Further Electrical Machines and Drives: A Comprehensive Project

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FURTHER ELECTRICAL MACHINES AND DRIVES
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Table of Contents
LO1:.................................................................................................................................................3
Task 1...........................................................................................................................................3
Task 2...........................................................................................................................................4
Task 3...........................................................................................................................................7
Task 4...........................................................................................................................................9
Task 5.........................................................................................................................................10
Task 6.........................................................................................................................................12
LO2:...............................................................................................................................................13
Task 7.........................................................................................................................................13
Task 8.........................................................................................................................................14
Task 9.........................................................................................................................................15
Task 10.......................................................................................................................................15
Task 11.......................................................................................................................................19
Task 12.......................................................................................................................................19
LO 3...............................................................................................................................................21
Task 13.......................................................................................................................................21
Task 14.......................................................................................................................................23
Task 15.......................................................................................................................................24
Task 16.......................................................................................................................................25
Task 17.......................................................................................................................................26
Task 18.......................................................................................................................................26
Task 19.......................................................................................................................................27
LO4................................................................................................................................................28
Task 20.......................................................................................................................................28
Task 21.......................................................................................................................................28
Task# 22.....................................................................................................................................29
Task 23.......................................................................................................................................29
Task24........................................................................................................................................30
Task 25.......................................................................................................................................30
References:....................................................................................................................................32
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List of figures
FIGURE 1 SPEED TORQUE CURVE....................................................................................................7
FIGURE 2 EQUIVALENT CCT OF IM..................................................................................................7
FIGURE 3 DC MACHINE CLASSIFICATION.........................................................................................8
FIGURE 4 SPEED-TORQUE CURVE....................................................................................................8
FIGURE 5 SYNCHRONOUS MOTOR....................................................................................................9
FIGURE 6 COIL PERPENDICULAR TO MAGNETIC FIELD.....................................................................9
FIGURE 7 COIL PARALLEL TO MAGNETIC FIELD.............................................................................10
FIGURE 8 DC MOTOR MATLAB SIMULATION.................................................................................10
FIGURE 9 IM CONSTRUCTION........................................................................................................11
FIGURE 10 EQ.CCT OF IM..............................................................................................................11
FIGURE 11 DC MOTOR MATLAB OPERATION..................................................................................13
FIGURE 12 AC-DC CONTROL CONVERTER CCT.............................................................................13
FIGURE 13 AC-DC CONVERTER WAVEFORMS...............................................................................14
FIGURE 14 AC-DC CONVERTER.....................................................................................................15
FIGURE 15 DC-DC CONVERTER.......................................................................................................16
FIGURE 16 DC DRIVES MODES OF OPERATION................................................................................17
FIGURE 17 ARMATURE VOLTAGE CONTROL...................................................................................18
FIGURE 18 ARMATURE RESISTANCE CONTROL..............................................................................18
FIGURE 19 FIELD FLUX CONTROL...................................................................................................18
FIGURE 20 CHOPPERS.....................................................................................................................19
FIGURE 21 CHOPPER VOLTAGE WAVEFORM...................................................................................20
FIGURE 22 CHOPPER CURRENT WAVEFORM...................................................................................20
FIGURE 23 DC DRIVE CLOSED LOOP...............................................................................................20
FIGURE 24 OPEN LOOP DC MOTOR CIRCUIT....................................................................................21
FIGURE 25 DC DRIVE CICUIT..........................................................................................................21
FIGURE 26 AC DRIVE CIRCUIT......................................................................................................23
FIGURE 27 AC DRIVES OUTPUT WAVEFORMS................................................................................23
FIGURE 28 AC DRIVE CLOSE LOOP DIAGRAM................................................................................24
FIGURE 29 OPEN LOOP DIAGRAM OF IM........................................................................................24
2

LO1:
Task 1
Categories and Industrial Applications of Electric Machines
Induction motors
Induction motors are types of motors that run on the of electromagnetic induction principle
where current is induced in rotor bars as result of a change of flux.It has two types
 1- ᶲ induction motor
 3- ᶲ induction motor
1- ᶲ induction motor as the name suggests works on single-phase power due to which they
are not self-starting as there is no phase difference between in its field. To make it self
starting different arrangements of capacitors are used to provide the necessary shift.
These motors are normally used where required output is just in few Kw that’s why they are
built-in fractional horsepower. Some of applications are in fans, mixers, vacuum cleaners,
washing machines, and kitchen equipment.
Synchronous machines
These machines as the name suggest runs on synchronous speed with magnetically locked rotors
ability
a) Synchronous generators
b) Synchronous motors
c) Synchronous compensatory
A. Synchronous generators are classified further according to the type of prime mover used like
 Turbo generators
 Hydro generators
 Engine-driven generators
B. Motors: The synchronous motor is of 2 types
 The synchronous induction motor: it has a cylindrical or salient pole rotor.
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 The plain synchronous motor: again cylindrical or salient pole rotor. This type has high
efficiency for constant speed drives like compressors, blowers, pumps with an advantage
of power factor control
C. Compensators
With ratings up to 100 MVAR, these are used for controlling KVAR of power supply systems
DC Machines
These were used widely until say World War 2 before the ac system takes over the industries.
But still there is application where it offers advantage over ac motors due to possibility of its
precise torque control like in rolling mills, battery control vehicles, overhead crane, tape
recorders, cameras.
Small dc generators are widely used in aircraft for power supply, automobiles, and other vehicles
due to isolation from the ac supply network
Task 2
The maneuver of DC Mechanisms and Induction Motor: circuit drawings and waveforms
Induction motors are a type of motors that works as same principle as transformer as in which
when stator is supplied with emf then as result of electromagnetic in rotor, voltage induces. The
speed of rotor emf is always less than that of synchronous speed due to this relative difference
motor runs.
It speed-torque characteristic shows that induction motor requires starting torque due to which it
requires high current in start after that it can work on low current
4

Figure 1 Speed Torque Curve
Equivalent CT shows the parameters of motor like copper losses and resistive losses with the
help of inductor and resistor
Figure 2 Equivalent cct of IM
DC Machines
These machines work when in a coil that is placed in magnetic field generates torque when
magnetic force acts on it which rotated it.DC generators convert mechanical to electrical whereas
motor converts dc electrical energy to mechanical to run load.
On the basis of type of excitation, there are four types of it
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 Dc machine with Separate excitation
 Dc machine shunt excited
 Series of Dc machine excited
 Dc machine compound excited
Figure 3 Dc machine Classification
Its torque-speed characteristics are below shown: Torque is inversely proportional to speed, less
speed more torque requirement and vice versa.
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Figure 4 Speed-Torque Curve
Task 3
Synchronous Machines, Categories, and Applications
Construction
These machines have two parts rotor: the rotating part and stator the stationary part. There are
field poles and conductors included in the rotor parts. In generators, when field rotates in the
presence of armature conductors power is produced as voltage induces in it.
Figure 5 Synchronous motor
Working principle
7

It works on the principle of electromagnetic induction in which due to relative motion in
conductors and flux, emf induces in it.
Consider a coil ABCD placed in two oppositely pole conductors. When the conductor is
perpendicular to magnetic line, flux link will be max.
Figure 6 Coil perpendicular to the magnetic field
When lines are parallel with a conductor, no flux will cut and current will be zero.
Figure 7 coil parallel to the magnetic field
Thus with the interaction of magnetic field of rotor and magnetic field of the stator,three-phase
output power will be produced on stator in case of generator and three-phase power will be given
to stator in case of motor to rotate the load from rotor.
The synchronous generator is the most widely used generators as they have high efficiency and
provide better power factor and unlike induction machines the increase in load is provided by
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change in rotor angle means it gives up part of it synchronizing power to compensate for increase
in load.
Task 4
Efficient Modeling and Simulation of DC Motor using Matlab
Here dc motor is simulated for separately excited machines
Figure 8: DC motor Matlab Modeling
Figure 9: DC motor Matlab Simulation
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Figure 10: Simulation Results for DC motor simulation along with the signal statistics
Task 5
Induction Motors: Characteristics and Equivalent Circuits
Induction motor is asynchronous machines. The stator at synchronous speed rotates while rotor
can never attain synchronous speed, due to this difference this motor works and this contrast in
speed is called slip.
When 3-ᶲ supply is supplied to the stator, there is production of rotating magnetic. The rotor is
stationary so when the RMF cuts stationary rotor bars, emf is induced in it.Rotor conductors are
shorted by end rings. The flux produces current in rotor and in turn torque produces.The
direction of toque is in same direction as rotating magnetic field and rotor starts rotating.
10

Figure 11 IM Construction
Its equivalent circuit is shown as:
Figure 12 Equivalent circuit of IM
The total power transfer to the rotor is
Pt =3 I2 R2
s
Pc=Pt−Pr
Pc=3 I2 R2
s −3 I 2 R2
Pc=3 I2 R2 ( 1−s )
s
Pc= ( 1−s ) Pt
The final output obtained by subtracting rotational loss from P converted;
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