scooter, electrical bicycle, motor-scooters, electrical vehicles for disabled passengers). Motors used in two-wheel or four-wheel conveyances are permanent magnet direct current motors, manufactured by brushless technology. The operation, starting and speed control characteristics of the brushless direct current motor designed must correspond to certain conditions of competitiveness and to high exigencies imposed by the complex equipments used in passenger-transport vehicles. The study carried out and the simula-tions presented aim at identifying the important losses in order to reduce them. The widespread use of command electronics associated with power components, in brushless direct current motors supply, enabled the optimization of their operation, with special performances. In this paper there is presented the revised computation relation for iron losses, known in design, by establishing separately the two components: hysteresis losses and eddy-current losses. This way, the efficiency obtained in the design stage gets close to the experimentally established efficiency, the error being less than 2%. images