52
Futuristic car

Futuristic Carmmmmm

Embed Size (px)

DESCRIPTION

mmjjnknlllllllllllllllllllll

Citation preview

Page 1: Futuristic Carmmmmm

Futuristic car

Page 2: Futuristic Carmmmmm

Abstract

Renewable energy is rapidly gaining importance as an energy resource as fossil fuel prices

fluctuate. At the educational level, it is therefore critical for engineering and technology students

to have an understanding and appreciation of the technologies associated with renewable energy.

One of the most popular renewable energy sources is solar energy. This paper describes a

capstone design project where a student in mechanical engg designed a solar car. Solar car

enables more energy to be utilized because the solar panel is able to maintain a perpendicular

profile to the sun’s rays. This system builds upon a prior senior design project where students

built a solar-powered battery charger, thus making this system ideally self-contained. The student

was able to demonstrate a working system, thus validating the design. Potential improvements to

the system are presented.

Introduction

There are three ways to increase the efficiency of a photovoltaic (PV) system. The first is to

increase the efficiency of the solar cell. The second is to maximize the energy conversion from

the solar panel. A solar panel under an open circuit is able to supply a maximum voltage with no

current, while under a short circuit is able to supply a maximum current with no voltage. In

either case, the amount of power supplied by the solar panel is zero. The key is to develop a

method whereby maximum power can be obtained from the voltage and current multiplied

together. This “maximum power point” is illustrated by looking at a voltage-current (VI) curve,

and finding the “knee” of the curve. A number of maximum power point tracking (MPPT)

algorithms have been developed and employed.

Thus we are utilizing the solar energy in running our car which is totally dependent on solar

energy which we get from sun, the energy we get from sun will charge our battery and the motor

of the car will run from the energy stored.

Page 3: Futuristic Carmmmmm

The third method to increase the efficiency of a PV system is to employ a solar panel tracking

system. Development of solar panel tracking systems has been ongoing for several years now. As

the sun moves across the sky during the day, it is advantageous to have the solar panels track the

location of the sun, such that the panels are always perpendicular to the solar energy radiated by

the sun. This will tend to maximize the amount of power radiated by the sun. It has been

estimated that the use of a tracking system, over a fixed system, can increase the power output by

30% - 60%. When tracking the sun, it is noted that the direction of the sun, as seen by the solar

panel, will vary in two directions. The azimuth angle is the horizontal direction from the

observer to the sun. There is also an altitude angle, representing the vertical direction from the

observer to the

sun. More effective solar panel trackers are two-axis in nature5, 6, 7 and have been

demonstrated, for example, in the use of a solar oven concentrator.

Page 4: Futuristic Carmmmmm

System Design

At the beginning of the project, the student and faculty advisor agreed to the following design

requirements:

Must track the sun during daylight hours

During the time that the sun is up, the system must follow the sun’s

position in the sky.

This must be done with an active control, timed movements are wasteful.

Self powered, must be fully autonomous

The system must operate on, and charge its own battery supply

Semi-permanent installation on the flat roof of a building

A base must be designed to allow installation without fasteners onto a flat section

of roof

Weather resistant

This system will be designed to be fully functional outdoors and resist any wind

and weather complications.

Remote instrumentation to monitor status

A method will be implemented to allow the system to be monitored remotely.

Page 5: Futuristic Carmmmmm

Dc Motor Driver system

CAR

Solar panel

Left Motors Right Motors

Auto Light sensor

Battery

Block Diagram:

Page 6: Futuristic Carmmmmm

Working:

As indicated above, an Advance system is employed to control the movements of the Dc motor

which control solar panel. This whole system is chosen because of the energy conservation

perspective. Three power measurements are made at and around the last azimuth angle of the

solar panel. The location of the largest power measurement becomes the new azimuth angle of

the solar panel. One of the key elements of the design is for the system to be autonomous. An

energy balance calculation was performed to determine if the overall energy consumption (to

drive the motor, etc.) would be less than the amount of energy generated by the solar panel.

The energy consumed during the 72 hour period may exceed the energy available to charge the

battery. In fact, although the system was able to operate in front of an audience during the senior

design day, the system eventually drained the batteries during subsequent testing during the

summer. This may have been due to the energy balance, a software glitch in the microcontroller,

or a combination of the two. Clearly, the major energy drain over a long period of time is due to

the system at idle.

LDR sensor/auto light: As shown in the circuit diagram the solar tracker consist of three LDR

circuit. The three Azimuths are selected and each LDR is faced towards this azimuth.

The microcontroller is programmed to continuously scan three analog input and compare analog

input coming from LDR. Based on comparison the uC rotate solar panel toward maximum

intensity.

A LDR photosensor is a complete assembly that includes the optical arrangement and electronic

circuitry that is coupled to an electronic component called a photocell. A photocell is typically

nothing but a light responding silicon chip that converts incident radiant energy into an electrical

signal. Photosensor generally includes a diffuser or lens (which may also be called an integrator)

that collects light from different directions within the room, and typically an optical filter that

rejects the UV and IR spectra, so as to simulate the human visual response to incident radiation.

The electronic circuitry amplifies the dc voltage generated by the photocell, and after comparing

it with a reference voltage, sends an appropriate signal (termed the photosensor signal) to the

control device.

Page 7: Futuristic Carmmmmm

The LDR light sensor is used to sense intensity of light. In the light sensor we use IC LM358 as a

main component. Pin no 8 is connected to the positive supply. Pin no 4 is connected to the

negative voltage. One capacitor is grounded from the pin no 3 for noise cancellation. Output is

available on the pin no 1. Sensor is connected to the pin no 3.

In case of high intensity of light LDR is all most shorted so LM 358 gives 5v as soon as light

intensity decreases voltage output of LM358 decreases up to 0v.

The voltage is inputted to the analog port of PIC. In this circuit AN0, AN1, AN2 is used for the

analog input port. Because it isn't using VREF+ and VREF-, the minimum of the A/D conversion is

Vss=0V and the upper limit is Vdd=+5V.

DC motors - operate from a direct current power source. Movement of the

magnetic field is achieved by switching current between coils within the motor.

This action is called "commutation". Very many DC motors (brush-type) have

built-in commutation, meaning that as the motor rotates, mechanical brushes

automatically commutate coils on the rotor. You can use dc-brush motors in a

variety of applications. A simple, permanent-magnet dc motor is an essential

element in a variety of products, such as toys, servo mechanisms, valve actuators,

robots, and automotive electronics. There are several typical advantages of a PM

motor. When compared to AC or wound field DC motors, PM motors are usually

physically smaller in overall size and lighter for a given power rating. Furthermore,

since the motor's field, created by the permanent magnet, is constant, the

relationship between torque and speed is very linear. A PM motor can provide

relatively high torque at low speeds and PM Field provides some inherent self-

braking when power to the motor is shutoff. There are several disadvantages

through, those being mostly being high current during a stall condition and during

instantaneous reversal. Those can damage some motors or be problematic to

control circuitry. Furthermore, some magnet materials can be damaged when

Page 8: Futuristic Carmmmmm

subjected to excessive heat and some loose field strength if the motor is

disassembled.

High-volume everyday items, such as hand drills and kitchen appliances, use a dc

servomotor known as a universal motor. Those universal motors are series-wound

DC motors, where the stationary and rotating coils are wires in series. Those

motors can work well on both AC and DC power. One of the

drawbacks/precautions about series-wound DC motors is that if they are unloaded,

the only thing limiting their speed is the windage and friction losses. Some can

literally tear themselves apart if run unloaded.

The term geared motor is used to define a motor that has a gear reduction system (or gearbox) integrally built into the motor. The gearbox increases the torque

generating ability of the motor while simultaneously reducing its output speed.

Page 9: Futuristic Carmmmmm

component discription

RELAY

Relay is a common, simple application of electromagnetism. It uses an electromagnet made from an iron rod wound with hundreds of fine copper wire. When electricity is applied to the wire, the rod becomes magnetic. A movable contact arm above the rod is then pulled toward the rod until it closes a switch contact. When the electricity is removed, a small spring pulls the contract arm away from the rod until it closes a second switch contact. By means of relay, a current circuit can be broken or closed in one circuit as a result of a current in another circuit.

Relays can have several poles and contacts. The types of contacts could be normally open and normally closed. One

Page 10: Futuristic Carmmmmm

closure of the relay can turn on the same normally open contacts; can turn off the other normally closed contacts.

Relay requires a current through their coils, for which a voltage is applied. This voltage for a relay can be D.C. low voltages upto 24V or could be 240V a.c.

A relay is an electrical switch that opens and closes under control of another electrical circuit. In the original form, the switch is operated by an electromagnet to open or close one or many sets of contacts. It was invented by Joseph Henry in 1835. Because a relay is able to control an output circuit of higher power than the input circuit, it can be considered, in a broad sense, to be a form of electrical amplifier.

These contacts can be either Normally Open (NO), Normally Closed (NC), or change-over contacts.

Normally-open contacts connect the circuit when the relay is activated; the circuit is disconnected when the relay is inactive. It is also called Form A contact or "make" contact. Form A contact is ideal for applications that require to switch a high-current power source from a remote device.

Normally-closed contacts disconnect the circuit when the relay is activated; the circuit is connected when the relay is inactive. It is also called Form B contact or "break" contact. Form B contact is ideal for applications that require the circuit to remain closed until the relay is activated.

Change-over contacts control two circuits: one normally-open contact and one normally-closed contact with a common terminal. It is also called Form C contact.

Operation

When a current flows through the coil, the resulting magnetic field attracts an armature that is mechanically linked to a moving contact. The movement either makes or breaks a connection with a fixed contact. When the current to the coil is switched off, the armature is returned by a force that is half as strong as the magnetic force to its relaxed position. Usually this is a spring, but gravity is also used commonly in industrial motor starters. Relays are manufactured to

Page 11: Futuristic Carmmmmm

operate quickly. In a low voltage application, this is to reduce noise. In a high voltage or high current application, this is to reduce arcing.If the coil is energized with DC, a diode is frequently installed across the coil, to dissipate the energy from the collapsing magnetic field at deactivation, which would otherwise generate a spike of voltage and might cause damage to circuit components. If the coil is designed to be energized with AC, a small copper ring can be crimped to the end of the solenoid. This "shading ring" creates a small out-of-phase current, which increases the minimum pull on the armature during the AC cycle. [1]

By analogy with the functions of the original electromagnetic device, a solid-state relay is made with a thyristor or other solid-state switching device. To achieve electrical isolation, a light-emitting diode (LED) is used with a photo transistor.

Relays are used:

to control a high-voltage circuit with a low-voltage signal, as in some types of modems, to control a high-current circuit with a low-current signal, as in the starter solenoid of an

automobile, to detect and isolate faults on transmission and distribution lines by opening and closing

circuit breakers (protection relays), to isolate the controlling circuit from the controlled circuit when the two are at different

potentials, for example when controlling a mains-powered device from a low-voltage switch. The latter is often applied to control office lighting as the low voltage wires are easily installed in partitions, which may be often moved as needs change. They may also be controlled by room occupancy detectors in an effort to conserve energy,

to perform logic functions. For example, the boolean AND function is realised by connecting NO relay contacts in series, the OR function by connecting NO contacts in parallel. The change-over or Form C contacts perform the XOR (exclusive or) function. Similar functions for NAND and NOR are accomplished using NC contacts. Due to the failure modes of a relay compared with a semiconductor, they are widely used in safety critical logic, such as the control panels of radioactive waste handling machinery.

to perform time delay functions. Relays can be modified to delay opening or delay closing a set of contacts. A very short (a fraction of a second) delay would use a copper disk between the armature and moving blade assembly. Current flowing in the disk maintains magnetic field for a short time, lengthening release time. For a slightly longer (up to a minute) delay, a dashpot is used. A dashpot is a piston filled with fluid that is allowed to escape slowly. The time period can be varied by increasing or decreasing the flow rate. For longer time periods, a mechanical clockwork timer is installed.

Page 12: Futuristic Carmmmmm

Obstacle sensor

The infrared intruder sensor is used to sense some unknown person like thief entering in your

house without your permission.

In the infrared sensor we use IC 555 as a main component. Pin no 4 and pin no 8 is connected to

the positive supply. Pin no 1 is connected to the negative voltage. One capacitor is grounded

from the pin no 5 for noise cancellation. Output is available on the pin no 3. Sensor is connected

to the pin no 2.

In the case of infra red sensor Pin no 2 is negative bias through the 33k ohm resistor and pin no

is positively biased through the photodiode. One infrared transmitter led is focused to the

Page 13: Futuristic Carmmmmm

photodiode. Infra red led is directly connected to the positive and negative supply through the

330ohm resistor.

In normal stage when light is focusing on the photodiode then pin no 2 is positively biased

photodiode. If pin no 2 is positive then negative output is available on the pin no 3. Now when

any body interrupts the light then there is no light on the photodiode and pin no 2 is now gets its

voltage from only 33 k ohm resistor. If pin no 2 is become negative then output is shifted to the

pin no 3. The output of the 555 timer is applied to the transistor BC548 which is used to drive

buzzer.

Power supply: The power supply section consists of step down transformers of 230V primary to

12V secondary voltages for the +5V power supplies respectively. The stepped down voltage is

then rectified by 4 1N4007 diodes. The high value of capacitor 1000 µF charges at a slow rate as

the time constant is low, and once the capacitor charges there is no resistor for capacitor to

discharge. This gives a constant value of DC. IC 7805 is used for regulated supply of +5 volts in

order to prevent the circuit ahead from any fluctuations. The filter capacitors connected after this

IC filters the high frequency spikes. These capacitors are connected in parallel with supply and

common so that spikes filter to the common. These give stability to the power supply circuit.

As can be seen from the above circuit diagrams, the rectified voltage from the 4 diodes is given

to pin 1 of the respective regulators. Pin 2 of the regulators is connected to ground and pin 3 to

Vcc. With adequate heat sinking the regulator can deliver 1A output current. If internal power

dissipation becomes too high for the heat sinking provided, the thermal shutdown circuit takes

over preventing the IC from overheating.

Page 14: Futuristic Carmmmmm

General Description

The LM555 is a highly stable device for generating accurate time delays or oscillation. Additional terminals are provided for triggering or resetting if desired. In the time delay mode of operation, the time is precisely controlled by one external resistor and capacitor. For astable operation as an oscillator, the free running frequency and duty cycle are accurately controlled with two external resistors and one capacitor. The circuit may be triggered and reset on falling waveforms, and the output circuit can source or sink up to 200mA or drive TTL circuits.

Page 15: Futuristic Carmmmmm

Features

Direct replacement for SE555/NE555

Timing from microseconds through hours

Operates in both astable and monostable modes

Adjustable duty cycle

Output can source or sink 200 mA

Output and supply TTL compatible

Temperature stability better than 0.005% per °C

Normally on and normally off output

Available in 8-pin MSOP package

Applications

Precision timing

Pulse generation

Sequential timing

Time delay generation

Pulse width modulation

Pulse position modulation

Linear ramp generator

Schematic Diagram

Page 16: Futuristic Carmmmmm

Connection Diagram

Page 17: Futuristic Carmmmmm

Absolute Maximum Ratings

Page 18: Futuristic Carmmmmm

If Military/Aerospace specified devices are required, please contact the National Semiconductor

Sales Office/ Distributors for availability and specifications.

Supply Voltage +18V

Power Dissipation

LM555CM, LM555CN 1180 mW

LM555CMM 613 mW

Operating Temperature Ranges

LM555C 0°C to +70°C

Storage Temperature Range −65°C to +150°C

Page 19: Futuristic Carmmmmm

APPLICATIONS INFORMATION

Monostable Operation

In this mode of operation, the timer functions as a one-shot. The external capacitor

is initially held discharged by a transistor inside the timer. Upon application of a

negative trigger pulse of less than 1/3 VCC to pin 2, the flip-flop is set which both

releases the short circuit across the capacitor and drives the output high.

Page 20: Futuristic Carmmmmm

The voltage across the capacitor then increases exponentially for a period of t = 1.1 RA C, at

the end of which time the voltage equals 2/3 VCC. The comparator then resets the flip-flop

which in turn discharges the capacitor and drives the output to its low state. Figure 2 shows

the waveforms generated in this mode of operation. Since the charge and the threshold level of

the comparator are both directly proportional to supply voltage, the timing internal is

independent of supply.

VCC = 5V Top Trace: Input 5V/Div.

TIME = 0.1 ms/DIV. Middle Trace: Output 5V/Div.

RA = 9.1kBottom Trace:

Capacitor Voltage 2V/Div.

C = 0.01μF

Page 21: Futuristic Carmmmmm

During the timing cycle when the output is high, the further application of a trigger

pulse will not effect the circuit so long as the trigger input is returned high at least

10μs before the end of the timing interval. However the circuit can be reset during

this time by the application of a negative pulse to the reset terminal (pin 4). The

output will then remain in the low state until a trigger pulse is again applied. When

the reset function is not in use, it is recommended that it be connected to VCC to

avoid any possibility of false triggering. Figure 3 is a nomograph for easy

determination of R, C values for various time delays.

Page 22: Futuristic Carmmmmm

ASTABLE OPERATION

If the circuit is connected as shown in Figure 4 (pins 2 and 6 connected) it will

trigger itself and free run as a multivibrator. The external capacitor charges through

RA + RB and discharges through RB. Thus the duty cycle may be precisely set by

the ratio of these two resistors.

In this mode of operation, the capacitor charges and discharges between 1/3 VCC

and 2/3 VCC. As in the triggered mode, the charge and discharge times, and

therefore the frequency are independent of the supply voltage.

Page 23: Futuristic Carmmmmm

VCC = 5V Top Trace: Output 5V/Div.

TIME = 20μs/DIV. Bottom Trace: Capacitor Voltage 1V/Div.

RA = 3.9k

RB = 3k

C = 0.01μF

Time period

The charge time (output high) is given by:

t1 = 0.693 (RA + RB) C

And the discharge time (output low) by:

t2 = 0.693 (RB) C

Thus the total period is:

T = t1 + t2 = 0.693 (RA +2RB) C

Page 24: Futuristic Carmmmmm

The frequency of oscillation is:

Figure 6 may be used for quick determination of these RC

values. The duty cycle is:

Frequency Divider

The monostable circuit of Figure 1 can be used as a frequency divider by adjusting the length of

the timing cycle. Figure 7 shows the waveforms generated in a divide by three circuits.

Page 25: Futuristic Carmmmmm

VCC = 5V Top Trace: Input 4V/Div.

TIME = 20μs/DIV. Middle Trace: Output 2V/Div.

RA = 9.1kBottom Trace: Capacitor

2V/Div.

C = 0.01μF

Pulse Width Modulator

When the timer is connected in the monostable mode and triggered with a continuous pulse train,

the output pulse width can be modulated by a signal applied to pin 5. Figure 8 shows the circuit,

and in Figure 9 are some waveform examples.

Page 26: Futuristic Carmmmmm

VCC = 5V Top Trace: Modulation 1V/Div.

TIME = 0.2 ms/DIV. Bottom Trace: Output Voltage 2V/Div.

RA = 9.1k

C = 0.01μF

Page 27: Futuristic Carmmmmm

Pulse Position Modulator

This application uses the timer connected for astable operation, as in Figure 10, with a

modulating signal again to the control voltage terminal. The pulse position varies the modulating

signal, since the threshold voltage and the time delay is varied. Figure 11 shows the waveforms

generated for a triangle wave modulation signal.

Page 28: Futuristic Carmmmmm

VCC = 5V Top Trace: Modulation Input 1V/Div.

TIME = 0.1 ms/DIV. Bottom Trace: Output 2V/Div.

RA = 3.9k

RB = 3k

C = 0.01μF

Page 29: Futuristic Carmmmmm

Linear Ramp

When the pullup resistor, RA, in the monostable circuit is replaced

by a constant current source, a linear ramp is generated.

Figure 12 shows a circuit configuration that will perform

this function.

Figure 13 shows waveforms generated by the linear ramp.

The time interval is given by:

Page 30: Futuristic Carmmmmm

VCC = 5V Top Trace: Input 3V/Div.

TIME = 20μs/DIV. Middle Trace: Output 5V/Div.

R1 =

47kBottom

Trace: Capacitor Voltage 1V/Div.

R2 = 100k

RE = 2.7 k

C = 0.01 μF

Page 31: Futuristic Carmmmmm

POWER SUPPLY

In alternating current the electron flow is alternate, i.e. the electron flow increases to maximum in one direction, decreases back to zero. It then increases in the other direction and then decreases to zero again. Direct current flows in one direction only. Rectifier converts alternating current to flow in one direction only. When the anode of the diode is positive with respect to its cathode, it is forward biased, allowing current to flow. But when its anode is negative with respect to the cathode, it is reverse biased and does not allow current to flow. This unidirectional property of the diode is useful for rectification. A single diode arranged back-to-back might allow the electrons to flow during positive half cycles only and suppress the negative half cycles. Double diodes arranged back-to-back might act as full wave rectifiers as they may allow the electron flow during both positive and negative half cycles. Four diodes can be arranged to make a full wave bridge rectifier. Different types of filter circuits are used to smooth out the pulsations in amplitude of the output voltage from a rectifier. The property of capacitor to oppose any change in the voltage applied across them by storing energy in the electric field of the capacitor and of inductors to oppose any change in the current flowing through them by storing energy in the magnetic field of coil may be utilized. To remove pulsation of the direct current obtained from the rectifier, different types of combination of capacitor, inductors and resistors may be also be used to increase to action of filtering.

NEED OF POWER SUPPLY

Perhaps all of you are aware that a ‘power supply’ is a primary requirement for the ‘Test Bench’ of a home experimenter’s mini lab. A battery eliminator can eliminate or replace the batteries of solid-state electronic equipment and the

Page 32: Futuristic Carmmmmm

equipment thus can be operated by 230v A.C. mains instead of the batteries or dry cells. Nowadays, the use of commercial battery eliminator or power supply unit has become increasingly popular as power source for household appliances like transreceivers, record player, cassette players, digital clock etc.

THEORY

U SE OF DIODES IN RECTIFIERS:

Electric energy is available in homes and industries in India, in the form of alternating voltage. The supply has a voltage of 220V (rms) at a frequency of 50 Hz. In the USA, it is 110V at 60 Hz. For the operation of most of the devices in electronic equipment, a dc voltage is needed. For instance, a transistor radio requires a dc supply for its operation. Usually, this supply is provided by dry cells. But sometime we use a battery eliminator in place of dry cells. The battery eliminator converts the ac voltage into dc voltage and thus eliminates the need for dry cells.

Page 33: Futuristic Carmmmmm

Nowadays, almost all-electronic equipment includes a circuit that converts ac voltage of mains supply into dc voltage. This part of the equipment is called Power Supply. In general, at the input of the power supply, there is a power transformer. It is followed by a diode circuit called Rectifier. The output of the rectifier goes to a smoothing filter, and then to a voltage regulator circuit. The rectifier circuit is the heart of a power supply.

RECTIFICATION

Rectification is a process of rendering an alternating current or voltage into a unidirectional one. The component used for rectification is called ‘Rectifier’. A rectifier permits current to flow only during the positive half cycles of the applied AC voltage by eliminating the negative half cycles or alternations of the applied AC voltage. Thus pulsating DC is obtained. To obtain smooth DC power, additional filter circuits are required.

A diode can be used as rectifier. There are various types of diodes. But, semiconductor diodes are very popularly used as rectifiers. A semiconductor diode is a solid-state device consisting of two elements is being an electron emitter or cathode, the other an electron collector or anode. Since electrons in a semiconductor diode can flow in one direction only-from emitter to collector- the diode provides the unilateral conduction necessary for rectification. Out of the semiconductor diodes, copper oxide and selenium rectifier are also commonly used.

Page 34: Futuristic Carmmmmm

FULL WAVE RECTIFIERIt is possible to rectify both alternations of the input voltage

by using two diodes in the circuit arrangement. Assume 6.3 V rms (18 V p-p) is applied to the circuit. Assume further that two equal-valued series-connected resistors R are placed in parallel with the ac source. The 18 V p-p appears across the two resistors connected between points AC and CB, and point C is the electrical midpoint between A and B. Hence 9 V p-p appears across each resistor. At any moment during a cycle of vin, if point A is positive

relative to C, point B is negative relative to C. When A is negative to C, point B is positive relative to C. The effective voltage in proper time phase which each diode "sees" is in Fig. The voltage applied to the anode of each diode is equal but opposite in polarity at any given instant.

When A is positive relative to C, the anode of D1 is positive

with respect to its cathode. Hence D1 will conduct but D2 will not.

During the second alternation, B is positive relative to C. The anode of D2 is therefore positive with respect to its cathode, and

D2 conducts while D1 is cut off.

There is conduction then by either D1 or D2 during the entire

input-voltage cycle.

Since the two diodes have a common-cathode load resistor RL, the output voltage across RL will result from the alternate

conduction of D1 and D2. The output waveform vout across RL,

therefore has no gaps as in the case of the half-wave rectifier.

The output of a full-wave rectifier is also pulsating direct current. In the diagram, the two equal resistors R across the input voltage are necessary to provide a voltage midpoint C for circuit connection and zero reference. Note that the load resistor RL is

connected from the cathodes to this center reference point C.

Page 35: Futuristic Carmmmmm

An interesting fact about the output waveform vout is that

its peak amplitude is not 9 V as in the case of the half-wave rectifier using the same power source, but is less than 4½ V. The reason, of course, is that the peak positive voltage of A relative to C is 4½ V, not 9 V, and part of the 4½ V is lost across R.

Though the full wave rectifier fills in the conduction gaps, it delivers less than half the peak output voltage that results from half-wave rectification.

BRIDGE RECTIFIERA more widely used full-wave rectifier circuit is the bridge

rectifier. It requires four diodes instead of two, but avoids the need for a centre-tapped transformer. During the positive half-cycle of the secondary voltage, diodes D2 and D4 are conducting and diodes D1 and D3 are non-conducting. Therefore, current flows through the secondary winding, diode D2, load resistor RL and diode D4. During negative half-cycles of the secondary voltage, diodes D1 and D3 conduct, and the diodes D2 and D4 do not conduct. The current therefore flows through the secondary winding, diode D1, load resistor RL and diode D3. In both cases, the current passes through the load resistor in the same direction. Therefore, a fluctuating, unidirectional voltage is developed across the load.

Filtration

Page 36: Futuristic Carmmmmm

The rectifier circuits we have discussed above deliver an output voltage that always has the same polarity: but however, this output is not suitable as DC power supply for solid-state circuits. This is due to the pulsation or ripples of the output voltage. This should be removed out before the output voltage can be supplied to any circuit. This smoothing is done by incorporating filter networks. The filter network consists of inductors and capacitors. The inductors or choke coils are generally connected in series with the rectifier output and the load. The inductors oppose any change in the magnitude of a current flowing through them by storing up energy in a magnetic field. An inductor offers very low resistance for DC whereas; it offers very high resistance to AC. Thus, a series connected choke coil in a rectifier circuit helps to reduce the pulsations or ripples to a great extent in the output voltage. The fitter capacitors are usually connected in parallel with the rectifier output and the load. As, AC can pass through a capacitor but DC cannot, the ripples are thus limited and the output becomes smoothed. When the voltage across its plates tends to rise, it stores up energy back into voltage and current. Thus, the fluctuations in the output voltage are reduced considerable. Filter network circuits may be of two types in general:

CHOKE INPUT FILTERIf a choke coil or an inductor is used as the ‘first-

components’ in the filter network, the filter is called ‘choke input filter’. The D.C. along with AC pulsation from the rectifier circuit at first passes through the choke (L). It opposes the AC pulsations but allows the DC to pass through it freely. Thus AC pulsations are largely reduced. The further ripples are by passed through the parallel capacitor C. But, however, a little nipple remains unaffected, which are considered negligible. This little ripple may be reduced by incorporating a series a choke input filters.

Page 37: Futuristic Carmmmmm

CAPACITOR INPUT FILTERIf a capacitor is placed before the inductors of a choke-input

filter network, the filter is called capacitor input filter. The D.C. along with AC ripples from the rectifier circuit starts charging the capacitor C. to about peak value. The AC ripples are then diminished slightly. Now the capacitor C, discharges through the inductor or choke coil, which opposes the AC ripples, except the DC. The second capacitor C by passes the further AC ripples. A small ripple is still present in the output of DC, which may be reduced by adding additional filter network in series.

CIRCUIT DIAGRAM

Page 38: Futuristic Carmmmmm

Advantages :

Page 39: Futuristic Carmmmmm

A great solution for Energy Crisis. A huge amount of electricity can be generated saving lot of money. If implemented will be very beneficial for government. Energy lost in environment can be utilized. Saves a lot of money. Once applied does not require much maintenance. Renewable source of energy

Page 40: Futuristic Carmmmmm