Section 3. Bldc Motor Control; Contents; Brushless Dc Motor Control Theory - Motorola M68HC08 Reference Manual

Designer Reference Manual — Sensorless BLDC Motor Control

3.1 Contents

3.2 Brushless DC Motor Control Theory

3.2.1 BLDC Motor Targeted by This Application
DRM028 — Rev 0
MOTOROLA
Freescale Semiconductor, Inc.

Section 3. BLDC Motor Control

3.2 Brushless DC Motor Control Theory. . . . . . . . . . . . . . . . . . . . .23
3.3 Used Control Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
3.4 Application Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
The brushless dc motor (BLDC motor) is also referred to as an
electronically commutated motor. There are no brushes on the rotor, and
commutation is performed electronically at certain rotor positions. The
stator magnetic circuit is usually made from magnetic steel sheets.
Stator phase windings are inserted in the slots (distributed winding) as
shown in Figure 3-1, or it can be wound as one coil on the magnetic
pole. Magnetization of the permanent magnets and their displacement
on the rotor are chosen in such a way that the back-EMF (the voltage
induced into the stator winding due to rotor movement) shape is
trapezoidal. This allows a rectangular shaped 3-phase voltage system
(see Figure 3-2) to be used to create a rotational field with low torque
ripples.
BLDC Motor Control
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Designer Reference Manual
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