NTRODUCTION

Our project is based on pulse width technology. As the inverter is usually a device which convert A.C power into DC power and vica versa.In ordinary inverter circuits there is just conversion of AC to DC by using usual Diode rectifier and transistor for inverter purpose which are not reliable and protection of Battery as well as circuit itself is very lessIn our circuit of about inverter we are using PULSE WIDTH MODULATION TECHNOLOGY and MOSFET for inverter purpose. The circuits have complete protection about the circuit itself as well as the battery. i.e. we can charge the battery accordingly to our setting of charging current.Also by using PULSE WITH MODULATION TECHNOLOGY our circuit is give the completely stabilize voltage at the output from (0-270) Volts as per the setting

VARIOUS PROTECTION AND STAGES OF INVERTER: -

OCILLATOR CICUIT TO MAKE 50hz PULSES TO TRIGGER THE MOSFET TO Get 50hz 230 V a c OUPUT.

CONVERSION OF AC TO DC AND VICA VERSA BY USING MOSFET. OVER LOAD SENSING CICUIT CHANGE OVER WORKING CIRCUIT LOW BATTERY CUT CIRCUIT CHARGING SENSING CIRCUIT CARGING CONTROL CIRCUIT AC MAIN SENSING CIRCUIT

1

WHAT IS INVERTER: -

A device that converts dc power into ac power at desired voltage and frequency is called inverter. DC power input to the inverter is obtained from an existing power supply network or from a battery. The configuration of ac to dc and dc to ac inverter is called a dc-linked converter. This conversion can be achieved ether by transistors or by SCRs or MOSFET. For low & medium power outputs, transistorized inverter are suitable but for high power outputs SCR should be used . For low power self oscillating transistorized inverters are suitable, but for high power outputs MOSFET driven invertors are more common than self – oscillating ones.

Inverter can be broadly classified into to types1. Voltage fed inverter2. current fed inverter

a voltage fed inverter or voltage source inverter, is one whih the dc source has small or negligible impedance. In other words, a voltage source inverter has stiff dc voltage source at its input terminals.A current- fed inverter or current source is fed with adjustable current from a dc source of high impedence from a stiff dc source. In this case output current waves are not affected by load.

OCSCLLATOR CIRCUIT: -

The oscillatory circuit is one of the important part of the inverter circuit. The main requirement the circuit i.e. to achieve the 50 Hz standard frequencies is achieved by this circuit. For oscillatory circuit we use IC SG 3524 which also provide PWM technique for the inverter operation.

The IC SG3524 is one of the important part in the whole circuit. The internal working and main description of IC SG 3524 is explained below.

IC SG3524 PIN DESCRIPTION: -

Pin no 1:-> this pin is used as a feedback signal. This pin basically a input pin.

Pin no 2:-> this pin provides the response voltage regarding pin 16.

Pin no 3:-> this pin works as a output pin of oscillator circuit.

Pin no4 & 5:-> this pin is ground pin which attach the amplifier circuit.

2

Pin no 6:-> this pin used as a pre set pin.

Pin no 7:-> timing capacitor is attaching that pin to fix the oscillator.

Pin no 8:-> this pin is used for –ve supply purpose.

Pin no 9:-> this pin shows the function of PWM.

Pin no 10:-> this pin is a shut down input pin. It gives the 0.6v every time. If the pin give more voltage than the inverter not works.

Pin no 11:-> this pin give the mos drive voltage to oscillator circuit.

Pin n0 12 & 13:-> that pin used for getting the +ve supply.

Pin no 14:-> that pin give MOS drive voltage.

Pin no 15:-> this pin also used for +ve supply.

Pin no 16:-> this pin give 5v reference voltage.

FIG :- INTERNAL VIEW OF IC SG 3524 :-

3

WORKING OF OSCILLATOR CIRCUIT: -

Firstly give the +ve supply from the +ve terminal of battery through pin no. 15 and give the negative supply to the pin no. 8 of IC SG3524 Pin no. 12 & 13 is used for output pin and pin 6no . 6&7 used for oscillator purpose. Timing capacitor is connected pin no. 7 and this pin is attached to the capacitor and it is grounded also. This pin basically creates 50hz frequency. Pin no. 6 is a timing resistance pin with the help of that pin we can change the resistance which stabelize the frequency.

With the help of variable resistance value we can attach the variable pin with the help of variable p we can adjust the required fr. Demand oscillator signal going to IC. In internal structure of IC flip-flop are attached that show one time +ve signal & other time show –ve signal . The output is given through npn internal buses of ic . Emitter is attached ic pin 13& 14. That pin are also grounded pin as shown in fig.

The collector of transistor is attached 12 & 13. From the help of pin 12 & 13.180 phase 50hz phase is obtained. With the help of pin 6& 7 we can oscillate the circuit. Pin no. 12 & 13 also called MOS drive voltage ckt the pulses of pin no . 13 is amplify through t11, t13,t14. The voltage of pin no.12 is amplify through t12,t15,t16. Two channel are working of MOS driver circuit . When we use two channel then please check frequency of both the channels are same and voltages are also same. That voltage basically lie 3 to 4v.we can see both channels show 50hz fr.

We got the signal going one after the other at both channels. The procedure of on-off of both channels are very fast . In one second that on-off procedure is 50 turns. That procedure is known as switching procedure. We can generate the current at secondary of transformer. 270v tapping is used with relay than give the output signal to output circuit.

4

WORKING OF OSCILLATOR: -

5

PULSE WIDTH MODULATION TECHNOLOGY (PWM TECH.)

Voltage control in single phase system:->

AC loads may requires constant voltages at their inputs terminals . when such loads are fed by inverters, it is essential that outputs voltage of inverter is so controlled as to fulfill by requirements of ac loads .examples of such requirements are as under:->

1> An ac load may require a constant input voltage through at different levels. For such a loads any variation in dc inputs voltages must be suitably compensated in order to maintain a constant voltage at the ac loads terminals at a desired levels.

2> In case inverter supplies power to a magnetic circuit such as an induction motor, the voltage to frequency ratio at inverter output terminals must be kept constant .

The various methods for the control of output voltages of inverter are as under:->

a> External control of ac output voltageb> External control of dc input voltagesc> Internal control of inverter

Internal control of inverter :->

Output voltage from inverter can also be adjusted by exercising a control with in the inverter itself .The most efficient method of doing this is by plus width modulation control used with in an inverter.

Pulse width modulation control:->

In this method a fixed dc input voltage is given to the inverter and a controlled ac output voltage is obtained by adjusting the on and off period of the inverter components.This is the most popular method of controlling the output voltage .

Advantages :->

The output voltage controlled with this method can be obtained without any additional components.

With this method lower order harmonic can be eliminated along with its output voltage control . As higher order harmonic can be filtered easily the filtering requirements are minimized.

The main disadvantages of this method is that the scrs are expensive as they must possess low trun on and trun off time .

6

Constant frequency system:->

The on time Ton is varied but chopping frequency f is kept constant. variation of Ton means adjustment of pulse width as such this scheme is called pwm.This scheme has also been referred to as time ratio control.

WORKING OF PWM CIRCUIT: -

Stable pwm basically used to maintain the 220v output fr.if the feed back of ic is properly Work than pwm work very accurately. If it is not feed back properly them output at the Pin 12&13 show not accurate output.the duty cycle change many time and effect the output Give the output270v at pin no1(cn-4).and through pin 1 can also given output R36,d15,d16,d17&d18&bridge rectifire.that rectifier change the ac supply to dc.

The five Terminal of bridge rectifier is attatched ic 4n35 pin no 1&five terminal attatched pin no 2 . The Internal structure show one led & photo transmission. Pin no i&2 are connected lrd when The invertor joined dc mode than led show lighting. The light fall internal photo Transmission of IC than transistor show working. pin 5 is attached transistor collector & Pin 4attatch photo transistor emitter.121v supply is given to pin5 . This supply is given r45 Through ic pin 1.c has also operation simplifier that works as error voltage amplifier.

That Amplifier attatched pin 1,2,9. Pin no1 inverting, pin no 2 non inverting supplies given to pin no4 if the voltage level going increases & decreases then it effect the pin no9 . But pwm maintain The output . This is not matter duty cycle work up/down. If pwm not work it effect the output. Pin no 9 attached to vr3 , with the help of vr3 we can maintain the output voltage.

WORKING OF VARIOUS STAGES IN INVERTER: -

As the inverter is used to convert ac to dc and vica versa. For proper working of the inverter circuit the protection operation is also main requirement other then the basic operation of the circuit i.e. to convert into ac to dc and ac to dc.The main stage of inverter circuit are: -

1. OCSILLATOR CIRCUIT:-

Oscillator circuit is the main part of the circuit which provide the required trigger signal to the power circuit of inverter to achieve the inverter operation with required output frequency and output voltageIn our circuit the oscillator circuit is also provided with the pulse with modulation circuit so that the inverter operation should be in constant voltage mode

7

The main component used in this circuit is IC SG3524, which is inbuilt with oscillator circuit and PWM circuit

MOSFET CIRCUIT or POWER CIRCUIT:-

Mosfet circuit is the power circuit of our inverter circuit .Its carries the load current as well as the battery charging current. The mosfet are worked in enhancement mode for conversion of dc to ac. The operation of ac to dc also carried out by the mosfet circuit because the mosfet have a inbuilt diode that convert ac to dc In out circuit we use three MOSFET in parallel to share the current as equally and for proper operation according the rated load condition.

A FET is a device in which the number of current carriers available in conducting region is controlled by the application of an electric field on the surface of semiconductor or it is a device which operates an the principles that the thickness and hence the resistance of a conducting channel of semiconductor may be regulated by the magnitude of a potential applied to its input terminalA field effect transistor has a very high input resistance, less noise better thermal stability then the bipolar transister.The mosfet circuit is shown in fig with its associate’s circuitry.

INVERTER POWER CIRCUIT: -

8

As the basis operation of the inverter circuit to convert ac to dc and ac to dc. The complete operation of the inverter circuit required various sensing circuit and the protection circuitAs we mention earlier the various protection and sensing circuits that we are Applying in our circuit i.e.

OVER LOAD SENSING CICUIT CHANGE OVER WORKING CIRCUIT LOW BATTERY CUT CIRCUIT CHARGING SENSING CIRCUIT CARGING CONTROL CIRCUIT AC MAIN SENSING CIRCUIT

Now various protection and sensing circuits with their associate circuitry are explained below.

OVERLOAD PROTECTION AND SENSING CICUIT:-

The overload protection is essential for the proper operation of the inverter circuit.If the overload protection is not provided in the circuit then overloading may causes the temperature rise of the transformer as well as the MOSFET of the power circuit of the inverter.This protection is provide in the circuit in such a way that first we sense the current at Mosfet drain and source terminal continuously, and we can set the sensing current with some reference value to achieve the desired load current operation of the circuit.The overload sensing circuit with its explanation is as below.

Working of overload section:->

When the load is more its rated value then there is a risk to the mosfet circuit. Therefore in The inverter circuit, we have provide the prevision for shutdown the inverter during Overload . For overload protection we are using IC7(lm339) pin no. 1,6,7,10,11 and 13 when the Inverter is overloaded we got overload indication from 0.1 ohm resistance in the Mosfet Source circuit . This signal sent to pin no .6 and 7. Pin no. 7 is inverting pin Vr5 is used to set the overload voltage. By resetting the vr5, we can change the voltage of pin no. 7. The pin No 1 is the output pin & pin no .6 and 7 are the input pin. During the normal load pin no 6 & 7 having equal voltage and pin no 1 have more voltage than 7.7v. Which give the base of T17 And activate the transistor and give 5 volt. Approximately. Further this voltage give to the Pin no. 7 of IC 555 through d33 and r83 . An IC 555 work as multivibrator & give overload signal to led . When there is no overload IC7 voltage is more the pin no 6. Therefore pin no 1 Give high output and pnp t17 have more voltage at the base then emitter, there is no current Source and there is zero voltage at the collector. In the collector side of T17

9

the pin no. 7 Of ic 555 is connected and its output at the pin no 3 go to the base of t18 . And the output of T18 becomes high. Which is used in the following section of inverter circuit.

To shut down pin ic6. To led through r112. To buzzer through r63.

MAIN SUPPLY SENSING CIRCUIT: -

The inverter and converter operation never run simultaneously. When there is inverter operation then there is no any charging operation. Because we are using Mosfets in the circuit that are used both for inverter as well as rectifier due to inbuilt diode in the MosfetTherefore the circuit should have a provision that when there is inverter operation then the charging operation should be cut out.Therefore the circuit should have a sensor the check that the main supply from the distributor is coming or not, which is achieved by a circuit which get the main supply which is compare with the reference battery supply.The main supply sensing circuit and its associate’s circuitry is shown in fig below.

Working of ac main sensing circuit:->

To find out the ac main i.e for ac sensing 0-18v / 1 amp transformer, t5 (lm 7812) and Operational amplifier ic2 are used pin no 8,9,10 of ic2 (lm324) are used for ac main sensing. Pin No 9 is ground pin. When we switched on ac main, +12 v supply is given to pin no 10. Through r22, which is made from 0-18v-trigger transformer & regulator, lm (7812) unregulating supply is given through pin no 9, through +ve terminal of rectifier & r38. On pin no 10&9 approximately 0.5-3.5v are obtained. The o/p on pin no 8 is only 1v including ac sensing pluses. These pluses are given to t1 base through r11. When pulse is given to transistor it starts working on Collector ac main sensing pulse is obtained.

10

BATTERY LOW CHARGING INDICATOR: -

In our circuit of inverter there is provision that the Battery not deep discharge in any condition. If the battery is discharger below certain level then the its automatically cut from the inverter operation, otherwise the deep discharging of battery occur and the battery plates causes sulphation at its surface and the life of battery is reduced

The circuit arrangement and its working is explained in circuit below.

In our circuit of inverter there is a provision of Low battery out that is when the voltage of battery Come down below some specified value the inverter circuit is shut down. for this protection We use pin no 4,5-2 of IC3 which is operational amplifier. Internally build in the ict. pin no 4 is Inverting pin and pin no 5 is non-inverting pin. Pin no 5 got a battery supply through vrt and Rtt.when the voltage of the battery is more than 10v than output of pin no 4,5 at pin no2 is about 7v. Which is given to the base of t19, and the transistor will not work due to high base Voltage that is zero volt at the collector of transistor. and the emitter of transistor got 8v.when the voltage of battery about 10v and opp. pin no2 have got low voltage & also the Base of t19 got less voltage. And we got the signal at the collector of t19 this collector Signal g given to the buzzer through d29. Also this signal is given through r62. Also this Signal is given to the pin no 10 that is shut down pin of sg3524.therefore inverter is shut down by getting how voltage indication

11

BATTERY SIGNAL PROCESSOR CIRCUIT: -

CHANGE OVER SENSING CIRCUIT: -

12

Usually in the inverter circuit the changer over from charging operation to inverter or discharging operation is made by using supply from the main i.e. the relay is on when the supply is coming and the relay setting is towards the charging mode of battery. And in out circuit the relay in on when the main supply is off and the normally open contacts of relay is put to inverter operation that discharging operation.For being achieve this requirement the relay is switched on and of f by using accocitate electronic circuitry which sense the main supply as explained above and main sensing is compare with referee dc battery signal voltage by using comparator circuits.

BATTERY CHARGING CIRCUIT:-

13

When the inverter operation is off and the main an supply I coming the inverter is in charging mode i.e. the inverter is convert ac into dc and charge the battery. Our circuit has a completer protection of the battery during charging to prevent any suphation during charging the protections are 1. The battery is cut out from changing when the its full charged 2. We can control the battery charging current.3. The battery is charged at control or continuous regulate voltage by using SCR circuitry whose gate is trigger by sensing battery signal the control the charge.4. Deep discharge protection of battery

When the circuilt at the charging mode the transformer duty is working to step down charging dc voltage to the battery through inbuilt diodes of MOSFET.For ahieve the above said operation, both the ends of the trasformer is connected the drain terminal of mosfet and we got the positive supply at the center tappin of the transformer terminal which is connected to the poisitive terminal of battery.The source of the mosfset is connected to the negative terminal of the battery through the .001 ohm sensing resiter. Which sense the battery voltage and current for futher utilized for processing the and provide the protection .The circuilt contain IC3 (LM325), IC (MOC3021) and IC(LM34)With two SCR to provide required control charging current the battery.

CHARGING CONTROLL S.C.R. CIRCUILT: -

14

COMPONENTS REQUIRMENT :-

15