Transcript 18 C H A P ... Special-Purpose Electric Machine PRINCIPLES AND APPLICATIONS OF ELECTRICAL ENGINEERING

PRINCIPLES AND APPLICATIONS OF ELECTRICAL ENGINEERING
THIRD EDITION
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Special-Purpose Electric Machine
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GIORGIO RIZZONI
© The McGraw-Hill Companies, Inc. 2000
PRINCIPLES AND APPLICATIONS OF ELECTRICAL ENGINEERING
THIRD EDITION
Figure 18.1(a) Two-pole brushless DC motor
with three-phase stator winding
a
N
c'
b
S
b'
c
a'
(a)
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GIORGIO RIZZONI
© The McGraw-Hill Companies, Inc. 2000
PRINCIPLES AND APPLICATIONS OF ELECTRICAL ENGINEERING
THIRD EDITION
Figure 18.3 Transistor and SCR drives for a
brushless DC motor
a
T1
+_
T2
T3
a'
Variable
DC supply
T5
T4
b
T6
c
c'
b'
Stator
Transistor supply for brushless DC motor
a
S1
+_
S2
S3
a'
Variable
DC supply
S4
S5
S6
b
c'
b'
Stator
c
SCR supply for brushless DC motor
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GIORGIO RIZZONI
© The McGraw-Hill Companies, Inc. 2000
PRINCIPLES AND APPLICATIONS OF ELECTRICAL ENGINEERING
THIRD EDITION
Figure 18.4 Phase voltages and transistor (SCR) switching
sequences for the brushless DC motor drive of Figure 18.3
1 = Transistor on
0 = Transistor off
Phase-to-phase
stator voltage
T1
Va-b
1
0
1
0
1
0
1
0
1
0
1
0
T2
T3
V b-c
T4
T5
V c-a
T6
60 120 180 240 300 360 60 120 180
Electrical degrees
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60 120 180 240 300 360 60 120 180
Electrical degrees
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GIORGIO RIZZONI
© The McGraw-Hill Companies, Inc. 2000
PRINCIPLES AND APPLICATIONS OF ELECTRICAL ENGINEERING
THIRD EDITION
Figure 18.5 Performance and efficiency
characteristics of brushless DC motor
Efficiency Curve
475
350
80%
300
Performance Curve
475
300
407
250
339
200
272
150
204
100
136
50
68
500
1000 1500 2000 2500
Speed, rev/min
200
204
94%
136
150
100
68
50
500 100 150 200 250 300 350 400
0 0 0 0 0 0 0
Speed, rev/min
(a)
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407
339
90%
272
250
Torque, Nm
350
85%
(b)
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GIORGIO RIZZONI
© The McGraw-Hill Companies, Inc. 2000
PRINCIPLES AND APPLICATIONS OF ELECTRICAL ENGINEERING
THIRD EDITION
Figure 18.8 Stepping motor configurations
i
N
Torque
S
(a) Permanent-mag
stepping motor
i
net
Torque
(b) Variable-reluctance
stepping motor
i
N
Torque
S
(c) Hybrid stepping motor
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GIORGIO RIZZONI
© The McGraw-Hill Companies, Inc. 2000