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Motorola M68HC08 User Manual

Page 14

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Introduction

Designer Reference Manual

DRM028 — Rev 0

14

Introduction

MOTOROLA

Once using the semiconductor components, it is opened to replace
classical universal and DC-motors with maintenance-free electrically
commutated BLDC motors. This brings many advantages of BLDC
motors when the system costs could be maintained equivalent.

The advantages of BLDC motor versus universal and DC-motors are:

high efficiency

reliability (no brushes)

low noise

easy to drive features

To control the BLDC motor, the rotor position must be known at certain
angles in order to align the applied voltage with the back-EMF, which is
induced in the stator winding due to the movement of the permanent
magnets on the rotor.

Although some BLDC drives uses sensors for position sensing, there is
a trend to use sensorless control. The position is then evaluated from
voltage or current going to the motor. One of the sensorless technique is
sensorless BLDC control with back-EMF (electromotive force)
zero-crossing sensing.

The advantages of this control are:

Save cost of the position sensors & wiring

Can be used where there is impossibility or expansive to make
additional connections between position sensors and the control
unit

Low cost system (medium demand for control MCU power)

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Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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