Ch-13 DC Motor Drives
Ch-13 DC Motor Drives
Ch-13 DC Motor Drives
DC Motor Drives
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A Table of Contents
1. Introduction
3. Permanent-Magnet dc Motors
6. Dc Servo Drives
7. Adjustable-Speed dc drives
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Introduction
1. Traditionally, dc motor drives have been used for speed and
position control applications.
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Equivalent Circuit of dc Motors 1/3
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Equivalent Circuit of dc Motors 2/3
dia
vt ea Ra ia La
dt
d m
Tem J Bm TWL (t )
dt
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Equivalent Circuit of dc Motors 3/3
Tem kT I a
Ea k E m
Vt Ea Ra I a
1 R
Permanent-magnet dc motor m (Vt a Tem )
KE kT
equivalent circuit
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Permanent-Magnet dc Motors 2/3
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Permanent-Magnet dc Motors 3/3
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Dc Motors With a Separately Excited Field Winding
1 Ra
m ke f (Vt kt f Tem )
Va<100% Va=100%
Flux = 100% Flux <100%
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Effect of Armature Current Waveform
Form Factor
The form factor for the dc motor armature current is defin
ed as
I a (rms)
Form factor
I a (average )
Torque Pulsations
Electromagnetic torque Tem (t ) developed by the motor is
proportional to the instantaneous armature current ia (t ) .
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Dc Servo Drives 1/12
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Dc Servo Drives 2/12
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Dc Servo Drives 3/12
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Dc Servo Drives 4/12
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Dc Servo Drives 5/12
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Dc Servo Drives 6/12
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Dc Servo Drives 7/12
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Dc Servo Drives 9/12
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Dc Servo Drives 10/12
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Dc Servo Drives 11/12
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Dc Servo Drives 12/12
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Adjustable-Speed dc drives 1/9
Switch-Mode dc-dc
Converter
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Adjustable-Speed dc drives 2/9
Switch-Mode dc-dc
Converter
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Adjustable-Speed dc drives 3/9
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Adjustable-Speed dc drives 4/9
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Adjustable-Speed dc drives 6/9
Effect of discontinuous I a on m .
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Adjustable-Speed dc drives 7/9
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Adjustable-Speed dc drives 8/9
(b) switch-
Power Factor of the Line current in mode converter
Adjustable-Speed Drives drive
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