How Brushless DC Motors Work
The armature of an ordinary DC motor is on the rotor, and the stator generates a fixed magnetic field. In order to rotate the DC motor, it is necessary to continuously change the direction of the current in the armature winding through the commutator and brushes, so that the directions of the two magnetic fields are always kept perpendicular to each other, thereby generating a constant torque to drive the motor to rotate continuously.
In order to remove the brushes, the brushless DC motor puts the armature on the stator, and the rotor is made of permanent magnets. This structure is just the opposite of the ordinary DC motor; however, even this change is not enough, because the armature on the stator passes through the DC current. After that, only a constant magnetic field can be generated, and the motor still cannot rotate. In order to make the motor turn, it is necessary to commutate the phases of the stator armature windings continuously, so that the stator magnetic field can be continuously changed with the position of the rotor, so that the stator magnetic field and the rotor permanent magnetic field can always maintain the left and right space angle, Generates torque that pushes the rotor to spin