TÀI LIỆU ĐIỆN Ô TÔ CƠ BẢN (ENGLISH)

Electricity is an energy that originates from the positive charge (+) and negative charge () of atomic nuclei, which are contained in all elements. Like other energies, electricity also has the characteristic of being conducted from one location to another. Put simply, electricity can be defined as an invisible flow of energy

Module 1 Basic Electronics & Electricity

1 Electricity and Magnetism

3.2 Automotive Electrical Communication

4 Tools & Equipment

4.1 Safety Sign & Advice

4.2 Multi Meter Use

4.3 Use of GDSas Diagnostic Equipment

Learning

Objectives

 Describe the basic concept of electrics and electronics.

 Understand circuit diagram components and be able read circuit diagrams.

 Explain communications modes used in vehicles.

 Use inspection tools and diagnostic equipment appropriately.

1) What is an electron ?

All metals are made up of electrons It is one of the differentparticles that make up an atom As the moon circles the earth,electrons circle the center of an atom The center of an atom iscalled a "core."A core comprises protons and neutrons

An electron is negatively charged, a proton is positively chargedand a neutron is neutral In metals, some of the electrons circlingthe atomic nucleus is loosely connected to the nucleus Suchelectrons are called "free electrons", and

Fthey are capable of moving from one atom to another It is the movement of free electronsthat create a flow of electrons With increased temperature, the movement of electrons is mademore rigorous This flow of electrons can be defined as "electricity."

1.2 Current

As explained earlier, connecting a negatively chargedobject with a positively charged on results in electronsmoving from (-) to (+) In such an instance, it is said that

a "current flows" in the conducting wire As such,currents are formed by the movement of free electrons.The volume of electric charge movement is referred to as

a "current."

However, the direction of current flows is not the same

as the direction of electron flows As the direction of acurrent is defined as the direction of (+) electricity,current direction is the opposite of electron direction

causes the ionization of said metals Here, thecopper will undergo an electron shortage andbecome positively charged, while the zincundergoes an electron excess to become negativelycharged Connecting a conducting wire to these twopolarities moves the electrons of the zinc to thecopper, thus creating a current Car batteries takeadvantage of this chemical action

conducting wire through it, and create a currentbefore sprinkling some ground metal over it Theground metal will form a concentric circle around theconducting wire, and end up on the surfaceperpendicular to the conducting wire This isbecause a magnetic field was created by themagnetic action of the current Likewise, a coil madefrom a conducting wire that has a flowing currentcreates a magnetic field This is constitutes thebasic mechanism of a motor The ignition coil,starter motor, wiper motor and alternator of a vehicleuse this magnetic action of currents to function

Ground metal

(-)

(+)

Thick paper

is referred to as "voltage."

A current continues to flow until the electric potentialdifference at the two ends of the conductor becomes 0 Adevice designed to maintain such an electric potentialdifference is a battery or power supply device As suchvoltage can be defined as an "electric potentialdifference that makes a current flow through a circuit."

2) Serial and Parallel Circuit of Cells

 Serial circuit : Cells are connected in a

line Total voltage is the sum of each cells'voltage

 Parallel circuit: Cells are connected

parallel to each other Total voltage equalsthe voltage of a single cell

3) What is resistance?

A vehicle is unable to pick up its speed on an unpaved road that is bumpy or muddy The roadsurface hinders the vehicle from doing so Similarly, the property that hinders the flow ofelectrical currents is defined as "resistance."

Conductor wires are designed to promote current flow, but at the same time exert resistanceagainst current flow; so low-resistance wires are more efficient In some instances, a channelthrough which a current travels must have resistance, i.e the filament of a light bulb

Conducting wire resistance R

R= ρ·S/l

l: Conducting wire length(m)

S: Conducting wire cross ection(m)²

ρ: Conductor resistance

rate(Ω·m)

The electrical resistance of a resistant body, such as carbon or metal, is marked by wrapping a nonconductor around the resistant body and placing a colored band The type shown in the photograph is primarily used for small currents that are less than 1A If larger currents are required, the size must be increased to withstand the heat generated from resistance.

<Symbol of electrical resistance>

1.4 Circuit Theory

1) Ohm's law (a) shows three light bulbs connected to one

cell, and (b) shows one light bulb connected totwo cells The light light bulb in (b) will light upbrighter According to Ohm's law, the size of acurrent flowing through a conductor isproportional to the voltage at the two ends ofthe conductor, and inversely proportional toresistance (light bulb)

The size of total resistance in a serial circuit can be

calculated by combining all resistances

R = R1 + R2 + R3 , according to Ohm's law, the

current is I = V/R = V/(R1 + R2 + R3)

 Parallel circuit

In a parallel circuit, where the two ends of two or more

resistances is connected to a single source, the total

size of resistances can be calculated as follows

1/R = 1/R1 + 1/R2 + 1/R3, according to Ohm's law, the

As all elements are connected to a single set of two points in a circuit, the voltage of each element equals the total voltage of the circuit.

Current

Being connected via a single conducting wire makes the current flowing through each element equal to the circuit's total current

A circuit's total current is divided at the parallel junction and varies according to the resistance of each element The total of all elements' currents equals the circuit's total current.

Even if one light bulb gets disconnected, the others are not affected.

Connecting the light bulbs in a serial circuit increases total circuit resistance, reducing the brightness of each light bulb.

Connecting the light bulbs in a parallel circuit does not subject the current to total circuit resistance, so there is no change in the brightness of bulbs.

3) Kirchhoff's law

Kirchhoff's law is a theory that wholly reflects the characteristics of a serial circuit and parallelcircuit explained earlier Kirchhoff's first law addresses currents and the second law voltage

 Kirchhoff's first law

The sum of currents flowing in matches the sum of currents flowing out

Voltage applied to a parallel circuit by power supply makes a current flow in each resistance.However, total currents in the circuit gets divided at the parallel junction to flow inverselyproportional to each resistance

Circuit's total currents I = (1/R1 + 1/R2)·V = (1/2 + 1/5)·10 = 7A

I1 = V/R1 = 10/2 = 5A, I2 = V/R2 = 10/5 = 2A → I = I1 + I2

If 7A flows through the circuit, 5A flows against a resistance of 2 ohm and 2A flows against aresistance of 5 ohm to make the current total 7A again

 Kirchhoff's second law

The total of voltage drops occurring in a closed circuit equals the electromotive force (voltage

of the power supply device) of the circuit

Creating a flowing current in an electrical circuit with resistance results in the circuit's voltagedecreasing by the level of voltage at the two ends of the resistance This is called a voltage drop

The voltage of power supplied to a serial circuit is divided proportional to the resistance of eachelement and consumed In short, a voltage drop occurs for each resistance

Total voltage of a circuit V = I·R1 + I·R2 + I·R3, I = R/V = (R1 + R2 + R3) / V = (2 + 3 + 5)/10 = 1A

V = 2 + 3 + 5 = 10 → V = V1 + V2 + V3

A voltage drop of 2V occurs for a resistance of 2 ohm, 3V for a resistance of 3 ohm and 5V for aresistance of 5 ohm The sum of all voltage drops equals the total electromotive force of 10V

1.5 Electric Power and Electric Power Level

1) What is electric power?

Moving electric charge generates heat in a circuit or drives a motor A flowing current changeselectric energy into another energy; the ratio of this change is referred to as "electric power."Electric power equals the multiplication of voltage and current

Electric power (P) = Voltage ( V) X Current (I) , the unit W(watt) is used.

2) What is an electric power level?

Electric power level is calculated by multiplying electric power by time Electric power thatremains constant results in increased electric power consumption over time

Electric power level (W) = Electric power level (P) X Time (t) = Voltage (V) X Current (I) X Time (t) , The unit Wh(watt-hour) is used

P = V·I , I = P/V

I = 500/220 + 100/200 + 50/220 = Approx 2.95A

As such, a fuse that allows a maximumcurrent flow of 2.95A and higher must beinstalled In general, a fuse's maximumallowed current is 1.2 to 1.5 times that ofthe used current

 Ampère's law

Groun

d metal

(-) (+) Thick paper

When a conducting wire with aflowing current is grabbed with theright hand with the thumb pointing inthe direction of the current, amagnetic field forms in the direction

of the other fingers Ground metalplaced around a current-flowingconducting wire lines up in a setdirection - the same direction as theone in which a magnetic field formswhen a conducting wire is gripped.This is "Ampère's law."

 Magnet

A magnet is a magnetic object Magnets are categorized into permanent magnets andelectromagnets The rotor coil in a motor, rotor coil in an alternator, and a solenoid coil use anelectromagnet that becomes magnetic temporarily when a current flows through it Fuel pumpsand wiper motors use both permanent magnets and electromagnets

 What is a magnetic field?

An area in which magnetic force is exerted is called a magnetic field For example, the areaaround a magnet in which metals are pulled in toward the magnet is a magnetic field

 The Right-hand screw rule

Forming a circle with a conducting wire and flowing a current through it creates a magnetic line

of force that penetrates the surface created by the circular current Here, turning the right-handscrew in the direction of the current sets the right-hand screw's progressive direction as themagnetic field direction

An examination of a magnetic field formed by a coil is as follows A solenoid coil is a conductingwire wound tightly in a cylindrical shape Applying the right-hand screw rule, turning the right-hand screw in a current's direction changes the magnetic field's direction from right to left.Another way of understanding this concept is gripping a coil with the right-hand with the fourfingers in the direction of current flow; it can be observed that a magnetic field forms in thedirection of the thumb

Four fingers:

Current direction

Thumb: Magnetic field direction

<Coil-generated magnetic field>

Right-hand

Current(I) Current(I)

Circular Loop Conductor

Direction of Current Direction of

Current

 Mechanism of a relay

A relay is an electronic part used for driving and signaling electrical/electronic products, and iswidely used in vehicles also Flowing a current through an iron core wrapped with a coil makesthe iron core an electromagnet that pulls in a steel plate to close the switch on the steel plate.This mechanism of a relay is used to open and close circuits

1.7 Alternating Current

1) What is an alternating current?

(a) Direct current

Current direction Current direction

A direct current is represented as "DC." It is a current that flows in a single direction, i.e from (+)

to (-) Because the terminals of a battery always maintain the same polarities, currents only flow

in a single direction in an electrical circuit On the other hand, an alternating current isrepresented as "AC." Alternating currents flow in no set direction, i.e current direction alternates.The reason for this is constantly changing voltage

2) Alternating current generation

Magnetism is always present where electricity is Magnetism is formed by a conducting wire with

a flowing current Also, electricity can be generated by magnetism Faraday and Henry made thediscovery that placing a magnet in and out of a coil creates a current flow in the conducting wire

 Inducing voltage in a coil

Change the volume of a magnetic field in a coil

• Move a coil in close proximity to a magnet

• Move a magnet in close proximity to a coil

• Change the current flowing in another coil in closeproximity to a coil

Induced voltage increases when the number of copperconducting wires moving within a magnetic fieldincreases or if the speed at which a magnetic line offorce goes in and out of a coil increases

3) Fleming's Right-hand Rule

Fleming's right-hand rule is useful for finding the direction of a currentinduced in a conducting wire by electromagnetism Positioning the thumb,index finger and middle finger so that a right angle forms between each ofthem, if the thumb points in the direction of conducting wire movement andthe index finger the direction of a magnetic field, the middle finger points inthe direction of an inducted current

: Signifies a current flowing into a coil : Signifies a current flowing out of a coil

0 90 0

0 90 180

magnetic pole makes induced voltage the lowest of (=0).

magnetic pole makes induced voltage the lowest of (=0).

magnetic pole.

maximum volume as it nears the

S pole.

0 90 180 270

 Interval, frequency and phase

• Interval : Time required for one cycle

to change [T]

• Frequency : Number of cyclesrepeated for one second[Hz]

• Phase : Time difference between two

or more currents of the same frequency,e.g the phase of v2 is later than that ofv1

5) What is a three-phase alternating current?

e1

I2 I3

I1

A three-phase alternating current is generated by a three-phase alternator It is made up ofcurrents that share the same frequency and amplitude of voltage and current, and have aphase difference of 120 degrees Arrange coils at an interval of 120 degrees and rotate themagnetic pole clockwise inside the coils to obtain a three-phase current as shown in thediagram

When three electromotive forces e1, e2 and e3 are generated by a 3-phase alternator, theyare supplied to loads 1, 2 and 3 through 3 conducting wires Although e1, e2 and e3 share thesame size and frequency, their change in time is each delayed by a one-third interval (120degrees) Compared to a single-phase alternating current, a three-phase can send the samevolume of electric power using a lighter conducting wire and consume less heat in the circuit.Also, three-phase AC motors are in wide use as the are far superior to single-phase ACmotors

 Motor

A power device containing a rotor (amateur) that rotates when supplied with electricity Power

is generated from electricity supply

2) Types of semiconductor

 Intrinsic semiconductor

A semiconductor covalently bonded with elements (silicone and germanium) that have fourpure electrons Currents cannot flow through an intrinsic semiconductor as the electronsbonded to its atomic nucleus cannot move

 P-type semiconductor

Mixing a small quantity of an element with three electrons (Al and In) with silicone with fourelectrons results in a (+) electron hole with no electrons Applying voltage in this statetriggers the electron hole to absorb electrons; it appears as if the electron hole is moving Inthis instance, the electron hole (+: positive) is the carrier of electricity; hence the name p-typesemiconductor

 N-type semiconductor

Mixing a small quantity of an elementwith five electrons (As and P) with silicone with fourelectrons results in a covalent bond with the one extra electron being removed Applyingvoltage in this state turns the excess electron into a free electron, which then creates aflowing current In this instance, the electron (-: negative) is the carrier of electricity; hencethe name n-type semiconductor

1.9 Diode and Transistor

1) Diode

 Diode

A semiconductor device made up of a p-type semiconductor and n-type semiconductorjoined via a single junction A terminal is attached to each end of a diode The conductioncan be enabled and disabled by controlling the polarity of voltage applied to the terminals.Current flow only takes from an anode to a cathode

<+> <->

 Forward bias

Constant voltage is applied to the anode and negative voltage to the cathode of a diode.When this happens, electrons are supplied to n-type semiconductors and electron holes to p-type semiconductors, resulting in a carrier increase These carriers combine near the junction

As a result, electrons flow from the cathode to anode (current flows from the anode tocathode), and the current increases when forward bias voltage increases

 Reverse bias

Negative voltage is applied to the anode and constant voltage to the cathode of a diode In ap-type semiconductor, electrons are supplied and combined with p-type electron holes; in ann-type semiconductor, electron holes are supplied and combined with n-type electrons As aresults, carriers decrease in numbers and current flow is no longer possible

2) Diode rectification

As explained earlier, currents flowtoward only one polarity in a diode If ACvoltage, in which a (+) and (-) alternatingcurrent flows, a waveform is onlygenerated at the top This is referred to

as a "diode rectifier."

 3-phaseFull-wave Rectification

Three-phase full-wave rectifiers are a rectifier circuit used in

vehicle alternators Six diodes are used to rectify three-phase

alternating currents Currents that are virtually direct currents

are produced as the rectified waveform undergoes little change

such voltage is referred to as zener voltage

 This characteristic is used to maintain constant voltage in a circuit

4) Transistor

 Transistor

A device created from a double junction in the P-N junction of a semiconductor A n-typesemiconductor is in the center and a PNP-type and NPN-type is at each side Althoughcompact, reliable and long-lasting, transistors are critically affected by temperature andunable to function at high temperatures A transistor has three terminals: an emitter (E), base(B) and collector (C)

<NPN type>

<PNP type>

emitter and base moves electron holes from

the emitter to base and electrons from the

base to emitter As a result, a forward

current flows from the emitter to the base.

than the forward voltage supplied between the collector and base moves the majority of electron holes entering the base from the emitter to the collector by the high voltage at the collector In other words, most currents flow to the collector and only small currents flow to the base.

Electrons holes are moved from the emitter to the base by VBE Electron holes that enter theterritory of the base become closer to the collector, which has much higher voltage, and soget pulled into the collector As such, increasing VBE increases the number of electron holespulled into the collector By increasing the base current (lb) of a PNP transistor with VBE,increased collector currents (lc) can be obtained

emitter and base moves electrons from the

emitter to base and electron holes from the

base to emitter As a result, a forward

current flows from the base to the emitter.

than the forward voltage supplied between the collector and base moves the majority of electrons entering the base from the emitter

to the collector by the high voltage at the collector In other words, the majority of currents flow from the collector to the emitter.

Electrons are moved from the emitter to the base by VBE Electrons that enter the territory ofthe base become closer to the collector, which has much higher voltage, and so get pulledinto the collector As such, increasing VBE increases the number of electrons pulled into thecollector NPN transistor increases VBE to increase currents flowing through the base, whichresults in an increase in currents flowing through the collector as well

5) Transistor's function

 Switching: Current flow can be enabled from the emitter to the collector or vice versa,

depending on power supply to the base terminal

 Amplification: A large signal of a large energy can be generated from a small signal of a

small energy

 Switching

The following is a review of the transistor characteristics explained earlier By adjusting VBEand creating a current flow in the base, the emitter and collector become conducted.Consequently, a current flowing from the emitter to the collector (PNP transistor) or from thecollector to the emitter (NPN transistor) can be generated

The following is a description of theswitching function of the transistor used in avehicle BCM When the BCM suppliespower to the base terminal of the NPNtransistor, the emitter and collectorterminals become conducted as basecurrents start to flow As a result, thecurrent standing by in the collector afterhaving passed the relay coil flows into theemitter and the relay becomes magnetized,switching the switch off and operating thelamp The current flowing from the collector

to the emitter can be controlled bycontrolling the base current in this manner

 Amplification

NPN transistor's amplification is provided as an example below Applying forward voltageVBE to the base and emitter terminal moves the electrons from the emitter to the base,creating a current flowing from the base to the emitter If VCE is applied at the same time, acurrent flowing from the collector to the emitter forms and, as a result, the current flowing inthe emitter becomes the sum of the currents flowing in the base and collector As can beseen, a transistor is capable of obtaining large output signals from the emitter using onlysmall base input signals

The term "amplification" does not signify an unconditional enlargement of small signals.Amplification can be defined as the generation of a large signal that shares the form of a smallsignal at the output (emitter) when a small signal is used for control (base current) in a smallenergy source

1.10 Sensor

1) What is a sensor?

The function of a sensor is similar to the five senses of humans (sight, hearing, touch, smelland taste) As humans collect information through the five senses, the ECU uses a sensor toassess the surroundings and control various movements A vehicle's sensors include atemperature sensor, pressure sensor, optical sensor, RPM sensor and oxygen sensor

2) Temperature sensor

As a human must maintain the normal temperature range of 36-37℃ to stay healthy, theengine of a vehicle needs to maintain a temperature of approximately 90℃ for normalfunctioning A temperature sensor provides information for the engine to maintain normaltemperature, and also allows the adjustment of fuel injection volumes according to engineand air temperature It can be used for purposes other than engine control Temperaturesensors are an essential component of the FATC in convenience/safety systems andtemperature-sensitive systems, such as ventilated seats Temperatures sensors come in anon-contact-type and contact-type Contact-type ones are widely in use Contact-typetemperature sensors include platinum resistance temperature sensors, thermistors, thermoelectric devices and IC temperature sensors.Thermistorsare predominantly used in vehicles

 Application: Coolant temperature sensor, intake temperature sensor, exhaust gas

temperature sensor, interior/exterior air & evaporator sensor for air-conditioners

 Thermistor

A metallic oxide that has been heated and solidified Resistance changes according totemperature Based on their characteristic of changing resistance according to temperature,thermistors can be categorized into two types

 NTC-type: Acronym for "Negative Temperature Coefficient." Resistance rises iftemperature drops; resistance drops if temperature rises

 PTC-type: Acronym for "Positive Temperature Coefficient." Resistance rises if temperaturerises; resistance drops if temperature drops

NTC-type thermistors are widely used in vehicles The reason is because the NTC-type canmeasure a wider range of temperature than the PTC-type, and also produces more uniformresistance changes according to temperature changes

Signal monitoring

5V

GND

NTC

ECU

 Temperature detection by the ECU

There is pull-up resistance inside the circuit of the ECU

Voltage of 5V is supplied and flows into the ground via the

thermistor

• Temperature increase (NTC resistance decrease): If NTC

resistance becomes lower than pull-up resistance, the

voltage drop that takes place through pull-up resistance

becomes larger than the one that takes place through NTC

resistance As a result, the ECU detects the lower voltage

• Temperature decrease (NTC resistance increase): If NTC

resistance becomes higher than pull-up resistance, a

larger voltage drop takes place through NTC resistance

As a result, the ECUmonitors the higher voltage

 Application: Atmospheric pressure sensor, ABS oil pressure sensor, air-conditioner

pressure sensor, manifold pressure sensor, etc

• Air-conditioner refrigerant pressure sensor

The mechanism of MAP sensors and conditioner refrigerant pressure sensors isused in the majority of pressure sensors.Increased pressure increases piezoresistance, and decreased pressuredecreases piezo resistance

air Pressure detection by the ECU

Supplying power of 5V to a sensor andapplying high air-conditioner refrigerantpressure to piezo resistance increaseresistance As increased resistance increasesvoltage in piezo resistance, the voltagedetected by the sensor signal terminalbecomes close to 5V Conversely, a lowrefrigerant pressure will result in low voltagebeing detected

4) Photo sensor

Photo sensors are used for automatic light-sensitive headlight activation or detection of heatfrom sunlight for automatic interior temperature control Photo sensors use semiconductordevices, including photo diodes, photo transistors, optical ICs and cadmium sulfide Ingeneral, photo transistors are used in vehicles

 Application: Autolight sensor, sunlight sensor, etc.

 Photo transistor

A switch that enables electricity flow when light is detected

B+

In daytime, the photo transistor activates

and conduction occurs between its

emitter and collector, resulting in all of

B+ power getting grounded through the

photo transistor With general transistors,

the lamp does not activate as power is

not supplied to their base in this

Gener

al TR

In nighttime, the photo transistordeactivates and no conduction occursbetween its emitter and collector As aresult, B+ power flows to the base, andthe emitter and collector becomeconducted The lamp becomes lit as aconsequence

<Autolight mechanism (day) > <Autolight mechanism (night) >

Reference entered

Approx 5V entered by the ECU 5V

●T/Valve closed

Reference entered

Approx 0V entered by the ECU

5V

●T/Valve partially opened

Reference entered

Approx 0-5V entered by the ECU 5V

<Throttle valve position sensor>

 Hall IC-type

A hole element is a type of semiconductor that changes electron directions from the influence

of magnetic fields

 Supply power to each end of the hall

element and connect perpendicular to

the power supply A current flows inside

the hall element due to the power supply

at the two ends, but no output voltage is

produced as the output terminal is set in

a different direction

 Placing a magnet close to the hall element

to apply a magnetic field causes some ofthe current flowing inside the hall element

to break away to the output terminal base.The emitter and collector becomeconducted, and the 5V power supplied tothe collector flows to the ground anddecreases to 0V

A hall element does not react to magnetic bodies placed far away, producing no voltage at itsoutput terminal, but produces voltage when a magnetic body is placed in its vicinity When ahall sensor uses a hall element to rotate a shaft with a single protrusion, voltage is generated

as the protrusion nears the hall sensor; this serves as verification of a single rotation by theshaft The protrusion on the shaft is fixed, which means that shaft position can also be known

Voltage

2 Circuit

2.1 Basic Circuit Knowledge

A vehicle is a machine designed to function according to a large number of computers' control.The computer parts that make up a vehicle - the units - do not function individually, but inconjunction with one or more of other units Different units can function together organically due

to the electrical flow between them A circuit diagram shows such organic relationships andelectrical flows in signs and figures By reading and analyzing a circuit diagram, one canunderstand system operation and also identify areas of trouble

The above circuit diagram is a common vehicle electronic circuit diagram The circuit is made up

of a parent control module, various components (sensor, switch, fuse, etc.), wires andconnectors The components of a circuit diagram are explained below

of terminals The text and numbers to the right are connector names.

NPN transistor

Responsible for switching and amplificationGround

Signifies the end of a wire connected to a metallic part of a vehicle

PNP transistor

Fuse

Supplied when ignition is on and displayed along with fuse name and capacity

Switch

A device for connecting/disconnecting an electrical circuit

Lamp

Single filament lamp

Sensor

Diode

-A diode that passes currents in a a single

a current is flowing Motor

Zener

diode

Instant conduction occurs when an over-the-limit current flows reversely

Relay

Switch is connected when a current flow takes place through

a coil

■ Component symbols

male

female