BÁO cáo CHUYÊN đề tiếng anh chuyên ngành

Ohm’s law of an electrical circuit regarding power sources The current through a resistor is in direct proportion to the voltage across theresistor's terminals.. Synchronous motors conta

DỢI HỌC DIỆÍ1 Lực

ELECTRIC POWER UNIVERSITY

BÁO CÁO CHUYÊN ĐỀ

NGÀNH: Công nghệ kỹ thuật điều khiển và tự động hóa

CHUYÊN NGÀNH: Tự động hóa và điều khiển thiết bị công nghiệp HỌC PHẦN: Tiếng Anh chuyên ngành

Giảng viên hướng dẫn: Nguyễn Ngọc Khoát

Nhóm sinh viên/ sinh viên thực hiện - Mã sinh viên:

Nhóm 3 : Nguyễn Khánh Hùng Khôi - 19810430152

Trần Lâm Hải Long - 19810430211

Lê Hoàng Minh - 19810430138Trần Anh Thắng - 19810430273Lớp : D14TDH&DKTBCN3

HÀ NỘI, 2/2022

Đề tài nhóm 3:

Chương 1: Introduction to power sources (DC and AC power)

1.1 Deíinition

1.2 How to use power sources in an electrical Circuit?

1.3 How to produce power sources?

1.4 How internal resistance of power sources affects operation of an electrical circuit?1.5 Ohm’s law of an electrical circuit regarding power sources

1.6 Applications of power sources

Chương 2: Synchronous AC motors

3.2 What are differences between PLC and traditional relay circuits?

3.3 Select and present brieíly a PLC of Mitsubishi

LỜI CẢM ƠN

Trong thời gian làm báo cáo chuyên đề, em đã nhận được nhiều sự giúp đỡ,đóng góp ý kiến và chỉ bảo nhiệt tình của thầy cô và bạn bè Em xin gửi lời cảm onchân thành đến thầy Nguyễn Ngọc Khoát, giảng vên người đã tận tình hướng dẫn,chỉ bảo em trong suốt quá trình làm chuyên đề điều khiển số Em cũng xin chânthành cảm on thầy cô giáo trường Đại học Điện Lực nói chung, các thầy cô bộ mônđiện tử công suất nói riêng đã hướng dẫn cho em kiến thức về cách trình bày và nộidung đồ án, giúp em có được co sở lý thuyêt và tạo điều kiện gúp đỡ em trong quátrình làm báo cáo chuyên đề Tuy vậy, với kinh nghiệm và kiến thức còn thiếu sótnên bản báo cáo chuyên đề của em còn chưa được hoàn thiện lắm, em mong được sửchỉ dẫn chân thành của các thầy cô

Cuối cùng, em xin chân thành cảm ơn thầy cô và bạn bè đã luôn tạo đều kiện,quan tâm, giúp đỡ em trong suốt quá trình học tập và hoàn thành báo cáo

Chương 1: Introduction to power sources (DC and AC power)

1.1 Deíinition

Alternating current power is the Standard electricity that comes out of poweroutlets and is deíined as a flow of charge that exhibits a periodic change in direction.AC's current flow changes between positive and negative because of electrons-electrical currents come from the flow of these electrons, which can move in either apositive (upward) or negative (downward) direction This is known as the sinusoidal

AC wave, and this wave is caused when alternators at power plants create AC power.Alternators create AC power by spinning a wire loop inside a magnetic field Waves ofalternating current are made when the wire moves into areas of different magneticpolarity—for example, the current changes direction when the wire spins from one ofthe magnetic field's poles to the other This wave-like motion means that AC powercan travel farther than DC power, a huge advantage when it comes to delivering power

to consumers via power outlets

Direct current (DC) power, as you may guess from the name, is a linearelectrical current—it moves in a straight line

Direct current can come from multiple sources, including batteries, solar cells, fuelcells, and some modified alternators DC power can also be "made" from AC power byusing a rectifier that converts AC to DC DC power is far more consistent in terms ofvoltage delivery, meaning that most electronics rely on it and use DC power sourcessuch as batteries Electronic devices can also convert AC power from outlets to DCpower by using a rectifier, often built into a device's power supply A transformer willalso be used to raise or lower the voltage to a level appropriate for the device inquestion

1.2 How to use power sources in an electrical Circuit?

Power sources do two important things:

+) They supply energy to the circuit in the form of an electric potential difference.+) They provide a source and sink for electrons in a circuit

As a simple analogy, you can think of a power source as the heart of a circuit;just as our heart circulates blood to enable our bodies to function, electric powersources pump or circulate electrons, enabling electric circuits to function

You can think of a power source as a ‘pump’ that keeps electrons flowing in acircuit Without a power source, a circuit will quickly lose energy due to the electricalresistance of its components

Power sources are known as active components because they supply energy tothe electric circuit

Power sources supply electric power by pushing and pulling the electrons in acircuit Without a power source, circuits quickly stop working due to energy losses.Think about the battery in your phone or tablet When the battery runs out of charge, itstops functioning as a power source and your device quickly shuts down Powersources are really important because every circuit and component relies on them inorder to function We start our discussion on circuits with power sources because theyare the beating heart of every circuit

1.3 How to produce power sources?

The three major categories of energy for electricity generation are fossil fuels(coal, natural gas, and Petroleum), nuclear energy, and renewable energy sources.Most electricity is generated with steam turbines using fossil fuels, nuclear, biomass,geothermal, and solar thermal energy Other major electricity generation technologiesinclude gas turbines, hydro turbines, wind turbines, and solar photovoltaics

1.4 How internal resistance of power sources affects operation of an electrical Circuit?

In the case of circuits, the equivalent of ‘friction’ is something called electricresistance Every electric component has some amount of electric resistance Evenconductors like wires have some resistance to the movement of electrons That’sbecause conductors don’t conduct electricity perfectly, and they lose some energy asheat as a result The energy loss quickly causes all the electrons in the circuit to stopmoving when disconnected from the power source, even if the circuit remains closed

In AC circuits, resistance is called impedance That’s because the total

‘resistance’ to current flow in an AC circuit doesn’t just come from electric resistance.Capacitance and inductance also contribute to the overall opposition to current flow in

an AC circuit The total opposition to current flow, caused by resistance, capacitanceand inductance is called impedance

1.5 Ohm’s law of an electrical circuit regarding power sources

The current through a resistor is in direct proportion to the voltage across theresistor's terminals This relationship is represented by Ohm's law:

Where I is the current through the conductor in units of amperes, V is thepotential difference measured across the conductor in units of volts, and R is theresistance of the conductor in units of ohms (symbol: Q)

1.6 Applications of power sources

• The Lilypad-based D&D Dice Gauntlet

• Flat-screen TVs (AC goes into the TV, which is converted to DC)

• Hybrid and electric vehicles

Chương 2: Synchronous AC motors

2.1 Concept

A synchronous electric motor is an AC electric motor in which, at steady State,the rotation of the shaft is synchronized with the frequency of the supply current; therotation period is exactly equal to an integral number of AC cycles Synchronous

motors contain multiphase AC electromagnets on the stator of the motor that create amagnetic field which rotates in time with the oscillations of the line current The rotorwith permanent magnets or electromagnets turns in step with the stator field at thesame rate and as a result, provides the second synchronized rotating magnet field ofany AC motor A synchronous motor is termed doubly fed if it is supplied with

independently excited multiphase AC electromagnets on both the rotor and stator

The synchronous motor and the induction motor are the most widely used types

of AC motors The difference between the two types is that the synchronous motorrotates at a rate locked to the line frequency since it does not rely on current induction

to produce the rotor's magnetic field By contrast, the induction motor requires slip: therotor must rotate slightly slower than the AC alternations in order to induce current inthe rotor winding Small synchronous motors are used in timing applications such as insynchronous clocks, timers in appliances, tape recorders and precision

servomechanisms in which the motor must operate at a precise speed; speed accuracy

is that of the power line frequency, which is carefully controlled in large

interconnected grid systems

Synchronous motors are available in self-excited sub-fractional horsepowersizes to high power industrial sizes In the fractional horsepower range, mostsynchronous motors are used where precise constant speed is required These

machines are commonly used in analog electric clocks, timers and

correct time is required In higher power industrial sizes, the synchronousmotor

provides two important functions First, it is a highly efficient means of

Beside speed, synchronous motors can be classiíied by type There are differenttypes of synchronous motors based on the way they are excited

• Non Excited Synchronous Motors

• Current Excited Synchronous Motors

Non Excited Synchronous Motor

The rotor is made up of steel The external magnetic field magnetizes the rotor,and it rotates in synchronism with it The rotor is generally made of high retentivitysteel such as cobalt steel

Non-excited motors are available in three designs:

+) Hysteresis Motor

Hysteresis motors are single phase motors in which the rotor is made up offerromagnetic material The rotors are cylindrical in shape and have high hysteresisloss property They are generally made up of chrome, cobalt steel or alnico The stator

is fed by single phase AC supply The stator has two windings:

1 main windings and

2 auxiliary windings

The combination of the two produces a revolving magnetic field from a singlephase supply They are self-starting and do not need additional windings When singlephase AC supply is given, a rotating magnetic field is produced This rotating

magnetic field induces eddy currents in the rotor The rotor starts to move initiallywith a slip When the rotor reaches synchronous speed, the stator pulls the rotor intosynchronism So initially the motor starts as an induction motor and later runs as asynchronous motor

+) Reluctance Motor

The reluctance motor is based on the principle that an unrestrained piece of ironwill move to complete a magnetic flux path where the reluctance is minimum Thestator has the main winding and the auxiliary windings just like the hysteresis motor.These help to create a rotating magnetic field The rotor of a reluctance motor is a

squirrel cage rotor with some teeth removed to provide the desired number of salient

poles The reluctance becomes minimum when the rotor is aligned with the magnetic

field of the stator

When single phase AC supply is given, the motor starts as an induction motor.The rotor tries to align itself with the magnetic field of the stator and experiencesreluctance torque But due to inertia, it exceeds the position and again tries to alignitself during the next revolution In this manner, it starts to rotate Once it reaches 75%

of synchronous speed, the auxiliary windings are cut off When the speed reachessynchronous speed, the reluctance torque pulls it into synchronism The motor remains

in synchronism due to synchronous reluctance torque

+) Permanent Magnet Synchronous Motors

The rotor is made up of permanent magnets They create a constant magneticflux The rotor locks in synchronism when the speed is near synchronous speed Theyare not self-starting and need elecfronically controlled variable frequency stator drive

Direct Current Excited Motor

Direct current excited synchronous motors need a DC supply to the rotor togenerate rotor magnetic fĩeld A direct current excited motor has both stator windings

as well as rotor windings They can either have cylindrical rotors or salient pole rotors.They are not self-starting and need damper windings to start Initially, they start as aninduction motor and later attains synchronous speed

2.3 Structure

The construction of synchronous motor is similar to that of a synchronousalternator Most of the synchronous motors construction uses the stationary armatureand rotating field winding This type of construction as an advantage than DC motortype where the armature used is of rotating type

2.4 Working principle

The principle of operation of a synchronous motor can be understood by

considering the stator windings to be connected to a three-phase alternating-currentsupply The effect of the stator current is to establish a magnetic field rotating at

120 f/p revolutions per minute for a frequency off hertz and for p poles A direct

current in a p-pole field winding on the rotor will also produce a magnetic field

rotating at rotor speed If the rotor speed is made equal to that of the stator field andthere is no load torque, these two magnetic fĩelds will tend to align with each other Asmechanical load is applied, the rotor slips back a number of degrees with respect to therotating field of the stator, developing torque and continuing to be drawn around bythis rotating field The angle between the fĩelds increases as load torque is increased.The maximum available torque is achieved when the angle by which the rotor fieldlags the stator field is 90° Application of more load torque will stall the motor

One advantage of the synchronous motor is that the magnetic field of the

magnetic f lux lines

-slip rings

iron rotor field conductor

statorconductor

^-irori stator

end Cũnnection

The power factor of the stator electrical input can be directly controlled byadjustment of the field current If the field current is increased beyond

the value required to provide the magnetic field, the stator current changes to include acomponent to compensate for this overmagnetization The result will be a total statorcurrent that leads the stator voltage in phase, thus providing to the power system

reactive volt-amperes needed to magnetize other apparatuses connected to the systemsuch as transformers and induction motors Operation of a large synchronous motor atsuch a leading power factor may be an effective way of improving the overall powerfactor of the electrical loads in a manufacturing plant to avoid additional electric

supply rates that may otherwise be charged for low power-factor loads

2.5 Speed control methods for the synchronous AC motors

Synchronous motors are constant speed motors They run at the synchronousspeed of the supply They are generally used for constant speed operation under noload conditions such as to improve the power factor Synchronous motors have fewerlosses than induction motors at a given rating

The speed of a synchronous motor is given by