COURSE PLANNER

SUBJECT: Power Electronics – II [2160902]

B.E. – Third Year

Class–Electrical 2014

Term: 16/2 (DEC-16 to APR-17)

Faculty: PROF. C.D.DESAI PROF. J.B.MISTRY PROF. N.B.KANTHARIA PROF. R.H.MISTRY

Contents: 1. Course Outcomes 2. Course Contents[Syllabus] 3. List of Reference Books 4. List of Experiments

5. Major Equipment required for Experiments 6. List of Open source software and learning websites required for

experiments 7. Active Learning Assignments and Tutorial.

Instructionsfor Assignment/Tutorial:

[1] This set of Assignment-Tutorial consist the collection of questions of past GTU Question

papers.

[2] Attend those questions which are bold marked and/or frequently asked in GTU exam.

[3] Students should make a separate Chapter wise Files[write on File Pages] to solve these

Questions.

[4] Students must solve these given set of Assignments by themselves only.

[5] Assessment of given assignment should be done regularly after completion of each

chapter by Students from the respective faculty members.

[1] Course Outcomes:

After the completion of this course, the student shall able to do

1. Ability to use the techniques, skills and modern engineering tools

necessary for engineering practice.

2. Simulate power electronic converters and their control scheme.

3. Analyze, operate and design dc-to-ac inverters.

4. Analyze, operate and design ac-to-ac converters like AC Voltage

Controller and Cyclo-Converter.

5. Apply the knowledge of power electronic converter for speed control of

AC motors.

6. Control a supply voltage using converters.

7. Select a suitable power electronic device for different applications.

8. Foster ability to understand the use of power converters in commercial

and industrial applications.

9. Ability to analyze various single phase and three phase power converter

circuits and understand their applications.

[2] Course Contents:

CHAPT

ER

NO.

SYLLABUS

Total

Hrs

%

Weightage

1

DC TO AC CONVERTERS: INVERTERS Performance parameters of Inverters; Classification of Inverters: Voltage source inverters and Current source inverters; Single phase inverters: series, parallel and bridge type (Half wave and Full wave) inverters; Forced Commutated, Line commutated and Self-Controlled Switches based Inverters; Three phase bridge inverters: 180 degree conduction, 120 degree conduction and their comparison PWM Inverters: Principle of PWM control, PWM techniques classifications, Unipolar and Bipolar PWM, Effect of Switching frequency on Harmonic Spectrum, Sinusoidal PWM, Third harmonic PWM, Selective Harmonic Elimination, Hysteresis band current control PWM, Space vector pulse width modulation technique, Comparison of PWM techniques, Voltage and frequency control of single phase and three-phase inverters, Harmonic Cancellation techniques Gating circuits for switches of inverter, Gate driver ICs having high side and low side reference output for driving switches of legs of inverters (like IR25604) Current Source Inverters: single phase and three phase ASCI and self-controlled switch based inverters; Comparison of Voltage and Current source Inverters.

15 15

38

2

AC VOLTAGE CONTROLLERS Concept of On-Off or integral cycle control and Phase control; Various single phase full wave ac-ac controllers with R, L and RL load; Analysis for phase control and integral cycle control; Gating requirements; Sequence Control of AC regulators; 3-phase full wave converter configurations with Y and Δ connected loads and their analysis with R load; AC Voltage controller with PWM control; Basic principle of matrix converter

08

20

3

CYCLOCONVERTERS Introduction; Basic Principle; Single to single-phase cycloconverters; Three-phase half-wave cycloconverters; Cycloconverters for three phase output; Output voltage equation; Output harmonics in cycloconverter; Comparison between cycloconverter and DC link Converter; Load Commutated cycloconverter

06

16

4

Induction Motor Drives Comparison of ac & dc drive; their selection for particular application; Review of Induction Motor fundamentals: Equivalent circuit, Characteristics, Basic Equations and speed control methods; motoring and braking Soft starting: Stator voltage control with AC voltage controller; Six-step VSI inverter based drives; PWM-VSI drives; Braking and multi-quadrant operation of VSI drives; Cycloconverter based induction motor drive; Variable frequency control from a current source; Slip power control using Rotor resistance along-with chopper; Closed loop control schemes; Effect of non-sinusoidal wave form on AC machine performance;

09

18

5

Synchronous Motor Drives Three phase synchronous motors; variable speed drives; variable frequency control; self-controlled synchronous motor drive employing load commutated thyristor inverter, self controlled synchronous motor drive employing a cycloconverter.

03

08

[3] List of Reference Books : 1. M D Singh and K B Khanchandani, “Power electronics”, TMH, New Delhi, 2nd ed., 2007.

2. Muhammad H. Rashid, “Power Electronics - Circuits, Devices and Applications”, Prentice Hall of India, 3rd ed., 2003.

3. VedamSubramanyam, “Power Electronics – Devices, Converters and Applications”, New Age International Publishers Pvt. Ltd., Bangalore, 2nd ed. 2006.

4. P.S. Bimbhra, “Power Electronics”, Khanna Publishers, New Delhi, 2012..

5. Ned Mohan, Undeland and Robbins, “Power Electronics – Converters, Applications and Design”, John Willey & sons, Inc., 3rd ed., 2003.

6. V.R.Moorthi, “Power Electronics”, Oxford University press, 2005. 7. G..K. Dubey, S.R. Doradla, A. Joshi, and R.M.K. Sinha, “Thyristorised Power Controllers”, New Age International Ltd. Publishers, 1986 (Reprint 2008).

8. P.T. Krein, “Elements of Power Electronics”, Oxford University Press, 1998.

9. G..K. Dubey, “ Fundamentals of Electrical Drives”, Narosa Publishing House, New Delhi, 2nd ed. 2001.

[4] List of Experiments:

SR.

NO. LIST OF PRATICALS

1 TO PERFORM THE WORKING OF SINGLE PHASE SERIES INVERTER

2 TO PERFORM THE WORKING OF SINGLE PHASE PARALLEL INVERTER

3 TO PERFORM MODIFIED MC-MURRAY & BEDFORD INVERTER

4 TO PERFORM THE WORKING OF SINGLE PHASE PWM INVERTER

5

TO PERFORM 3 PHASE INVERTER AND OBSERVE THE INPUT AND OUTPUT

WAVEFORMS FOR 120˚ & 180˚ CONDUCTION MODES

6

TO PERFORM 3 PHASE INVERTER AND OBSERVE THE INPUT AND OUTPUT

WAVEFORMS FOR SPWM & SVM

7 TO PERFORM SINGLE PHASE INDUCTION MOTOR DRIVE

8 TO PERFORM THREE PHASE INDUCTION MOTOR DRIVE

9 TO PERFORM THE WORKING OF SINGLE PHASE CYCLOCONVERTER

[5]Major Equipment required for Experiments: 1. Power semiconductor devices 2. Power electronic converter kits 1. 1-Ø AC POWER CONTROL (AC REGULATOR BY TRIAC & DIAC 2. MICROCONTROLLER BASED 3-ф INDUCTION MOTOR DRIVE 3. 3-ф INVERTER TRAINER (DC-AC) 4. SCR SERIES INVERTER TRAINER 5. 1-ф CYCLOCONVERTER 6. 1-ф BRIDGE INVERTER 7. MODIFIED MC-MURRAY & BEDFORD INVERTER 3. CRO/DSO 4. Load bank 5. Voltage and current probes 6. AC load and motors 7. Simulation tools like MATLAB, PSIM etc.

[6]List of Open source software and learning websites required for Experiments: 1.http://nptel.iitm.ac.in/coursecontents_elec.php 2.ocw.mit.edu/courses/electrical.../6-334-power-electronics-spring-2007

[7]Learning Assignments /Tutorial:

Chapter-1

DC TO AC CONVERTERS: INVERTERS: Performance parameters of Inverters; Classification of Inverters: Voltage source inverters and Current source inverters; Single phase inverters: series, parallel and bridge type (Half wave and Full wave) inverters; Forced Commutated, Line commutated and Self-Controlled Switches based Inverters; Three phase bridge inverters: 180 degree conduction, 120 degree conduction and their comparison PWM Inverters: Principle of PWM control, PWM techniques classifications, Unipolar and Bipolar PWM, Effect of Switching frequency on Harmonic Spectrum, Sinusoidal PWM, Third harmonic PWM, Selective Harmonic Elimination, Hysteresis band current control PWM, Space vector pulse width modulation technique, Comparison of PWM techniques, Voltage and frequency control of single phase and three-phase inverters, Harmonic Cancellation techniques Gating circuits for switches of inverter, Gate driver ICs having high side and low side reference output for driving switches of legs of inverters (like IR25604) Current Source Inverters: single phase and three phase ASCI and self-controlled switch based inverters; Comparison of Voltage and Current source Inverters.

ATTEMPT BOLD QUESTIONS:

SR

NO. QUESTION YEAR MARKS

1 Explain half bride and full bridge topology of inverter. May-11 Dec-15

07

2 Explain 3 phase inverter operation for 1800 May-11, Dec-15 May-16 May-15

07

3 Give comparison between current source inverter and voltage source inverter.

May-11 May-13 Nov-13 May-14 May-15

07

4 What is PWM? Explain SPWM techniques.

May-11 Dec-15 Dec-11 Jan-13 Nov-13 May-14 May-15

07

5 Explain space vector pulse modulation techniques. May-11 07

6 Explain inverter operation for 120 May-11 May-15

07

Nov-14 Jan-13 Dec-15

7 Explain McMurray inverter with each mode of operation. Give its limitation.

May-11 May-12

07

8 Draw and explain the series Inverter circuit employing Class-A type commutation. Draw and discuss the important waveforms.

Dec-11 Dec-15

07

9

Design a series Inverter circuit for operation in the frequency range 1 to 5 kHz. The load resistance may vary from 25% to 100%.The peak load current is limited to 3A and the supply voltage is 100 V.

Dec-11 07

10

A parallel capacitor commutated inverter with an Ideal transformer issupplying a resistive load and has a very large smoothening reactor inthed.c. line. Draw a circuit diagram, sketch the relevant wave formsand explain the operation.

Dec-11 07

11 Describe with neat circuit diagram a 1 phase Mac-Murray Inverter employing auxiliary thyristor commutation method.

Dec-11 May-14

07

12

A three phase bridge inverter has 120° conduction interval for itsSCRs. Draw its power circuit and state the conduction sequences ofthe SCRs. How is commutation achieved here without any auxiliary thyristors.

Dec-11 07

13 Describe in brief about various methods of voltage control of single phase Inverter.

Dec-11 07

15 Explain Third harmonic PWM in detail with output waveforms.

May-12 07

16 Explain Space Vector switching and Space Vector sequence used for Space Vector Modulation (SVM)

May-12 May-13 Nov-14

07

17

A single phase-bridge inverter delivers power to a series connected load with R=3 Ohms and X

l=12 Ohms. The

periodic T=0.2 ms. What value of C should the load have in order to obtain load commutation for the SCRs. The thyristor turn-off time is 12 micro-sec. Assume the circuit turn off time as 1.5 t

q. Assume load current contains only

fundamental component.

Jan-13 07

18

Draw waveforms of line voltage, phase voltage and load current for 1200 and 1800 conduction mode of 3-phase bridge inverter with Y connected resistive load. Compare them and make comment on output voltage and harmonics present in the load current.

May-13 07

19 Discuss parallel inverter in brief. May-13 May-14 Nov-14

07

May-15

20

Explain PWM principle. Discuss selected harmonic elimination PWM technique to eliminate 5th and 7th

harmonics from the output voltage waveform. List various PWM methods used in inverters for Harmonic reduction and explain Sinusoidal Pulse Modulation with necessary waveforms

May-13 07

21 Draw the power circuit of a parallel inverter and discuss its operation. Also explain how voltage control can be obtained with this inverter..

Nov-13 May-16

07

22 Describe using a neat circuit diagram, waveform and operation of PWM inverter and also explain how the output voltage can be controlled in this scheme.

Nov-13 07

23

A three phase bridge inverter has 180° conduction interval for it’s SCRs. Draw it’s power circuit and state the conduction sequences of the SCRs with necessary waveforms.

Nov-13 07

24 Describe using a neat circuit diagram, waveform and operation of PWM inverter and also explain how the output voltage can be controlled in this scheme.

May-14 07

25 State the merits & demerits of current source inverter & voltage source inverter.

Nov-14 07

26

What are the methods for harmonic reduction in inverter? Explain SPWM method in brief.

List various PWM methods used in inverters for Harmonic reduction and explain Sinusoidal Pulse Modulation with necessary waveforms.

Nov-14 May-16

07

27 Give comparison between series and parallel inverter. Dec-15 07

28 Derive Fourier Analysis of load voltage wave-form of Half wave Inverter topology.

Dec-15 07

29 What is the third harmonic injection method for PWM techniques? What are merits of it over sine wave PWM?

Dec-15 07

30 What are line commutated inverters? How do they operate? Explain the difference between line commutated and force commutated inverters.

May-16 07

31

Describe the working of a single phase half bridge inverter. What is its main drawback? Explain how this drawback is overcome.

May-16 07

32

Explain series single phase inverter with ckt. Diagram and wave-form. What are the merits and demerits of it?

Dec-15 07

Chapter-2

AC VOLTAGE CONTROLLERS : Concept of On-Off or integral cycle control and Phase control; Various single phase full wave ac-ac controllers with R, L and RL load; Analysis for phase control and integral cycle control; Gating requirements; Sequence Control of AC regulators; 3-phase full wave converter configurations with Y and Δ connected loads and their analysis with R load; AC Voltage controller with PWM control; Basic principle of matrix converter.

ATTEMPT BOLD QUESTIONS:

SR

NO. QUESTION YEAR MARKS

1 Explain the basics of Matrix converter.

May-11 May-12 May-13 Nov-13 May-14 Nov-14 Dec-15

07

2 Give the comparison between On/Off control and phase control of A.C voltage controller.

May -11 Nov-14

07

3 Explain full wave controller with R-L load. Draw the necessary wave-form.

May -11 07

4

Explain the operation of single phase A C voltage controller using two anti parallel SCR’s with R-L load for firing angle α equal to and less than load phase angle O. derive relevant equation and draw the waveforms with neat circuit diagram.

Dec-11 May-13 May-14 May-15 May-16

07

5

A single phase A C voltage controller with R-L load has the followingdetails: a. The control range of firing angle, b. The maximum value of RMS load current, c. The maximum power and power factor, d The maximum values of average and RMS thyristor current e. The maximum possible value of di/dt that may occur inthe SCR and f. The conduction angle α = 0 and α = 120° assuming agate pulse of duration Π radian.

Dec-11 Jan-13

07

6 Explain Single phase transformer connection changers in

detail. May-12 07

7 For a single phase full wave AC controller, the input rms voltage is Vs=120V,60Hz. The load is L=6.5 mH and

May-12 07

R=2.5Ω.The delay angles of thyristorsareequal i.e. α1= α2=π/2. Determine (a) the conduction angle δ of the thyristor,which conducts for positive half cycle (b) the rms output voltage Vo (c) the rmsthyristor current IR (d) the rms output current Io (e) the average current of athyristor IA and (f) the input PF.

8 Explain AC voltage controllers with PWM control

May-12 Jan-13Nov-14 May-14

07

9

An a.c. voltage controller operating in integral cycle mode

feeds a resistive load of 10 ohm from a single phase a.c.

voltage source at 230 V, 50 Hz. The Thyristor switch is on

for 25 cycles followed by 75 cycles of extinction period.

Determine (a) the r.m.s. value of load voltage and load

current. (b) The input power factor (c) the average value of

Thyristor current.

Jan-13 07

10 Draw different configurations of three phase AC-AC Voltage controller. Write the difference between them.

Jan-13 07

11

A single phase full wave ac controller has a resistive load of R=10 Ω and the input voltage is 120 V (rms), 60 Hz. The delay angle of thyristor T1 and T2 are equal: α1=α2=α=π/2. Find (a) rms value of output voltage, (b) the input PF, (c) average current of thyristor and (d) rms current of thyristor.

May-13 07

12 Discuss 3-phase full wave AC voltage controller with Y and Δ connected load.

May-13 07

13

Explain the operation of a single phase voltage controller supplying R-L load when the firing angle “α” is (1) less than the load angle ф (2) equal to load angle ф (3) greater than load angle ф

Nov-13 07

14 Write a brief note on 1 phase AC voltage controller with PWM control with necessary waveforms

Nov-13 07

15 Describe the principle of working of a single phase to single phase bridge type step down cyclo converter feeding R-L load.

Nov-13 May-14

07

16 Derive equation for Average & RMS value of voltage for single phase AC controller with RL load.

Nov-14 07

17 Explain principle of integral cycle control for AC voltage controller

Dec-15 07

18

A single phase full wave ac controller has R=10Ω, input voltage=120V(rms), 60Hz. Delay angle α1=α2=л/2. Determine (a)Output Voltage (b)Average Thyristor current, (c) Input PF.

May-15 07

19 Describe the working of a two stage sequence control of voltage controller for both R and RL load

May-16 07

20

A singe phase voltage controller has input voltage of 230V,50Hz and a load of R=15Ω. For 6 cycle on and 4cycle off, determine (a) rms output voltage, (b) input power factor, (c) average and rmsthyristor currents.

May-16 07

Chapter-3

CYCLOCONVERTERS: Introduction; Basic Principle; Single to single-phase cycloconverters; Three-phase half-wave cycloconverters; Cycloconverters for three phase output; Output voltage equation; Output harmonics in cycloconverter; Comparison between cycloconverter and DC link Converter; Load Commutated cycloconverter.

ATTEMPT BOLD QUESTIONS:

SR

NO. QUESTION YEAR MARKS

1 Explain basic principle of cyclo-converter with circuit diagram and wave from?

May -11 Dec-15 Jan-13 Nov-14 May-16

07

2 Explain three phase to single phase cycloconvrter May -11 07

3

Describe the operating principle of single phase to single phase step up bridge type cyclo converter. Illustrate your answer with appropriate circuit and waveforms. The conduction of various thyristors must also be indicated in the waveforms.

Dec-11 May-13

07

4

In a single phase to single phase cycloconverter, the input voltage is 120V(rms),60 Hz. The load resistance is 5Ω and the load inductance is L=40 mH. Thefrequency of the output voltage is 20Hz. If the converters are operated as semiconverters such that0 ≤ α ≤ π and the delay angle is αp =2π/3, determine (a) therms value of output voltage Vo, (b) the rms current of each thyristor IR, and (c)the input PF.

May-12 07

5 Explain three phase Cycloconverter. Jan-13 May-14 May-15

07

6 How load commutated cycloconverter is different than line commutated cycloconverter? Explain with suitable load example.

May-13 07

7 Describe the principle of working of a single phase to single phase bridge type step down cycloconverter feeding R-L load.

Nov-13 May-14

07

8

Explain the operation of a self-controlled (closed loop) synchronous motor drive fed from a cycloconverter to control the speed of synchronous motor with necessary schematic diagram.

May-14 07

9 What is load commutated cycloconverter? How does it differ from line commutated cycloconverter?

May-16 07

10 Give the comparison between a cycloconverter and a dc link converter

May-16 07

11

A three pulse cycloconverter feeds a single phase load of 190V,45A at a power factor of 0.7 lagging. Determine: (a) the required supply voltage, (b) thyristor RMS current and PIV (c) power factor of the supply current.

May-16 07

Chapter-4

INDUCTION MOTOR DRIVES: Induction Motor Drives Comparison of ac & dc drive; their selection for particular

application; Review of Induction Motor fundamentals: Equivalent circuit,

Characteristics, Basic Equations and speed control methods; motoring and braking

( 3 Hrs) Soft starting: Stator voltage control with AC voltage controller; Six-step

VSI inverter based drives; PWM-VSI drives; Braking and multi-quadrant

operation of VSI drives; Cycloconverter based induction motor drive; Variable

frequency control from a current source; Slip power control using Rotor resistance

along-with chopper; Closed loop control schemes; Effect of non-sinusoidal wave

form on AC machine performance; ( 6 Hrs)

ATTEMPT BOLD QUESTIONS:

SR

NO. QUESTION YEAR MARKS

1 Explain slip-power recovery by Static Scherbius method for speed control of induction motor.

May-11 Dec-11 May-12 May-13 Nov-13 May-14 May-15

07

2 Explain V/f control of induction motor drives? Give its merits and demerits.

May-11 Dec-15 May-15 Jan-13 Nov-13 May-14 May-16

07

3 Explain the method of rotor resistance control using static device forwound rotor motor.

May-11 Dec-11 Dec-15 May-14 May-16

07

4 Explain the stator voltage control of induction motor drives. May-11 07

5 Name the different methods of speed control of 3-O Induction motor. Explain the principle of speed control of it by PWM method

Dec-11 07

6 State the various points of comparisons and their choice/criterion forselection between AC and DC drives.

Dec-11 May-12 May-15 Nov-13 May-14 Nov-14

07

7 A 400V, 4 pole, 50Hz, 3 phase, star connected induction motor has the following parameters No. of stator turns/phase is

May-12 07

twice the number of rotor turns/phase, r1=0.64 Ω, x1=1.1 Ω, r2=0.8 Ω, x2=0.12 Ω. The load torque is proportional to square of speed and is 40 N-m at 1440 rpm. If the motor speed is 1300 rpm, find (a) load torque (b) rotor current (c) stator applied voltage. Neglect no load current.

8 Explain static Kramer drive. Jan-13 07

9 Explain effect of non-sinusoidal supply voltage on AC motor operation. Also discuss principle of variable frequency control.

May-13 07

10 Discuss closed loop control of induction motor. May-13 Nov-14 May-16

07

11 Draw the torque speed characteristics of 3 phase Induction motor and explain the following regions. (1).Plugging (2).Motoring (3).Generating.

Nov-13 07

12 What are the methods of speed control of induction motor? Explain any one method in detail.

Nov-14 07

Chapter-5

SYNCRONOUS MOTOR DRIVES: Three phase synchronous motors; variable speed drives; variable frequency control; self-controlled synchronous motor drive employing load commutated thyristor inverter, self-controlled synchronous motor drive employing a cycloconverter

ATTEMPT BOLD QUESTIONS:

SR

NO. QUESTION YEAR MARKS

1

Explain the operation of a self-controlled (closed loop) synchronous motor drive fed from a cycloconverter to control the speed of synchronous motor with necessary schematic diagram.

Dec-11 Jan-13 May-15

07

2 Discuss volts/hertz control and self-controlled synchronous motor drives with basic schematic arrangements.

May-12 07

3 Explain Self-controlled Synchronous motor drive employing load commutated Thyristor inverter.

Jan-13 07

4 Explain self-controlled synchronous motor drive. How it can be implemented?

May-13 Nov-13

07

5 Distinguish circulating current mode and non-circulating current mode with cycloconverter.

Nov-13 07

6 Write a note on speed control of Synchronous motor employing cycloconverter

May-16 07