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Project Id :- 68640                                                                     Table of contents  


CHAPTER                                                                                   PAGE NO.

TABLE OF CONTENTS                                                               i

FIGURES  LIST                iv

  ABBREVIATION                                                                         v

  ABSTRACT                                                                                  vi

  CHAPTER 1. Introduction 1

            1.1 Problem Summary                                                           1

            1.2 Aim & objective of the project                                    1

1.3 Problem specification                                     1

 1.3.1 Harmonics contain in inverter                  1

 1.3.2 Switching loss                                              2

   1.4 Literature review                                           2

   1.4.1 Introduction of TLI technology                  2

            1.5 Plan of work                                                                     4

            1.6 Material & tools require                                                4

            1.6.1 Capacitor                                                                       4

Electrical Engineering                        i

Project Id :- 68640                                                                     Table of contents  

            1.6.2 Diode                                                                       4

            1.6.3 Power switches                            4

            1.6.4 Micro controller                          4

            1.6.5 Transformer                                                                4

            1.6.6 Photovoltaic cell                                                         5

            1.6.7 Other tools                                                                  5

   CHAPTER 2. Design Methodology                                                      6

             2.1 Design method                                                              6

             2.1.1 Neutral point clamped                                             6

              2.1.2 Flying capacitor                                      7

              2.1.3 Cascaded H-bridge                                                   8

              2.2 Working of inverter                                                     8

              2.3 Canvas                                                 9

              2.3.1 Empathy canvas                                                9

              2.3.2 Ideation canvas                               11

              2.3.3 Product development canvas                               12

              2.3.4 AEIOU canvas                                      13

    CHAPTER 3. Project Adv. Disadv. Application                                15

              3.1 Project Advantages                                                    15

              3.2 Project Disadvantages                                               15

              3.3 Project Application                                                     15

Electrical Engineering                                  ii

Project Id :- 68640                                                                     Table of contents  

              3.3.1 Energy conversion                                                   15

              3.3.2 In Three Phase machine                                         16

              3.3.3 Train Traction                                        16

    CHAPTER 4. Work plan & Future Work                                            18

              4.1 Work Plan                                             18

              4.2 Future Work                                      18

    CONCLUSION                                                            19

Electrical Engineering                                         iii

Project Id :- 68640                                                                               Figures List  


FIGURE NO. & CONTENT                                                   PAGE NO.

   1.3.1 Harmonics contain in inverter                                             2

   1.4.1 Introduction to TLI technology                                           3

   2.1 Design Method                                                                       6

   2.1.1 Neutral point clamped                                                         7

   2.1.2 Flying capacitor                                                                   7

   2.1.3 Cascaded H-bridge                                      8

   2.3.1 Empathy canvas                                                                  10

   2.3.2 Ideation canvas                                                                   11

   2.3.3 Product development canvas                                              13

   2.3.4 AEIOU canvas                                                                    14

   3.3.1 Energy conversion                                                              15

   3.3.2 In Three phase machine                                                      16

   3.3.3 Train traction                                                                       17

Electrical Engineering            iv

Project Id :- 68640Abbreviation


1. DC :- Direct Current

2. AC :- Alternating Current

3. NPC :- Neutral Point Clamped

4. MCU :-  Micro Controller

5. PWM :- Pulse Width Modulation

6. IGBT :- Insulated Gate Bipolar Transistor

7. PCB :- Printed circuit board

8. FC :- Flying Capacitor

9. CHB :- Cascaded H-Bridge

10. Ex. :- Example

11. TLI :- Three Level Inverter

Electrical Engineering    v

Project Id :- 68640                                                                                             Abstract


Now a days 3-level inverter has many applications in medium voltage, high voltage power application such as variable speed drive, power compensation, rolling mills and renewable energy. The close loop control modelling and prototype implementation of conventional 3-level neutral point clamped (NPC) controller is done. This project focuses on hardware implementation of 3-level inverter using controller and balancing the neutral point potential (NPP), here by reducing the output voltage distortion. It has capability to handle high power with less total harmonics distortion, reduce switching losses and good power quality.

Electrical Engineering                              vi

Project Id :- 68640   Introduction


It is an Electronic device that change direct current (DC) to alternating current (AC).The input voltage of the inverter depends on the design and purposed of inverter. In our project we use photovoltaic Cell as a green energy source as an input of inverter.

INPUT VOLTAGE: A power inverter device or circuit requires a relatively stable DC power source capable of supplying sufficient current for the intended power demands of the system. The input voltage depends on the design and purpose of the inverter.

OUTPUT WAVEFORM: When input voltage given to inverter it can produce square wave, modified sine wave, pulse sine wave, PWM wave or sine wave as per design consideration.

1.1 Problem Summary

In this project we havetry to make inverter output pure sine wave, reduced harmonics,operate in any weather condition, portable power supply, low costing,reduce switching loss, high operating frequency.

1.2 Aim and Objective of the project

To make low cost inverter by using cheap microcontroller and mobile power supply.

1.3 Problem Specifications

Usually the inverter output contains a harmonic and switching losses which reduces the efficiency of inverter which result in more costly operation.

1.3.1 Harmonics contain in Inverter

A harmonics referred to power quality in ideal world means how pure the voltage is how pure the current wave form is in its sinusoidal form.

Electrical Engineering    1

Project Id :- 68640                                                                                Introduction

Power quality is very importantto commercial and industrial power system design. It shouldbe present dueto many reasons like external disturbance and switching.

FIGURE 1.3.1

1.3.2 Switching Loss

As switching frequency increase, it becomes of Paramount importance to reduce the switching losses in the converter.  It is loss associated with transition of switch from its on state to off state and vice versa.

1.4 Literature Review

1.4.1 Introduction to Three Level Inverter (TLI) Technology

The 3-level inverter offers several advantages over the more common two level inverter. As compared to two level inverters, three level inverters have smaller output voltage steps that minimize motor issues due to long power cables between the inverter and the motor. These issues consist surge voltages and rate of voltage rise at the motor terminals and motor shaft bearing currents. In addition, the clean output waveform provides an effective switching frequency twice of the actual switching frequency. Should an output filter be required, the components will be smaller and less costly than for an equivalent rated two level inverter.

Electrical Engineering                                                                                              2

Project Id :- 68640                                                                                Introduction

Most often the NPC inverter is used for high voltage inverters. Because the IGBTs are only subjected to half of the bus voltage, lower voltage IGBT modules can be used.

Basic Circuit Configuration and Its Behaviour:

 Figure 1.4.1 shows the circuit configuration of the NPC inverter. Each leg has four IGBT switches connected in series. The applied voltage on the IGBT is one-half that of the conventional two level inverter. The bus voltage is dividing in two by the connection of equal series connected bus capacitors. Each leg is completed by using the addition of two clamp diodes. This topology traditionally has been used for medium voltage drives both in industrial and other applications. In addition to the ability of handling higher voltages, the NPC inverter has several favourable features like lower line-to-line and common-mode voltage steps and lower output current ripple for the same switching frequency as that used in a two level inverter.

                                    FIGURE 1.4.1

Summary :

The TLI series IGBT modules, specifically designed for low & medium voltage NPC or three level inverters, provide a cost effective approach for the design of an inverter with the following desirable characteristics:

• High quality output voltage and current waveforms result in less motor         stress even for long power cables.

Electrical Engineering                                                                                              3

Project Id :- 68640                                                                                Introduction

• High efficiency design due to decrease switching losses

ʉۢ Reduced output filter component size and cost as compared to a two level inverter

ʉۢIGBT module reliability

1.5 Plan Of Work

To use microcontroller for switching control of power switches(IGBT) to increase operating frequency.

1.6 Material and Tools Required

1.6.1 Capacitor

It is a passive two-terminal electrical component used to temporarily store electrical energy in an electric field. It measure in FARADAY.

1.6.2 Diode

It is a two-terminal electronic component that conducts primarily in one direction (asymmetric conductance).

1.6.3 Power Switches

It is an electrical switch that switches a load between two sources. Some transfer switches are manual, in that an operator effects the transfer by throwing a switch, while others are automatic and trigger when they sense one of the sources has lost or gained power.

1.6.4 Micro Controller

MCU is a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals.

1.6.5 Transformer It is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction.

Electrical Engineering                                                                                              4

Project Id :- 68640                                                                                Introduction

1.6.6 Photovoltaic Cell

It is an electrical device that converts the energy of light directly into electricity by the photovoltaic effect.

1.6.7 Other Tools


• Soldering Machine

• Connecting Wire

• Multimeter

Electrical Engineering                                                                                              5

Project Id :- 68640                                                                 Design Methodology

CHAPTER  2                   Design Methodology

2.1  Designing Method

                   FIGURE   2.1

2.1.1  Neutral Point Clamped(NPC) :

A NPC converter is basically composed of two traditional two-level VSCs

stacked one over the other with some minor modifications. It can be seen in

Fig. 2.1.1, the negative bar of the upper converter and the positive bar of the

    lower one are joined together to form the new phase output, while the original

    phase outputs are connected through two clamping diodes to form the neutral

point N, dividing the dc-link voltage in two. Now each power device has to

block only half of the total converter voltage; hence with the same

Semiconductor technology,the power rating of the converter can be doubled.

 In addition, the neutral point enables the generation of a zero voltage level,

obtaining a total of three different voltage levels.This method has some       

    Advantages so we refer this method.

Electrical Engineering                                                                                              6

Project Id :- 68640                                                                 Design Methodology

                                            FIGURE 2.1.1

2.1.2 Flying Capacitor

The FC topology is in some way similar to the NPC, with the main difference being that the clamping diodes are replaced by flying capacitors, as can be seen in Fig. 2.1.2. Here the load cannot be directly connected to the neutral of the converter to generate the zero voltage level. Instead, the zero level is obtained by connecting the load to the positive or negative bar through the flying capacitor with opposite polarity respect the dc-link. Like with the NPC, only two gating signals are necessary per phase to avoid dclink and flying capacitor short-circuit. However, in the FC, the inverted gating signals are related to different switching devices, as shown in Fig. 2.1.2.

                                               FIGURE 2.1.2

Electrical Engineering                                                                                              7

Project Id :- 68640                                                                 Design Methodology

2.1.3 Cascaded H-Bridge

CHB are multilevel converters formed by the seriesconnection of two or more single-phase H-bridge inverters, hence the name. Each H-bridge corresponds to two voltage source phase legs, where the line–line voltage is the converter output. Therefore, a single H-bridge converter is able to generate three different voltage levels. Each one leg has only two possible switching state, to avoid dc-link capacitor short-circuit. Since there are two legs, four different switching states are possible, although two of them have redundant output voltage. Fig. 2.1.3 shows the three different output voltage levels and their corresponding equivalent circuits. The zero level can be generated connecting the phase outputs to the positive or the negative bars of the inverter.

                                       FIGURE 2.1.3

2.2 Working of inverter

3-level is indicate that its output will change three times (+Vdc/2, 0, -Vdc/2).Here Vdc is a supplying DC voltage. We use a solar cell to generate a dc & it will store in battery and then give to input of inverter. NPC is also called as Diode Clamped.The voltage Vdc    is split into three levels by two connected bulk capacitors C1& C2. The middle point of the two capacitors n can be

Electrical Engineering                                                                                              8

Project Id :- 68640                                                                 Design Methodology

defined as the neutral point. The output voltage Van has three states: +Vdc/2, 0 -Vdc/2.

For voltage level  +Vdc/2,switches  S1  and  S2 need to be turned on;for Voltage level -Vdc/2, switches S1’  and S2’   need to be turned on;for the 0 , S1’ and S2  need to be turned on. Refer Figure 2.1.1.

2.3 Canvas

2.3.1 Empathy canvas

From the empathy canvas we can know about users and stakeholder who are invest there amount in project. Activities around the project also include in it.

Users : Family member, Business men, Bank person, Office worker, Hospital worker, College admin etc.

Stakeholders : Director of Industry, Hospital, Railway, Family member, Bank, School/College trustee etc.  

Activities : Worker work in industry, Operation of Patient, Student Study,Older person reading newspaper, Employee work on the PC, Running appliance in car etc.

Story Boarding : The Story Boarding is an activity where it is needed to incorporate emotions related with activities, user, stakeholders identified. The story made up here tells about emotional attachment including historical aspect connected (maybe) however it is lacking of on hand experience or a user at present.

Electrical Engineering                                                                                             9

Project Id :- 68640                                                                 Design Methodology

                                   FIGURE : 2.3.1

Electrical Engineering                                                                                            10

Project Id :- 68640                                                                 Design Methodology

2.3.2 Ideation Canvas

People : The project can be used by persons are include in it. Ex. Business men, Bank person, office worker, Railways etc.

Activities : With thought on people involved in different activities, an attempt was made to think up on possibilities or various activity. Ex. Worker work in industry, Operation of Patient, Student Study, Older person reading newspaper, Employee work on the PC, Running appliance in car etc.

Situation/context/Location : We attempted to identify different location that are involved in performing such activities that was relevant to activities. Ex. Power cut, Summer/winter/rainy, Industries, Bank, Railway etc.

Props/Possible Solution : This is section ideation canvas help in carving out different in line with attempting/looking forward to have an idea about addressing a problem.

FIGURE : 2.3.2

Electrical Engineering                                                                                            11

Project Id :- 68640                                                                 Design Methodology

2.3.3 Product Development Canvas

The canvas begins with mention of purpose and people. By this, it has brought down to a very limited set off people that are thought to be directly involved in major of the activities. The Product Experience was to be mentioned as the product is giving experience to the users.

Purpose : Comfort, Time saving, Increase efficiency, Low cost etc.

People : The project can be used by persons are include in it. Ex. Business men, Bank person, office worker, Railways etc.

Product Experience : Comfortable, Time saving, Low cost, Good efficiency etc.

Product Function : Continuous Power supply, Useful in traction system, DC to AC conversion.

Product Feature : Low cost Controller, Solar base input, Economical, Near by sinusoidal output.

Component : IGBT, Diode, Controller, Connecting Wire, Battery, Solar plate, PCB, Soldering Machine.

Customer Revalidation : Comfortable, Working good, Less battery charge during rainy season, Very useful for hospital, individual supply to ach switch.

Reject, Redesign, Retain : Weight> use parallel battery supply, Less Battery charge during rainy season> Use back-up DC source during rainy season.

Electrical Engineering                                                                                        12

Project Id :- 68640                                                               Design Methodology

                                          FIGURE 2.3.3

2.3.4 AEIOU Canvas :

In this Canvas we can about Activities, Environment, Interactions, Object, and Users.

Electrical Engineering                                                                                        13

Project Id :- 68640                                                                 Design Methodology

                                          FIGURE 2.3.4

Electrical Engineering                                                                                        14

Project Id :- 68640                  Project Adv. Disadv. Application

CHAPTER 3Project Adv. Disadv. Application

3.1 Project Advantages

1) It can generate output voltages with extremely low distortion and lower dv/dt .

2) It can operate with a lower switching frequency.

3) High efficiency.

4) Economical cost.

3.2 Project Disadvantages

1) Complimentary circuit.

2) External DC supply require to each insulated gate bipolar transistor (IGBT) switches.

3) Harmonics affecting the output signal.

3.3 Project Applications

3.3.1 Energy Conversion

In energy Conversion inverter mostly used. In DC generation like wind plant or solar plant for conversion of DC to AC inverter is used. It is also be possible to convert DC into AC for small appliance like car auxiliary.

                                       FIGURE 3.3.1

Electrical Engineering                                                                                        15

Project Id :- 68640                  Project Adv. Disadv. Application

3.3.2 In 3-phase Machine

Generally motors has starter for speed control and Protection purpose. We can use inverter as speed control of machine. A combination of rectifier and inverter is used in industry for speed control.

                                       FIGURE 3.3.2

3.3.3 Train Traction

In traction system to control the speed of wheels can be possible by inverter. The voltage from the line is given to the rectifier through pantograph and circuit breaker. Rectifier converts it in DC then 3-level inverter with NPC topology convert into AC. Speed can be control through firing angle.

Electrical Engineering                                                                                        16

Project Id :- 68640                  Project Adv. Disadv. Application

                                          FIGURE 3.3.3

Electrical Engineering                                                                                        17

Project Id :- 68640                                                         Work plan & Future work

CHAPTER 4                     Work plan & Future work

4.1 Work Plan

In the starting stages of this phase study about the research topic was carried out & this topic, Design and simulation of 3-level inverter by using solar cell were found the potential one. There were many problem found the for selecting this topic. After it we take knowledge about it and do project work.

    Table:4.1   Work plan details

    June – July Project Search/ Finalized Project

   July  - August Canvas Activity

   August – September Research about Project theory

   September – October Report and preparation of Presentation

4.2 Future Work

In the 8th semester we will collect the components of the project and with help     of internal guide we implementing the hardware of this project.

Electrical Engineering                                                                                        18

Project Id :- 68640                                                                                   Conclusion


The project that was undertaken by us was the unique one with few applications followed by few drawbacks also. It is used in industry, railway for RPM control. The 3-level inverter is a novel design which can be easily operates when supply given to it. It simply convert the DC to AC, it has some advantages compare to simple inverter. The output is more sinusoidal and harmonics are reduced. It can be uses for both domestic and industrial purpose. However yet some issue are present such as weight and size, but it is less affect to working. Considering the financial aspect in designing the 3-level inverter initial cost is high as the parts purchased are genuine, but if we manufacture this in mass production cost can be minimized based on the type of application.

Electrical Engineering                                                                                        19

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