Problem Summary and Introduction
We have study the speed control of induction motor by various methods like Rotor resistance and voltage frequency control and other. But the problem in this method is that they are very complex for speed control of induction motor. So, we are trying to solve these above two problems so we can easily solve in minimum cost and simply. We can control the speed of induction motor reliable.
The v/f control method widely used for the speed control of 3-phase induction motor. Mostly v/f control method used in industry due to its reliability, simplicity, low cost, low maintenance, smooth speed control. So, v/f control method mostly widely used.
The speed control and braking operation are possible from zero to above base speed.
Starting, breaking and speed reversal also possible.
Copper loss reduce
High efficiency
High power factor
Drop in speed from No load to full load is small
Aim and objectives of the project
Our aim is to control the speed of induction motor very smoothly, with minimum cost and make easy to use.
We know that in all field induction motor used about 95%. So, it is necessary to control the speed of induction motor reliable. Our first aim is to control the speed of induction motor very smoothly, with minimum cost and make easy to use. As we know that induction motor also used in traction system where highly speed control, reliable speed control and smooth speed control and during breaking time motor will feed back the power to supplies and increase efficiency.
Problem Specifications
As we know that one method use for speed control of induction motor is that rotor resistance. In which sleep ring and external resistance are required. Squirrel cage induction motor is mountain on shaft and external leads are connected to the squirrel cage induction motor. But the problem is there by varying can efficiently control speed of speed control of induction motor. So, we are trying to modify this method in such a way that less power loss with efficient speed control can be achieve. Another method use for speed control of induction motor is v/f control method in this method we approve maintain the constant flux in the air gap by keeping the v/f ratio constant which is very complex and difficult to maintain this ratio constant. So, we are trying to modified this method so that we can easily maintain the v/f ratio constant and make less complex circuit for speed control of induction motor
Brief literature review
We know that in early year in every DC motor was used because the speed control of DC motor can be easily control by using conventional method. But one disadvantage is that it is required more maintenance due to the sparking occur at brushes during the supplies resulting more power used. But after sometime power electronic branch has been developed due to advanced technology in the power electronic branch various power electronic device are used for speed control of induction motor before that conventional method was not able to control the speed of induction motor because we know that speed of induction motor can be control by using following methods:
From rotor side
From stator side
v/f control method
change in supplies frequency
In above methods, we know that after the construction of induction motor we can’t change number of pole also the supply frequency is also fixed in AC main.
But after advanced development in power electronic branch we easily control the speed of induction motor by using various semiconductor devices like Triac, Diac, IGBT, GTO and Thyristor. Now a day about 95% AC motor use due to fix rugged construction, Simple design, less operating and initial cost as well as less maintenance.
1.5 Plan of work
7
CHAPTER: -2 Analysis, Design Methodology
BUSINESS MODEL CANVAS: –
Fig. 1 Business model canvas
KEY PARTNERS: –
Earth Movers
Building Lifts
Big industries
Continues process industries
Small industries
KEY ACTIVITIES: –
Power electronic devices
Motor 3-phase or 1-phase
PLC
Wires or probe
MCB
Relay
KEY RESOURCE: –
Financial support
Technical support
Perfect rating of power electronic device
Reliable PLC programming
VALUE PROPOSITIONS: –
Simple speed control
No skill person required
Low cost
Reliable speed control
Step less speed control
Simple operation
Less complexity
CUSTOMER RELATIONSHIP: –
Automatic control
Low cost
Reliable service
Simple operation
Less complexity
Full service
CUSTOMER SEGMENTS: –
Building lifts
Food process industries
Rolling mills
Steel mills
Paper making industries
Earth movers
Practical purpose in laboratory
CHANNELS: –
Advertisement
Home delivery
Direct purchase from company
COST STRUCTURE: –
PLC
Power electronic device such as converter, IGBT, diode, Triac, Diac etc.
MCB
Relay
REVENUE STREAMS: –
Low cost
Simple operation
No skill person required
Automatic speed control also possible
Reliable operation
Low power requirement
CHAPTER: – 3 Summary
Summary of the results
In this project check the relay is properly work or not. Push button is properly work or not.
The SMPS output is constant or not. Check the indicator is properly indicated or not. And all
components are checking and we get result positive.
After completed relay circuit we are try to operate motor by using relay. We get result
successfully motor runs forward as well as reverse direction. Then after we experienced that
any error is not present in our circuit. Then result motor is smoothly rotated.
Our practical model is shown in fig. In this model, we done relay circuit testing and get result.
Fig. WORKING MODEL
P
N
FIG. BLOCK DIAGRAM
MCB:
Miniature Circuit Breaker. The function of MCB is to protect the motor against the fault here we used 10A rating MCB which is connect in series with the supply. The power come from switch board is connected input side of MCB and output of MCB is connected to SMPS.
SMPS
Switched-mode power supply (switching-mode power supply, switch-mode power supply, SMPS, or switcher) is an electronic power supply that incorporates a switching regulator to convert electrical power efficiently.
Like other power supplies, an SMPS transfers power from a source, like mains power, to a load, such as a personal computer, while converting voltage and current characteristics.
Unlike a linear power supply, the pass transistor of a switching-mode supply continually switches between low-dissipation, full-on and full-off states, and spends very little time in the high dissipation transitions, which minimizes wasted energy. Ideally, a switched-mode power supply dissipates no power.
Voltage regulation is achieved by varying the ratio of on-to-off time. In contrast, a linear power supply regulates the output voltage by continually dissipating power in the pass transistor. This higher power conversion efficiency is an important advantage of a switched-mode power supply.
Switched-mode power supplies may also be substantially smaller and lighter than a linear supply due to the smaller transformer size and weight.
Switching regulators are used as replacements for linear regulators when higher efficiency, smaller size or lighter weight are required. They are, however, more complicated; their switching currents can cause electrical noise problems if not carefully suppressed, and simple designs may have a poor power factor.
SMPS is convert AC to DC. In our project PLC required 24V DC. So, it is necessary to convert the 230V AC main line to 24V DC using SMPS.
Power Factor Correction (PFC)
Most power conversion applications consist of an AC-to-DC conversion stage immediately following the AC source. The DC output obtained after rectification is subsequently used for further stages. Current pulses with high peak amplitude are drawn from a rectified voltage source with sine wave input and capacitive filtering. Regardless of the load connected to the system, the current drawn is discontinuous and of short duration. Because many applications demand a DC voltage source, a rectifier with a capacitive filter is necessary. However, this results in discontinuous, short duration current spikes.
Two factors that provide a quantitative measure of the power quality in an electrical system are Power Factor (PF) and Total Harmonic Distortion (THD). The amount of useful power being consumed by an electrical system is predominantly decided by the PF of the system. To understand PF, it is important to know that power has two components:
• Working (or Active Power) Working Power is the power that is actually consumed and registered on the electric meter at the consumer's location. Working power is expressed in kilowatts (kW), which register as kilowatt hour (kWh) on an electric meter.
• Reactive Power Reactive Power is required to maintain and sustain the electromagnetic field associated with the industrial inductive loads such as induction motors driving pumps or fans, welding machines and many more. Reactive Power is measured in kilovolt ampere reactive (kVAR) units. The total required power capacity, including Working Power and Reactive Power, is known as Apparent Power, expressed in kilovolt ampere (kVA) units.
PLC
The PLC is Programmable Logic Control it can be program according to our requirement.
Detail of PLC: –
Delta Company
Series: – 12SA2
X= INPUT = 8
Y= OUTPUT = 4
PLC is connected to PC by using RS-232 cable. This cable also called single communication cable. In PLC software program is made by Ladder Language. We can also make the program FBD (Function Block Diagram) language is not supported in Delta company PLC.
A programmable logic controller, PLC, or programmable controller is a digital computer used for automation of typically industrial electromechanical processes, such as control of machinery on factory assembly lines, amusement rides, or light fixtures. PLCs are used in many machines, in many industries.
Machine control design is a unique area of engineering that requires the knowledge of certain specific and unique diagramming techniques called ladder diagramming. Although there are similarities between control diagrams and electronic diagrams, many of the component symbols and layout formats are different. This chapter provides a study of the fundamentals of developing, drawing and understanding ladder diagrams. We will begin with a description of some of the fundamental components used in ladder diagrams. The basic symbols will then be used in a study of boolean logic as applied to relay diagrams. More complicated circuits will then be discussed.
Basic Components and Their Symbols
We shall begin with a study of the fundamental components used in electrical machine controls and their ladder diagram symbols. It is important to understand that the material covered in this chapter is by no means a comprehensive coverage of all types of machine control components.
PLC FEATURE
The main difference from other computers is that PLCs are armored for severe conditions (such as dust, moisture, heat, cold), and have the facility for extensive input/output (I/O) arrangements. These connect the PLC to sensors and actuators. PLCs read limit switches, analog process variables (such as temperature and pressure), and the positions of complex positioning systems. Some use machine vision.
On the actuator side, PLCs operate electric motors, pneumatic or hydraulic cylinders, magnetic relays, solenoids, or analogy outputs.
The input/output arrangements may be built into a simple PLC, or the PLC may have external I/O modules attached to a computer network that plugs into the PLC.
AC DRIVE
Fig. Diagram of AC Drive
AC Drive is used to drive the load like 3-phase induction motor. The function of AC Drive is to convert the 1-phase supply to 3-phase supply with control voltage according to frequency coming from the PLC.
Rating of AC Drive
Input = single phase, 230 V, 50 Hz
Output = Three phase, 440V, 0-400 Hz, 0.5 HP Drive
Company of AC Drive = Alley bradely Power flex 4m
The AC Drive contain start, stop, reverse and forward button,
Start button: It is used to start the motor at time of first input command signal
Stop button: It is used to stop the motor.
Reverse and Forward button: It is used to change the direction of motor.
The input of AC Drive come from the SMPS which is connected to the input side of AC Drive.
The output of AC Drive contains RYB three phase terminal which is connected to 3-phase induction motor.
CABLES:
The cable is used to interface the communication between to devices in our project. We use two types of cable 1) RS-485, 2) RS-232
RS-485: – This cable is connected between AC Drive and PLC. So, it will be interface the communication between PLC and AC Drive in both direction, this cable also interface multiple communication more than two device. It can also use in ring connection so it can transfer data in both direction.
RS-232: – This cable is connected between the PLC and Computer. This is also called single communication cable because it can’t interface the communication in the both direction. It is unidirectional cable so it will be transfer the data from software to PLC in only one direction.
3-PHASE INDUCTION MOTOR:
3-phase induction motor: we know that in our India 3- phase induction motor mostly uses as compared to dc motor due to some advantages of 3-phase induction motor.3-phase induction motor mostly use in domestic, commercial, food making industry paper making industry, ceramic industry, rolling mills etc. In all this field, the 3-phase induction motor are use.
So, in this field the motor does not run at constant speed.it rotate at rated speed in some field. while in some field the motor rotates below the rated speed so it is necessary to control the speed the induction motor to control the speed of induction motor we can use following method
1)control from stator side
2)control from rotor side
3)by changing number of pole
In the method of number of pole change we can’t change the number of pole after the construction of motor so this method cannot be use we can use v/f control method to change speed of induction motor
Rating of 3-phase induction motor
Rating in kw = 0.18kw
Rating in hp = 0.25hp
Rated voltage=440v
Rated current=0.5 amp
Class of insulation=F
Frame=11
Frequency=50hz
Type of induction motor=squirrel cage induction motor
EXPLAIN V/F CONTRO METHOD:
We know that to vary the speed of induction motor we can use v/f control method.in this method we have change the both supply voltage as well as supply frequency by using power electronic device such as IGBT, DIODE, MOSFET, BJT and cyclo converter as well as ac drive to drive ac load such as 3-phase induction motor
In this method, we have to maintain the air gap flux constant by changing the supply voltage and supply frequency
V/F=constant
if we want to change supply frequency from f to f1 then the voltage will change corresponding to the changed frequency f1 and new voltage become v1
V1=kf1
Also, we know that the slip of induction motor will inversely proportional to the supply frequency
S=k/f
From this equation, we can say that if supply frequency changed then slip also change the slip of induction motor given by below equation.
S= Ns-Nr /Ns
Where s=slip of induction motor
Nr = actual rotor speed
Ns = synchronous speed
From above equation, we can easily say that with change in supply frequency the slip of induction motor will change and finally it will change the actual rotor speed of induction motor.
ADVANTAGES: –
Step less control
Acceleration control
Less power loss
It can be run at adjustable speed
Good control capability
Better efficiency
Less fluctuation
DISADVANTAGES: –
Speed control of induction motor is difficult
Medium Costly
Proper Programming Required
SMPS required for PLC
APPLICATION: –
Industry
Rolling mills
Paper making mills
Practical purpose in Lab
Reference
SITES: –
http://google.com
http://en.wikipedia.org
http://www.circuitsgallary.com
BOOKS: –
Power electronic by P S Bimbhra
Machine Theory by D P Kothari
AC Machine by J G Jamnani