M.E. Project PPT

Simulation, Analysis & Open Loop Constant V/Hz Speed Control of Multilevel Inverter fed Induction Motor based on SPWM Control

MOHAMMED ANNAS1604-13-743-011

Power Electronics Systems (PES)

Under the Guidance of

Mr. J.E.Muralidhar, Associate Professor, EED

Muffakham Jah College of Engineering & Technology, Banjara Hills, Hyderabad

2

Overview

INTRODUCTION TO INVERTER CONCEPT OF MULTI LEVEL INVERTER MULTI LEVEL INVERTER TOPOLOGIES

CASACADE H-BRIDGE INVERTER DIODE CLAPMED INVERTER FLYING CAPACITOR INVERTER

SINUSOIDAL PWM TECHNIQUES IN-PHASE DISPOSITION (PD) PHASE OPPOSITION DISPOSITION (POD) ALTERNATE PHASE OPPOSITION DISPOSITION (APOD)

MODELING OF PHASE DISPOSITION(PD) MODULATION TECHNIQUE GENERATION OF MODULATING SINE WAVE GENERATION OF TRIANGULAR CARRIER WAVE GENERATION OF FIRING PULSES FOR 3-LEVEL & 5-LEVEL INVERTER

SIMULINK MODEL OF 3-LEVEL & 5-LEVEL DIODE CLAPMED INVERTER SIMULATION RESULTS

3

Overview

Performance characteristics of induction motor connected to Conventional 2-Level and Diode Clamped multi-level invertera) On RATED Loadb) On Variable Load

Study of Transients During Starting of 3-Phase I.M. MATLAB Code for generating OPEN LOOP controlled Speed-Torque

Characteristics of 3-Phase I.M. Open Loop V/Hz Speed Control of 2-level & 5-level Inverter fed I.M. CONCLUSION REFERENCES

4

INTRODUCTION TO INVERTER• A power inverter, or inverter, is an electronic device or circuitry that

changes direct current (DC) to alternating current (AC).• The input voltage, output voltage and frequency, and

overall power handling depend on the design of the specific device or circuitry. The inverter does not produce any power; the power is provided by the DC source.

5

CONCEPT OF MULTI-LEVEL INVERTER Mostly a two-level inverter is used in order to generate the AC voltage from DC voltage A two-level Inverter creates two different voltages for the load---

If Input Voltage is VdcThen it produces output as +Vdc/2 AND –Vdc/2 based on switching of power devices.

This method of generating AC output seems to be Effective but posses following drawbacks:• High Harmonic Distortion in Output Voltage.• High dv/dt.

3-Phase two Level Inverter 2-Level Line Voltage Output Waveform (one leg)

6

CONCEPT OF MULTI-LEVEL INVERTER In order to create a smoother stepped output waveform, more than two voltage levels are combined together and the output waveform obtained in this case has lower dv/dt and also lower harmonic distortions.

2-Level output 3-Level Output 5-Level Output

Smoothness of the waveform is proportional to the voltage levels, as we increase the voltage level the waveform becomes smoother but the complexity of controller circuit and components also increase.

Voltage Waveform Type Number of levels

Line-Line Voltage 0 Level, +ve or -ve levels

Phase-Neutral Voltage 0 Level, +ve Levels & -ve Levels

7

MULTI LEVEL INVERTER TOPOLOGIES The elementary concept of a multilevel converter to achieve higher power is to use a series of

power semiconductor switches with several lower voltage dc sources to perform the power conversion by synthesizing a staircase voltage waveform.

Capacitors, batteries, and renewable energy voltage sources can be used as the multiple dc voltage sources.

however, the rated voltage of the power semiconductor switches depends only upon the rating of the dc voltage sources to which they are connected.

There are several topologies of multilevel inverters available. The difference lies in the mechanism of switching and the source of input voltage to the multilevel inverters. Three most commonly used multilevel inverter topologies are:

• Cascaded H-bridge multilevel inverters• Diode Clamped multilevel inverters• Flying Capacitor multilevel inverters

Advantages of Multilevel Inverters:• Better Staircase waveform Quality.• Lower Common-Mode (CM) Voltage.• Less Distorted Input Current.• Possibility of Higher Switching Frequency.

8

MULTI LEVEL INVERTER TOPOLOGIESCASCADE H-BRIGDE MULTI LEVEL INVERTER

Each cell contains one H-bridge and the output voltage generated by this multilevel inverter is actually the sum of all the voltages generated by each cell i.e. if there are k cells in a H-bridge multilevel inverter then number of output voltage levels will be 2k+1.

Advantages of Cascade H Bridge Multilevel Inverters• Output voltages levels are doubled the number of sources• Manufacturing can be done easily and quickly• Packaging and Layout is modularized.• Cheap

Disadvantages of Cascade H Bridge Multilevel Inverters• Every H Bridge needs a separate dc source.• Limited applications due to large number of sources.

Cascaded inverter circuit topology and its associated waveform

9

MULTI LEVEL INVERTER TOPOLOGIESDIODE CLAMPED MULTI LEVEL INVERTER

This topology uses clamping diodes in order to limit the voltage stress of power devices. It was first proposed in 1981 by Nabae, Takashi and Akagi. A k level diode clamped inverter needs

• (2k – 2) switching devices, • (k – 1) input voltage source and • (k – 1) (k – 2) diodes in order to operate.

Vdc is the voltage present across each diode and the switch.

Three level diode clamp multi-level inverter (one leg) Switching states in one leg of the three-level diode clamped inverter

10

MULTI LEVEL INVERTER TOPOLOGIESDIODE CLAMPED MULTI LEVEL INVERTER

Five level diode clamp multi-level inverter (one leg) Switching states in one leg of the five-level diode clamped inverter

Advantages of Diode Clamped Multilevel Inverters • Capacitance of the capacitors used is low.• Back to back inverters can be used.• Capacitors are pre charged.• At fundamental frequency, efficiency is high.Disadvantages of Diode Clamped Multilevel Inverters• Clamping diodes are increased with the increase of each level.• Dc level will discharge when control and monitoring are not precise.

11

MULTI LEVEL INVERTER TOPOLOGIESFLYING CAPACITOR MULTILEVEL INVERTER

This configuration is quite similar to previous one except the difference that here flying capacitors is used in order to limit the voltage instead of diodes.

The input DC voltages are divided by the capacitors here. The voltage over each capacitor and each switch is Vdc. A k level flying capacitor inverter requires

• (k - 1) x (k - 2)/2 auxiliary capacitors per phase leg• (2k – 2) switches and • (k – 1) number of capacitors in order to operate.

Switching state is same as diode clamped Multilevel Inverter

Advantages of Flying Capacitor Multilevel Inverters• Static var generation is the best application of Capacitor Clamped Multilevel Inverters.• For balancing capacitors’ voltage levels, phase redundancies are available.• We can control reactive and real power flow

Disadvantages of Flying Capacitor Multilevel Inverters• Voltage control is difficult for all the capacitors• Complex startup• Switching efficiency is poor• Capacitors are expansive than diodes

Three level Flying Capacitor multi-level inverter (one leg)

12

Sinusoidal PWM Technique In this technique, an isosceles triangle carrier wave of frequency fc is compared with the fundamental

frequency fr sinusoidal modulating wave, and the points of intersection determines the switching points of power devices.

Two important parameters of the design process are • Amplitude Modulation Index Ma where Vr = Peak amplitude of reference control signals Vc = Peak amplitude of the Triangular carrier wave.• Frequency Modulation Index Mf = where fc = frequency of the carrier wave fr = reference sinusoidal signal frequency.

Ma determines the magnitude of output Voltage fr controls the frequency of output voltage fc determines switching frequency of power semiconductor devices.

13

Sinusoidal PWM Technique Types of Multiple Carrier-based SPWM Techniques:

Sinusoidal PWM can be classified according to carrier and modulating signals. This work used the intersection of a sine wave with a triangular wave to generate firing pulses.There are many alternative strategies, such as:

I. In-Phase Disposition (PD)II. Phase Opposition Disposition (POD)III. Alternative Phase Opposition Disposition (APOD)

I. In-Phase Disposition (PD):

In this technique, All the triangular carrier waves are In-Phase with each other.

14

Sinusoidal PWM TechniqueII. Phase Opposition Disposition (POD):

In this technique, the carrier signal above Zero reference are In-Phase but Phase shifted by 180° from those carrier signals which are below zero reference.

III. Alternative Phase Opposition Disposition (APOD): In this method, each carrier signal is phase shifted by 180° from the adjacent carrier signal.

15

MODELING OF PHASE DISPOSITION(PD) MODULATION TECHNIQUE

GENERATION OF MODULATING SINE WAVE In order to generate fundamental component of output voltage at 50Hz frequency, the frequency of reference sine wave is set to 50Hz itself.

This option is used to apply PHASE SHIFT in Sine wave in terms of RADIANS. 120° = 2*pi/3240° = -2*pi/3

This option is used to apply desired frequency of Sine wave in terms of RADIANS

16


GENERATION OF TRIANGULAR CARRIER WAVE Let the switching frequency, fs = 1.1 kHz Fundamental(Output) Frequency, fr = 50 HzHence, Frequency Modulation ratio, Mf = 22() which means there exist 22 cycles of triangular wave for each cycle of Sine wave.Time Period, = = 9.09 * 10-4 sec. Let, = 0.0002273 sec.

17


GENERATION OF FIRING PULSES PD SPWM GENERATION FOR 3-LEVEL INVERTER :• Three level pulse width modulated waveforms can be generated by sine-carrier PWM. • Sine carrier PWM is generated by comparing the three reference control signals (one for each phase) with two

triangular carrier waves. Vdc/2 , Vref,i > Vtri,1

Vio = 0 , Vtri,1 > Vref,i > Vtri,2 Where i= a, b or c phase

-Vdc/2 , Vtri,2 > Vref,

Simulated SPWM output for 3-Level Inverter

18


GENERATION OF FIRING PULSES PD SPWM GENERATION FOR 3-LEVEL INVERTER :

Simulink Model for 3-Level PD SPWM Generation Firing Pulses for Upper & Lower Switches for a-Phase of 3-Level inverter

19


GENERATION OF FIRING PULSES PD SPWM GENERATION FOR 5-LEVEL INVERTER :• Five level pulse width modulated waveforms can be generated comparing the three reference

control signals (one for each phase) with four triangular carrier waves.

Vdc/2 , Vref,i > Vtri,1 Vdc/4 , Vref,i > Vtri,2 Vio = 0 , Vtri2 > Vref,i > Vtri,3 -Vdc/4 , Vtri,3 > Vref,i -Vdc/2 , Vtri,4 > Vref,i

Where i = a, b or c phase

Simulated SPWM output for 5-Level Inverter

20



Simulink Model for 5-Level PD SPWM Generation

Firing Pulses for UPPER 4 Switches

Firing Pulses for LOWER 4 Switches

21



Firing Pulses for Upper Switches(S1, S2, S3 & S4) for a-Phase of 3-Level inverter

22

SIMULATION MODELS OF DIODE CLAMPED MULTILEVEL INVERTER Specifications(For both 3-Level & 5-Level Inverter):• Supply Voltage = 200V• Fundamental Frequency (fr) = 50 Hz• Switching Frequency (fs) = 1.1 KHz• Amplitude Modulation Index (Ma) = Variable• Frequency Modulation Index (Mf) = 22

Simulink Model of THREE Level Diode Clamped SPWM Inverter

23

SIMULATION MODELS OF DIODE CLAMPED MULTILEVEL INVERTER

Simulink Model of FIVE Level Diode Clamped SPWM Inverter

24

SIMULATION RESULTS

Simulated Line voltage of 3-Level diode clamped inverter

Harmonic Spectrum of 3-Level diode clamped inverter for R= 25Ω/phase and ma=0.9

25

SIMULATION RESULTS

Simulated Line voltage of 5-Level diode clamped inverter

Harmonic Spectrum of 5-Level diode clamped inverter for R= 25Ω/phase and ma=0.9

26

SIMULATION RESULTSMa 3-Level Inverter Line Voltage 5-Level Inverter Line Voltage

0.5

0.8

1.1

27

SIMULATION RESULTS

Comparison of the calculated Line voltage THD for fixed R Load

Modulation Index

(ma)

% THD3-Level

% THD5-Level

1.1 31.94 15.93

1 35.25 17.23

0.9 39.20 17.45

0.8 42.03 21.73

0.7 44.30 24.18

0.6 49.17 26.43

0.5 68.54 35.29

28

PERFORMANCE CHARACTERISTICS OF 2-LEVEL AND DIODE CLAMPED MULTI INVERTER FED INDUCTION

MOTORThe Performance Characteristics of Induction Motor is analyzed when loaded with a) Rated Torque b) Variable Torque

Specifications of Induction Motor: 4kW, 400V, 50Hz and 1500 RPM (a) Rated Torque --- rated

Hence, Trated = 26.71 N-m(b) Variable Torque---In this case, Load Torque is applied in the form of steps i.e. different magnitude at different time.

Variable Load Torque

29

Simulink Model of Two Level SPWM Inverter fed Induction motor Drive

PERFORMANCE CHARACTERISTICS OF 2-LEVEL INVERTER FED INDUCTION MOTOR

30

• Stator Current, Rotor Current, Speed & Electromagnetic Torque variations at RATED Load Torque (26.71 N-m)

Stator Current of 2-Level inverter fed I.M.

Rotor Current of 2-Level inverter fed I.M.


31


Speed Variation of 2-Level inverter fed I.M.

Electromagnetic Torque of 2-Level inverter fed I.M.


32

• Electromagnetic Torque variations at VARIABLE Load Torque

Variable Load Torque, Speed variation & Electromagnetic torque variation of 2-Level inverter fed I.M.


33

Simulink Model of Three Level Diode Clamped SPWM Inverter fed Induction motor Drive

PERFORMANCE CHARACTERISTICS OF 3-LEVEL DIODE CLAMPED MULTI INVERTER FED INDUCTION MOTOR

34





35





36

• Electromagnetic Torque variations at VARIABLE Load Torque

Variable Load Torque, Speed variation & Electromagnetic torque variation of 3-Level inverter fed I.M.


37

Simulink Model of Five Level Diode Clamped SPWM Inverter fed Induction motor Drive


38





39





40

• Speed variations at VARIABLE Load Torque

Load Torque & speed variation of 5-Level Diode Clamped Inverter fed I.M.


INVERTER LEVEL Stator Current

(amps) Speed(rpm)Electromagnetic

Torque(N-m)

2 14.41 1384 33.14

3 12.46 1294 27.04

5 31.38 1500 30.24

• Magnitudes of Induction Motor Parameters for 2,3 & 5-level inverter at RATED Load Torque (26.71 Nm)

41

Comparison of Line-Line Voltage THD for 2, 3 & 5 Level Inverter fed I.M.

The comparison between the total harmonic distortion with respect to the modulation index for 2, 3 and 5-level Diode clamped inverter is shown below in figure. It can be observed that the THD is lower in 5-level inverter.

42

Study of Transients during Starting of 3-Phase Induction Motor

• A model of a 3-Phase induction motor was setup in MATLAB SIMULINK and the rotor and stator currents, speed & electromagnetic torque were observed with different values of rotor and stator resistances and impedances.

• Stator Inductance:Low ~ 0.05mHMedium ~ 0.7mHHigh ~ 2mH

• Rotor Resistance:Low ~ 0.1 ohmHigh ~ 0.5 ohm

• Stator Resistance:Low ~ 0.16 ohmHigh ~ 0.8 ohm

All the simulations were made for Zero Load Torque. However, the inertia and friction were taken into consideration.

43


VALUE STATOR_I(amps) SPEED(rpm)

Low 49.79 1500

Medium 25.48 1499

High 25.9 1499

STATOR INDUCTANCE:


Low 26.62 1500

High 26.92 1496

ROTOR RESISTANCE:


Low 41.96 1500

High 9.665 1398

STATOR RESISTANCE:

44


On the basis of the above outcomes, the following observations were made: • On increasing the motor inductance (either rotor or stator), the

transients lasted for longer period i.e., the machine took longer time to achieve its steady state speed, current and torque. Also the start was a bit jerky.

• On increasing the rotor resistance, there was no effect on the steady state time but the machine started with lesser jerks, i.e., the fluctuations in the transient period was reduced. Also the maximum torque occurred at a lower speed.

• On increasing the stator resistance, the steady state time increased as well as the machine started with more jerks. Thus the stator resistance must be kept as low as possible.

45

MATLAB Code for Generating OPEN LOOP Constant V/Hz speed control Characteristics

function out = inductionconstVf() Vll=input('Suppy Voltage (line to line) RMS value @ 50 Hz: '); f2=input('Enter the second frequency: '); f3=input('Enter the third frequency: '); f4=input('Enter the fourth frequency: '); f5=input('Enter the fifth frequency: '); P=input('Enter the number of poles: '); Rs=input('Stator Resistance: '); Rr=input('Rotor Resistance: '); Xs=input('Stator Leakage Reactance @ 50 Hz frequecny: '); Xr=input('Rotor Leakage Reactance @ 50 Hz frequecny: '); Ls=Xs/(2*pi*50); Lr=Xr/(2*pi*50); Vlnf1=Vll/(3^0.5); Vlnf2=Vlnf1*f2/50; Vlnf3=Vlnf1*f3/50; Vlnf4=Vlnf1*f4/50; Vlnf5=Vlnf1*f5/50; Wsync1=4*pi*50/P; Wsync2=4*pi*f2/P; Wsync3=4*pi*f3/P; Wsync4=4*pi*f4/P; Wsync5=4*pi*f5/P;

46


Tmf2=zeros(Wsync2*500+1,1); Tmf3=zeros(Wsync3*500+1,1); Tmf4=zeros(Wsync4*500+1,1); Tmf5=zeros(Wsync5*500+1,1); Tmf1=zeros(Wsync1*500+1,1); m=1; for Wrotor1=0:0.002:Wsync1 Tmf1(m)=(3*(((Vlnf1^2)*Rr/((Wsync1-Wrotor1)/Wsync1))/((Rs+Rr/((Wsync1-Wrotor1)/Wsync1))^2+(2*pi*50*Ls+2*pi*50*Lr)^2))/Wsync1); %star connected m=m+1; end m=1; for Wrotor2=0:0.002:Wsync2 Tmf2(m)=(3*(((Vlnf2^2)*Rr/((Wsync2-Wrotor2)/Wsync2))/((Rs+Rr/((Wsync2-Wrotor2)/Wsync2))^2+(2*pi*f2*Ls+2*pi*f2*Lr)^2))/Wsync2); m=m+1; end m=1;for Wrotor3=0:0.002:Wsync3 Tmf3(m)=(3*(((Vlnf3^2)*Rr/((Wsync3-Wrotor3)/Wsync3))/((Rs+Rr/((Wsync3-Wrotor3)/Wsync3))^2+(2*pi*f3*Ls+2*pi*f3*Lr)^2))/Wsync3); m=m+1; end m=1; for Wrotor4=0:0.002:Wsync4 Tmf4(m)=(3*(((Vlnf4^2)*Rr/((Wsync4-Wrotor4)/Wsync4))/((Rs+Rr/((Wsync4-Wrotor4)/Wsync4))^2+(2*pi*f4*Ls+2*pi*f4*Lr)^2))/Wsync4); m=m+1; end

47


m=1; for Wrotor5=0:0.002:Wsync5 Tmf5(m)=(3*(((Vlnf5^2)*Rr/((Wsync5-Wrotor5)/Wsync5))/((Rs+Rr/((Wsync5-Wrotor5)/Wsync5))^2+(2*pi*f5*Ls+2*pi*f5*Lr)^2))/Wsync5); m=m+1; end plot(Tmf1); hold on; plot(Tmf2); plot(Tmf3); plot(Tmf4); plot(Tmf5); hold off; ylabel('Torque(N-m)'); xlabel('Rotor Speed(Rad/s) * 100'); end

48

Speed-Torque Characteristics for Open Loop Constant V/Hz control of Induction Motor

49

Open Loop V/Hz Speed Control of 2-level Inverter fed IM

• Comparison of speed at various Frequencies• At 50Hz Frequency (1460 rpm)

• At 40Hz Frequency (1134 rpm)


50


• Comparison of Torque at various Frequencies• At 50Hz Frequency

• At 40Hz Frequency


51


• Comparison of Stator Current at various Frequencies• At 50Hz Frequency ( 11.37 Amps)

• At 40Hz Frequency ( 9.7 Amps)


52

Open Loop V/Hz Speed Control of 5-Level Diode Clamped Inverter fed I.M.

• Comparison of speed at various Frequencies• At 50Hz Frequency (1479 rpm)



53


• Comparison of Torque at various Frequencies• At 50Hz Frequency



54


• Comparison of Stator Current at various Frequencies• At 50Hz Frequency ( 4.9 Amps)



55

%THD of Line Voltage, Stator Current & Speed for open loop V/Hz Control

Load Torque = 10 N-m with step time of 0.15 Simulation time 2 level output --- 400.5AC 50Hz at 568.5 DC Input @ 0.9 Ma

5 level output --- 400.1AC 50Hz at (179 * 4) DC Input @ 0.9 Ma

As can be observed form above waveforms, The V/Hz Speed control (open loop mode) can be achieved just by varying MODULATION INDEX of SPWM.

Tabular Columns states that at various frequencies different speeds can be obtained by keeping V/f ratio constant & also Electromagnetic Torque fluctuates near Rated Load Torque.

Frequency (Hz) 2 * Ma AC Supply

voltage (V) V/fLine

Voltage %THD

Stator Current

(A)

Speed (rpm)

50 1.8 400.5 8.01 0.796*100 11.37 146040 1.16 321.4 8.035 1.219*100 9.7 113430 0.65 240.7 8.023 2.605*100 6.801 752

Frequency (Hz) 2 * Ma AC Supply

voltage(V) V/fLine

Voltage %THD

Stator Current

(A)

Speed (rpm)

50 1.8 400.1 8.002 0.1744*100 4.919 147940 1.42 319.8 7.995 0.2432*100 4.653 117330 1.04 240.8 8.013 0.3351*100 4.753 873

56

CONCLUSION This Presentation briefly explains the theory of Phase Disposition Sinusoidal Pulse Width

Modulation (PDSPWM) for three and five level inverter. The simulation of 3-Level and 5-Level Diode clamped multilevel inverter was carried

using sinusoidal pulse width modulation (PWM). It has shown that reduction in line voltage THD takes place as we move from three level

inverter to five level inverter and performance of both inverters were investigated using R Load.

Also a comparison of %THD for both the inverters has been tabulated for different values of amplitude modulation index (ma).

Performance characteristics of induction motor connected to Conventional 2-Level and Diode Clamped multi-level inverter has been studied and found that as the level of inverter increases motor performance becomes better.

Transient during starting of 3-Phase I.M. are studied for variable motor parameters. MATLAB Code is generated to plot the Speed-Torque Characteristics of Open Loop

controlled Induction Motor. Open loop constant V/Hz speed control of I.M. can be easily achieved from Multi Level

Inverters just by manually varying the MODULATION INDEX in SPWM.

57

REFERENCES[1] J.-S. Lai and F. Z. Peng, “Multilevel converters—A new breed of power converters,” IEEE Trans. Ind. Appl., vol. 32, no. 3, pp. 509–517, May/Jun. 1996. [2] A. Nabae, I. Takahashi, and H. Akagi, “A new neutral-point clamped PWM inverter,” IEEE Trans. Ind. Appl., vol. IA-17, no. 5, pp. 518–523, Sep./Oct. 1981. [3] Jose Roriguez, Jih-Sheng, and Fang Zheng Peng, “Multilevel Inverter: A Survey of Topologies, Controls, and Applications,” IEEE Transactions on Industrial Electronics, Vol. 49, No. 4, pp. 724-738August 2002. [4] Andreas Nordvall, “Multilevel Inverter Topology Survey”, Master of Science Thesis in Electric Power Engineering, Department of Energy and Environment, Division of Electric Power Engineering, CHALMERS UNIVERSITY OF TECHNOLOGY, Goteborg, Sweden, 2011. [5] Kapil Jain and Pradyuman Chaturvedi, “Matlab-based Simulation & Analysis of Three-level SPWM Inverter”, International Journal of Soft Computing and Engineering (IJSCE), Volume-2, Issue-1, March 2012. [6] Ritu chaturvedi, “A Single Phase Diode Clamped Multilevel Inverter and its Switching Function,” Journal of Innovative trends in Science, Pharmacy & Technology, Vol.1(1), pp.63-66, 2014. [7] Ashwini Kadam and A.N.Shaikh, “Simulation & Implementation Of Three Phase Induction Motor On Single Phase By Using PWM Techniques”, International Journal of Engineering Research and General Science Volume 2, Issue 6, pp.93-104, October-November, 2014. [8] Bhabani Shankar Pattnaik, Debendra Kumar Dash and Joydeep Mukherjee, “Implementation Of PWM Based Firing Scheme For Multilevel Inverter Using Microcontroller”, Bachelor Of Technology Thesis, Department Of Electrical Engineering, National Institute Of Technology, Rourkela.

58

THANK YOU

M.E. Project PPT

Documents

Transcript of M.E. Project PPT