ABSTRACT
In conventional DCmotors with brushes, the field winding is on the stator and armature winding is on the rotor. Because of the brushes, the motor is expensive and needs maintenance. In addition, accumulation of the brush debris, dust, and commutator surface wear as well as arcing cannot be permitted in certain hazardous locations, which limits the application of DC brushed motors. As solid-state switching devices have been developed, it became possible to replace themechanical switching components (commutator and brushes) by electronic switches. In fact, a brushless DC (BLDC) motor has a permanent magnet rotor and a wound field stator, which is connected to a power electronic switching circuit. Rotor position information is required for the power electronic driver. Figure 8.1 shows brushless DC motor drives and Fig. 8.2 a typical BLDC motor.
