User's Manual

Bi-Phase BLDC Motor
Variable Speed DC Fan Control using the MC9RS08KA2, Rev. 0
Freescale Semiconductor 9
1.4 Bi-Phase BLDC Motor
The brushless DC motor (BLDC) design for DC fan is commonly consist of a permanent magnet attached
on the rotor and the stator phase coil windings are mounted on the motor shaft as illustrated in Figure 1-2.
The BLDC has no brushes on the rotor and the commutation is performed electronically at certain rotor
positions.
Figure 1-2. Bi-Phase BLDC Motor Diagram
Fan Hub
Permanent
Magnets
Axle
Hall Effect
Sensor
Stator
Coil