International Journal of Research in Computer Applications and Robotics
International Journal of Research in Computer Applications and Robotics
International Journal of Research in Computer Applications and Robotics
9, Pg: 109-116
December 2013
INTERNATIONAL JOURNAL OF
RESEARCH IN COMPUTER
APPLICATIONS AND ROBOTICS
ISSN 2320-7345
DESIGN AND IMPLEMENTATION OF A FUZZY LOGIC
CONTROLLER FOR MULTILEVEL INVERTER TOPOLOGY
A.Mahendran1, K.Muthulakshmi2 , D.Edison Selvaraj3 and Lieutenant.J.Ganesan4
1
PG Student, Department of Electronics and Communication Engineering, Kamaraj College of Engineering and
Technology, Virudhunagar, India
2
Associate Professor, Department of Electrical and Electronics Engineering, Kamaraj College of Engineering and
Technology, Virudhunagar, India
3
Assistant Professor, Department of Electrical and Electronics Engineering, Sree Sastha Institute of Engineering and
Technology, Chennai, India
4
Assistant Professor, Department of Electrical and Electronics Engineering, Sree Sowdambika College of
Engineering, Aruppukkotai, India
Abstract
It has been found that by using Fuzzy Logic Control scheme can greatly reduce harmonics distortions generated by
the Multilevel Inverter. Harmonics reduction is the main consideration in the inverter circuit. The performance of the
multilevel inverter increased by the reduction of THD. Multilevel inverters widely accepted for high-power highvoltage applications. In this research work, a new topology with a reversing-voltage component is proposed to
improve the multilevel performance. This topology requires fewer components compared to existing inverters
(particularly in higher levels) and requires fewer carrier signals and gate drives. The output voltage is regulated at a
desired level in the face of source voltage disturbances or load disturbances using fuzzy logic control scheme. Both
PI control scheme and fuzzy logic control scheme are analysed by using Matlab simulation. The inverter is proposed
to deliver 40V / 300W. The source voltage variation can be anywhere between 24 volts and 50 volts DC. A prototype
of the seven-level proposed topology is built and tested to show the performance of the inverter by experimental
results. The percentage THD values of the multilevel inverter was analysed by using PI control scheme and Fuzzy
Logic Control scheme. In this research work the current harmonics distortion was reduced by using Fuzzy Logic
Control scheme, there was reduction of current THD 2.49 % , which increases the performance of the multilevel
inverter.
1. Introduction
Multilevel inverter is an effective solution for increasing power and reducing harmonics of ac waveform. Multilevel
power conversion was first introduced more than two decades ago. The general concept involves utilizing a higher
number of active semiconductor switches to perform the power conversion in small voltage steps. There are several
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advantages to this approach when compared with the conventional power conversion approach. The smaller voltage
steps lead to the production of higher power quality waveforms and also reduce voltage (dv/dt) stress on the load
and the electromagnetic compatibility concerns. Another important feature of multilevel converters is that the
semiconductors are wired in a series-type connection, which allows operation at higher voltages and the series
connection is typically made with clamping diodes, which eliminates overvoltage concerns. The multilevel output is
generated with a multi winding transformer. However, the design and manufacturing of a multi-winding transformer
are difficult and costly for high-power applications. A novel four-level inverter topology is also proposed, and it is
valid for inverters with even number of voltage levels and not capable of outputting a zero-voltage state. As a result,
the inverter output phase voltage for zero modulation indexes is a bipolar waveform taking two distinct values and
exhibits high RMS value and considerable harmonic energy concentrated at the switching frequency. This is a
disadvantage of the proposed
inverter, particularly when it should output low or zero voltage to a load. Another approach is selection based on a
set target which can be either the minimum switches used or the minimum used dc voltage. It also requires different
voltage source values which are defined according to the target selection. However, this approach also needs basic
units which are connected in series, and the basic units still require more switches than the proposed topology.
Another disadvantage of the topology is that the power switches and diodes also need to have a different rating
which is a major drawback of the topology. In this research a new topology with a reversing-voltage component is
proposed to improve the multilevel performance by compensating the disadvantages mentioned. This topology
requires fewer components compared to existing inverters (particularly in higher levels) and requires fewer carrier
signals and gate drives. Hence this new topology is named as Reversing Voltage (RV) topology.
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December 2013
Arc furnaces
Welding units and Computers
3. Proposed Work
The inverter output voltage may not retain stable due to the disturbances that may occur in the source and load sides.
To overcome this draw back Fuzzy logic control scheme are used in seven level inverter circuit.PIC microcontroller
are used in Fuzzy logic control scheme. In this research work the performance of the multilevel inverter was
improved by reverse voltage topology. This topology requires fewer components compared to existing inverters and
requires fewer carrier signals and gate drives. The output voltage is regulated at a desired level by using fuzzy logic
control scheme.
4. Development of seven level Inverter using RV topology with PI controller and Fuzzy
logic controller
A Seven level inverter using RV topology with PI controller model was implemented in Matlab Simulink software
with PD-SPWM technique. The following Figure1 shows the simulation circuit diagram of seven level inverter
using RV topology with PI controller.
Figure 1 simulation circuit diagram of seven level inverter using RV topology with PI controller
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A Seven level inverter using RV topology with fuzzy logic controller model was implemented in Matlab Simulink
software with PD-SPWM technique. The following Figure 2 shows the simulation circuit diagram of seven level
inverter using RV topology with Fuzzy logic controller.
Figure 2 Simulation model of seven level inverter using RV topology with Fuzzy logic controller
The following Figure 3 shows the experimental setup of seven level RV topology inverter with Fuzzy logic
controller. It consists of level generation and polarity generation and microcontroller units.
Figure 3 Experimental setup for Seven level inverter using RV Topology with Fuzzy logic controller
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The following Figure 6 shows the voltage THD of the seven level RV topology inverter with PI Controller.
Figure 6 Voltage THD - FFT analysis of the seven level RV topology inverter with PI Controller
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The following Figure 7 shows the voltage THD of the seven levels RV topology inverter with PI
Controller.
Figure 7 Current THD - FFT analysis of the seven level RV topology inverter with PI Controller
5.2 Output Voltage waveform and THD analysis of the seven level inverter using RV Topology with
Fuzzy Logic controller
The following Figure 8 and 9 shows the output voltage and current waveform of the seven level inverter using RV
Topology with Fuzzy logic controller.
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The following Figure 10 shows the voltage THD of the seven level RV topology inverter with Fuzzy logic
controller.
Figure 10 Voltage THD - FFT analysis of the seven level RV topology inverter with PI Controller
The following Figure 11 shows the voltage THD of the seven level RV topology inverter with Fuzzy logic
controller.
Figure 10 Voltage THD - FFT analysis of the seven level RV topology inverter with PI Controller
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6. Acknowledgement
Thank God and His almighty power to finish His research work by using me and my Project Guide my friend for
His ultimate work.
CONCLUSION
The percentage THD values of the multilevel inverter was analysed by using PI control scheme and Fuzzy Logic
Control scheme. The result shows that the current harmonics distortion was reduced by using Fuzzy Logic Control
scheme, there was reduction of current THD 2.49 %, which increases the performance of the multilevel inverter.
In this topology, the switching operation is separated into high- and low-frequency parts. This will add up to the
efficiency of the converter as well as reducing the size and cost of the final prototype. The PD-SPWM control
method is used to drive the inverter.
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