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UNIT-IV
INVERTERS
EE2301-POWER ELECTRONICS
Single-Phase Inverters
Half-Bridge Inverter
One of the simplest types of inverter. Produces a square wave output.
EE2301-POWER ELECTRONICS
Single-Phase Inverters (cont’d)
Full Bridge (H-bridge) Inverter
Two half-bridge inverters combined.
Allows for four quadrant operation.
EE2301-POWER ELECTRONICS
Single-Phase Inverters (cont’d)
Quadrant 1: Positive step-down converter (forward motoring) Q1-On; Q2 - Chopping; D3,Q1 freewheeling
EE2301-POWER ELECTRONICS
Single-Phase Inverters (cont’d)
Quadrant 2: Positive step-up converter
(forward regeneration)
Q4 - Chopping; D2,D1 freewheeling
EE2301-POWER ELECTRONICS
Single-Phase Inverters (cont’d)
Quadrant 3: Negative step-down converter (reverse motoring) Q3-On; Q4 - Chopping; D1,Q3 freewheeling
EE2301-POWER ELECTRONICS
Single-Phase Inverters (cont’d)
Quadrant 4: Negative step-up converter
(reverse regeneration)
Q2 - Chopping; D3,D4 freewheeling
EE2301-POWER ELECTRONICS
Single-Phase Inverters (cont’d)
Phase-Shift Voltage Control - the output of the H-bridge inverter can be controlled by phase shifting the control of the component half-bridges. See waveforms on next slide.
EE2301-POWER ELECTRONICS
Single-Phase Inverters (cont’d)
EE2301-POWER ELECTRONICS
Single-Phase Inverters (cont’d)
The waveform of the output voltage vab is a quasi-square wave of pulse width . The Fourier series of vab is given by:
The value of the fundamental, a1=
The harmonic components as a function of phase angle are shown in the next slide.
1,3,5...
4sin cos
2d
abn
V nv n t
n
4sin / 2dV
EE2301-POWER ELECTRONICS
Single-Phase Inverters (cont’d)
EE2301-POWER ELECTRONICS
Three-Phase Bridge Inverters
Three-phase bridge inverters are widely used for ac motor drives. Two modes of operation - square wave and six-step. The topology is basically three half-bridge inverters, each phase-shifted by 2/3, driving each of the phase windings.
EE2301-POWER ELECTRONICS
Three-Phase Bridge Inverters (cont’d)
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Three-Phase Bridge Inverters (cont’d)
EE2301-POWER ELECTRONICS
Three-Phase Bridge Inverters (cont’d)
The three square-wave phase voltages can be expressed in terms of the dc supply voltage, Vd, by Fourier series as:
10
1,3,5...
2( 1) cos( )nd
an
Vv n t
10
1,3,5...
2 2( 1) cos( )
3nd
bn
Vv n t
10
1,3,5...
2 2( 1) cos( )
3nd
cn
Vv n t
EE2301-POWER ELECTRONICS
Three-Phase Bridge Inverters (cont’d)
The line voltages can then be expressed as:
0 01,3,5...
2 3cos( / 2) cos( 2)d
bc b cn
Vv v v t n t
0 01,3,5...
2 3cos( 5 / 6) cos( 5 6)d
ca c an
Vv v v t n t
0 01,3,5...
2 3cos( / 6) cos( 6)d
ab a bn
Vv v v t n t
EE2301-POWER ELECTRONICS
Three-Phase Bridge Inverters (cont’d)
The line voltages are six-step waveforms and have characteristic harmonics of 6n1, where n is an integer. This type of inverter is referred to as a six-step inverter.
The three-phase fundamental and harmonics are balanced with a mutual phase shift of 2/3.
EE2301-POWER ELECTRONICS
Three-Phase Bridge Inverters (cont’d)
If the three-phase load neutral n is isolated from the the center tap of the dc voltage supply (as is normally the case in an ac machine) the equivalent circuit is shown below.
EE2301-POWER ELECTRONICS
Three-Phase Bridge Inverters (cont’d)
In this case the isolated neutral-phase voltages are also six-step waveforms with the fundamental component phase-shifted by /6 from that of the respective line voltage. Also, in this case, the triplen harmonics are suppressed.
EE2301-POWER ELECTRONICS
Three-Phase Bridge Inverters (cont’d)
For a linear and balanced 3 load, the line currents are also balanced. The individual line current components can be obtained from the Fourier series of the line voltage. The total current can be obtained by addition of the individual currents. A typical line current wave with inductive load is shown below.
EE2301-POWER ELECTRONICS
Three-Phase Bridge Inverters (cont’d)
The inverter can operate in the usual inverting or motoring mode. If the phase current wave, ia, is assumed to be perfectly filtered and lags the phase voltage by /3 the voltage and current waveforms are as shown below:
EE2301-POWER ELECTRONICS
Three-Phase Bridge Inverters The inverter can also operate in rectification or regeneration
mode in which power is pushed back to the dc side from the ac side. The waveforms corresponding to this mode of operation with phase angle = 2/3 are shown below:
EE2301-POWER ELECTRONICS
Three-Phase Bridge Inverters (cont’d)
The phase-shift voltage control principle described earlier for the single-phase inverter can be extended to control the output voltage of a three-phase inverter.
EE2301-POWER ELECTRONICS
Three-Phase Bridge Inverters (cont’d)
EE2301-POWER ELECTRONICS
Three-Phase Bridge Inverters (cont’d)
The three waveforms va0,vb0, and vc0 are of amplitude 0.5Vd and are mutually phase-
shifted by 2/3.
The three waveforms ve0,vf0, and vg0 are of
similar but phase shifted by .
EE2301-POWER ELECTRONICS
Three-Phase Bridge Inverters (cont’d)
The transformer’s secondary phase voltages, vA0, vB0, and vc0 may be expressed as follows:
where m is the transformer turns ratio
(= Ns/Np). Note that each of these waves is a function of angle.
0 0 0( )A ad a dv mv m v v
0 0 0( )B be b ev mv m v v
0 0 0( )C cf c fv mv m v v
EE2301-POWER ELECTRONICS
Three-Phase Bridge Inverters (cont’d)
The output line voltages are given by:
While the component voltage waves va0, vd0, vA0 … etc. all contain triplen harmonics, they are eliminated from the line voltages because they are co-phasal. Thus the line voltages are six-step waveforms with order of harmonics = 6n1 at a phase angle .
0 0AB A Bv v v
0 0BC B Cv v v
0 0CA C Av v v
EE2301-POWER ELECTRONICS
Three-Phase Bridge Inverters (cont’d)
The Fourier series for vA0 and vB0 are given by:
01,3,5...
4sin cos
2d
An
mV nv n t
n
01,3,5...
4sin cos 2 / 3
2d
Bn
mV nv n t
n
EE2301-POWER ELECTRONICS
Three-Phase Bridge Inverters (cont’d)
The Fourier series for vAB is given by:
Note that the triplen harmonics are removed in vAB although they are present in vA0 and vB0.
1,5,7,11...
4 2sin cos cos
2 3d
n
mV nn t n t
n
0 0AB A Bv v v
EE2301-POWER ELECTRONICS
PWM Technique
While the 3 6-step inverter offers simple control and low switching loss, lower order harmonics are relatively high leading to high distortion of the current wave (unless significant filtering is performed).
PWM inverter offers better harmonic control of the output than 6-step inverter.
EE2301-POWER ELECTRONICS
PWM Principle
The dc input to the inverter is “chopped” by switching devices in the inverter. The amplitude and harmonic content of the ac waveform is controlled by the duty cycle of the switches. The fundamental voltage v1 has max. amplitude = 4Vd/ for a square wave output but by creating notches, the amplitude of v1 is reduced (see next slide).
EE2301-POWER ELECTRONICS
PWM Principle (cont’d)
EE2301-POWER ELECTRONICS
PWM Techniques
Various PWM techniques, include:
• Sinusoidal PWM (most common)
• Selected Harmonic Elimination (SHE) PWM
• Space-Vector PWM
• Instantaneous current control PWM
• Hysteresis band current control PWM
• Sigma-delta modulation
EE2301-POWER ELECTRONICS
Sinusoidal PWM
The most common PWM approach is sinusoidal PWM. In this method a triangular wave is compared to a sinusoidal wave of the desired frequency and the relative levels of the two waves is used to control the switching of devices in each phase leg of the inverter.
EE2301-POWER ELECTRONICS
Sinusoidal PWM (cont’d)
Single-Phase (Half-Bridge) Inverter
Implementation
EE2301-POWER ELECTRONICS
Sinusoidal PWM (cont’d)
when va0> vT T+ on; T- off; va0 = ½Vd
va0 < vT T- on; T+ off; va0 = -½Vd
EE2301-POWER ELECTRONICS
Sinusoidal PWM (cont’d)
EE2301-POWER ELECTRONICS
Sinusoidal PWM (cont’d)
Definition of terms:
Triangle waveform switching freq. = fc (also called carrier freq.)
Control signal freq. = f (also called modulation freq.)
Amplitude modulation ratio, m = Vp
VT
Frequency modulation ratio,
mf (P)= fc / f
Peak amplitudePeak amplitudeof control signalof control signal
Peak amplitudePeak amplitudeof triangle waveof triangle wave
EE2301-POWER ELECTRONICS
Multiple Pulse-Width Modulation
• In multiple-pulse modulation, all pulses are the same width
• Vary the pulse width according to the amplitude of a sine wave evaluated at the center of the same pulse
EE2301-POWER ELECTRONICS
Generate the gating signal
2 Reference Signals, vr, -vr
EE2301-POWER ELECTRONICS
Comparing the carrier and reference signals
• Generate g1 signal by comparison with vr
• Generate g4 signal by comparison with -vr
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Comparing the carrier and reference signals
EE2301-POWER ELECTRONICS
Potential problem if Q1 and Q4 try to turn ON at the same time!
EE2301-POWER ELECTRONICS
If we prevent the problem
Output voltage is low when g1 and g4 are both high
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This composite signal is difficult to generate
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Generate the same gate pulses with one sine wave
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Alternate scheme
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rms output voltage
• Depends on the modulation index, M
2
1
pm
o S S m
pV V V
Where δm is the width of the mth pulse
EE2301-POWER ELECTRONICS
Fourier coefficients of the output voltage
2
1
4 3sin sin sin
4 4 41,3,5,..
pS m m m
n m mm
V nB n n
nn
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Harmonic Profile
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Compare with multiple-pulse case for p=5
Distortion Factor is considerably less
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Series-Resonant Inverter
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Operation
T1 fired, resonant pulse of current flows through the load. The current falls to zero at t = t1m and T1 is “self – commutated”.
T2 fired, reverse resonant current flows through the load and T2 is also “self-commutated”.
The series resonant circuit must be underdamped,
R2 < (4L/C)
EE2301-POWER ELECTRONICS
Operation in Mode 1 – Fire T1
11 1
1
1(0)
(0) 0
(0)
C S
C C
diL Ri i dt v Vdt C
i
v V
EE2301-POWER ELECTRONICS
21 1
12 2
2
11
0
1
( ) sin
1
4
( ) sin
2
RtL
r
r
s c
t r
ts cr
r
i t A e t
R
LC L
V VdiA
dt L
V Vi t e t
L
R
L
EE2301-POWER ELECTRONICS
To find the time when the current is maximum, set the first derivative = 0
1
1
1
0
sin cos 0
.....
tan
tan
1tan
2
t ts cr r r
r
rr m
r mr m
rm
r
di
dt
V Ve t e t
L
t
tt
t
EE2301-POWER ELECTRONICS
To find the capacitor voltage, integrate the current
1
1
1
1
1
0
0
1
1 1
1( ) ( )
1( ) sin
...
( ) ( ) ( sin cos ) /
0 ( )
( ) r
t
C c
tts c
C r Cr
tC s C r r r r s
mr
C m C s C s
v t i t dt VC
V Vv t e t dt V
C L
v t V V e t t V
t t
v t V V V e V
The current i1 becomes = 0 @ t=t1m
EE2301-POWER ELECTRONICS
EE2301-POWER ELECTRONICS
Operation in Mode 2 – T1, T2 Both OFF
2 1
2 2 1
2
2
( ) 0
( )
( )m
C C
C C C
i t
v t V
v t V V
EE2301-POWER ELECTRONICS
t2m
EE2301-POWER ELECTRONICS
Operation in Mode 3 – Fire T2
3
3 2 1
33 3
3
1(0) 0
(0) 0
(0)
C
C C C
diL Ri i dt vdt C
i
v V V
EE2301-POWER ELECTRONICS
1
3 1
1
3
3
3
0
3
( ) sin
1( )
( sin cos )( )
0 ( )m
C tr
r
t
C C
tC r r r
Cr
r
Vi t e t
L
v t i dt VC
V e t tv t
t t
EE2301-POWER ELECTRONICS
3 3 1
1 1
1
1
3
1
( )
( ) ( )
.
.
1
1
1
r
m
r
m
C C C C
C C S C S
C S z
z
C S z
C S C
v t V V V e
v t V V V e V
V Ve
eV V
eV V V
EE2301-POWER ELECTRONICS
• Space Vector Diagram
1V
0V
3V
2V
4V
5V
6V
j
POO
PPOOPO
OPP
OOP POP
refV
OOOPPP
SECTOR ISECTOR III
SECTOR IV SECTOR VISECTOR V
SECTORII
• Active vectors: to (stationary, not rotating)
• Zero vector:
1V
6V
0V
• Six sectors: I to VI
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Space Vectors
• Three-phase voltages
0)()()( tvtvtv COBOAO
• Two-phase voltages
)(
)(
)(
3
4sin
3
2sin0sin
3
4cos
3
2cos0cos
3
2)(
)(
tv
tv
tv
tv
tv
CO
BO
AO
• Space vector representation)()()( tvjtvtV
(2) (3)
3/43/20 )()()(3
2)( j
CO
j
BO
j
AO etvetvetvtV
where xjxe jx sincos
(3)
(1)
(2)
(4)
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Space Vectors (Example)
Switching state [POO] S1, S6 and S2 ON
dBOdAO VtvVtv3
1)(,
3
2)(
dCO Vtv3
1)( and
(5) (4)
(7)
(5)
(6)0
1 3
2 j
d eVV
Similarly,
3)1(
3
2
kj
dk eVV
.6...,,2,1k
1V
0V
3V
2V
4V
5V
6V
j
POO
PPOOPO
OPP
OOP POP
refV
OOOPPP
SECTOR ISECTOR III
SECTOR IV SECTOR VISECTOR V
SECTORII
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Active and Zero Vectors
S p a c e V e c t o r S w it c h in g S t a t e ( T h r e e P h a s e s )
O n - s t a t e S w it c h V e c t o r
D e f in it io n
[ P P P ] 531 ,, SSS Z e r o V e c t o r 0V
[ O O O ] 264 ,, SSS 00 V
1V
[ P O O ] 261 ,, SSS 01 3
2 jd eVV
2V
[ P P O ] 231 ,, SSS 32 3
2
j
d eVV
3V
[ O P O ] 234 ,, SSS 3
2
3 3
2
j
d eVV
4V
[ O P P ] 534 ,, SSS 3
3
4 3
2
j
d eVV
5V
[ O O P ] 564 ,, SSS 3
4
5 3
2
j
d eVV
A c t iv e V e c t o r
6V
[ P O P ] 561 ,, SSS 3
5
6 3
2
j
d eVV
• Active Vector: 6
• Zero Vector: 1
• Redundant switching states: [PPP] and [OOO]
1S
2S
3S 5S
4S 6S
B
C
P
N
dV
A
Space Vector Modulation
EE2301-POWER ELECTRONICS
(8)
• Reference Vector Vref
• Definition
1V
0V
3V
2V
4V
5V
6V
j
POO
PPOOPO
OPP
OOP POP
refV
OOOPPP
SECTOR ISECTOR III
SECTOR IV SECTOR VISECTOR V
SECTORII
• Angular displacement
t
dtt0
)( (9)
jrefref eVV
• Rotating in space at ω
Space Vector Modulation
f 2
EE2301-POWER ELECTRONICS
• Relationship Between Vref and VAB
• Vref is approximated by two active and a zero vectors
• Vref rotates one revolution, VAB completes one cycle
• Length of Vref corresponds to magnitude of VAB
1V
2V
refV
1VT
T
s
a
2VT
T
s
b
SECTOR I
Q
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Dwell Time Calculation• Volt-Second Balancing
0
0021
TTTT
TVTVTVTV
bas
basref
(10)
• Ta, Tb and T0 – dwell times for and , 21 VV
0V
• Ts – sampling period
• Space vectors
d
j
refref VVeVV3
2, 1
3
2 3
2 j
d eVV
00 V
, and
(11) (10)
bdsref
bdadsref
TVTV
TVTVTV
3
1)(sin
3
1
3
2)(cos
:Im
:Re
(11)
(12)
1V
2V
refV
1VT
T
s
a
2VT
T
s
b
SECTOR I
Q
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Dwell Times
Solve (12)
bas
d
refs
b
d
refs
a
TTTT
V
VTT
V
VTT
0
sin3
)3
(sin3
3/0 (13)
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Vref Location versus Dwell Times
refV Location 0
60
6
36
3
Dwell Times 0
0
b
a
T
T baTT baTT baTT 0
0
b
a
T
T
1V
2V
refV
1VT
T
s
a
2VT
T
s
b
SECTOR I
Q
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Modulation Index
cbs
asb
asa
TTTT
mTT
mTT
0
sin
)3
(sin
(15)
d
ref
a V
Vm
3 (16)
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Modulation Range
• Vref,max
32
3
3
2max,
ddref
VVV (17)
1V
0V
3V
2V
4V
5V
6V
j
POO
PPOOPO
OPP
OOP POP
refV
OOOPPP
SECTOR ISECTOR III
SECTOR IV SECTOR VISECTOR V
SECTORII
(17) (16)
• ma,max = 1
• Modulation range: 0 ma 1 (18)
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Switching Sequence Design
• Basic Requirement:
Minimize the number of switchings per
sampling period Ts
• Implementation:
Transition from one switching state to
the next involves only two switches in
the same inverter leg.
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Seven-segment Switching Sequence
dV
20T
2aT
2bT
2aT
BNv
ANv
CNv
0
1V
1V
2V
0V
2V
POOOOO PPO PPP PPO POO OOO
dV
dV
40T
40T
2bT
sT
0
0
0V
0V
• Total number of switchings: 6
• Selected vectors: V0, V1 and V2
• Dwell times: Ts = T0 + Ta + Tb
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Undesirable Switching Sequence
• Vectors V1 and V2 swapped
dV
20T
2aT
2bT
2aT
BNv
ANv
CNv
0
1V
1V
2V
2V
POOOOO PPO PPP PPOPOO OOO
dV
dV
40T
40T
2bT
sT
0
0
0V
0V
0V
• Total number of switchings: 10
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Switching Sequence Summary (7–segments)
Sector Switching Sequence
0V 1V
2V
0V
2V
1V
0V
I OOO POO PPO PPP PPO POO OOO
0V 3V
2V
0V
2V
3V
0V
II OOO OPO PPO PPP PPO OPO OOO
0V 3V
4V
0V
4V
3V
0V
III OOO OPO OPP PPP OPP OPO OOO
0V 5V
4V
0V
4V
5V
0V
IV OOO OOP OPP PPP OPP OOP OOO
0V 5V
6V
0V
6V
5V
0V
V OOO OOP POP PPP POP OOP OOO
0V 1V
6V
0V
6V
1V
0V
VI OOO POO POP PPP POP POO OOO
Note: The switching sequences for the odd and ever sectors are different.
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Simulated Waveforms
ABv
AOv
0
0
0
Ai
dV
3/2 dV
2 3
2 3
VIVISector
III
IIIIV
V
III
IIIIV
V
f1 = 60Hz, fsw = 900Hz, ma = 0.696, Ts = 1.1ms
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Waveforms and FFT
0
0.1
0.2
n
0
0
ABv
AOv
Ai
THD =80.2%
THD =80.2%
THD =8.37%
THD =80.2%
dV
3/2 dV
2
dVVAB 566.01
1 5 10 15 20 25 30 35 40 45 50 55 60
dn VVAB /
0 2 3
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Waveforms and FFT (Measured)
23
AOv
ABv d
n
V
VAB
0.2
0.1
0
(a) Waveforms 2ms/div (b) Spectrum (500Hz/div)
14
34
10 4758
THD = 80.3%
8
16 29 43
Space Vector Modulation
EE2301-POWER ELECTRONICS
0 0.2 0.4 0.6 0.80
0.05
0.10
0.15
10 16 20
dnAB VV /
am
1n
2n 4 8
14
(a) Even order harmonics
57111317n = 19
0.05
0.10
0.15
dnAB VV /
0 0.2 0.4 0.6 0.8 am
1n
(b) Odd order harmonics
0
100
200
300
0
THD(%)
THD
• Waveforms and FFT (Measured)
Hz601 f sec720/1sT ( and )
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Even-Order Harmonic Elimination
BNv
ANv
CNv
0
5V
4V
0V
OOPOOO OPP PPP OPP OOP OOO
0
0
0V
0V
ABv0
dV
4V
5V
dV
dV
dV
Type-A sequence (starts and ends with [OOO])
BNv
ANv
CNv
0
0
0
ABv0
dV
5V
OOP4V
OPP
dV
dV
dV
4V
OPP5V
OOPPPP0V
0V
OOO PPP0V
Type-B sequence (starts and ends with [PPP])
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Even-Order Harmonic Elimination
1V
3V
2V
4V
5V
6V
SECTOR ISECTOR III
SECTOR IV SECTOR VI
SECTOR V
SECTOR II
a
ba
a
a
aa
b
b
bb
b
Type-A sequence
Type-B sequence
30
30
Space vector Diagram
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Even-Order Harmonic Elimination
(a) Waveforms 2ms/div
AOv
ABv
0.2
0.1
0
d
n
V
VAB
(b) Spectrum (500Hz/div)
23
13 47
35
7
17
65
THD = 80.5%
41
5
• Measured waveforms and FFT
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Even-Order Harmonic Elimination
17
1913
75
11
100
200
300
0
THD(%)
0 0.2 0.4 0.6 0.8 am0
0.1
0.2
0.3
dnAB VV /
1nTHD
Hz601 f sec720/1sT ( and )
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Five-segment SVM
dV
2aT
bT2aT
BNv
ANv
CNv
0
1V
1V
2V
0V
POOOOO PPO POO OOO
dV
sT
0
0
0V
20T
20T
dV
aT
1V
2V
0V
PPP PPO POO PPP
dV
sT
0V
20T
20T
(a) Sequence A
2V
PPO
dV
2bT
2bT
(b) Sequence B
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Switching Sequence ( 5-segment)
S ector S w itch in g S eq u en ce (A )
0V
1V
2V
1V
0V
I
O O O P O O P P O P O O O O O 0CNv
0V
3V
2V
3V
0V
II
O O O O P O P P O O P O O O O 0CNv
0V
3V
4V
3V
0V
III
O O O O P O O P P O P O O O O 0ANv
0V
5V
4V
5V
0V
IV
O O O O O P O P P O O P O O O 0ANv
0V
5V
6V
5V
0V
V
O O O O O P P O P O O P O O O 0BNv
0V
1V
6V
1V
0V
V I
O O O P O O P O P P O O O O O 0BNv
Space Vector Modulation
EE2301-POWER ELECTRONICS
• Simulated Waveforms ( 5-segment)
dV
2 4
1gv
3gv
5gv
ABv
0
0
Ai
3/2
2 4
2 4
• No switching for a 120° period per cycle. • Low switching frequency but high harmonic distortion
• f1 = 60Hz, fsw = 600Hz, ma = 0.696, Ts = 1.1ms
Space Vector Modulation