modern multilevel inverter for application of drive with

Modern Multilevel Inverter for Application of Drive with

Grid Connected Renewable Energy Sources

Muthyala Naresh Kumar 1, K. Ezhil Vignesh 2

1PG scholar, Dept. of EEE, Malla Reddy Engineering College, Dulapally Road Maisammaguda

Post via. Kompally Rangareddy Dt Secunderabad, Hyderabad, Telangana ,India.

2Assistant Professor, Dept. of EEE, Malla Reddy Engineering College, Dulapally Road

Maisammaguda Post via. Kompally Rangareddy Dt Secunderabad, Hyderabad, Telangana,

India.

Abstract:The grid with integration of PV-FC system

efficiency and performance can be improved up to a large

extent because of the invention of modern DC-DC &

multilevel power electronic converters. For a few years

ago, the conditioning unit (CU) was utilized to coherence

advanced power electronic devices which has got an

important position in the study of power electronics. The

present paper fetches the explained analysis of 5-level

multilevel inverter with motor drive along with boost

converters. The pv side dc/dc converter utilizing

maximum power point tracking (MPPT) algorithm, i.e., P

& O (Perturb & Observe) type of MPPT algorithm. In

suggested paper the arrangement is consists of pv, fuel

cell with dc/dc converters, DC bus and grid/load(drive). In

this paper the grid/drive side inverter replaced with

neutral point clamped multilevel inverter.The proposed

multilevel inverter topology improve the efficiency and

reduces harmonics. The obtained simulation results

would be carried out under environment of MATLAB

simulation

Index Terms: Multilevel inverter, Hybrid system,

Hysteresis controller, Maximum Point Tracking,

Grid, Drive.

I. INTRODUCTION

In the present condition, there is huge need for

energy requirement for all round development of

nation. In order to fulfill the requirement of the usage

of electrical power with emerging population, we

require renewable & non-renewable energy resources

have broadly used[1]. The different sources such as

gas, coal & oil etc which are limited & also came to

end within few years. Widely, renewable energy

resources begins with important role in the generation

of power & also attached consumers because of its different features list as environmental friendly,

availability etc[2].

Photovoltaic system and fuel-cells considered as one

of the crucial renewable energy sources because of its

agile development of generation of power & also add

features known as pollution free, maintenance low,

non-moving parts & decentralization of grid. Photo

Voltaic systems and fuel-cells are broadly used in

world-wide[3]. Photo Voltaic cell is a device which

converts solar energy into electrical energy. It adds semiconductor material, that works on photovoltaic

effect principle under physics state. Solar cell is

manufactured from silicon wafer[4]. Sunlight photon

hits the solar panel that are absorbed by silicon

(semiconductor material), when the electrons strike

the material which separated atoms & flow through

the material which generate electricity[5]. The

electrons permitted to move in a single direction. The

PV cell performance can be found out in case of

performance during conversion of photovoltaic.

The basic operation of PV system is obtained by

using opt setup & DC power can be achieved from

PV output cell changed into AC with the help of

multilevel inverter[7]. It has several benefits known

as decreased switching losses, low dv/dt stress, to

decrease the harmonics which are on AC which poses

high voltage capability[8-9]. There are several multi-

level topologies for several applications. For

industrial & domestic applications such as capacitor clamped & cascaded H-bridge of multilevel inverter

broadly utilized. The multilevel inverter is chosen

based on total load which is connected to PV system.

The ratings of inverter are 200 VA, 100 VA, 500 VA

etc.

The reasonable cost for water pump framework for

presentation of industries. Centrifugal pump is

basically utilized due to its less cost when compared with other water pumps. In the present category of

pump, the centrifugal _pumps are broadly used for

longer duration with low maintenance & irradiation.

In this paper the arrangement is consists pv , fuel cell

with dc/dc converters, DC bus, motor pump and grid.

In this paper the grid/load(drive) side inverter

Journal of Information and Computational Science

Volume 10 Issue 3 - 2020

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replaced with neutral point clamped multilevel

inverter[10].The proposed multilevel inverter

topology improve the efficiency and reduces

harmonics.

II. PROPOSED SYSTEM

The proposed system indicated in figure.1.The

suggested scheme has photovoltaic source, fuel cell,

DC bus, boost converters and multilevel inverter

(neutral point clamped inverter) and motor pump

indicated in figure.1. The photovoltaic system and

fuel cells are associated with DC-DC converters.

These are linked with the DC bus.In PV side DC-DC

converter is operated by P & O MPPT process because compared to another MPPT methods P & O

method gives accuracy. In proposed model the grid

side inverter is replaced by multilevel inverter for

improve the wave shape as sinusoidal shape and

reduces the total harmonic distortion. And this

multilevel inverter can be controlled by SVPWM

hysteresis controller control technique. The

arrangement of suggested scheme is indicated in

figure.1

Figure 1: Block diagram

A) MPPT Evolution Algorithm

The following are the steps to be considered to work

the PV system utilising MPPT algorithm.

STEP 1: The output values are obtained from PV cell

& provided to MPPT controller.

STEP 2: Evaluate the difference between old & new

voltage & current values

i.e., i.e., ∆V=Vnew - Vold, ∆I= Inew - Iold

STEP 3: Evaluate the finding of MPPT utilizing the

formula

STPE 4 : Calculate the error by imparting In cond

di/dv & instant con di/v which is e = i/v + di/dv.

STEP 5: To decrease the error value to zero. The calculated error is provided to PI controller that

reduces to zero.

B) INC ALGORITHAM

The inconvenience of the perturb and

observe system to track the peak power

under fast varying atmospheric condition is

overcome by IC method . The IC can

determine that the MPPT has reached the

MPP and stop perturbing the operating

point. If this condition is not met, the

direction in which the MPPT operating point

must be perturbed can be calculated using

the relationship between dl/dV and –I/V

This relationship is derived from the fact

that dP/dV is negative when the MPPT is to

the right of the MPP and positive when it is

to the left of the MPP. This algorithm has

advantages over P&O in that it can

determine when the MPPT has reached the

MPP, where P&O oscillates around the

MPP. Also, incremental conductance can

track rapidly increasing and decreasing

irradiance conditions with higher accuracy

than P and O

Fig:2 INC Algorithm



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If there is an increment in the power, the

perturbation should be kept in the same direction

and if the power decreases, then the next

perturbation should be in the opposite direction.

Based on these facts, the algorithm is

implemented. The process is repeated until the

MPP is reached. Then the operating point

oscillates around the MPP.

C) SVPWM

The main objectives of space vector pulse

width modulation generated gate pulse are

the following.

Wide linear modulation range

Less switching loss

Less total harmonic distortion in the

spectrum of switching waveform

Easy implementation and less

computational calculations

D) Voltage source Converter

Fig:3Voltage source Converter

A voltage source converter is a device which is

used to convert DC into AC. It's a converter in

which the de voltage always has one polarity

and the power reversal takes place through

reversal of the current polarityThed.c to a.c.

power converters are known as inverters. In

other words,an inverter is a circuit which

converts a D.C. power into an AC power

atdesired output voltage and frequency.

The AC output voltage could befixed at a

fixed or variable frequency. This conversion can

be achievedeither by controlled turn-on and

turn-off devices. For low and mediumpower

outputs, the power devices are suitable but for

high poweroutputs, thyristors should be used.

The output voltage waveforms of anideal

inverter should be sinusoidal. The voltage

waveforms of practical inverters are, however,

non-sinusoidal and contain certain harmonics.

Square wave or quasi -squarewave voltages may

be acceptable for low and medium

powerapplications, and for high power

applications low, distorted, sinusoidalwaveforms

are required.

The output frequency of an inverter

isdetermined by the rate at which the

semiconductor devices are switchedon and off

by the inverter control circuitry.

The harmonic contents ofoutput voltage can be

minimized or reduced significantly by switching

techniques of available high speed power

semiconductor devices.

ADVANTAGES

The three phases share a common DC-

bus minimizing the capacitance

requirements.

The DC-link capacitors can be pre-

charged, as a group.

High efficiency for fundamental

frequency switching.

D) Multilevel Inverter

An MIT researcher takes over control the concept

of utilising multiple small levels in change of

voltage to carry out the methods of power

conversion. The benefits in the concept of

multilevel are decreased in the losses of switching,

high quality of power, enhanced capability of

voltage & better electromagnetic capability (EMC).



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In the recent years, the enhancement has available

in the field of power electronics utilising the

concept of multilevel inverter due to various

advantages which are connected with switching

approaches. In future, the concept of multilevel will provides a important path for medium voltage

applications in the field of power electronics.

Additionally, multilevel inverters are intend as

bridge inverters as the connection of them is

connected in series to stack the level. The

construction of multi-level inverter will manage

less number of switching devices, able to resist

maximum voltage & minimum switching frequency

with respect to multilevel method.

F) FUEL CELL

The fuel-cell is a device which converts chemical

energy into electricity. Fuel-cells are more different

form compared to batteries. Fuel-cells are producing

electricity continuously for provided that O2 and Fuel

are delivered. There are various types fuel cells each

contains cathode, anode, and electrolyte. The

chemical reaction of H2 and O2 electricity

produces.in this project PEM fuel-cells are used for

better accuracy.

G) DC/DC CONVERTER

Figure 4: Representation of Buck/Boost

Converter

The CC for buck/boost converter within Vx = Vin

where transistor Q is ON & Vx = Vo where the

transistor is ON & Vx = Vo when transistor is OFF.

To get zero net current change over a period the

mean voltage across the inductor will be zero.

Figure 5: Waveforms for Buck-Boost

Converter

VinTon+ VoToff= 0 (1)

which providesvoltage ratio

andequivalent current

From duty _ratio “D” which lies among 1 &

0, the voltage output can change among lowest or

highest from the voltage i/plevel. The sign “-“shows a reversal of o/p voltage.

III. PROPOSED HYSTERESIS

CURRENT CONTROLLER

The modulation of hysteresis for power electronic

converter is made in several applications because of

its broad command-tracking bandwidth &

mismatched dynamic response. In this controller, a feedback current control method which records the

current of reference closed in a hysteresis band.

Figures (6) & (7) reveals the block diagram of

hysteresis current band & voltage respectively. This

controller gives the sinusoidal current which

considers as reference one with desired frequency &

magnitude. If current value increases beyond the

range of hysteresis band of current, the level of

voltage has selected the current error to minimum

value. Differently, the level of voltage inverter is not

sufficient to feedback the current error to a minimum value, so the inverter has to change the next level

which is selected. Therefore, the current fed back into

hysteresis band & actual current value to get path of

reference current existed in the hysteresis band.

Double offset band 3 level, & time-based 3 level

hysteresis controllers which are basically 3 types of

controllers utilized to design the real selection of



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voltage level [13, 14]. The main limitation of control

in hysteresis is that the changes of parameters in load

& operating situations affect the frequency switching

& hence results in problems in resonance. Besides,

switching losses reduces the usage of hysteresis control to decrease the levels of power.

Figure 6: Block Diagram of Hysteresis

Control of an H-Bridge

Figure 7: Characteristics of Hysteresis

Current Band and Voltage

IV. SIMULATION RESULTS

EXISITNG SIMULATION RESULTS

Fig 8 Grid connected PV-FC hybrid system

Fig. 9, 10 and 11 indicates the simulation results of

the system operating strategy.

Fig 9 Operating strategy of the hybrid

source.

Fig 10 Operating strategy of the whole

system.

Fig 11 Change of operating modes.

Fig 12indicates workingpolicy of hybrid source. Fig

13 indicates Workingpolicy of whole scheme. Fig 14

shows the Change of operating modes.

Fig 12Functioningpolicy of hybrid source



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Fig 13Workingapproach of whole scheme

Fig 14 Change of operating modes.

EXTENSION SIMULATION RESULTS

The Photovoltaic (PV) simulation circuit consists 5-

level Multi Level Inverter (MLI) with in between boost converter utilizing the MPPT method which is

revealed in figure (8). The power output of PV array

sent to the side of load which can be enhanced using

Perturb & Observe (P & O) control algorithm. In the

present paper, the maximum power point tracking

algorithm method is deployed using PV system. The

complete analysis of Perturb & Observe algorithm is

obtained of PV array with tracking continuously

besides maximum power point (MPP). The

performance & simulation of 5-level multilevel

inverter with boost converter utilizing the maximum power point tracking algorithm is executed utilizing

MATLAB/Simulink software.

Figure 15 Simulation PV Fed Five-Level

MLI with Intermediate Boost Converter

Using MPPT Technique

Fig:16Grid three phase source parameters

Fig:17Grid output voltage

Fig:18 Grid output current

Solar cell

Fig 16 indicates pv array subsystem, Figure 17

indicates the Solar Subsystem V-I characteriscts

Waveforms.

Figure 19: Solar Subsystem



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Fig:20 Solar cell parameters

Figure21: Solar Subsystem V-I

characteriscts Waveforms.

The efficiency & performance of PV array based

multilevel inverter was analyzed motor driven pump

system. PD-PWM method is deployed for reducing

the gate pulse for MLI .

MPPT

Figure 22 Circuit model of MPPT

Figure 23 solar output voltage by using

MPPT with respect to time.

FUEL CELL

Figure 24 Circuit Model of Fuel Cell

Fig:25 Fuel cell parameters

Figure 20 indicates Fuel-cell voltage, current and

power, Figure 21 Indicates the Multilevel inverter

voltage, Figure 22 indicates the Current and Fig 24

indicates Motor speed and torque

Figure26 Fuel cell wavforms a)

Fuel flow rate (lpm b) Utilization c) Stack

consumption d) Stack Effeciency

Fig:27 Fuel cell a) voltage b) Current C)

Fuel input



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Multi Inverter and asynchronous

machine

Fig:28 Inverter Connected to Asynchronous

Machine

Fig:29 Multilevel inverter parameters

Fig:31 Parameters of asynchronous

machine

Fig:32 Inverter output voltage

Fig:33 Inverter output current

Fig.34 Motor output waveformsa) Rotor

Speed b) Torque

SVPWM

Space vector modulation (SVM) is an

algorithm for the control of pulse width

modulation (PWM).

[1] It is used for the creation of alternating

current (AC) waveforms; most commonly to

drive 3 phase AC powered motors at varying

speeds from DC using multiple class-D

amplifiers. There are variations of SVM that

result in different quality and computational

requirements. One active area of

development is in the reduction of total

harmonic distortion (THD) created by the

rapid switching inherent to these algorithms.

A three-phase inverter as shown to the right

converts a DC supply, via a series of

switches, to three output legs which could be

connected to a three-phase motor.



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Figure 35 Circuit Model of SVPWM

Fig:36 SVPWM output level voltage

V. CONCLUSION

In this paper PV-FUEL cell system is associated

drive with grid presented. In the suggested system

the grid/load(drive) side inverter replaced with

neutral point clamped multilevel inverter for improve

the efficiency and reduces harmonics at grid side.Based on the existing discussion, it can be

explained that neutral point clamped multilevel

inverter needs minimum quantity of components as

compared with various types of multilevel inverters.

Then it gives an enhanced output besides less

quantity of semiconductor switches. The suggested

system simulation results would be carried out under

MATLAB simulation

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modern multilevel inverter for application of drive with

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