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5/21/2018 8407 Slides Topic9 Current CSI
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1
Topic 9
PWM Current Source Inverters (CSI)
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
EE8407
Power Converter Systems
PWM CSI fed MV drive Courtesy of Rockwell Automation
2
Lecture Topics
Single Bridge Inverter
Trapezoidal Modulation (TPWM)
Selective Harmonic Elimination (SHE)
Space Vector Modulation (SVM) Dual Bridge Inverter
Topic 9PWM Current Source Inverters (CSI)
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
EE8407
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Inverter Topology
Features:- Simple topology no antiparallel diodes
- Reliable short circuit protection constant dc current
- Very lowdv/dt on motor terminals
Symmetrical GCTs1S
2S
3S 5S
4S 6S
dI
wi
ci
si
fC
4g 6g 2g
1g
3g
5g
A
B
C
fC fC
LOAD
O
ABv
Function of Cf:
- Assist GCT commutation
- Reduce harmonic distortion
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Single Bridge Inverter
EE8407
4
DC Current SourceId
Implementation of dc current source:
- use a large size dc chokemakingId smooth;
- use dc current feed back controlkeepingIdconstant
SCR
or
PWM
Rectifier
PWM
Inverter
Controller
dIdL
*dI
Utility
Supply
M
asv
bsv
csv
fC
A
B
C
dI
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Single Bridge Inverter
EE8407
5/21/2018 8407 Slides Topic9 Current CSI
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Trapezoidal PWM (TPWM)
Selective Harmonic Elimination (SHE)
Space Vector Modulation (SVM)
Constraints on Switching Pattern Design
- dc currentIdcannot be interrupted
- inverter output current waveform
must be defined.
At any time instant, only two switches are
turned on, one connected to the positivedc bus, and the other to the negative dc bus.
1S
2S
3S 5S
4S 6S
dI
wi
4g
6g
2g
1g
3g
5g
A
B
C
P
N
Modulation Techniques
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Single Bridge Inverter
EE8407
6
Trapezoidal PWM (TPWM)
Number of pulses per half cycle:Np = 7
1gv
2gv
3gv
4gv
5gv
6gv
0
wi
3
3
2 2
t
t
t
t
t
t
tdI
2
3
3
2t
crv mv
mV crV
0 2
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Trapezoidal Modulation
EE8407
5/21/2018 8407 Slides Topic9 Current CSI
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Harmonic Content (TPWM)
Np = 15
Fundamental does not
change much with ma
ma = 0.85am
am
max,1wwn II
max,1wwn II
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Trapezoidal Modulation
EE8407
8
Waveforms(TPWM)
Hz180
,13,Hz8.131
=
==
sw
p
f
Nf
Hz155
,31,Hz55
=
==
sw
p
f
Nf
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Trapezoidal Modulation
EE8407
5/21/2018 8407 Slides Topic9 Current CSI
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Selective Harmonic Elimination (SHE)
Not all the switching angles are independent.
Only two harmonics can be eliminated withNp = 5.
No modulation index control the magnitude of inverter output
current is controlled byId
Number of harmonics to be eliminated: 2/)1( = pNk
3
3
2 21 2
6
23
dI
t
wi
13
0
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Selective Harmonic Modulation
EE8407
10
Fourier Analysis
=
=1)sin()(
nnw tnati
=++
+++
=++
+++
=
even.k)()sin(...)()sin(
)()sin(...)()sin(
;oddk)()sin(...)()sin(
)()sin(...)()sin(
4
2
3
3
6
2
3
3
3
6
1
1
2
1
1
1
2
1
tdtntdtn
tdtntdtn
tdtntdtn
tdtntdtn
Ia
k
k
k
k
k
k
dcn
= 20 )()sin()(4
tdtntia wn
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Selective Harmonic Modulation
EE8407
5/21/2018 8407 Slides Topic9 Current CSI
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=+
++
=++
++
=
even.k)6
cos()]3
(cos[)cos(
...)]3
(cos[)cos()]3
(cos[)cos(
;oddk)6
cos()]3
(cos[)cos(
...)]3
(cos[)cos()]3
(cos[)cos(
4
2211
2211
nnn
nnnn
nnn
nnnn
n
Ia
kk
kkdc
n
Expression foran
Fourier Analysis
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Selective Harmonic Modulation
EE8407
12
Switching Angle Calculation
To Eliminatenthharmonic, setan = 0
kiF ki ...,,2,10)...,,,,( 321 ==
For 5th, 7th and 11th harmonic elimination:
0)6
11cos()]
3(11cos[)11cos(
)]3
(11cos[)11cos()]3
(11cos[)11cos(
0)6
7cos()]
3(7cos[)7cos(
)]
3
(7cos[)7cos()]
3
(7cos[)7cos(
0)6
5cos()]
3(5cos[)5cos(
)]3
(5cos[)5cos()]3
(5cos[)5cos(
33
22113
33
22112
33
22111
=++
+=
=++
+=
=++
++=
F
F
F
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Selective Harmonic Modulation
EE8407
5/21/2018 8407 Slides Topic9 Current CSI
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Switching Angles (SHE)
Switching Angles Switching AnglesHarmonicsEliminated 1 2 3
Harmonics
Eliminated 1 2 3 4
5 18.00 - - 7,11,17 11.70 14.12 24.17 -
7 21.43 - - 7,13,17 12.69 14.97 24.16 -
11 24.55 - - 7,13,19 13.49 15.94 24.53 -
13 25.38 - - 11,13,17 14.55 15.97 25.06 -
5,7 7.93 13.75 - 11,13,19 15.24 16.71 25.32 -
5,11 12.96 19.14 - 13,17,19 17.08 18.23 25.84 -
5,13 14.48 21.12 - 13,17,23 18.03 19.22 26.16 -
7,11 15.23 19.37 - 5,7,11,13 0.00 1.60 15.14 20.26
7,13 16.58 20.79 - 5,7,11,17 0.07 2.63 16.57 21.80
7,17 18.49 23.08 - 5,7,11,19 1.11 4.01 18.26 23.60
11,13 19.00 21.74 - 5,7,13,17 1.50 4.14 16.40 21.12
11,17 20.51 23.14 - 5,7,13,19 2.56 5.57 17.82 22.33
11,19 21.10 23.75 - 5,7,17,19 4.59 7.96 17.17 20.55
13,17 21.19 23.45 - 5,11,13,17 4.16 6.07 16.79 22.04
13,19 21.71 23.94 - 5,11,13,19 5.13 7.26 17.57 22.72
5,7,11 2.24 5.60 21.26 5,11,17,19 6.93 9.15 17.85 22.77
5,7,13 4.21 8.04 22.45 5,13,17,19 7.80 9.82 18.01 23.255,7,17 6.91 11.96 25.57 7,11,13,17 5.42 6.65 18.03 22.17
5,11,13 7.81 11.03 22.13 7,11,13,19 6.35 7.69 18.67 22.74
5,11,17 10.16 14.02 23.34 7,11,17,19 8.07 9.44 19.09 22.93
5,13,17 11.24 14.92 22.98 7,13,17,19 8.88 10.12 19.35 23.22
7,11,13 9.51 11.64 23.27 11,13,17,19 10.39 11.14 20.56 23.60
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Selective Harmonic Modulation
EE8407
14
Inverter Waveforms (SHE)
Harmonic eliminated: 5th, 7th and 11th; fsw = 420Hz
wi
2 4
dI
max,1wwn II
1)1(3 pN 1)1(3 +pN
6
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Selective Harmonic Modulation
EE8407
5/21/2018 8407 Slides Topic9 Current CSI
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Waveforms (SHE)
0
7,20
)(
1175
1
===
==
www
p
III
NHzf
a
0
3,60
)(
5
1
=
==
w
p
I
NHzf
c
0
5,35
)(
75
1
==
==
ww
p
II
NHzf
b
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Selective Harmonic Modulation
EE8407
16
Space Vector Modulation
Six active current vectors and one zero vector
Six sectors.
SECTOR I
SECTOR III
SECTOR IV
SECTOR VISECTOR V
j
SECTOR II
1I
r
2Ir
3Ir
6Ir
5I
r
4Ir
refIr
0Ir
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Space Vector Modulation
EE8407
5/21/2018 8407 Slides Topic9 Current CSI
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Switching State
Leg ASwitching
State1S 4S wI
[1] On Off dI
[-1] Off On dI
[0] Off Off 0
[2] On On 0
1S
2S
3S 5S
4S 6S
dI
LOAD
wi
ci
oi
fC
4g 6g 2g
1g
3g
5g
A
B
C
fC fC
Z
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Space Vector Modulation
EE8407
18
Switching States and Space Vectors
Space Vector Switching State On-state SwitchVector
Definition
[2 0 0] 41 S,S
[0 2 0] 63 S,S Zero
Vector 0Ir
[0 0 2] 25 S,S
00 =Ir
1Ir
[1 -1 0] 16 S,S 6/
13
2 = jdeIIr
2Ir
[1 0 -1] 21 S,S 6/
23
2 = jdeIIr
3Ir
[0 1 -1] 32 S,S 6/3
23
2 = jdeIIr
4Ir
[-1 1 0] 43 S,S 6/5
43
2 = jdeIIr
5Ir
[-1 0 1] 54 S,S 6/7
53
2 = jdeIIr
Active
Vector
6Ir
[0 -1 1] 65 S,S 6/9
63
2 = jdeIIr
[1]: Upper switch on
[-1]: Lower switch on
[0]: None of the switches
in a leg turned on
[2]: Both switches in a
leg turned on(bypass mode)
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Space Vector Modulation
EE8407
5/21/2018 8407 Slides Topic9 Current CSI
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Dwell Time Calculation
++=
++=
021
002211
TTTT
TITITITI
s
sref
rrrr
2Ir
refIr
22 IT
T
s
r
11 IT
T
s
r
1Ir
+=
+=
)(3
1
)(sin
)()(cos
21
21
TTITI
TTITI
dsref
dsref
:Im
:Re
Following the same principle
of SVM for the NPC inverter
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Space Vector Modulation
EE8407
20
Dwell Time Calculation
=
+=
=
210
2
1
)6
(sin
)6
(sin
TTTT
TI
IT
TI
IT
s
s
d
ref
s
d
ref
=
+=
=
210
2
1
)6
(sin
)6
(sin
TTTT
TmT
TmT
s
sa
sa
d
w
d
ref
aI
I
I
Im 1
==
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Space Vector Modulation
EE8407
5/21/2018 8407 Slides Topic9 Current CSI
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Switching Sequence
Requirements:1) Transition from one switching state to the next involves only
two switches
2) At any time only two switches are on.
1Ir
16 ,SS
1gv
2Ir
0Ir
1Ir
2Ir
0Ir
21 ,SS 41 ,SS 16 ,SS 21 ,SS 41 ,SS
1T 2T 0T
6gv
5gv
4gv
3gv
2gv
sT sT
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Space Vector Modulation
EE8407
22
Switching Sequence (Over one cycle)
1gv
Sector
1 0 6 1 06
VI I II III IV V
2 0 1 2 01 3 0 2 3 02
wi
0 2
dI
...3,2,1Ir
sT sT
)( 6Ir
2gv
3gv
4gv
5gv
6gv
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Space Vector Modulation
EE8407
5/21/2018 8407 Slides Topic9 Current CSI
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Inverter Output Waveforms (SVM)
wi
si
ABv
2 4
2 4
f1 = 60Hz, fsw = 540Hz,Np = 9 andma = 1
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Space Vector Modulation
EE8407
24
Harmonic Spectrum (SVM)
max,1/ ABABn VV
max,1/ ssn II
max,1/ wwn II
f1 = 60Hz, fsw = 540Hz,Np = 9 andma = 1
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Space Vector Modulation
EE8407
5/21/2018 8407 Slides Topic9 Current CSI
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Harmonic Content (SVM)
9,Hz540(a) == psw Nf
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Space Vector Modulation
EE8407
26
Converter Configuration
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Dual Bridge Inverter
EE8407
fC
1i1L 2L
2i
dv
3i
4i
1S 5S3S 1S 5S3S
4S 2S6S 4S 2S6S
wi si
5/21/2018 8407 Slides Topic9 Current CSI
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Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Space Vector Diagram
Topic 9 PWM CSI
Dual Bridge Inverter
EE8407
1Ir
7Ir
2Ir
8Ir
9Ir
10Ir
17Ir
16Ir
15Ir
18Ir
11Ir
12Ir
3Ir
4Ir
5Ir
6Ir
14Ir
13Ir
0Ir
refIr
19 vectors and 51 switching states
28
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Dual Bridge Inverter
EE8407
1i1L 2L
2i
dv
3i
4i
1S 5S3S 1S 5S3S
4S 2S6S 4S 2S6S
Current paths with switching state [16;56]
DC Current Balance Control
5/21/2018 8407 Slides Topic9 Current CSI
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Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
DC Current Balance Control
Topic 9 PWM CSI
Dual Bridge Inverter
EE8407
Current paths with switching state [16;56]
30
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Space Vector Diagram
Topic 9 PWM CSI
Dual Bridge Inverter
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PWM Scheme Comparison
Item SVM TPWM SHE
DC Current Utilization
dw II /max,1 0.707 0.74 0.73 to 0.78
Dynamic performance High Medium Low
Digital Implementation Real timeReal time or
look-up tableLook-up table
Harmonic Performance Adequate Good Best
dc Current Bypass Operation Yes No Optional
Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
Topic 9 PWM CSI
Summary
EE8407
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Textbook: Bin Wu, High-Power Converters and AC Drives, Wiley-IEEE Press, 2006
EE8407
Topic 9PWM Current Source Inverters (CSI)