Brushless DC motors are divided into two-phase and three-phase according to the number of drive coils (number of phases). There are also several ways to drive and wire the coil.
Motor wiring diagram of three-phase drive coil:
Among them, (c) is unipolar drive. One end of the driving coils LA, LB, and LC is connected to +VCC, and the driving current of each coil is switched by a transistor switch. Since the voltage applied to each coil has the same polarity, it is called unipolar drive. The characteristic of unipolar drive is that the drive circuit is simple and easy to achieve low cost. However, the torque and rotation smoothness of the motor are not as good as bipolar drive.
Figures (a) and (b) are bipolar drive, the drive coil is driven by two transistors on each upper arm (power side) and lower arm (ground side). In the bipolar drive mode, there are two ways of wiring the motor coils: the star connection shown in figure (a) and the delta connection shown in figure (b). In the case of the same coil diameter and number of turns, the delta connection has a larger current, which is suitable for large torque designs.
Wiring diagram of coreless brushless motor:
Wiring diagram of industrial brushless motor:
Wiring diagram of integrated brushless motor: