Design of Multilevel Inverter using Single DC Source

Design of Multilevel Inverter using Single DC Source

Special Issue – 2019

International Journal of Engineering Research & Technology (IJERT)

ISSN: 2278-0181

ETEDM – 2019 Conference Proceedings

M. Tamilmani, V. Sivajanani, A. Yaazhini Mrs. K. Veeralakshmi

M. E., Electrical and Electronics Engineering Velammal College of Engineering and Technology, Madurai.

capacitor can reduce the oscillations,voltage ripples and will

Abstract This paper presents a new single-phase nine-level inverter with capacitor balancing is proposed with a pulse width- modulated (PWM) control scheme which is used to generate the PWM signals for the inverter. This nine-level inverter with reduced number of switches converts DC to AC which is capable of producing nine levels of output-voltage levels (Vdc, 3Vdc/4, Vdc/2, Vdc/4, 0,-Vdc/4,-Vdc/2, -3Vdc/4, – Vdc) from the dc supply voltage. The Pulse Width Modulation (PWM) signals are generated to the inverter by using sine PWM and the total harmonic distortion (THD) results are compared. The LC-filter is modeled to obtain pure sine-wave and is given to drive a single-phase induction motor. The voltage control of Single-Phase Induction Motor for better performance is modeled and implemented in MATLAB / SIMULINK environment. The Simulation circuit is analyzed and results are presented for the system.

Index Terms Multilevel inverters, H-Bridge with capacitor balancing clamped circuit, Total harmonic distortion (THD), Renewable energy systems.

I

I

1. INTRODUCTION

   N the current scenario, due to the environmental issues and limited fossil resources, the demand for renewable

   energy is increasing. To meet this growing demand, Photovoltaic (PV), Fuel Cell and Wind Turbine (WT)

   systems have become the important integral part of grid connected renewable energy systems (RES).

   Harnessing of electrical energy from the PV systems contributes to clean power Efficiency and pollution free power generation are theadvantagesof PV systems the multilevel configurations.In this paper battery or power supply is used as a source only one dc current global climatic conditions. Long lasting, high source is used. It will give nine level output. If more level is needed, the additional H-briges and switches can be added. The capacitor balancing concept is used for dividing single voltage source to four voltages. The

   give smoothen output.Basically Inverter is a device that converts DC power to AC power at desired output voltage because of other advantages such as high power quality , lower order harmonics, lower switching losses, and better electromagnetic interference, and frequency. Demerits of inverter are less efficiency , high cost, and high switching losses. To overcome these demerits, were going to multilevel inverter. Multilevel inverter output voltage produce a staircase output waveform, this waveform look like a sinusoidal waveform. The multilevel inverter output voltage having less number of harmonics compare to the conventional bipolar inverter output voltage. If the multilevel inverter output increase to N level, the harmonics reduced to the output voltage value to zero. The multilevel inverters are mainly classified as Di ode clamped, Flying capacitor inverter and cascaded multi-level inverter. The cascaded multilevel control method is very easy when compare to other multilevel inverter because it doesnt require any clamping diode and flying capacitor. Moreover, abundant modulation techniques have been developed i n cascade multilevel inverter and reducing the power losses. The most attractive features of multilevel inverters are as follows.

   1. They can generate output volt ages with extremely low distortion and lower order harmonics.

   2. They draw input current with very low distortion.

   3. In addition, using sophisticated modulation types of methods, CM voltages can be eliminated.

   4. They can operate with a less switching frequency.

   Multilevel inverter output voltage produce a staircase output waveform, this waveform look l ike a sinusoidal waveform. The multilevel inverter output voltage having less number of harmonics compare to the conventional bipolar inverter output voltage. If the multilevel inverter output increase to N level, the harmonics reduced to the output voltage value to zero. The multi

   Volume 7, Issue 06

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   Special Issue – 2019

   International Journal of Engineering Research & Technology (IJERT)

   ISSN: 2278-0181

   ETEDM – 2019 Conference Proceedings

   level inverters are mainly classified as Diode clamped, Flying capacitor inverter and cascaded multi level inverter.

2. PROPOSED MODEL

   A. SOFTWARE MODEL

   In order to validate the performance of the multilevel inverter, the system is designed with the source modeling in MATLAB

   /Simulink and the experimental waveforms are obtained. The performance of the inverter is studied under steady state condition. The performances of the inverter are validated with the models to their efficiency conditions.

   PROPOSED SIMULINK MODEL

   A.SINGLE PHASE SIMULINK MODEL FOR PROPOSED TOPOLOGY

   In this proposed topology capacitor balancing method is used.In this circuit single dc source alone used. This the major advantage in this capacitor balancing method. Also reduced number of switches are used. This will reduce the cost and weight of the system.

   THREE PHASE SIMULINK MODEL OF PROPOSED

   SYSTEM

   B.SINGLE PHASE NINE LEVEL VOLTAGE AND CURRENT OUTPUT

   Special Issue – 2019

   International Journal of Engineering Research & Technology (IJERT)

   ISSN: 2278-0181

   ETEDM – 2019 Conference Proceedings

   C.THREE PHASE NINE LEVEL VOLTAGE OUTPUT

   The obtained output voltage contains 9 voltage levels of +Vdc,

   +3Vdc/4, +Vdc/2, +Vdc/4, 0, -Vdc/4, -Vdc/2, -3Vdc/4, -Vdc.

   THREE PHASE SIMULINK MODEL FOR CURRENT OUTPUT

   TOTAL HARMONIC DISTORTION OF OUTPUT VOLTAGE

   Fundamental frequency=50

   Total harmonic distortion=11.19%

   THE HARMONIC DISTORTION WITH MOTOR LOAD

   The harmonic didtortion gets reduced by increasing the Levels in the waveform. The harmonic distortion reduced. The capacitor filter is used by smoothening the waveform.

   The harmonic distortion values are compared . The harmonic The filtered output of total harmonic distortion. The 9 level

   distortion values of motor load and R load are compared. The analysis was done.

   filtered output voltage of proposed topology contains total harmonic distortion of 7.12%.The total harmonic distortion gets

   Special Issue – 2019

   International Journal of Engineering Research & Technology (IJERT)

   ISSN: 2278-0181

   ETEDM – 2019 Conference Proceedings

   reduced in this tree phase motor load . The induction motor is CAPACITOR

   used as a load here.

   B.HARDWARE MODEL A.COMPONENTS USED IN HARDWARE

   1. MOSFET -IRF840

   2. Opto coupler -MCT2F

   3. Voltage regulator -7815

   4. Voltage regulator -7805

   5. Transformer -230 V/18 V 6) PIC -16F877A

   1. Bridge rectifier -MIC W10M

   2. Resistors

   3. Capacitors

   MOSFET IRF840

   In order to avoid voltage fluctuations and maintain the constant output voltage capacitors are used in both input and output side of the circuit.

   PIC 16F877A

   The pic microcontroller pic 16f877a is one of the most renowned microcontroller.This controller is very convenient to use nd the coding is also easier.One of the main advantage is that it can be write-erase as many times as possible. Because it has flass memory technology.It has totally 40 pins and there are 33 pins for input and output.Cmos Flasf based 8-bit microcontroller packs powerful pic architerture into 40 or 44 pin package.

   B.BLOCK DIAGRAM:

   This mosfet is used because of its advanced features.they are 1.Fast switching 2.dynamic dv/dt rating 3.Low switching loss

   4. More robust 5.High voltage bloacking capacity. These switches are complementry in nature.

   OPTO COUPLER MCT2E

   MCT2E is a phototransistor Optocoupler, as the name

   Input DC source

   Modified MLI

   topolgy PWM

   Multilevel Output

   phototransistor suggests it has a transistor which is controlled based on light (photon). So this IC basically has an IR led and a photo-transistor inside it. When the IR led is powered the light from it falls on the transistor and it conducts.

   VOLTAGE REGULATOR 7805

3. METHODOLOGY

   The Multilevel inverter comprises a single-phase conventional H-bridge inverter, three bidirectional switches, and a capacitor voltage divider formed by C1, C2,C3 and the

   It has three terminals.They are input,output and ground. The modified H-bridge topology is significantly advantageous over

   voltage provided by batteries are typically 1.2V, 3.7V, 9V and other topologies, less power switch, power diodes, and less

   12V. This is good for circuits whose voltage requirements are in

   that range. But, most of the TTL ICs work on 5V logic and capacitor for inverters of the same number of levels. The PV

   hence we need a mechanism to provide a consistent 5V arrays can be used instead of battery. Then Photovoltaic (PV)

   Supply. Here comes the 7805 Voltage Regulator IC to the

   rescue. It is an IC in the 78XX family of linear voltage arrays were connected to the inverter via a dcdc boost

   regulators that produce a regulated 5V as output.

   VOLTAGE REGULATOR 7815

   converter. The power generated by the inverter is to be delivered to induction Motor.

   The dcdc boost converter was required because the PV

   Heat sink is required for reducing the heat.7815 is a15V voltage arrays had a voltage that was lower than the single-phase

   regulator that restricts the voltage output to 15V and draws 15V

   regulated power supply to provides a convenient power source voltage. High dc bus voltages are necessary to ensure that

   for most TTL components.

   BRIDGE RECTIFIER

   power flows from the PV arrays to the single-phase induction

   motor. The LC-filter is modeled to obtain pure sine-wave and is given to drive a single-phase induction motor.. Proper

   more diode for efficiently convert ac to dc.

   more diode for efficiently convert ac to dc.

   Bridge rectifier is a type of full wave rectifier which uses four or switching of the inverter can produce nine output-voltage-

   levels (Vdc, 3Vdc/4, Vdc/2, Vdc/4, 0,,Vdc/4, Vdc/2, – 3Vdc/4,- Vdc) from the dc supplyvoltage.

   Special Issue – 2019

   International Journal of Engineering Research & Technology (IJERT)

   ISSN: 2278-0181

   ETEDM – 2019 Conference Proceedings

   The proposed inverters operation can be divided into nine All other controlled switches are OFF; the voltage applied to switching states. The required nine levels of output voltage the load terminals is 3Vdc/4.

   were generated as follows. Maximum negative output (Vdc): S2 is ON, connecting the

   Maximum positive output (Vdc): S1 is ON, connecting the load negative terminal to Vdc, and S3 is ON ,connecting the load positive terminal to Vdc, and S4 is ON, connecting the load positive terminal to ground. All other controlled switches load negative terminal to ground. All other controlled are OFF; the voltage applied to the load terminals is Vdc. switches are OFF; the voltage applied to the load terminals is Table shows the switching combinations that generated the

   Vdc. nine output-voltage levels (Vdc, 3Vdc/4, Vdc/2, Vdc/4,0,

   Three-fourth positive output (3Vdc/4):The bidirectional ,Vdc/4, Vdc/2, -3Vdc/4,- Vdc)

   switch S5 is ON, connecting the load positive terminal, and S4 is ON, connecting the load negative terminal to ground.

4. OPERATION

   The microcontroller is programmed to generate the pwm

   All other controlled switches are OFF; the voltage applied to pulses for MOSFET switches. The circuit is divided into

   the load terminals is 3Vdc/4. control circuit and power circuit.the pulse generation time is

   Half of the positive output (Vdc/2): The bidirectional switch 20ms and frequency is 50Hz.The brige rectifier is used in S6 is ON, connecting the load positive terminal, and S4 is ON, control circuit and power circuit.The voltage regulators 7805 connecting the load negative terminal to ground. All other and 7815 is used for regulated power supply. Individual opto- controlled switches are OFF; the voltage applied to the load coupler or opto-isolator for all mosfet switches.The opto-

   terminals is Vdc/2. coupler is optically connected. The opto coupler isolate the

   One-fourth of the positive output (Vdc/4): The bidirectional driver section and control section.By changing the switching switch S7 is ON, connecting the loadpositive terminal, and S4 sequence in a certain time sequence nine level output is is ON, connecting the load negative terminal to ground. All generated.For smoothening purpose capacitor filter is used. other controlled switches are OFF; the voltage applied to the

   load terminals is Vdc/4.

   Zero output: This level can be produced by two switching combinations; switches S3 and S4 are ON, or S1 andS2are ON, and all other controlled switches are OFF; terminal ab is a short circuit, and the voltage applied to the load terminals is zero.

   One-fourth negative output (Vdc/4): The bidirectional switch S5 is ON, connecting the load positive terminal, and S2 is ON, connecting the load negative terminal to Vdc. All other controlled switches are OFF; the voltage applied to the load terminals is Vdc/4.

   Half of the negative output (Vdc/2): The bidirectional switch S6 is ON, connecting the load positive terminal, and S2 is ON, connecting the load negative terminal to ground. All other controlled switches are OFF; the voltage applied to the load terminals is Vdc/2.

   Three-fourth negative output (3Vdc/4): The bidirectional switch S7 is ON, connecting the load positive terminal, and

   S2 is ON, connecting the load negative terminal to ground.

   Special Issue – 2019

   International Journal of Engineering Research & Technology (IJERT)

   ISSN: 2278-0181

   ETEDM – 2019 Conference Proceedings

   Capacitor divides the supply voltage.If the supply voltage Is VII.FUTURE SCOPE

   200 means, all four capacitor get equally diveded.Then only The Multilevel as the form contain minimal number of switches capacitor balancing is maintained. The blocking diodes are compared to the conventional H bridges and uses a single dc used in inverter section. By increasing more levels, the source, which can be used to integrate renewable sources are the waveform looks like a sinusoidal waveform.So the harmonic major needs to adopt renewable sources, further in order to extend

   content gets reduced.

   Switching sequence

5. CONCLUSION

their operation in the renewable sources the inverters can be

modified as the Z source inverters which may require the voltage boosting capabilities in the un consistent states for the renewable sources. Extending the inverter towards the renewable systems variations and operating in to reliable states would be the extension to the current form.

VII.REFERENCE

1.H. Abu-Rub, J. Holtz, J. Rodriguez, and G. Baoming,Medium-Voltage Multilevel Converters-State of the Art,Challenges, and Requirements in Industrial Applications,IEEE Trans. Ind. Electron., vol.57, no.8, pp. 2581- 2596,August2010.

2.S. Kouro, M. Malinowski, K. Gopakumar, J. Pou, L. G.Franqucelo, B. Wu, J. Rodrigues, M. A.Perez, and J. I.Leon,

Recent advances and industrial applications ofmultilevel converters, IEEE Trans. Ind. Electron., vol.57, no. 8, pp. 2553- 2580, August 2010.

3. S. Daher, J. Schmid, and F. L. M. Antunes,

A multilevel inverter that operates in a single dc and the MultilevelInverter Topologies for Stand-Alone PV Systems, minimum number of switches has been proposed. The capacitor IEEETrans. Ind. Electron., vol. 55, no.7, pp.2703-2712, July2008. balancing modulation technique for the proposed scheme has 4. K. K. Gupta, and S. Jain, Comprehensive review of been generated and validated to generate the multilevel pattern. arecently proposed multilevel inverter, in PowerElectronics, IET, The multilevel generated contains a three capacitors that vol.7, no.3, pp. 467-479, March 2014.

balancing the voltage is done through the PWM modulation. This inverter uses a single dc sources and reduced number of dc sources which are minimal compared to the existing schemes, and also it can provides an additional space to modify the number of levels without touching the main circuit, with the addition of sub blocks and the capacitors the voltage level addition can be included and the addition of the such voltage levels without any modification in the modulation scheme too. As the system has the minimal switches the requirement of the hardware drivers are being reduced Therefore, construction cost of the proposed multilevel inverter is lower and it is not bulky.