beautypg.com

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

background image

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

.

..