Page 342 - CITS - Electronic Mechanic - TT - 2024

ELECTRONICS MECHANIC - CITS

Hall Sensor

Hall sensors synchronize the stator armature excitation by sensing the position of the rotor. The commutation of
BLDC motors is controlled electronically causing the stator windings to be energized in sequence to rotate the
rotor. Before a winding can be energized, the Hall sensor identifies the position of the rotor. Most BLDC motors
have three Hall sensors that are placed in the stator. Each of the sensors generates a low and high signal when
the rotor poles pass near them.
Benefits of BLDC Motor
• Absence of mechanical commutator to avoid wear
• High efficiency
• High speed of operation in loaded and unloaded conditions

• Smaller motor geometry and lighter weight
• Long life
• Higher dynamic response because of low inertia and carrying windings in the stator
• Less electromagnetic interference
• Low noise and quiet operation

Uses for DC Motors
Diesel Electric Locomotives
In a diesel electric locomotive, combustion from the diesel engine is converted into rotational energy by the diesel
engine, which is coupled with a generator that converts it to electrical energy. The converted electrical energy is
fed to DC motors that are coupled with the wheels on the engine.
Electric Vehicles

Brushed DC motors are used in electric vehicles for retracting and positioning electrically powered windows.
Since brushed motors tend to wear out rapidly, many electric vehicle applications use brushless motors due to
their long life span and noiselessness. Brushless DC motors are used for windshield wipers and CD players. All
of the recent hybrid electric vehicles depend on brushless DC motors.
Cranes
In applications with overhauling loads, it is important for the motor to have the ability to hold a full load at zero
speed where mechanical brakes may not be required. In those situations, DC motors are the most cost effective
and safest option. A major benefit of their use is their size and weight.

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CITS : E & H - Electronics Mechanic - Lesson 205 - 222