Speed Control Of Induction Motor

PRO JE CT RE PO RT FOR COM PL ETIO N OF B. TECH. IN ELECTRICAL ENGINEERING Under West Bengal University of Technology (U. Tech.)

Year : 2005-2006

Name of the Project : PWM based

Inverter fed Induction Motor Submitted by – Group Workers University Roll No.

Roll No.

Abhra Ray

12003

12716021007

Amit Nag

12004

12716021008

Arijit De Arijit Dey

12007

12716021004 12008

12716021047

Arkendu Mitra

12010

12716021011

Ayanava Chatterjee

12012

12716021013

Kunal Pahari Mainak Dey

12022

12716021046 12024

12716021021

Soumya Subhra Niyogi 12716021031

12042

Saurav Paul

12043

12716021048

Subrata Sinha Roy

12050

12716021051 This project is done under the guidance of Mrs. Shilpi Bhattacharya

81, Nilgunj Road Agarpara, Pin - 700109

Acknowledgement We, the student of Electrical Engineering, Narula Institute of Technology, 81 Nilgunj Road, Kolkata – 700109, have completed our project successfully under the guidance of Mrs. Shilpi Bhattacharya, Lecturer, Department of Electrical Engineering, Narula Institute of Technology, Agarpara, without whose guidance, advice, interest, encouragement and also disbursement of money for purchasing the components at proper time, our project could not have achieved its grand success. We also express our respect and profound sense of gratitude to Prof. Amlan Chakrabarti, Head of the Department, Electrical Engineering, Narula Institute of Technology, Agarpara for his moral encouragement and advisement at different stages to build up our project. At last, we will thankful endlessly to the respective personality, Prof. Biswarup Basak, Department of Electrical Engineering, Bengal Engineering & Science University, Shibpur, who spent his expensive time to illustrate how the project circuitry can be developed. NAME

ROLL

Abhra Ray Amit Nag Arijit De Arijit Dey

12003 12004 12007 12008

UNIVERSITY ROLL NO. 12716021007 12716021008 12716021004 12716021047

Arkendu Mitra 12010 Ayanava Chatterjee 12012 Kunal Pahari 12022 Mainak Dey 12024 Soumya Subhra Neyogi 12042 Saurav Paul 12043 Subrata Sinha Roy 12050

12716021011 12716021013 12716021046 12716021021 12716021031 12716021048 12716021051

Contents Topic 1. 2.

3. 4. 5. 6.

7. 8. 9. 10. 11.

Introduction to Pulse Width Modulation (PWM) Objective Speed Control of Induction Motors 2.1 Pole Changing 2.2 Stator Voltage Control 2.3 Supply Frequency Control Advantages of Frequency Control Advantage and Disadvantage of PWM 4.1 Advantage 4.2 Disadvantage Industrial Applications of PWM Overview of the Project 6.1 Controlling Part 6.2 Power Part 6.3 Loading Part Components Tools and Instruments 8.1 For Testing Purpose 8.2 For Final Project Circuitry Bolck Diagram of the Whole Project Total Project Circuitry Project Details 11.1 Controlling Part

Page No. 1 2 2 2 4 4 5 6 6 6 6 7 7 7 7 8 9 9 9 10 11 12 12

11.2

12. 13. 14. 15. 16.

Power Part 11.2.1 Supply Part 11.2.2 Inverter Bridge Part 11.3 Loading Part Test Tools Test Procedure Test Results Precautions Inference

24 24 24 25 27 27 27 28 28

1

Introduction to Pulse Width Modulation (PWM) In this technique several pulses are produced in each half – cycle but the width of the pulses is not the same as in case of multiple – pulse width modulation, however the width of each pulse is varied in accordance with the amplitude of the sine wave reference voltage. The width of the pulse at the center of the half – cycle is maximum and decreases on either side. The figure 6(a) shows the generation of the output signal by comparing a sinusoidal reference signal fr with a triangular carrier wave of frequency fc. The carrier and reference waves are mixed in a comparator and when sinusoidal wave of has a higher magnitude than the triangular wave the comparator output is high, otherwise it is low. This output of comparator is used to turn on the MOSFETs in the bridge configuration of Figure 6(b), which generates the output voltage. The reference signal frequency fr determines the output frequency fo of the inverter, and its peak amplitude Ar, controls the modulation index M, and thereby the rms output voltage vo. Thus varying the amplitude of the sine wave within the range of zero to Vp, where Vp is the peak of the triangular wave, controls the output voltage. The number of pulses in each half – cycle depends on the carrier frequency. If the ratio of these two signals (reference and carrier) is equal to m, then the number of pulses in each half – cycle is (m - 1).

G1

M1

G3

M3

G2

M2

Load

Vs

G4

M4

(a)

(b)

(c) Fig. – 1 Sinusoidal Pulse Width Modulation (a) Single Phase bridge inverter (b) Gate signal voltage and (c) Output Voltage

2

1. Objective : To vary the speed of a single phase squirrel-cage induction motor by varying supple frequency with the help of Pulse Width Modulator (PWM) based Inverter. (Note: to change the frequency we change the resistance of controlling circuit.)

2. Speed Control of Induction Motors : Induction motors are of two types - Squirrel-cage motor and Wound-rotor motor. There are various types of speed control methods of induction motor. These are – (i) Pole Changing, (ii) Stator Voltage Control, (iii) Supply Frequency Control, (iv) Eddy-current Coupling,

(v) Rotor Resistance Control, (vi) Slip Power Recovery. (i) is applicable for squirrel-cage motor, (ii) to (iv) is applicable for both wound-rotor and squirrel-cage motor and (v) and (vi) is applicable for wound-rotor. For squirrel-cage type motor, here pole changing, stator voltage control and supply frequency control methods are discussed.

2.1 Pole Changing : For a given frequency speed is inversely proportional to number of poles. Synchronous speed, and therefore, motor speed can be changed by changing the number of poles. Provision for changing of number of poles has to be incorporated at the manufacturing stage and such a machine is called “pole changing motor” or “multi-speed motor”. In squirrel cage motor the number of poles are same as the Stator winding. So there is no provision for changing the number of poles. But for wound rotor arrangement for changing the number of poles in rotor is required, which complicates the machine. So it is only used for Squirrel cage induction motor. A simple but expensive arrangement for changing number of stator poles is to use two separate winding which are wound for two different pole numbers. An economical and common alternative is to use single stator winding divided into few coil groups. Changing the connections of these coil groups change number of poles. Theoretically by dividing winding into a number of coil group and bringing out terminals of these group a number of arrangements of different pole numbers is obtained.

Fig. – 2 Stator phase connection for 6-poles Figure 2(a) above shows a phase winding consisting of six coils divided into two groups – a-b consisting of odd number coils (1, 3,5) connected in series and c-d consisting even numbered coils (2,4,6) 3

connected in series. The coils can be made to carry currents in the given directions by connecting coil groups either in series or parallel as shown in figure B and C. With this connection machine has six poles. If the current through the coil group a-b is reversed [Fig. 3(a)], then all coils will produce north poles. Fluxes coming out of the north poles will now find paths through Interpol spaces for going out consequently producing south poles in Interpol spaces. The machine will now have 12 poles. Here again the direction of current through coils can be obtained by connecting two sections a-b and c-d either in series or parallel for both pole numbers 6 and 12.

Fig. – 3 Stator phase connection for 12-poles Further three phases of the machine can be connected to form delta or star connection by choosing a suitable combination of series and parallel connection between coil groups of each phase, and star and delta connection in each phase, speed change can be obtained with constant power or variable torque operation. Connections and speed-torque curves for these operations are shown in Figs. 4 to 6.

Fig. – 4 Constant torque control

Fig. – 5 Constant power control

4

Fig. – 6 Variable torque control

2.2 Stator Voltage Control : This is a slip control method with constant frequency variable voltage being supplied to the motor stator. Obviously the voltage should only be reduced below the rated value. For a motor operating at full load slip, if the slip is to be doubled for constant load torque then the voltage must 1 be reduced by a factor of and the corresponding current rises to 2 of the full load value. The 2 motor, therefore, tends to get overheated. The method therefore is not suitable for speed control. It has a limited use for motor driving fan type load whose torque requirement is proportional to the square of speed. It is a commonly used method for ceiling fans driven by single-phase induction motors that have large standstill impedance limiting the current drawn by the stator.

2.3 Supply Frequency Control : f . P And, motor speed, N r = (1 − s ) N s . Now, it is evident that varying synchronous speed, which can vary by varying the supply frequency, can vary the motor speed. Voltage induced in stator is proportional to the product of supply frequency f s and air-gap flux φm . Synchronous speed N s = 120

E = 4.44k w φm f sT ps If stator drop is neglected, then E is equal to V. Then the supply voltage will become proportional to f s and φm . V = 4.44k w φm f sT ps Any reduction in the supply frequency f s keeping the supply voltage constant causes the increase of air-gap flux φm . Induction motors designed to operate at the knee point of the magnetization characteristic to make a full use of magnetic material. Therefore, the increase in flux will saturate the motor. This will increase the magnetizing current and distort the line current and voltage, increase in core loss and stator I 2 R loss and produce a high-pitch acoustic noise. Also, a decrease in flux is also avoided to retain the torque capability of motor. Therefore, variable frequency control below rated frequency is generally carried out at rated air gap flux by varying V supply voltage with frequency so as to maintain ratio constant at the rated value. f

5

3. Advantages of Frequency Control : The variable frequency control provide good running and transient performance due to the following features – (i) Speed control and breaking operation are possible from zero speed to base speed. (ii) During transient the operation can be carried out at the maximum torque with reduce current giving good dynamic response (iii) Copper losses are low and the efficiency and power factor are high. (iv) Drop speed from no load to full load is small. The most important advantage of variable frequency control is that it allows a variable speed drive with above mentioned good running and transient performance to be obtained from a squirrel cage induction motor. The squirrel cage motor has a number of advantages over a DC motor. It is cheap, rugged and long lasting. Because of absence of commutator and brushes it requires practically no maintenance; it can be operated in an explosive and contaminated environment, and can be designed for higher speeds, voltages and power ratings. Though the cost of induction motor is lesser than DC motor of same power rating but still the cost of variable frequency drive are higher in general. But because of the advantages listed above the induction motor drives of variable frequency type is mostly preferable over DC motor drives. Because of the above advantages we are dealing with this type of speed control for controlling induction motor that has a large number of industrial applications as follows – (i) It can be used for any type of underground and underwater installation. (ii) In applications involving explosive and contaminated environment (iii) In application in tractions, steel mills, pumps, fans, blowers, compressors, spindle drivers etc.

6

4. Advantage and Disadvantage of PWM : 4.1 Advantage : Load efficiency is almost always a critical factor in renewable energy systems. An additional advantage of pulse width modulation is that the pulses are at the full supply voltage and will produce more torque in a motor by being able to overcome the internal motor resistances more easily. A resistive speed control will present a reduced voltage to the load, which can cause stalling in motor applications. Finally, in a PWM circuit, common small potentiometers may be used to control a wide variety of loads, whereas large and expensive high power variable resistors are needed for resistive controllers.

4.2 Disadvantage : The main disadvantages of PWM circuits are the added complexity and the possibility of generating radio frequency interference (RFI). Locating the controller near the load, using short leads, and in some cases, using additional filtering on the power supply leads, may minimize RFI.

5. Industrial Applications of PWM : PWM A.C. drive is very popular in industry. By controlling the speed of the induction motor, production can be varied as needed. The industries that use PWM drive are 1. Water plant. 2. Conveyer belt. 3. Lift. Etc.

7

6. Overview of the Project : Basically the speed of a “single phase permanent capacitor squirrel-cage induction motor” which is fed from a PWM based inverter circuit, is controlled. The entire circuit is divided into three parts,

6.1 Controlling Part : To control the speed of the induction machine a control circuit is made. There a sinusoidal pulse and a triangular pulse is generated separately and then compare these pulses by comparator and get triggering pulse to trigger the PWM based inverter circuit. Here sinusoidal pulse is the supply pulse of controlling network and triangular pulse is the carrier pulse of network. To vary the frequency, just vary the external resistance of the sinusoidal circuit through POT.

6.2 Power Part : For power part a D.C. supply of 220V is used. This D.C. supply is inverted to A.C. by PWM based inverter. Though this converted A.C. is not an exact sinusoidal response by taking consideration of harmonics we get sinusoidal pulse. PWM based Inverter circuit (Pulse Width Modulation inverter) is used for frequency control technique. Inverter circuit consists of power transistors or power MOSFETs (depending upon the rating of the machine). These power transistors or power MOSFETs are needed to be triggered and that triggering pulse is sending from the control circuit. The variable frequency helps to vary the timing of trigger of inverter, which varies the frequency of the supply of induction machine.

6.3 Loading Part : In the loading part single-phase squirrel cage permanent capacitor induction motor is loading where single-phase line enters, produce air-gap flux and help to run the motor.

8

7. Components : Sl. No. 1.

Name OPAMP (741)

2.

GATE (7405, 7408)

3.

5.

OPTOCOUPLER (MCT2E) POWER MOSFET (IRF720) RESISTOR

5.

POT

6.

CAPACITOR

4.

Components Character in Project It is the heart of the project. By using this we produce controlling pulses (comparing sinusoidal & triangular). It is used to design the comparator circuit. 75LS05N known as Logic inverter is used to invert the square pulse of 50 Hz. Then 75LS08N known as Logic AND Gate is used to ANDing the square pulse with the output of the OPAMP in which sine wave and triangular carrier pulse is compared. To isolate the triggering pulses for buffering and then for sending to the inverter circuit. We use to build inverter bridge by which we invert the DC voltage into AC voltage by using gate pulse. To build controlling circuit we use external resistor of different specification, sometimes for getting desired time constant and sometimes for getting different gain for opamp output. It is variable resistance which is used to change frequency & leveling the pulses over a base line. To generate sinusoidal and triangular pulse using opamp, capacitor charging and discharging phenomena is used from which we get square wave and then by using second order low-pass filter and integrator we get sinusoidal and triangular wave.

Industrial Specification Given in data sheet. Given in data sheet.

Given in data sheet. Given in data sheet. 

47.5 kΩ, 2 MΩ 10 nF, 100 nF.

9

8. Tools and Instruments : 8.1 For Testing Purpose : Sl. No. 1.

2.

Description of Tools and Instruments Use The whole circuit design is done on this board. In this board middle holes are on vertically same potential and up and down holes are on horizontally same potential. Hook up wire These wires do the whole circuit design.

Quantity

Name Bread Board

3.

Cutter

4.

Plus

To remove insulation at the ends of the wires cutter is used. It is used to straight the wire; also remove the broken wires from bread board.

4 As required 1 1

8.2 For Final Project Circuitry : Sl. No. 1. 2. 3. 4. 5.

Description of Tools and Instruments Use It is used to represent the final project circuit by shouldering. Multi-Stripped It is used to connect the component of the circuit Wire by shouldering. Cutter To use wire we have to remove insulation at the ends by cutter. Plus It is used to straight the wire; also remove the broken wires from Vero board. Solder Iron and It is used to design the circuit on Vero Board Solder Alloy permanently. Name Vero Board

Quantity 4 As required 1 1 1

10

9. Block Diagram of the Whole Project : Square wave (variable frequency)

Square wave (5 kHz)

Sine Wave (variable frequency)

Second order Low pass filter

Integrator

Inverted Sine Wave (variable frequency)

Inverter

Triangular Wave (5 kHz)

Comparator

Logic AND

Comparator

Logic AND

Logic Inverter

B L O C K D I A G R A M

Pulse

OptoIsolator

+

Pulse

OptoIsolator

1 2 3 4 Inverter

D.C.

-

-

Motor 11

10. Total Project Circuitry :

12

11. Project Details : There are three parts in the total project circuitry, they are as follows –

11.1 Controlling Part : At first a square wave of 50 Hz is generated by an OP-AMP. Here a POT of value 2 MΩ is used to vary the frequency of the square wave above 50 Hz. The necessary circuit arrangement and its output are given below – R5 47kOhm_5% R1 Key = a 2M_LIN

75%

U1

4 2

6 3 7 C1

V1

100nF

12V

1

5 741

R3 100kOhm_5%

R2 10kOhm_5%

V3 12V

(a)

(b)

square wave of variable frequency

Fig. – 7 Square Wave Generator (a) Required Circuitry and (b) Output Waveform 13

Then the square wave is filtered through a second-order low pass filter made by another OP-AMP to generate the required sine wave of 50 Hz. To vary the frequency of sine wave, just vary the frequency of square wave through the POT. The function of the second-order low pass filter with an OP-AMP is describe below – The schematic diagram of a second order low-pass filter is shown below -V R Square wave of variable frequency

R

C

4 2

R1

741

6

Sine wave of variable frequency

3 7 1 5

C

+V

Fig. – 8 Second order Low-pass Filter The transfer function will be given by – 2

H ( s) =

vo v

in

=

=

where K = 2, ω0 =

=

( RC ) 2  1   1  s + s +    RC   RC 

2

2

Kω02

ω  s 2 +  0  s + ω02 Q K 2

 s  1 s    +   + 1  ω0  Q  ω0 

1 , Q = 1. RC

The second-order low pass filter with specified components and its output is given in Fig. –

14 R2

R6 200kOhm_5% C2 100nF 200kOhm_5% 49.9kOhm_1%

square wave (variable)

R7

R5

1kohm U1

4

6 3

C1 100nF

7

1

5 741

1kohm R3

U3

4

R1

2

2 6 3

49% 50kOhm Key = c

7

1

sine wave

5 741

V2 12V

V1 12V

R4 1kohm

(a)

(b) Fig. – 9 Second order Low-pass Filter (a) Circuitry with specified components and (b) Output Waveform

Now with the help of another OP-AMP, an inverting amplifier (described below) is made, which inverts the sine wave at a phase shift 180°. Here another POT of value 50 kΩ is used to maintain the same level of two sine waves (actual and inverted). The connection method for producing the inverted gain using OP-AMP is called inverting amplifier. The OP-AMP makes use of single resistor (r1) and a single feedback resistor (r2). The inverting amplifier produces a phase shift of 180° in voltage from input to output. Thus the input and output signals of the inverting amplifier are not in phase with each other. We know that OP-AMP gain without any feedback is very high. This means that the voltage at the inverting terminal must be small. As a matter of fact, the input voltage at the inverting terminal will be very nearly at the same potential as the non-inverting terminal. Now since the noninverting input is 15

grounded, the inverting input of an OP-AMP is also at the ground potential and is referred to as virtual ground. r2

-V

4

r1 Actual sine wave of variable frequency

2

741

6

3 7 1 5

Inverted sine wave of variable frequency

+V

Fig. – 10 Inverting Amplifier Now recall that voltage gain (Av) of an amplifier is defined as the ratio of output voltage to the input voltage. Mathematically, voltage gain output voltage vo r Av = = =− 2 input voltage vin r1

The inverting amplifier circuit with specified components and its output is given in Fig. –

R2 1kohm

actual sine wave

1kohm

U1

4

R1 2

6 3

V1

7

12V

1

inverted sine wave

5 741

V2 12V

(a)

16

(b) Fig. – 11 Inverting Amplifier (a) Required Circuitry and (b) Output Waveform (inverted sine wave) After adjusting the level of two sine waves by the POT 50 kΩ, the obtained output is as below –

Fig. – 12 Two variable Sine Waves (actual and inverted) in a same oscilloscope Thereafter another square wave of fixed frequency (about 5 kHz) is generated. The necessary circuit arrangement and its output are given below –

17 R3 10kOhm_5% U1

4 2

6 3 7

C1 10nF

1

5

R1 741

100kOhm_5%

V1 12V R2 10kOhm_5%

V2 12V

(a)

high frequency square wave

(b) Fig. – 13 High Frequency Square Wave Generator (a) Required Circuitry and (b) Output Waveform Integrating this high frequency square wave, the triangular wave (also called carrier signal) is generated. The description of integrator circuit with an OP-AMP is as follows – Integrator is a circuit whose output is proportional to the area of its input waveform. The RC circuit itself acts as a simple integrator. But the problem with such a simple circuit is that the output voltage is not a linear triangular output as it should be. The function of the OP-AMP is to linearize the output. It may be noted from the diagram that the inverting input to the OP-AMP is held at virtual ground by the differential amplifier in the OP-AMP input circuit.

18

R2

-V

C 4

Square wave of R1 high frequency

2

741

3 7 1 5

6

Triangular wave of high frequency

+V

Fig. – 14 Integrator The second-order low pass filter with specified components and its output is given in Fig. –

R2 15kOhm_5%

R1

C1 4 100nF

1kohm

U1

2

square wave (high frequency)

6 V1

3 7

12V

1

triangular wave (carrier signal)

5 741

V2 12V

(a)

(b) Fig. – 15 Integrator circuit with specified components (a) Required Circuitry and (b) Output Waveform 19

Now two sine waves (actual and inverted) and the triangular wave (carrier signal) are compared using two OP-AMPs. The comparator circuit using OP-AMP is as follows – The comparator is a circuit that is used to compare two voltages and provide an output indicating the relationship between two voltages. Generally speaking, comparators are used to compare either, (i) Two changing voltages to each other, as comparing two sine waves. (ii) A changing voltage to a set D.C. reference voltage. Figure shows the circuit of an OP-AMP comparator. It may be noted that there is no feedback path in the circuit. In this circuit the sine wave (actual and inverted) is applied to the inverting input terminal and high frequency triangular carrier signal is applied to the inverting terminal of the OPAMP.

-V 4

R

sine wave

2

triangular wave

R

741

6

Output after comparison

3 7 1 5

+V

Fig. – 16 Comparator The simulation circuit and its outputs are given below –

actual sine wave

1kohm R3 1kohm

U1

4

R1 2

6 3 7

1

5

output of comparator I

741

triangular wave

inverted sine wave

1kohm R4 1kohm

U2

4

R2 2

6 3 7

V1

1

5

output of comparator II

741

12V

V2 12V

(a)

20

(b)

(c) Fig. – 17 Comparator circuit with specified component (a) Required Circuitry, (b) Output Waveform of Comparator – I and (c) Output Waveform of Comparator – II At last the output of the first comparator is ANDed with the square wave of variable frequency by using chip 7408 and the output of the second comparator is ANDed with the inverted square wave of variable frequency (inverted by using logic inverter 7404) to generate the triggering pulse for triggering the POWER MOSFETs. The simulation circuit of ANDing and its outputs are given in the figure below –

21

square wave (variable frequency) U1A 1

3

2

output pulse 74LS08N

1

comparator output I

U2A 74LS04N

2 U1B

comparator output II

4

6

5

output pulse 74LS08N

(a)

(b) Fig. – 18 ANDing the output of Comparator – I and II with Variable Square Wave (a) Required Circuitry and (b) Output Pulses The pulses are isolated trough four opto-couplers, so that each POWER MOSFET of the inverter bridge is being triggered separately. The opto-couplers connections and the outputs of four opto couplers, i.e., individual triggering pulses for each MOEFET are shown in Figs. below –

22 U4

output of AND (7408) pin no - 3

To MOSFET M1

V1 12V R4 1.0kOhm_5%

U1

To MOSFET M2

V2 12V R3 1.0kOhm_5%

U2

To MOSFET M3

output of AND (7408) pin no - 6

V3 12V R2 1.0kOhm_5%

U3

To MOSFET M4 V4 12V R1 1.0kOhm_5%

(a)

(b)

23

(c)

(d)

(e) Fig. – 19 Separation of Pulses with Opto-isolators (a) Opto-isolator connection and (b) – (e) Four separate Pulses to trigger the MOSFET 1 – MOSFET 4 24

11.2 Power Part : To run a motor we need voltage supply. In speed variation of single phase induction motor by varying frequency variation method we have to vary external resistance of the control part of the control circuit to vary frequency of the supply of motor. The power part consists of two parts, (i) Supply Voltage Part. (ii) Inverter Bridge Part.

11.2.1 Supply Part : In supply part, 230 V A.C. is required for the motor. To obtain this voltage, the value of required D.C. voltage we can obtain by the following equation – Vac = 0.612maVdc

where, Vac = supply voltage for the induction motor. Vsin ma = modulation index = Vtri Vdc = supply D.C. voltage for inverter Vac 230 ∴ Vdc = = = 537 V 0.612ma 0.612 × 0.7 But 270 V D.C. source is available in the laboratory, so the maximum voltage can be applied to the motor terminal is Vac = 0.612 × 0.7 × 270 = 116 V

11.2.2 Inverter Bridge Part : By using power MOSFET IRF720 the inverter bridge circuit is developed, as we know inverter is used to invert DC voltage to AC voltage. In Inverter Bridge four IRF720 MOSFETs are used. For single-phase A.C. we need two phases, one of which is earthed. Suppose we denote the MOSFETs by M1, M2, M3, and M4. Now we arrange the MOSFETs crosswise, M1 M3 M4 M2 In the bridge for the source pins of M1 and M3 are shorted and the drain pins of these two are connected to the sources of M4 and M2 respectively. Also drain pins of M4 and M2 are shorted. Now source pins of M1 and M3 are connected with the positive side of 230V D.C. supply. The outputs of the controlling circuit are connected to the gate pins of all MOSFETs, as we know that, MOSFETs are automatic switches operated by gate pulse. By using same convention, we use control circuit pulses to ON or OFF the MOSFETs of the bridge to get sinusoidal A.C. supply. The drain pins of M4 and M2 are connected with the negative side of 230V D.C. supply. Now when M1 is ON due to gate pulse the D.C. current flows through it, then M2 is ON and make a closed loop through load attached in the middle of the bridge. So, the upper half of the sinusoidal pulse appears across the load. Next, M3 is ON and D.C. current flows through it. When M4 become ON, the current flows through the load and the 25

lower part of the sinusoidal supply appears across the load. The Inverter circuit and its output is given in the following Figs. –

triggering pulse from opto-coupler 3 M1

triggering pulse from opto-coupler 1

270V

M3 R1

output (phase) neutral

L1

1.0uH 1.0kOhm_5%

triggering pulse M4 from opto-coupler 4

C1 2.0nF

C2 2.0nF

M2

triggering pulse from opto-coupler 2 (a)

(b) Fig. – 20 Circuitry of the total Power Part (a) Inverter Bridge and (b) Output of the Inverter, fed to the motor Now we get the desired A.C. supply for motor. Here every MOSFET is become ON when the amplitude of the gate pulse is 3.8V ≅ 4V.

11.3 Loading Part : This part mainly consists of “SINGLE PHASE PERMANENT CAPACITOR INDUCTION MOTOR”. The load part motor is of rating, 26

Power =

1

hp; 12 Current = 0.85 A; Voltage = 230 V; Speed = 6500 r.p.m.; Power factor = 0.8 (a) (b) Fig. – 21 Loading Part (a) The Single Phase Induction Motor and (b) Rating of the Motor As we know that in single phase the alternating phases are absent due to which the rotating flux is not generated; so rotation of the rotor is not possible. For that reason permanent split capacitor is used to generate two balanced phases, due to which a rotating flux generated. There are several types of single-phase motors in market but permanent capacitor type motors are used because here two balanced phases generate rotating flux for which the backward rotating flux is absent. Due to which motor become more efficient and operated in better power factor. This type of load is used in ceiling fans and table fans now a day. In our project, the two phases coming from Inverter Bridge is fed to the load where any one phase is earthed; so that it acts as neutral in singlephase supply. By this supply starting torque is generated and the motor starts to rotate.

27

12. Test Tools : Sl. No. 1. 2.

Name Oscilloscope Digital Multimeter

Description of Tools Specification Use To get the response of the parts of the 230 V, 20 MHz control circuit. To measure the voltage, Resistances used, Resistance = upto 400 kΩ capacitor used, in the circuit. Also to verify Voltage = 0 to 1000 V whether parts of the circuit is active or not. Capacitor = 0 nF to 10 uF

13. Test Procedure : For testing the circuitry we use oscilloscope to verify the response of the part of the circuit if the response is desirable then we proceed for the next portion of circuit. At the begging of the project we make the total possible circuit in MULTISIM simulation software and see the responses of every possible part of circuit. These responses are compared with the original circuit responses and if there is any wrong thing appear we clarify the original circuit for better response. To understand the speed variation we use tachometer to measure the speed. V [Note: As we know that in PWM fed inverter the variation of should be f constant under base frequency. But here we can’t vary voltage and frequency simultaneously so we vary frequency only over base frequency to do the speed variation]

14. Test Results : Type of wave Square Sine Square Triangular Output Pulse

Frequency (above) 50 Hz (above) 50 Hz 5 kHz 5 kHz -

Voltage (V) 11 (p-p) 7 (p-p) 11 (p-p) 10 (p-p) 4.5

28

15. Precautions : To do this project various types of problems appear in front of us those are as follows with solve, (i) First of all things, connection should be correct and perfect. (ii) During soldering careful about burning hazards. (iii) Use “chip base” to prevent the burning of chip due to direct soldering. (iv) Soldering should be done in right process otherwise there may appear short-circuit among pins and connecting wires. (v) Use Multi-Striped wire to prevent loose connection after soldering. (vi) All the open contacts should be closed to prevent shock hazards. (vii) Take measures to minimize the noise in the signal; like using capacitor to block the noise.

16. Inference : After finishing the “simulation of the circuit” by using Multisim software, we get the specific results and wave forms when we design the circuit part by part like “square wave generator, then second order filter, then we get sinusoidal pulse. Again square wave generator of high frequency pulse, then integrator and we get carrier signal triangular pulse”. But in the case of hardware design, many difficulties will occur such as frequency is not in the proper range, many noises in the required wave form etc. and so we use capacitors and resistors in much more quantity than that used in software. From all the above analysis and waveforms, we conclude that if we vary the POT of Fig. 7(a), the frequency of the Square wave of Fig. 7(b) changed as the time constant RC will be changed. So the frequency of the sine wave will also vary and as well as comparison of Sine wave with the triangular wave will vary and the frequency of the pulses which trigger the MOSFETs will also vary and at last we will get the variable inverter output. But, we know that, frequency control below base speed can carry out by keeping

V ratio constant. Since there is no such option to vary the supply f

voltage with its frequency, so the frequency as well as the speed of the motor is varied above the base speed.

DATASHEET OF OPERATIONAL AMPLIFIER (OP-AMP) LM741

Absolute Maximum Ratings (Note

August 2000

2)

If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. (Note 7) LM741 Operational Amplifier Supply Voltage

LM741A

LM741

± 22V

± 22V

LM741C

± 18V output, when the common mode range is ex500 mW no latch-up 500 mW 500 mW ceeded, as well as freedom from oscillations. ± ± ± Differential Input Voltage 30V 30V 30V The LM741 series are general purpose operational The LM741C is identical to the LM741/LM741A except that amplifi- ers which feature ± 15V ± 15V Input Voltageimproved (Note 4) performance over ± 15V the LM741C has their performance guaranteed over a 0˚C to industry stan- dards like the LM709. They are direct, plug-in Output Short Circuit Duration Continuous Continuous +70˚C temperatureContinuous range, instead of −55˚C to +125˚C. replacements for the 709C, LM201, MC1439 and 748 in −55˚C to +125˚C −55˚C to +125˚C 0˚C to +70˚C most applications. Operating Temperature Range

General Description

Power Dissipation (Note 3)

Features −65˚C to +150˚C

Storage Range −65˚C to +150˚C The amplifiers offer manyTemperature features which make their application nearly foolproof: overload protection on the input and Junction Temperature 150˚C

−65˚C to +150˚C

150˚C

100˚C

260˚C

260˚C

Soldering Information

Connection N-Package Diagrams (10 seconds)

260˚C

J- or H-Package (10 seconds) Metal Can Package M-Package

300˚C

300˚C 300˚C Dual-In-Line or S.O. Package

Vapor Phase (60 seconds)

215˚C

215˚C

215˚C

Infrared (15 seconds)

215˚C

215˚C

215˚C

See AN-450 “Surface Mounting Methods and Their Effect on Product Reliability” for other methods of soldering surface mount devices. ESD Tolerance (Note 8)

400V

Electrical Characteristics

(Note 5)

Order Number LM741H, LM741H/883 (Note 1), Parameter Conditions LM741AH/883 or LM741CH See NS Package Number H08C Input Offset Voltage TA = 25˚C Ceramic Flatpak RS ≤ 10 kΩ

400V 00934103

00934102

Note 1: LM741H is available per JM38510/10101

400V

Order Number LM741J, LM741J/883, LM741CN See NS Package Number J08A, M08A or N08E LM741A LM741 LM741C Min

RS ≤ 50Ω

Min

Typ

Max

1.0

5.0

Min

Units

Typ

Max

Typ

Max

0.8

3.0

2.0

6.0

mV

4.0

mV

mV

TAMIN ≤ TA ≤ TAMAX RS ≤ 50Ω RS ≤ 10 kΩ

6.0 00934106

Average Input Offset Order Number LM741W/883 Voltage Drift See NS Package Number W10A Input Offset Voltage TA = 25˚C, VS = ± 20V

7.5

15

mV µV/˚C

± 10

± 15

± 15

mV

Adjustment Range

Typical Application Input Offset Current

TA = 25˚C

3.0

TAMIN ≤ TA ≤ TAMAX Offset Nulling Circuit Average Input Offset

30

20

200

70

85

500

20

200 300

0.5

nA nA nA/˚C

Current Drift Input Bias Current

TA = 25˚C

30

TAMIN ≤ TA ≤ TAMAX Input Resistance

80

80

0.210

TA = 25˚C, VS = ± 20V

1.0

TAMIN ≤ TA ≤ TAMAX,

0.5

6.0

500

80

1.5 0.3

2.0

500 0.8

0.3

2.0

nA µA MΩ MΩ

VS = ± 20V Input Voltage Range

TA = 25˚C

00934107

± 12

TAMIN ≤ TA ≤ TAMAX

© 2004 www.national.com National Semiconductor Corporation

DS009341

± 12

2

± 13

± 13

V V

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Electrical Characteristics Parameter

(Note 5)

(Continued)

Conditions

LM741A Min

Large Signal Voltage Gain

Typ

LM741 Max

Min

Typ

LM741C Max

Min

Typ

Units Max

TA = 25˚C, RL ≥ 2 kΩ VS = ± 20V, VO = ± 15V

50

V/mV

VS = ± 15V, VO = ± 10V

50

200

20

200

V/mV

TAMIN ≤ TA ≤ TAMAX, RL ≥ 2 kΩ,

Output Voltage Swing

VS = ± 20V, VO = ± 15V

32

VS = ± 15V, VO = ± 10V VS = ± 5V, VO = ± 2V VS = ± 20V

10

V/mV

± 16 ± 15

V

RL ≥ 10 kΩ RL ≥ 2 kΩ

V/mV 25

15

V/mV

V

VS = ± 15V

± 12 ± 10

RL ≥ 10 kΩ RL ≥ 2 kΩ Output Short Circuit

TA = 25˚C

10

Current

TAMIN ≤ TA ≤ TAMAX

10

Common-Mode

TAMIN ≤ TA ≤ TAMAX

Rejection Ratio

RS ≤ 10 kΩ, VCM = ± 12V RS ≤ 50Ω, VCM = ± 12V

Supply Voltage Rejection

TAMIN ≤ TA ≤ TAMAX,

Ratio

VS = ± 20V to VS = ± 5V RS ≤ 50Ω

25

35

95

86

96

± 14 ± 13

V

25

mA

V mA

90

70

90

dB dB

dB 77

96

77

96

dB

TA = 25˚C, Unity Gain

Overshoot Bandwidth (Note 6)

TA = 25˚C

Slew Rate

TA = 25˚C, Unity Gain

Supply Current

TA = 25˚C

Power Consumption

TA = 25˚C

0.25

0.8

0.3

0.3

µs

6.0

20

5

5

%

0.5

0.5

0.437

1.5

0.3

0.7

MHz 1.7

VS = ± 20V

80

2.8

1.7

V/µs 2.8

150

VS = ± 15V

LM741

25

70 80

Rise Time

LM741A

± 12 ± 10

40

RS ≤ 10 kΩ Transient Response

± 14 ± 13

mA mW

50

85

50

85

mW

VS = ± 20V TA = TAMIN

165

mW

TA = TAMAX

135

mW

VS = ± 15V TA = TAMIN

60

100

mW

Note 2: “Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits.

3

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Electrical Characteristics

(Note 5)

(Continued)

Note 3: For operation at elevated temperatures, these devices must be derated based on thermal resistance, and Tj max. (listed under “Absolute Maximum Ratings”). Tj = TA + (θjA PD).

Cerdip (J)

DIP (N)

HO8 (H)

SO-8 (M)

θjA (Junction to Ambient)

Thermal Resistance

100˚C/W

100˚C/W

170˚C/W

195˚C/W

(Junction to Case)

N/A

N/A

25˚C/W

N/A

θjC

Note 4: For supply voltages less than ± 15V, the absolute maximum input voltage is equal to the supply voltage. Note 5: Unless otherwise specified, these specifications apply for VS = ± 15V, −55˚C ≤ TA ≤ +125˚C (LM741/LM741A). For the LM741C/LM741E, these specifications are limited to 0˚C ≤ TA ≤ +70˚C. Note 6: Calculated value from: BW (MHz) = 0.35/Rise Time(µs). Note 7: For military specifications see RETS741X for LM741 and RETS741AX for LM741A. Note 8: Human body model, 1.5 kΩ in series with 100 pF.

Schematic Diagram

00934101

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4

DATASHEET OF LOGIC INVERTER SN7405

November 1988 Revised February 2005

74AC08 • 74ACT08 Quad 2-Input AND Gate General Description

Features

The AC/ACT08 contains four, 2-input AND gates.

ICC reduced by 50% on 74AC only Outputs source/sink 24 mA

DATASHEET OF LOGIC AND GATE 74AC08

Ordering Code: Order Number

Package

Package Description

Number

74AC08SC

M14A

14-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150" Narrow

74AC08SJ

M14D

Pb-Free 14-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide

74AC08MTC

MTC14

14-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide

74AC08MTCX_NL (Note 1)

MTC14

Pb-Free 14-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide

74AC08PC

N14A

14-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300" Wide

74AC08PC_NL (Note 1)

N14A

Pb-Free 14-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300" Wide

74ACT08SC

M14A

14-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150" Narrow

74ACT08SCX_NL (Note 1)

M14A

Pb-Free 14-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150" Narrow

74ACT08MTC

MTC14

14-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide

74ACT08MTCX_NL (Note 1)

MTC14

Pb-Free 14-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide

74ACT08PC

N14A

14-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300" Wide

74ACT08PC_NL (Note 1)

N14A

Pb-Free 14-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300" Wide

Device also available in Tape and Reel. Specify by appending suffix letter “X” to the ordering code. (PC not available in Tape and Reel.) Pb-Free package per JEDEC J-STD-020B. Note 1: “_NL” indicates Pb-Free package (per JEDEC J-STD-020B). Use this number to order device.

Logic Symbol

Connection Diagram IEEE/IEC

Pin Descriptions Pin Names

Description

An , Bn

Inputs

On

Outputs

FACT ¥ is a trademark of Fairchild Semiconductor Corporation.

© 2005 Fairchild Semiconductor Corporation

DS009914

www.fairchildsemi.com

Absolute Maximum Ratings(Note 2) Supply Voltage (VCC)

Recommended Operating Conditions

0.5V to 7.0V

DC Input Diode Current (IIK) VI VI

Supply Voltage (VCC)

0.5V VCC

20 mA

0.5V

AC

20 mA

DC Input Voltage (VI)

0.5V to VCC

0.5V

VO

VCC

0V to VCC

Output Voltage (VO)

0.5V 0.5V

DC Output Voltage (VO)

4.5V to 5.5V

Input Voltage (VI)

DC Output Diode Current (IOK) VO

2.0V to 6.0V

ACT

0V to VCC

20 mA

Operating Temperature (TA)

20 mA

Minimum Input Edge Rate ('V/'t)

0.5V to VCC

0.5V

40qC to 85qC

AC Devices

DC Output Source

VIN from 30% to 70% of VCC

or Sink Current (IO )

r50 mA

VCC @ 3.3V, 4.5V, 5.5V

DC VCC or Ground Current

125 mV/ns

Minimum Input Edge Rate ('V/'t)

per Output Pin (ICC or IGND)

r50 mA

Storage Temperature (TSTG)

ACT Devices

65qC to 150qC

VIN from 0.8V to 2.0V

Junction Temperature (TJ)

VCC @ 4.5V, 5.5V

PDIP

140qC

125 mV/ns

Note 2: Absolute maximum ratings are those values beyond which damage to the device may occur. The databook specifications should be met, without exception, to ensure that the system design is reliable over its power supply, temperature, and output/input loading variables. Fairchild does not recommend operation of FACT¥ circuits outside databook

DC Electrical Characteristics for AC Symbol VIH

VIL

VOH

VOL

Parameter

VCC

TA

25qC

TA

40qC to 85qC

(V)

Typ

Guaranteed Limits

Minimum HIGH Level

3.0

1.5

2.1

2.1

Input Voltage

4.5

2.25

3.15

3.15

5.5

2.75

3.85

3.85

Units

Conditions VOUT

V

0.1V

or VCC

Maximum LOW Level

3.0

1.5

0.9

0.9

0.1V Input Voltage

4.5

2.25

1.35

1.35

V

or VCC

5.5

2.75

1.65

1.65

Minimum HIGH Level

3.0

2.99

2.9

2.9

Output Voltage

4.5

4.49

4.4

4.4

V

IOUT

5.5

5.49

5.4

5.4

3.0

2.56

2.46

4.5

3.86

3.76

5.5

4.86

4.76

V

VOUT

VIL or VIH 12 mA

IOH

24 mA

IOH

24 mA (Note 3)

IOUT

50 PA

0.002

0.1

0.1

Output Voltage

4.5

0.001

0.1

0.1

5.5

0.001

0.1

0.1

3.0

0.36

0.44

4.5

0.36

0.44

5.5

0.36

0.44

5.5

r0.1

r1.0

PA

VI

75

IIN

Maximum Input

(Note 5)

Leakage Current

IOLD

Minimum Dynamic

5.5

IOHD

Output Current (Note 4)

5.5

ICC

Maximum Quiescent

5.5

(Note 5)

Supply Current

2.0

VIN

VIL or VIH

IOL

12 mA

IOL

24 mA

IOL

24 mA (Note 3) VCC, GND

mA

VOLD

75

mA

VOHD

20.0

PA

VIN

1.65V Max 3.85V Min VCC

or GND

Note 3: All outputs loaded; thresholds on input associated with output under test. Note 4: Maximum test duration 2.0 ms, one output loaded at a time. Note 5: IIN and ICC @ 3.0V are guaranteed to be less than or equal to the respective limit @ 5.5V VCC.

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50 PA

IOH

3.0

V

0.1V

VIN

Maximum LOW Level

V

0.1V

2

DC Electrical Characteristics for ACT Symbol

VCC

Parameter

TA

25qC

TA

40qC to 85qC

(V)

Typ

Minimum HIGH Level

4.5

1.5

2.0

2.0

Input Voltage

5.5

1.5

2.0

2.0

VIL

Maximum LOW Level

4.5

1.5

0.8

0.8

Input Voltage

5.5

1.5

0.8

0.8

VOH

Minimum HIGH Level

4.5

4.49

4.4

4.4

Output Voltage

5.5

5.49

5.4

5.4

VIH

VOL

Units

Guaranteed Limits

4.5

3.86

3.76

5.5

4.86

4.76

Maximum LOW Level

4.5

0.001

0.1

0.1

Output Voltage

5.5

0.001

0.1

0.1

4.5

0.36

0.44

V V V

Conditions VOUT

0.1V

or VCC

0.1V

VOUT

0.1V

or VCC

0.1V

IOUT

50 PA

VIN

VIL or VIH

IOH

24 mA

V

IOH

24 mA (Note 6)

V

IOUT

50 PA

VIN

VIL or VIH

IOL

24 mA

IOL

24 mA (Note 6)

5.5

0.36

0.44

V

IIN

Maximum Input Leakage Current

5.5

r0.1

r1.0

PA

VI

VCC, GND

ICCT

Maximum ICC/Input

5.5

1.5

mA

VI

VCC

IOLD

Minimum Dynamic Output Current

5.5

75

mA

VOLD

IOHD

(Note 7)

5.5

mA

VOHD

ICC

Maximum Quiescent

0.6

75

5.5

Supply Current

4.0

40.0

PA

VIN

2.1V

1.65V Max 3.85V Min VCC

or GND

Note 6: All outputs loaded; thresholds on input associated with output under test. Note 7: Maximum test duration 2.0 ms, one output loaded at a time.

AC Electrical Characteristics for AC Symbol tPLH

Parameter Propagation Delay

tPHL

Propagation Delay

VCC

TA

25qC

(V)

CL

50 pF

TA

40qC to 85qC CL

50 pF

(Note 8)

Min

Typ

Max

Min

Max

3.3

1.5

7.5

9.5

1.0

10.0

5.0

1.5

5.5

7.5

1.0

8.5

3.3

1.5

7.0

8.5

1.0

9.0

5.0

1.5

5.5

7.0

1.0

7.5

Units

ns ns

Note 8: Voltage Range 3.3 is 3.3V r 0.3V Voltage Range 5.0 is 5.0V r 0.5V

AC Electrical Characteristics for ACT Symbol

Parameter

VCC

TA

25qC

(V)

CL

50 pF

TA

40qC to 85qC CL

50 pF

(Note 9)

Min

Typ

Max

Min

Max

Units

tPLH

Propagation Delay

5.0

1.0

6.5

9.0

1.0

10.0

ns

tPHL

Propagation Delay

5.0

1.0

6.5

9.0

1.0

10.0

ns

Note 9: Voltage Range 5.0 is 5.0V r 0.5V

Capacitance Typ

Units

CIN

Symbol

Input Capacitance

Parameter

4.5

pF

VCC

OPEN

CPD

Power Dissipation Capacitance

20.0

pF

VCC

5.0V

3

Conditions

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DATASHEET OF OPTOCOUPLER MCT2E

DATASHEET OF POWER MOSFET IRF720

BIBLIOGRAPHY 1.

Alok Jain – “Power Electronics and Its Applications”, Second Edition, Penram International Publishing (India) Pvt. Ltd.

2.

William H. Hayt, Jr., Jack E. Kemmerly, Steven M. Durbin – “Engineering Circuit Analysis”, Sixth Edition, Tata McGrawHill Publishing Company Limited, New Delhi.

3.

A. Chakrabarti – “Circuit Theory (Analysis and Synthesis)”, Dhanpat Rai & Co. (Pvt.) Ltd.

4.

Muhammad H. Rashid – “Power Electronics Circuits, Devices, and Applications”, Third Edition, Prentice-Hall of India Private Limited.

5.

D. Roy Choudhury, Shalil B. Jain – “Linear Integrated Circuits”, Second Edition, New Age International (P) Limited, Publishers.

6. Nisit K. De, Prasanta K. Sen – “Electric Drives”, Prentice-Hall of India Private Limited. 7.

M. Morris Mano – “Digital Logic and Computer Design”, Prentice-Hall of India Private Limited.

8. Dr. P. S. Bimbhra – “Generalized Theory of Electrical Machines”, Khanna Publishers. 9.

Gopal K. Dubey – “Fundamentals of Electrical Drives”, Second Edition, Narosa Publishing House.

10. M. C. Sharma Publications.

–

“41 Projects Using 741 I.C.”,

BPB