Section 3. Bldc Motor Theory - Motorola M68HC08 Manual

Designer Reference Manual — DRM046
DRM046 — Rev 0
MOTOROLA
Freescale Semiconductor, Inc.
A brushless DC (BLDC) motor is a rotating electric machine where the
stator is a classic three-phase stator like that of an induction motor, and
the rotor has surface-mounted permanent magnets (see
3-1. BLDC Motor - Cross
Figure 3-1. BLDC Motor - Cross Section
In this respect, the BLDC motor is equivalent to a reversed DC
commutator motor, in which the magnet rotates while the conductors
remain stationary. In the DC commutator motor, the current polarity is
altered by the commutator and brushes. On the other hand, in the
brushless DC motor, the polarity reversal is performed by power
transistors switching in synchronization with the rotor position.
Therefore, BLDC motors often incorporate either internal or external
position sensors to sense the actual rotor position, or the position can be
detected without sensors.
BLDC Motor Theory
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Section 3. BLDC Motor Theory

Section).
Figure
Stator
Stator winding
(in slots)
Shaft
Rotor
Air gap
Permanent magnets
Designer Reference Manual
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