Bldc motor cross section, Phase voltage system, Figure 3-1 – Motorola M68HC08 User Manual
Page 24: Or it can be, Figure 3-2, To be used to create a rotati
BLDC Motor Control
Designer Reference Manual
DRM028 — Rev 0
24
BLDC Motor Control
MOTOROLA
Figure 3-1. BLDC Motor Cross Section
The motor can have more than just one pole-pair per phase. This defines
the ratio between the electrical revolution and the mechanical revolution.
The BLDC motor shown has three pole-pairs per phase, which represent
three electrical revolutions per one mechanical revolution.
Figure 3-2. 3-Phase Voltage System
The easy to create rectangular shape of applied voltage ensures the
simplicity of control and drive. But, the rotor position must be known at
certain angles in order to align the applied voltage with the back-EMF
(voltage induced due to movement of the PM). The alignment between
STATOR
STATOR WINDING
(IN SLOTS)
SHAFT
ROTOR
AIR GAP
PERMANENT MAGNETS
30°
90°
150°
210°
270°
330°
electrical
angle
Phase A
Phase B
Phase C
120°
Voltage
VOLTAGE
PHASE A
PHASE B
PHASE C
120°
ELECTRICAL
ANGLE
30°
90°
150°
210°
270°
330°
F
re
e
sc
a
le
S
e
m
ic
o
n
d
u
c
to
r,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
c
.
..