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Transcript
Comparison of Simulation Results Three Level
and Five Level H-bridge Inverter and hardware
implementation of Single Leg H-Bridge Three
Level Inverter
ISSN 2319-9725
Mamta N. Kokate
M-Tech (Student): Dept. of Electrical Engg
Ramdeobaba College of Engineering and Management
Nagpur, (India)
Prof. Preeti V. Kapoor
Assistant Professor, Dept. of Electrical Engg
Ramdeobaba College of Engineering and Management
Nagpur, (India)
Abstract: The conventional two level inverter has many limitations for high voltage and
high power application. Multilevel inverter becomes very popular for high voltage and
high power application. The multilevel began with the three level converters. The
elementary concept of a multilevel converter to achieve higher power to use a series of
power semiconductor switches with several lower voltage dc source to perform the power
conversion by synthesizing a staircase voltage waveform. However, the output voltage is
smoother with a three level converter, in which the output voltage has three possible
values. This results in smaller harmonics, but on the other hand it has more components
and is more complex to control. In this paper, study of different three level inverter
topologies and SPWM technique is explain and SPWM technique has been applied to
formulate the switching pattern for three level and five level H-Bridge inverter that
minimize the harmonic distortion at the inverter output. This paper deals with comparison
of simulation results of three level and five level H-Bridge inverter and implementation of
single leg of three level H-Bridge inverter.
Keywords: Topologies of Multilevel inverter, Sinusoidal Pulse Width Modulation, THD.
April, 2013
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1. Introduction:
The conventional voltage source inverters produce an output voltage at the poles with levels +V dc/2 or
–Vdc/2 , where Vdc is the DC link voltage are known as two level inverter. To obtain a quality output
voltage or a current waveform with a minimum amount of ripple content, they require high switching
frequency along with various pulse width modulation strategies. In high voltage and high power
application these two level inverters however, have some limitations in operating at high frequency
mainly due to switching losses and constraint of device rating.
Multilevel inverters have been attracting in favor of academic as well as industry in the recent decade
for high-power and medium-voltage energy control. In addition, they can synthesize switched
waveforms with lower levels of harmonic distortion than an equivalently rated two-level converter.
The multilevel concept is used to decrease the harmonic distortion in the output waveform without
decreasing the inverter power output. This paper presents the most important topologies like diodeclamped inverter (neutral- point clamped), capacitor-clamped (flying capacitor), and cascaded
multilevel with separate dc sources.
Multilevel inverter is based on the fact that sine wave can be approximated to a stepped waveform
having large number of steps. The steps being supplied from different DC levels supported by series
connected batteries or capacitors[1][2]. The unique structure of multi- level inverter allows them to
reach high voltages and therefore lower voltage rating device can be used. As the number of levels
increases, the synthesized output waveform has more steps, producing a very fine stair case wave and
approaching very closely to the desired sine wave. It can be easily understood that as motor steps are
included in the waveform the harmonic distortion of the output wave decrease, approaching zero as the
number of levels approaches infinity. Hence Multi- level inverters offer a better choice at the high
power end because the high volt- ampere ratings are possible with these inverters without the
problems of high dv/dt and the other associated ones [2]
2. Multilevel Inverter Topology:
The basic three types of multilevel topologies used are [3]-[4]:
i.
Diode clamped multilevel inverters
ii.
Flying capacitors multilevel inverter or capacitor clamped multilevel inverter
iii.
Cascaded inverter with separate DC sources.
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2.1 Diode Clamped Multilevel Inverters:
The diode clamped multilevel inverter uses capacitors in series to divide up the dc bus voltage into a
set of voltage levels. To produce n levels of the phase voltage, an n level diode clamp inverter needs
(n-1) capacitors on the dc bus.
A1
C
C1
B1
Vdc
2
D1
A2
D1
B2
D1
C2
VA
VB
VC
O
Vdc
D2
C
A1
Vdc
2
D2
B1
D2
C1
A1
A2
B2
C2
Figure 1: Diode Clamped Three Level Inverters
In this paper, diode clamped multilevel inverters topology is used shown in fig 1.
2.2 Flying Capacitor Multilevel Inverter:
It uses ladder structures of dc side capacitors where the voltage on each capacitor differs from that of
the next capacitor. To generate n- level staircase output voltage, (n-1) capacitors in the dc bus are
needed. The size of the voltage increment between two capacitors determines the size of the voltage
levels in the output wave.
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C
Vol 2 Issue 4
A1
B1
C1
A2
B2
C2
Vdc
2
O
C2
C1
C3
VA
VB
VC
Vdc
A1
C
Vdc
2
B1
C1
B2
C2
A1
A2
Figure 2: Flying Capacitor Three Level Inverter
2.3 Cascaded Inverters With Separate DC Source:
This inverter is nothing but the series connection of single connection of single phase inverters with
separate dc source. This inverter can be avoiding the extra clamping diodes or voltage balancing
capacitors.
VA
A1
VB
B1
A2
Vdc
VC
B2
Vdc
A1
A2
C1
C2
C1
C2
Vdc
B1
B2
N
Figure 3: Cascaded Inverters with Separate DC Source
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3. Control Technique:
The sinusoidal PWM technique is very popular for industrial converters. Fig4. Shows the general
principle of SPWM, where an isosceles triangle carrier wave of frequency fc is compared with the
fundamental frequency f sinusoidal modulating wave, and the points of intersection determine the
switching points of power devices.[7]-[8]
Figure 4: Control Pulse Generation for Three
Figure 5: Control Pulse Generation for Five
Level SPWM
Level SPWM
Three level pulse width modulated waveforms can be generated by sine carrier PWM. Sine carrier
PWM is generated by comparing the reference control signals with two triangular carrier waves as
shown in fig: 4, similarly pulse generation for five level inverter is generated by comparing the
reference control signals with four triangular carrier wave shown in fig: 5
Vio = Vdc/2, when A1 =A2 =1
Vio = 0, when A1=1 A2 =0 or A1=0 A2 =1
Vio = -Vdc/2, when A1 =A2 =0
Where i = a, b or c
The reference control signals are phase shift 120 degree each other with same amplitude for three
phase system. Two carrier waves are in phase each other with dc voltage offset. Two important
parameters of the design process are amplitude modulation index ma = Vr/Vc,
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where Vr is the amplitude of reference control signals, Vc is the peak amplitude of the carrier wave,
and the frequency modulation index mf = fc/fr where fc is the frequency of the carrier wave and fc is
the carrier frequency.
4. Simulation Results:
Simulation of three phase H-bridge inverter using sinusoidal pulse width modulation was carried out
with the help of “MATLAB”. Simulation was carried out to observe the improvement in the line
voltage THD for RL load of three level and five level H-bridge inverter and it also observed that the
output is nearly equal to sine wave.
Table 1: Inverter parameters
DC Bus Voltage
100 V
Carrier frequency
1 kHz
Figure 6: Phase Voltage of 3-Level Inverter
International Journal of Innovative Research and Studies
Figure 7: Phase Voltage of 5-Level Inverter
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Figure 8: Output Voltage of 3-Level Inverter
Figure 9: Output Voltage for 5-level Inverter
Figure 10: Harmonic spectrum Line Voltage of 3-level inverter for R=10ohm and L=10H
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Figure 11: Harmonic spectrum Line Voltage of 5-level inverter for R=10ohm and L=10H
5. Hardware Implementation Of Single Phase Three Level Inverter:
The main steps which are followed while implementation of hardware is explain as below:
i.
CONTROL CIRCUIT
ii.
DRIVER CIRCUIT
iii.
POWER CIRCUIT
6. Design of Control Circuit:
Figure 12: Basic Scheme For Control Circuit
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Figure 13: Triangular Wave Generating Circuit
Figure 14: Setup for Triangular wave Generation Circuit
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Figure 15
Figure 16: Output of Control Circuit
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7. Design Of Deadband And Opto-Isolator Circuit (Driver Circuit):
Deadband circuitry allows accurate control of the deadband time to eliminate cross conduction.
Figure 17: deadband circuit while falling edge
Figure 18: deadband circuit while rising edge
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Figure 19: Pin Diagram of Driver IC (TLP 250)
For providing opto-isolation between the power stage and the drive signal stage, the opto-isolator
driver IC TLP 250 is used.
Following reasons justify the advantages of using TLP 250.
i.
Input threshold voltage current If = 5mA (max)
ii.
Supply Voltage 10V-35V
iii.
Output Peak current 2A
iv.
Response speed 0.5µs
v.
Isolation voltage 2500Vrms
Figure 20: Output of Driver Circuit with Deadband
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8. Design Of Power Circuit:
Figure 21: Design of Power Circuit
Figure 22: Final Setup
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Figure 23: Output of Single Phase Three Level Inverter
9. Conclusion:
LEVEL
Thee Level
% THD
42.02
Five
Level
21.63
Table 2: % THD analysis
From this analysis, it has shown that decrease in THD from three level inverter to five level inverter.
In this paper the performance of both inverters was tested using RL load in MATLAB simulation.
The simulation of the inverter namely Three Level and Five level H-bridge Inverter has been carried
out, and compare it’s results and it was shown that the output voltage levels are increased as the level
of inverters are increase, and output voltage approaches near sine wave, to get the higher voltage and
reduced Total Harmonic Distortion.
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References:
1. Muhammad H. Rashid, “Power electronic circuits, devices and applications”, 3rd edition
2003, Pearson Education Inc., chapter 9, pp 406-430.
2. J. Rodriguez, J. Lai, and F. Peng, “Multilevel inverters: A survey of topologies, controls and
applications,” IEEE Trans. Ind. Electron., vol. 49, no. 4, pp. 724–738, Aug. 2002.
3. M. M. Renge and H. M. Suryawanshi, “Five-level diode clamped inverter to eliminate
common mode voltage and reduce dv/dt in medium voltage rating induction motor drives,”
IEEE Trans. Power Electron., vol. 23,no. 4, pp. 1598–1607, Jul. 2008.
4. Kapil Jain, Pradyumn Chaturvedi , “ MATLAB -based Simulation & Analysis of Three -level
SPWM Inverter” International Journal of Soft Computing and Engineering (IJSCE) ISSN:
2231-2307, Volume-2, Issue-1, March 2012,pp. 56-59
5. L. M. Tolbert, F. Z. Peng, and T. Habetler, “Multilevel Converters for Large Electric drives,”
IEEE Trans. Ind. Applicat.,vol.35,pp. 36-44, Jan./Feb. 1999.
6. T.Prathiba, P.Renuga “A comparative study of Total Harmonic Distortion in Multilevel
inverter topologies in the paper” Journal of Information Engineering and Applications ISSN
2224-5782 (print) ISSN 2225-0506 (online) Volume- 2, No.3, 2012, pp.26-36.
7.
Pardasani Hitendra K. Arora Kapildev N. “Simulation of Three Level Inverter Using
Sinusoidal Pulse Width Modulation Technique by MATLAB” in National Conference on
Recent Trends in Engineering & Technology.
8. B.Shanthi and S.P.Natarajan, “Comparative Study on Carrier Overlapping PWM Strategies
for Five Level Flying Capacitor Inverter”, International Journal of Science and Techniques of
Automatic control & Computer Engineering, IJ-STA,Volume 4,No.1,July 2010.pp 1158-1173
9. [9] Xiaoming Yuan, Ivo Barbi, “ Soft-Switched Three-Level Capacitor Clamping Inverter
with Clamping Voltage Stabilization,” IEEE Transactions on Industry Electronics, vol. 36,
no. 4,July/Aug. 2002, pp. 1165-1173
10. R. Chibani, E.M. Berkouk and M.S. Boucherit, “Input DC Voltages of Three-level Neutral
Point Clamped Voltage Source Inverter Balancing Using a New Kind of Clamping Bridge”,
International Journal of Computer and Electrical Engineering, Vol. 2, No. 5, October, 2010
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Analysis of Three-Level Neutral Point Clamped Inverter Using Matlab/Simulink/Power
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12. Santiago Cobreces, , Josep Bordonau, , Joan Salaet, Emilio J. Bueno and Francisco J.
Rodriguez,“ Exact Linearization Nonlinear Neutral-Point Voltage Control for Single-Phase
Three-Level NPC Converters”, IEEE Trans. on power electronics, VOL. 24, NO. 10,
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