final lab (06esl48) final manual

8/13/2019 Final Lab (06ESL48) Final Manual

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POWER ELECTRONICS LAB JU

Dept. of EEE, Jain University

1

School of Engineering &

TechnologyGlobal Campus

Jakkasandra Post, Kanakapura Taluk,Ramanagara(D), Pin Code: 562 112

JAIN UNIVERSITYDeclared as Deemed-to-be University u/s 3 of the UGC Act 1956

IV SEMESTER

Dept. of ELECTRICAL ELECTRONICS ENGINEERING

POWER ELE TRONI SL B M NU L

NAME: ______________________________________________________________________

USN : ______________________________________________________________________

YEAR: ______________________________________________________________________


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INSTRUCTIONS:

1. Come well prepared for conducting the Lab experiment.

2. Maintain the silence in the Lab.3.

Keep the Lab Clean.

4. Keep your belongings in appropriate place provided to you.5. Do not come late to the Lab.6. Work only on table allotted for you.7. In the first half an hour of your Lab. session start, take required Components,

Instruments from the counter by submitting the Components Issue Slip (according to

experiment) .

8. Check all the Components before rig up the circuit.9. After completing the circuit connection, consult with the staff member before switching

it ON.

10.The CRO once switched ON need not switched OFF till the completion of theexperiment.

11.Before switching ON Power Supply and Function Generator , make sure that theVoltage/Amplitude control knob of these Instruments are at their minimum position and

while switching OFF the circuit, first switch OFF the Function Generator and then the Power Supply.

12.Be sure about the result expected and set the instruments in the expected range.13.After the completion of the experiment arrange all patch cords, CRO Probes and

Instruments properly on the table and ensure that all AC Power Supply switches of the

working table are switched OFF.

14.Return the Components taken from counter.


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POWER ELECTRONICS LABORATORY MANUAL[04EEL47]

Prepared By:

Raghu N

Aparna Rao S L


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CONTENTSSub Code : 12EEL48 C.I.A Marks: 80

Hrs/week : 03 Exam. Hours: 03Total Hrs : 42 Exam Marks: 20

Note:Each student has to do any one of the experiments given below in the examination

individually.

SL

NoTitle of the Experiments

Page

No

i. First Cycle Experiments

1Static characteristics of SCR.

2Static characteristics of MOSFET & IGBT.

3SCR turn-on circuit using Synchronized UJT relaxation oscillator.

4Single-phase full-wave rectifier with R and R-L loads

5

AC voltage controller using TRIAC and DIAC combination connected to R

and R-L loads.

6

SCR Digital triggering circuit for a single-phase controlled rectifier or A.C.

voltage controller.

ii. Second Cycle Experiments

1

Speed control of a separately excited DC motor using an IGBT

or MOSFET chopper.

2Speed control of Stepper motor.

3

Speed control of universal motor and single- phase induction motor using

A.C. voltage controller.

4MOSFET or IGBT based single-phase full-bridge inverter connected to R load.

5To construct and test the single phase series and parallel inverter.

6To study the turnoff method of thyristors and to plot the graph of voltage


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versus firing angle for class B and class D commutation circuits.

OBJECTIVES

Three-phase induction machines account for a high percentage of this country inindustrial application. To study 3-phase induction machines, by using its experimentally

developed setup and by obtaining its basic characteristics: torque/slip, current/slip and

efficiency /slip characteristics, etc.

Three-phase synchronous machines account for a high percentage of this country inpower generation sector. Understanding the machines behavior and determining its

equivalent network and performance characteristics are of prime importance to a power

engineer. Specific tests are run to determine equivalent circuit parameters, torque, power

factor control and efficiency.

PRE-REQUISITE

FOR STAFF AND STUDENTS: Staffs/students should know the theoretical knowledge of basic power devices like

diodes, Thyristor, etc. firing control.

IN LABORATORY:

We require following equipments: SCR, TRIAC, DIAC, MOSFET, IGBT Devices.

Power Supply, AC machines, DC machines. Rheostat, incandescent bulb. Lamp load. Inductive load. Measuring instruments (Voltmeter, Ammeter).


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First Cycle Experiments

1. STATIC V-I CHARACTERISTIC OF SCR

AIM: Obtain the static V-I characteristic of SCR and hence find the values of

latching current and holding current.

OR

Obtain the static characteristic of SCR, clearly indicating switching region.

Demonstrate that gate current has no effect on the device after it is turned on.

APPARATUS:

SLNO

NAME OF EQUIPMENTS/COMPONENTS

SPECIFICATIONS QTY

1. SCR Module 25RIA120 01

2. DC Power Supply 0-300 Volts \ 2 Amp. D.C. 01

3. DC Power Supply 0-30 Volts \ 2 Amp. D.C. 01

4. Rheostat 0-500 / 2Amps. 02

5. Voltmeter 0-200 Volts D.C. 016. Ammeter 0-1 Amp. D.C. 01

0-200 mA D.C. 01

Symbol:


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Circuit Diagram:

Observation column:

Ig= Il = Ih=

Forward Anode

Current IA (mA)

Forward Anode-

Cathode Voltage

VAK(volts)

500 Ohms

V

+

Ia

+PS1

(0-100)mA

VAK

0-30V)

+

-

500 ohms

Ig

-

G

-

A

+

RPS1

-

(0-30)mA

A

A

(0-300V)

K+

SCR

-

(0-300V)


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PROCEDURE:-

(i) Make the connections as per the circuit diagram.(ii) Keep both the power supplies TPS1 & RPS1 to zero position and switch ON the supply

mains.

(iii) By varying the gate-to-cathode power supply TPS1, the gate current Igis increased to acertain value say 29 mA, (but below Igmax) and is kept constant.

(iv) Using the anode-to-cathode power supply RPS1, the anode-to-cathode voltage VAKisincreased gradually in suitable steps .Once the SCR is turned ON , remove the gate signal

(Ig=0) and note down the value of latching current which keeps the device in the ON

state. Thereafter VAK is increased in steps and the corresponding readings of forward

anode current Ia is noted down.

(v) Now the anode-to-cathode voltage VAK is gradually decreased by varying RPS1. Atsome point anode current (Ia) becomes zero. The value of anode current just before zero

is the holding current.

(vi) Switch off the power supplies RPS1 & TPS1 and main power supply.(vii) Plot the static V-I characteristics of the SCR for the fixed gate current.(viii) The same procedure is repeated for different values of gate current.


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Static V-I Characteristics of SCR

IA (mA)

Forward Conduction Mode (OnState)

Ig= ------ mA

IL

IH

VBR

VBO VAK (volts)

Forward Blocking Mode

Reverse Blocking Mode

Application :

It is use for switching purpose. It is used for phase control operation. It is best suitable for controlled rectifiers. AC regulators, lighting and heating applications.

PROBABLE VIVA QUESTIONS:

1. What is a thyristor? Give the family of a thyristor.

2. Name the most popular thyristor.

3. Give the schematic diagram and symbol of a thyristor

4. Explain the different modes of operation of a thyristor with the help of its static V-I

Characteristic.

5. Distinguish between latching current and holding current of an SCR.


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6. Draw thyristor gate V-I characteristic, indicating clearly the gate drive limits and selection

of the operating point.

Result:

2. STATIC CHARACTERESTICS OF MOSFET

AIM: -Conduct an experiment to obtain drain and mutual characteristic of a

MOSFET and to plot the graph for the same.

ORConduct an experiment to obtain the mutual characteristic of a power

MOSFET. Find its transconductance gm.

APPARATUS:-

SLNO


SPECIFICATIONS QTY

1. MOSFET Module IRF840 01

2. DC Power Supply Dual Ch. 0-30 Volts 2 Amp. D.C. 02

3. Rheostat 0-500 / 2Amps. 024. Voltmeter 0-200 V Volts D.C. 01

0-20 V Volts D.C. 01

5. Ammeter 0-1 Amp. D.C. 01

0-200 mAmp. D.C. 01

Nature of the graphs:


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Mutual Characteristics (ID/ VGS) Drain Characteristics (ID/VDS)ID(mA)

ID(mA)

ID ID

VGS VDS0

VGT VGS(volts) VDS(volts)

Circuit Diagram:

Observation:

VGS(Volts) ID( mA)

-

-TPS1 TPS2

-

100 Ohms

+

(0-30 V)

VDS

(0-30 V)

DA

+

MOSFET

(0-30 V)

+

(0-30 V)

-

+

-

S

VGS

+V

V

(0-100)mA

100 Ohms

G

MOSFET IRF840


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Mutual Characteristics: Drain

Characteristics:

VDS= VGS=

PROCEDURE:

(A) Mutual Characteristics:

1) Circuit connections are made as per the circuit diagram.2) Keeping both the TPS1 and TPS2 at minimum positions, switch ON the power supplies.3) Using TPS2, the drain-source voltage VDS is increased to a certain value, say VDS=5v

and is held constant.

4) Using TPS1, the gate-source voltage VGSis gradually increased in steps and the draincurrent IDalso starts increasing and the threshold voltage VGT(below which the device

is off) is noted down.

5) Now the gate-source voltage VGS is gradually increased in suitable steps using TPS1,and note down the readings of VGS& IDfor each step.

6) Decrease VGS& VDSto zero and switch off the power supply.7) Plot the mutual characteristics IDversus VGSand compute the transconductance,

gm= ID/VGS __________mho for VDS = __________Constant

VDS(Volts) ID( mA)


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(B). Drain Characteristics:

1) Circuit connections are made as shown in the circuit diagram.2) Keeping both TPS1 and TPS2 at m inimum positions, switch ON the power supplies.3) Using RPS1 the gate-source voltage VGSis increased to a certain value, say VGS=5v and

is held constant.

4) Using TPS2 the drain-source voltage VDS is gradually increased in suitable steps andnote down the readings of VDS& IDfor each step.

5) Decrease VDS& VGSto zero position and switch off the power supply.6) Plot the drain characteristics IDversus VDSand compute the drain resistance

rd= VDS/ ID= _________ohms for VGS = ____________ Constant

Applications:

High frequency and low power inverters. High frequency choppers. High frequency SMPS. Low power AC & DC drives.


1. What is a power MOSFET? Give its basic structure and symbol.

2. Explain n-channel & p-channel enhancement power MOSFET.

3. Draw and explain the transfer and output characteristic of a power MOSFET.

4. Compare MOSFET and BJT.


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5. Compare MOSFET and SCR as switching devices.

6. Give few applications of MOSFET.

Result:

2. STATIC V-I CHARACTERSTICS OF IGBT

AIM: - Conduct an experiment to obtain Static and mutual characteristics of IGBT.OR

Conduct an experiment to obtain the static output characteristic of an IGBT.

Apparatus: -

SLNO


SPECIFICATIONS QTY

1. IGBT Module IRGBC20S 01

2. DC Power Supply 0-30 Volts 2 Amp. D.C. 023. Rheostat 0-500 / 2Amps. 02

4. Voltmeter 0-200 V Volts D.C. 01

0-20 V Volts D.C. 01


SYMBOL:

CASE STYLE TO-220AB


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Nature of the graphs:

Mutual characteristics: Static output characteristics:

IC IC

VGE VCE

VGET

Circuit Diagram:

-

IGBT

TPS1

-

(0-30 V)

G

+

V

+

(0-60)V

100 Ohms

C

100 Ohms

-

(0-60 V)

+

+

VGE

A

(0-30)V

(0-100)mA

-

EV

TPS2

+

-

VCE


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Observation Column:

Mutual Characteristics Static output Characteristics

VCE= VGE =

PROCEDURE:

(A) Mutual Characteristics:

1. Circuit connections are made as shown in figure.2. Keeping both TPS1 & TPS2 at minimum position, switch ON the main power supply.3. Using TPS2, adjust the voltage VCEto a constant value (say 5v or 6v).4. Using TPS1 gradually increase the voltage VGE in steps till the device breakdown and

at the same time note down the corresponding value of IC& the threshold voltage

VGET

.

5. Gradually increase VGE using TPS1 and note down the value of collector current. Takecare that Ic should not exceed its maximum value.

6. Now bring both the TPS1 & TPS2 to minimum position and switch off.7. Plot the mutual characteristics of IGBT (IC v/s VGE) and mark the threshold voltage

VGET.

(B) Static OR Output Characteristics:-

VCE(volts) Ic(mA)VGE(volts) Ic(mA)


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1. Circuit connections are made as shown in diagram.2. Keeping both the TTPS1 & TPS2 at minimum position, switch ON the main power

supply.

3. Using TRPS1 adjust the voltage VGE to a constant value (say 5v or 6v).4. Using TRPS2 gradually increase the voltage VCEin steps and at each step note the

corresponding IC& VCE. Take care that Icshould not exceed its maximum value.

5. Decrease the voltage of power supplies and switch off.6. Plot the static characteristics of IGBT (ICv/s VCE).


1. What is an IGBT? Give its basic structure and symbol.

2. Draw and explain the mutual and output characteristics of IGBT.

3. Give few applications of IGBT.

4. Compare IGBT with SCR as switching devices.

5. Compare IGBT with BJT and MOSFET as switching devices.

6. Mention few recent names of semiconductor materials used for switching devices.

Applications:

They're optimized for the design of high efficiency systems in solar inverter, UPS,welder, induction heating and power penetrator applications.

Result:

3. SCR TURN-ON CIRCUIT USING SYNCHRONIZED UJTRELAXATION OSCILLATOR

AIM: -To achieve synchronization of the triggering circuit with the applied A.C voltage to

the SCR using UJT.

OR

Conduct a suitable experiment to turn-on the given SCR using line synchronized UJT

triggering circuit (Ramp circuit).

APPARATUS:-

SLNO


SPECIFICATIONS QTY

1. Module of Synchronized UJT

Relaxation

Oscillator for HWR and FWR

01

2. CRO 25 MHz , Dual Channel 01


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3. Load Resistance 100 /5 watts 01

4. Voltmeter 0-200 V Volts D.C. 01

Symbol:

PROCEDURE:

1.Connections are made as per the circuit diagram2. With no supply to the SCR, the rectified voltage Vdc , zener voltage Vz and trigger

pulses across the pulse transformer are checked in the CRO.

3.The SCR is now connected AC supply and the supply voltage, zener voltage, capacitorvoltage, load voltage and SCR voltage are recorded from the CRO.

4.By varying the charging resistor Rc, the firing angle and hence the load voltage isvaried.

5. In case Rc is reduced, so that capacitor voltage Vc reaches UJT threshold voltagetwice or thrice in each half cycle, then there will be two or three pulses in each half

cycle as can be seen from the waveforms in the CRO. Only the first pulse is enough to

turn on the SCR and the other pulses in each half cycle are redundant.

Circuit diagram:


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E

x

p

e

c

t

e

d

W

a

v

e

f

o

rm

s

:

U

J

T

Relaxation Oscillator

Vs= VmSint


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What do you understand by line synchronization of triggering circuit? What are the various methods of gate triggering? What are the limitations of R and RC triggering? What are the advantages of UJT triggering circuit? What is UJT relaxation oscillator? What are the advantages of gate triggering? What is hard driving of a thyristor? What are its advantages?

Result :

4.SINGLE-PHASE FULL-WAVE RECTIFIER WITH R AND

R-L LOAD.

AIM: - To conduct a suitable experiment on Single phase Full Controlled Bridge Converter

(Rectifier with Resistive load/RL load) and

a. To obtain Output voltage waveforms


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b. To plot graph output DC voltage vs Delay Angle.APPARATUS:-

SL

NO

NAME OF EQUIPMENTS/

COMPONENTS

SPECIFICATIONS QTY

1. 1 phase Fully Controlled

Module

01

2. Isolation Transformer 0-30-60-115-180-230 Volts 013. Firing circuit module 01

4. Voltmeter 0-200 V D.C. 01


6. CRO 30 MHz, Dual Channel 01

7. Rheostat 0-150 /2A 01

8. Inductive load 0 mH-25mH-50mH-100mH-150mH 01

PROCEDURE:-

1.Connect the circuit diagram as shown in figure.

2. Switch on the AC supply.

3. Observe the firing pulses such as T1and1

1T are triggered at +ve half cycle and T2and

1

2T are triggered at ve half cycle of alternating voltage.

4. If the triggering pulses are correct, switch off AC supply.

5. Now connect the load across the load terminals as shown in the circuit diagram and

switch on the supply of converter circuit.

6.Vary the firing angle potentiometer in steps and observe the voltage across the load at

each step.

7. Readings are tabulated.

8. Later reduce the firing angle by potentiometer and Switch off AC supply.

9.Repeat the steps 5, 6 and 7 for different load R, RL with and without freewheeling diode.

10. Plot the curve of output voltage v/s firing angle ().

Note: If the output is zero after proper connections, then switch of the MCB, switch OFF theAC supply to the isolation transformer and just interchange AC input connections in the power

circuit. Then test for proper output. This is to make the firing circuit and the power circuit to

synchronize.


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Circuit Diagram:-


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Circuit Diagram:-


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Expected Waveforms: Single-Phase Full-wave Rectifier with R load.


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Expected Waveforms: Single-Phase Full-wave Rectifier with RL load.

Nature of Graph:

Output voltage

(VLDC)

Firing angle ( )


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Applications:-

Variable speed, DC drives.Battery chargers.DC power supplies.Power supplies for specific applications like Lasers.

Probable viva Questions:-

What is controlled rectifier? What is a full converter? Draw two full converter circuits. What are the effects of free-wheeling diode in full converter circuits? What is extinction-angle control of converters?

Result:


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5 AC voltage controller using TRIAC and DIAC combinationConnected to R and R-L loads.

AIM: - Rig up a circuit to control the illumination of an incandescent lamp. Obtain the

relevant wave forms. Plot a graph of load voltage v/s firing angle.

OR

To control AC voltage given to R and RL load using Triac-Diac combination

APPARATUS:-

SLNO


SPECIFICATIONS QTY

1. AC Regulator module 01

2. Lamp 230 V, 100 watts 01

3. AC voltmeter or DMM 0-400 V A.C. 01

4. Power Scope 30 MHz, Dual Channel 01

PROCEDURE:-

1. Connections are made as shown in Figure.2. Keep the value of R1(Resistance Pot.) in maximum position.3. Switch on AC mains of the AC regulator module.4. Now vary the firing angle , by varying thee value R1(pot) in steps.5. Observe the output waveforms for the different values of firing angle .6. Note down the value of VL(RMS) at every value of firing angle .7. Tabulate the reading in tabular column.8. Plot the graph of load voltage VL(RMS) v/s delay angle .

TRIAC Symbol DI AC Symbol


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Circuit Diagram:-

Construction


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Expected Waveforms:AC voltage controller using TRIAC and DIAC


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6.7.8.9.10.11.12.13.14.15.

16.17.18.19.20.21.22.23.

24.25.26.27.28.29.30.31.32.33.34.35.36.37.


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6.SCR Digital triggering circuit for a single-phase

controlled rectifier or AC voltage controller.

AIM: To trigger the given SCR using digital triggering circuit to control single phase voltage.

APPARATUS:-

SL

NO

NAME OF EQUIPMENTS/

COMPONENTS

SPECIFICATIONS QTY

01. Digital firing module 01

02. CRO 25 MHz, Dual Channel 01

PROCEDURE:

1. Switch ON mains supply to the unit.2. Observe AC reference signal and compare it with ZCD output A and test output C.

They are synchronized with the ac reference signal.

3. Observe the carrier frequency oscillator output 5 KHz.4. Now set 1800100 % selectors to 1800(converter) mode, observe the output.5. Next vary the firing angle from 1800to 00in steps and observe the variation

trigger outputs TP and TN.

6. Connect TPand TN to 1 and 2 input of pulse transformer isolation circuit.7. Now set the 1800-100% switch to 100% mode (chopper).8.

Keep the Duty cycle at 50 %.

9. Adjust the potentiometer R such that, a very small pulse output appears at thecounter output.

10. Now vary the duty cycle in steps from 99 % to 1 % and observe the counter outputand also observe the time variation between main pulse Tmand auxiliary pulse-TA.

11.Connect Tmand TAto input 1 and of pulse transfer Isolation.12. Observe the output voltage and device voltage and record the voltage and delay

angle.

Note: By varying the preset Input we can control the firing angle. The waveforms for digitalcontrol scheme are shown in figure.


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Circuit Diagram:-

Probable viva questions:-

Give a general layout of pulse firing scheme for SCRs. What are the main features of

firing?

What are the various turnon methods of a SCR. Which is more reliable turn-on method?

What are a pulse transformer and its use in firing circuits?

What are the necessary conditions for turning ON an SCR.?

What do you understand by digital triggering?

What are the advantages of digital triggering?Explain with the help of a block diagram the functioning of digital triggering scheme

T1T1

K

A

T1

T2

T1

TN

TP

TN

TP

ZCDAC InputClock

Gener

ator

Clock

Gener

ator

Logic

Circuit

Pulse

Transformer

IsolationT2

Triggering

Pulses

LOAD

AC

Supply

SCR


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Waveforms:

Over flowSignal

Flip-flopOutput B

Pulse to T1

Pulse to T2

B

Counteroutput

ZCD

Supply voltage

Q

Q


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FRONT PANEL DETAILS OF DIGITAL FIRING CIRCUIT:

1. Main Power ON/OFF switch to the unit with indicator

2. AC Ref. 10 V AC reference input for synchronization

3. Gnd Ground point of the unit to observe the waveforms

4. A ZCD output5. C Reset output for resetting counter

6. F.A/D.C. Thumb wheel switch to set the firing angle from 0 1800 and

Duty cycle from 0 to 100 %

7. 1800/100 % Switch to select 1800(1 ph converter) OR 100% (chopper) mode

8. FC(Oscillator) Carrier frequency generator 0 5 KHz

9. R 10 K potentiometer NO. of pulses from the clock generator

10. Clock Generator Astable oscillator to generator clock input to counter (180 pulses

or 100 pulses) 3 stage

11. Counter 4-bit up/down programmable counter

12. Logic Circuit

TP

TNTM

TA

Logic and modulator circuit to get TPTNfor converter and TonTA FOR CHOPPER EXPERIMENT

Train of pulses for +ve Cycle

Train of pulses for Ve CyclePulses of 200 sec for main SCR

Pulses of 200 sec for main SCR

13. ON/OFF ON/OFF switch for main SCR

14. PulseTransforms

Isolation

Pulse transform based on isolation circuit amplifier to isolate thelogic circuit from phase circuit.

15. Input 1 and 2 Input terminals to connect logic inputs.

16. Trigger Outputs

T1 and T1

T2 and T2

Pulse Transformer isolated trigger outputs to be connected to gate

and cathode of SCRS

Identical and isolated outputs for input 1

Identical and isolated outputs for input 2


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PROCDURE:-

1. Switch on the mains supply to the unit. Initially keep the VOLT-SELECT switch at OFFposition. The LCD display shows- POWER MOSFET/IGBT CHOPPER:

OFF DCY -0 FRQ 50

2. Measure the field voltage using digital voltmeter. It should be 220v10%approximately and the neon lamp glows.

3. Now keep the voltage select switch at position 1 and measure the voltage at V DCterminals. It should be 24 volts. The output voltage should be 48 volts, when the

switch at position 2, 110 volts when the switch at position 3 and 220 volts when the

switch at position 4 approximately.

4. Make sure that the DC supply is correct. Now observe the driver output using a CROby varying Duty cycle and frequency.

5. Make sure that the driver output is proper before connecting to the gate/emitter orgate/source of IGBT or MOSFET.

6. Now, if all the outputs are proper, then connect the load rheostat across the loadterminals as shown in the circuit diagram.

7. Vary the duty cycle and observe the load voltage and tabulate the voltmeter, ammeterreadings.

8. Change the frequency to some other value and change the duty cycle and note downthe readings.

9. Now replace load rheostat by DC motor armature across the load terminals. Connectfield supply to the field terminals properly.

10. Vary the duty cycle and observe the load voltage and tabulate the voltmeter,ammeter readings and also note down corresponding speed from tachometer.

11. Decrease the duty cycle, and switch off the power supply of the unit.Relative Equations

For average load voltage Vdcis given by:

Vdc= Ton/ (Ton+ Toff) Vs = Ton/T Vs= K Vs

Ton= on-time; Toff= off-time

T = Ton+ Toff= chopping period

D=K = Ton/T = duty cycle


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Circuit Diagram:-

CASE (a): R LOAD

Tabular Column:-

Sl No.Vinvolts

Frequency

f HZ

Duty Cycle

%

Output

Voltage

Vout

Vout

- +

S

D

G

DRIVER

CIRCUIT

AC

Supply

R Load

Vdc= Vin

MOSF

V


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Circuit Diagram:-

CASE (b): DC MOTOR as LOAD

Tabular Column:-

Circuit Diagram(In General):-Chopper Vo

+ + Vs Vdc

Vs FD Vo LOAD 0 Ton Toff t

_ T

io (RL load)

0

Sl

No.Vinvolts

Frequency

f HZ

Duty Cycle

%

Output

Voltage

Vout

Speed

N RPM

Current Io

Amps

Firing

angle

- +

Vout

- +

S

D

G

DRIVER

CIRCUIT

AC

Supply

Vdc= Vin

MOSFE

MA

V- +


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2. SPEED CONTROL OF A STEPPER MOTOR

AIM: -To study the speed control of a stepper motor using micro-controller.

Q1. Operate the given stepper motor in speed mode, take speed = -------- rpm.

Repeat the same for speed = -------- rpm.Or

Q2. Operate the given stepper motor in step mode, take the steps = --------.Repeat the same for steps = --------.

Apparatus:-

SL

NO

NAME OF EQUIPMENTS/

COMPONENTS

SPECIFICATIONS QTY

1. Steeper Motor

Permanent magnet, bifilar wound,

Step angle: 1.80 0.10

Steps/revolution = 200, Two- phase,

12V

01

2. Steeper Motor Module Micro-controller & power transistorbased driver circuit

01

PROCEDURE:-

Connect A1, A2, B1, and B2 leads of the stepper motor to the corresponding output terminal

points of the micro-controller and the common terminal to +Vccsupply.

Mode-1 SPEED SETTING

1. Switch on the mains supply to the unit and the unit displays S 00. Press INC/DEC Keys to

set speed mode.

2. Press SET & the display shows rpm. Press ENT, so that speed mode is set & it Displays n

00.

3. Press INC to set the rpm, say to 50 rpm and press ENT key, to enter the parameter(50

rpm) value, and the display shows the direction of rotation. Press INC/DEC keys to change the

direction of rotation. Then it displays Half step or Full step.

4. Again press INC/DEC keys to change to Half step or Full step. Finally press ENT key to set

Half step or Full step.

Now all the parameters are entered and the display shows n rpm which we have set. Nowpress RUN/STOP key, the stepper motor rotates at the speed of set value. The time required

for the set revolution is noted down using stop watch. To stop the motor press RUN/STOP key.

Mode-2 STEP- MODE:

The procedure is same as for speed setting, expect now we set the step-mode which displays

S steps, after all the parameter values are entered properly. In the step-mode if we press

RUN/STOP key, the motor moves the number of set steps and stop by itself.


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A pointer fixed to the shaft moves on the dial which indicates the number of steps the motor

moves. This can be compared with the set values and the error can be noted down.

Circuit Diagram:

A2

BLUE

BLACK

-VC

B2

GREEN

LOGIC CO NTROLLER

WHITE

RS

RED

B1

A1

RS

ORANGE

+VC


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TABULATED RESULT:

Speed set -------- Time recorded -----------

Step set ---------- Time recorded -----------


1. Explain what is a stepper motor?

2. Give few general applications of stepper motor.

3. What are the various types of stepper motor? Explain.

4. What do you understand by speed mode and step mode of a stepper motor?

5. Compare a conventional motor with a stepper motor.

Applications:

The stepper motor is widely used in x-y plotter, floppy disk drivers, M/c tools. The stepper motor is used in process control system, robotic printers, tape drivers and

variety of other industrial applications.

Result:


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Circuit Diagram:-

Tabular Column:-

Input Voltage Vin= VS = ----------

Output Voltage

VLVolts

Speed

N RPM

Firing angle


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3. SPEED CONTROL OF UNIVERSAL MOTOR & SINGLEPHASE INDUCTION MOTOR using AC VOLTAGE

CONTROLLER

AIM: - To study the speed control of universal motor for the variation of conduction angle.OR

To study the speed control of a single-phase induction motor using TRIAC and henceto plot the graph of motor speed (N rpm) versus firing angle ().

ORTo obtain the speed control of a universal motor OR Induction motor and hence toplot motor speed v/s delay angle graph.

APPARATUS:-

SLNO


SPECIFICATIONS QTY

1. Speed control module 01

2. Isolation Transformer 0-30-60-115-180-230 V 01

3. Volt meter (AC) or DMM 0-400 V (AC) 014. Power Scope 30 MHz, Dual Channel 01

5. Universal motor orInduction motor

220V/3A/6000rpm230V/2.5A/0-5HP/2280 pm

01

6. Digital Tachometer 01

PROCEDURE:

1. Connections are made as shown in the circuit diagram.2. Connect the trigger output to CRO and switch ON the main supply to the triac

firing unit and observe the train of pulses and their phase sequence in the CRO by

varying the firing angle from 180oto 0ousing the firing pot.

3. Make sure that the trigger outputs are proper before connecting to the powercircuit.

4. Connect the trigger outputs from the firing unit to MT1 & gate of the triac powercircuit.

5. Keep the auto-transformer knob at zero position and switch ON the main supply tothe power circuit. Gradually increase the input voltage from zero to the rated value

(230v).

6. Switch ON the trigger outputs of the firing unit, see that the motor starts running.By varying the firing angle , observe the input and output voltage waveforms in

the CRO & also note down the voltage, current & speed for different values of .

Finally plot the graph of speed (N) v/s delay angle ().


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Nature of Graph:

S eed N RPM

VL

volt


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Expected Wave Forms:

Vo

Ig

= (Toff / T) * 180o

Vs=VmSint


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Probable viva questions:

Distinguish between a Traic and SCR.

Give the schematic diagram, symbol and V-I characteristics of a triac.

What are different modes of operation of a triac?

Give few applications of a triac.

What are the various classical methods of speed control of induction motor?

On what factors do the speed of an induction motor depends.

What is an AC controller?

Name two methods of AC control.

Explain the principle of on-off Ac control.

Explain the principle of phase angle control type of Ac controller.

Applications:-

In many industrial applications, it is required to convert a fixed-voltage DC source into avariable voltage DC source. A DC chopper converts directly from DC(fixed or variable) to

DC (fixed or variable) so it is known as a DC-to-DC converter.

Choppers are widely used for traction motor control in electric automobiles, trolley cars,marine hoists, etc They provide smooth acceleration control, high efficiency and fast

dynamic response.

Results:


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Circuit Diagram:-

-

+

Vo

H H1

L L

2

1 2

RLA B

CRO

FULL BRIDGE INVERTER

DC Input

Voltage


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4.MOSFET or IGBT based SINGLE PHASE FULL-BRIDGE INVERTER connected to R load.

AIM: - Conduct an experiment to verify the operating principle of a single-phase

bridge Inverter connected to R load and plot the output voltage v/s

modulation index.

(OR)

Conduct an experiment to study the performance of a single phase full bridge

inverter for different modulation with R-load. Also plot the graph of output

voltage V/s modulation index.

APPARATUS:-

SL

NO

NAME OF EQUIPMENTS/

COMPONENTS

SPECIFICATIONS QTY

1. Series Inverter module 4 IGBTs unit builtin diodes

of rating 19A/600V

01

2. Power supply 0-24 V/2A D.C. 01

3. Power Scope 30 MHz, Dual Channel 01

4. Rheostat 0-50 /2 A 01

PROCDURE:-

1. Switch ON the mains supply to the controller unit.2. The LCD display shows single-phase PWM inverter with modulation type and M-(Duty

cycle or Modulation index) 00 and F-100 Hz and in OFF position.

3. Now M-(Modulation Index) blinks. Press INC key to set the duty cycle form 00-100%.Now Press FRQ/DTY key. Now F-100 blinks. Now use INC and DEC key to

increase or decrease the frequency from 20HZ to 100HZ.

4. After setting the duty cycle and frequency, press RUN/STOP key.5. Now the driver O/Ps pulses are available at O/Ps are comes to OFF with soft stop.6. Now set the modulation type to other type and check the outputs, So that the driver

outputs are proper before connecting to the power circuit.

7. Now, make the connections as given in the circuit diagram.8. Connect DC supply from 30V/2A regulated power supply unit.9. Connect driver output signals to the gate and Emitter of corresponding IGBTs.10. Switch ON the DC supply.11.Switch ON the driver outputs and observe the output voltage across the load.


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Expected Waveforms:

T1

T2

Vo

Expected AC

Probable viva questions:

What is an inverter?

What are line commutated inverters and force commutated inverters.

Compare VSI and CSI.

Can diodes be used to make an inverter circuits.

Explain 1-phase half-bridge and full-bridge inverters with R & RL loads.

Compare 1-phase half-bridge and full-bridge inverters.

Define performance parameters of an inverter.

What are the various methods of controlling the output voltage of an inverter?

Give few industrial applications of inverters.


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final lab (06esl48) final manual

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