The document presents research on asymmetrical cascaded H-bridge multilevel inverters. It summarizes the structure and operation of 5-level, 7-level symmetrical, and 7-level and 9-level asymmetrical configurations. Simulation results show that asymmetrical configurations reduce harmonics without increasing components compared to symmetrical configurations. The conclusion is that asymmetrical multilevel inverters can produce more output levels without adding components by using different progression factors.

1. “Asymmetrical Cascaded
H-Bridge Multilevel
Inverter”
Authors- Dr. S. S. Bharatkar
Mr. R. R. Bhoyar
Mr. S. A. Khadtare
1

2. OUTLINE OF PRESENTATION Abstract
 Introduction
 Concept of CHB MLI
 5-Level CHB MLI
 7- Level Symmetrical CHB MLI
 7- Level Asymmetrical CHB MLI
 9- Level Asymmetrical CHB MLI
 Result
 Conclusion
2

3. ABSTRACT The inverter can be categorized as two level conventional inverter
and multilevel inverter (MLI). These two level (conventional)
inverters have many drawbacks particularly for high voltage and
high power applications.
 The MLI is able to provide more number of levels in the output. The
harmonics are greatly reduced with increase in levels and output
voltage waveform approaches to sine wave.
 The MLI requires more components to produce more number of
levels in the output.
 This paper deals with, the study of Asymmetrical configuration for
seven level and nine level H-bridge multilevel inverter. The
simulations for five level symmetrical, seven level symmetrical and
asymmetrical and nine level asymmetrical configurations are carried
out in MATLAB. It is observed that, asymmetric MLI has ability to
provide more pure output without increasing the structure compared
to symmetrical MLI.
3

4. INTRODUCTIONINVERTER
TWO LEVEL
NCP MLI
MULTILEVEL
FLYING
CAPACITOR
MLI
CHB MLI
SYMMETRICAL
CHB MLI
ASYMMETRICAL
CHB MLI
4

5. Concept of CHB MLI-
Fig. 1 Structure of m-cells cascaded multilevel inverter 5

6. Fig. 2 H-bridge cell structure
6

7. 5-LEVEL CHB MLIA
S1
S3
B
S9
Vdc
Vdc
C
S11
S2
S12
S10
S5
S7
S13
S15
S6
S20
S18
S21
S23
S24
S22
Vdc
Vdc
S8
S19
Vdc
S4
Vdc
S17
S16
S14
7
N

8. 7-LEVEL SYMMETRICAL CHB MLIA
S1
S3
B
S13
Vdc
Vdc
S4
S2
S5
S7
C
S15
S25
S27
S28
S26
Vdc
S16
S9
Vdc
S6
S20
S18
S11
S21
S32
S30
S35
S36
S34
S23
Vdc
S12
S31
Vdc
Vdc
S8
S19
S29
S33
Vdc
S17
S14
S10
Vdc
S24
S22
8
N

9. 7-LEVEL ASYMMETRICAL CHB MLI-
9

10. Fig. 3 Seven level Asymmetrical cascaded H-bridge MLI for
10
Phase A

11. LEVELS
SWITCHES
3Vdc
S1, S5
2Vdc
S1
Vdc
S5
0
-Vdc
S1, S3, S5, S7 (OFF) &
S2, S4, S6, S8 (ON)
S7
-2Vdc
S3
-3Vdc
S3, S7
11

12. 9-LEVEL ASYMMETRICAL CHB MLI-
12

13. 400
Result-
For 5 level Inverter
300
Phase Voltage(Volts)
200
100
0
-100
-200
-300
-400
0
0.08
0.16
0.24
0.32
0.4
Time(Sec)
0.48
0.56
0.64
0.72
0.08
0.16
0.24
0.32
0.4
Time(Sec)
0.48
0.56
0.64
0.72
0.8
800
600
Line Voltage(Volts)
400
200
0
-200
-400
-600
-800
0
13
0.8

14. 400
For 7- Level Symmetrical Inverter
300
Phase Voltage(Volts)
200
100
0
-100
-200
-300
-400
0
0.08
0.16
0.24
0.32
0.4
Time(Sec)
0.48
0.56
0.64
0.72
0.4
Time(Sec)
0.48
0.56
0.64
0.72
0.8
800
600
Line Voltage(Volts)
400
200
0
-200
-400
-600
-800
0
0.08
0.16
0.24
0.32
14
0.8

15. For 7- Level Asymmetrical Inverter
400
300
Phase Voltage(Volts)
200
100
0
-100
-200
-300
-400
0
0.08
0.16
0.24
0.32
0.4
Time(Sec)
0.48
0.56
0.64
0.72
0.4
Time(Sec)
0.48
0.56
0.64
0.72
0.8
800
600
Line Voltage(Volts)
400
200
0
-200
-400
-600
-800
0
0.08
0.16
0.24
0.32
15
0.8

16. For 9- Level Asymmetrical Inverter
400
300
Phase Voltage(Volts)
200
100
0
-100
-200
-300
-400
0
0.08
0.16
0.24
0.32
0.4
Time(Sec)
0.48
0.56
0.64
0.72
0.08
0.16
0.24
0.32
0.4
Time(Sec)
0.48
0.56
0.64
0.72
0.8
800
600
Line Voltage(Volts)
400
200
0
-200
-400
-600
-800
0
16
0.8

17. THD and Vdc values for output line voltage of
400V
TYPE
VOLTAGE (volts)
THD (%)
5-LEVEL
SYMMECTRICAL
7-LEVEL
SYMMETRICAL
163.5
17.12
109
10.63
7-LEVEL
ASYMMETRICAL
109
10.63
9-LEVEL
SYMMETRICAL
79
7.90
9-LEVEL
ASYMMETRICAL
79
7.90
17

18. COMPARISON OF MLIType of Inverter No. of Switches No. of DC Sources
5-level
symmetrical
24
6
7-level
symmetrical
36
9
9-level
symmetrical
48
12
7-level
Asymmetrical
24
6
9-level
Asymmetrical
24
6
18

19. CONCLUSIONFrom the simulation results it is concluded
that, by taking different geometric progression
factor the output levels of Asymmetrical MLI can
be increased without any increased in
components. So the output of ACMLI has very
less amount of harmonic content i.e., the output
is smoother. As compare to SCMLI, the numbers
of bridges, DC sources required in ACMLI are
less for attaining same number of levels. So the
problem of requirement of more components to
achieve more number of output levels are
eliminated with proposed ACMLI topology.
19

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20

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21

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