1. Concept on drives
2. What is drives ?
3. How drive does ?
4. What is torque ?
5. What is Motor Torque ( Tm )?
6. What is Motor Speed?
7. Drive are two types
8. AC Drive
9. DC Drive
10. Pulse Width Modulation
11. Sinusoidal PWM
12. Components of ASTAT
13. What is DTC ?
14. Direct Torque Control
15. Control Display Panel
16. ABB ACS800 DRIVE FOR CRANE
1. To study of electronics control system by using drives in Tata steel
2. Mr. Shankar Banerjee
(Sr. Manager Training)
UNDER GUIDANCE OF
21th June 2016 TO 11th July 2016
Submitted By :- ROHIT SHRESTHA
VT No:- VT20160524
3. CERTIFICATE
This is to certify that ROHIT SHRESTHA, VT20160524
have successfully completed the project on,
“To study of electronics control system by using drives in Tata
steel”
as a part of Vocational Training at SNTI, TATA STEEL,
Jamshedpur during 21/06/2016 to 11/07/2016 under our
guidance.
He has successfully completed this project and worked very
sincerely to our satisfaction. He has been outstanding
throughout his training period.
Mr. Shankar Banerjee
(Sr. Manager Training)
4. ACKNOWLEDGEMENT
First and foremost, I would like to express my
heartly thanks and indebtedness to Mr. SHANKAR BANERJEE for his
help and encouragement throughout the project. It has been a
motivational and excellent learning process in his guidance. It would
have been impossible for me to have a clear idea and way of approach
without his support.
I am also thankful to SNTI department for allowing me for the project.
5. CONTENTo Concept on drives
• What is drives ?
• How drive does ?
• What is torque ?
• What is Motor Torque ( Tm )?
• What is Motor Speed?
o Drive are two types
• AC Drive
• DC Drive
o Pulse Width Modulation
o Sinusoidal PWM
o Components of ASTAT
• What is DTC ?
• Direct Torque Control
• Control Display Panel
• ABB ACS800 DRIVE FOR CRANE
7. Electric
Supply
Starter Motor Machine
Conventional Technology
Control over Torque & Speed of the motor ? NO !
Requirement of Modern Machines
Electric
Supply
Motor MachineConverter
Drive
Control over Torque & Speed of the motor ? YES !
8. AC INPUT
MOTOR
DRIVE
GB
ROLL
ROLL
10 V
FIELD
GEAR BOX
SPEED
REFERENCE
AC CT
T
TACHO
Operat
or
Loa
d
It is a system which fulfills requirement of both User and
Process by adjusting TORQUE and SPEED of the motor.
What is drive ?
9. What Drive Does ?
Electrical Energy
Current carrying
conductors
Magnetic Field
Motor
DRIVE
Torque
Mechanical Energy
Rotation
10. What is TORQUE?
Twisting Moment of Force about an Axis is called
TORQUE
R=Radiu
s
F=Force
F=Force
R=Radiu
s
Torque= Force x Radius
11. What is Motor Torque ( Tm )?
North Pole
South Pole
R=Radius
F=Force
F=Force
R=Radiu
s
+
F=Force = Bil
= Flux Density x Current x
Length
Tm = F x R
= (Bil)R
= Constant x Flux x
Current
12. GB
What is Motor Speed?
Revolution / Unit Time
ROLL
ROLL
Armature
Current
Field
Current
• If Tm > TL , Motor Accelerates
• If Tm < TL, Motor Decelerates
• If Tm = TL, Motor runs at Stable Speed or not
run at all
Tm = TL + J (dw/dt )
Tm TL
14. AC DRIVE
An AC Drive is a device that is used to control the speed and torque of a motor
depending upon the requirement of user or operator.
The electronic product that controls the power to an AC Motor is called AC
Drive. AC Drive takes fixed voltage, fixed frequency AC supply (eg. State Electric
supply companies) and converts it into a variable frequency and variable voltage
AC supply.
15. +
-
Ns
NsN
AC motor
Current is caused due to Relative Speed (Ns- N)
Relative speed and thus Current can
be increased by increasing Ns
OR
Relative speed and thus Current can
be increased by decreasing N
24. DC DRIVE
Dc drives are Dc motor speed control system . Since the speed of dc motor is
directly proportional to armature voltage and inversely proportional to motor flux
(which is a function of field current), either armature voltage or field current can be
used to control speed.
26. ACCTACCT
Tacho Generator
Field
Winding
VfV
a
Ia If
Very Basic Concept Of DC
Drive
DRIVE
Controlle
r Firing
Angle (α)
Desired
Speed
(N*)
Actual
Speed (N)
• Firing Angle (α) depends upon Error (
N* - N )
• Va depends upon α
• N and Tm depends upon Va
27. ACCTACCT
Tacho Generator
Field
Winding
VfV
a
Ia If
Very Basic Concept Of DC
Drive
DRIVE
Controlle
r α
N*
Firing
Circuit
N
V*
• V* depends upon Error ( N* - N)
• Firing Angle (α ) depends upon V*
• Va depends upon α
• N and Tm depends upon Va
38. Unidirectional Armature Voltage Controlled Thyristorised DC Drive
PE
Microprocessor
Memory
( EPROM,
EEPROM,
FLASHPROM,
RAM )
Counter
Programmable
Interrupt
Controller (PIC)
Programmable
Peripheral
Interface (PPI)
Bridge
Interface
Board
A/O
A/I
D/O
D/I
ADC
DAC
Optos
Relays
PA
FPB
FPB
System
Interface
Board
Power
Supply
115 V AC
Frequency Input
RS232/
RS485
Serial Link
E- Stop
E- Stop Reset
E- Stop OK
E -Stop OK
Fault
Drive OK
MC Close
24 V
24 V
10 V
10 V
24 V
0 V
0 V
24 V
39. Unidirectional Armature Voltage Controlled Thyristorised DC Drive
PE
Microprocessor
Memory
( EPROM,
EEPROM,
FLASHPROM,
RAM )
Counter
Programmable
Interrupt
Controller (PIC)
Programmable
Peripheral
Interface (PPI)
Bridge
Interface
Board
A/O
A/I
D/O
D/I
ADC
DAC
Optos
Relays
PA
FPB
FPB
System
Interface
Board
Power
Supply
115 V AC
Frequency Input
RS232/
RS485
Serial Link
E- Stop
E- Stop Reset
E- Stop OK
E -Stop OK
Fault
Drive OK
MC Close
24 V
24 V
10 V
10 V
24 V
0 V
0 V
24 V
40. Unidirectional Armature Voltage Controlled Thyristorised DC Drive
PE
Microprocessor
Memory
( EPROM,
EEPROM,
FLASHPROM,
RAM )
Counter
Programmable
Interrupt
Controller (PIC)
Programmable
Peripheral
Interface (PPI)
Bridge
Interface
Board
A/O
A/I
D/O
D/I
ADC
DAC
Optos
Relays
PA
FPB
FPB
System
Interface
Board
Power
Supply
115 V AC
Frequency Input
RS232/
RS485
Serial Link
E- Stop
E- Stop Reset
E- Stop OK
E -Stop OK
Fault
Drive OK
MC Close
24 V
24 V
10 V
10 V
24 V
0 V
0 V
24 V
55. Pulse Width Modulation
The PWM stands for “Pulse Width Modulation". The average voltage delivered to
the load is controlled by ratio of total on time and off time of voltage in half cycle.
By varying this ratio we can vary the voltage from zero to maximum.
The PWM voltage output is the preferred voltage output waveform. In this the
positive and negative halves of square wave output are "chopped". By chopping we
do not get a sinusoidal voltage at the output but we can make the current flowing
through the motor winding to take sinusoidal path.
56. It should be noted here that the motor winding is an
inductive load. The current being sinusoidal now
reduces the harmonics level and thereby improving
the quality of line supply
57. Sinusoidal PWM
In this method of modulation a comparison is made between a triangular wave
(carrier) and a sinusoidal signal or modulating wave (reference).
The frequency of the triangular signal is much higher than that of sine wave. The
resulting pulse train which is the outcome of comparison then controls the power
switching devices in the inverter.
58. The frequency of the sinusoidal voltage determines the output frequency and thus
the speed of the motor.
The magnitude of the output voltage is determined by the magnitude of sinusoidal
voltage as it determines the on and off time of the pulse in each half cycle.
This method -sinusoidal modulation -is preferred as it provides maximum on time
at 90 degrees and the same gradually reduces as we approach 0 degree and 180
degrees.
59. One can expect a very close to sinusoidal current in the motor winding using this
method. The frequency of modulating triangular wave is referred as carrier
frequency or switching frequency
60.
61. Signal for switches are generated by comparing sinusoidal reference signal with triangular
carrier signal
Pulse width of all the pulses in a half cycle are not uniform
Width of pulses is proportional to amplitude of sine wave at the center of the Pulse
No. of Pulse / Half Cycle is determined by the frequency of triangular carrier
62. Sinusoidal PWM technique can eliminate lower order harmonics
Lowest Order Harmonic ( LOH) present in Inverter O/P : LOH = (2P-1) Where, P=
No. of Pulse/Half Cycle
Larger the carrier/switching frequency, more is the elimination of lower order
harmonics (typical switching frequency = 2 KHz range: 1-16 KHz)
63.
64. Use of higher carrier frequency asks for higher
switching frequency of semiconductor devices used
in power circuit of inverter and also increases
switching losses and hence temperature of switches.
65.
66.
67. Case Study-1
A)Digital ASTAT Drive
ASTAT is a highly developed, well proven system for speed control of heavy duty
motors in cranes and other heavy industrial machinery.
ASTAT main components are the control system module that controls the motion
and the thyristor module that controls the torque of the slip ring induction motor.
68. For control of motor ASTAT uses two variables
A) Stator Voltage Control
B) Rotor Resistance Control
To supply desired stator voltage a set of thyristors are included in the staor circuits
which are turned on at appropriate firing angles.
To optimize motor torque either resistances are introduced in the rotor circuit or
withdrawn from the rotor circuit through a set of contactors.
69. ASTAT is a close loop speed control system which employs both stator voltage and
rotor resistance control.
ASTAT receives fixed voltage AC Supply at constant frequency. Keeping frequency
unchanged ASTAT supplies variable AC voltage to stator winding. A set of SCRs are
put in one leg. Six SCRs form a bridge.
According to desired stator voltage firing angle for SCRs are adjusted by a digital
controller.
70.
71. Components of ASTAT
ASTAT Drive comprises of the following:
A. Control system module DARA1001
B. Thyristor Module DASD 101
C. Rotor adoption module DADT100
D. Cabin I/O Module DAPM100
E. Overvoltage Protection Module
72. Control System module comprises of following:
1. DAPC100 Processor Board
2. DATX110 Process I/O Board
3. DAPU100 Communication interface
4. DATX132 Torque Estimation Board
5. DASA110 and DASA100 power supply unit
6. DAPU100 Communication board
73. Thyristor Module comprises of following:
1. SCRs
2. Snubber circuits
3. ACCTs(AC Current Transformer)
4. DATX100 System I/O Board
74.
75. Case Study-2
ABB ACS800 DRIVE FOR CRANE
ACS800 crane drive from M/S ABB is a drive which is used for electric overhead
crane operation.
It can control speed and torque of heavy duty squirrel cage induction motor with
multi-quadrant operations.
76.
77. Direct Torque Control (DTC) developed by ABB has improved motor control
accuracy without the requirement of speed feedback device. Accurate speed and
torque control of the manufacturing process optimizes the quality of the end
product.
Many applications no longer require additional speed feedback when the ACS800
with DTC is used.
78. What is DTC ?
Direct Torque Control (DTC) is an optimised AC drives control principle where
inverter switching directly controls the motor variables: flux and torque.
The measured input values to the DTC control are motor current and voltage.
The voltage is defined from the DC-bus voltage and inverter switch positions.
The voltage and current signals are inputs to an accurate motor model which
produces an exact actual value of stator flux and torque every 25 microseconds.
Motor torque and flux two-level comparators compare the actual values to the
reference values produced by torque and flux reference controllers.
79. The outputs from these two-level controllers are updated every 25 microseconds
and they indicate whether the torque or flux has to be varied.
Depending on the outputs from the two-level controllers, the switching logic
directly determines the optimum inverter switch positions. Therefore every single
voltage pulse is determined separately at "atomic level". The inverter switch
positions again determine the motor voltage and current, which in turn influence
the motor torque and flux and the control loop is closed.
80. Direct Torque Control
Let Ws and Wr be known stator flux and rotor flux respectively. Initially both the
vectors rotate at synchronous speed, in the same direction.
Rotor Flux vector lags behind the stator flux vector by delta angle. This angle
depends upon load torque.
If load torque increases then the angle also increases. Rotor flux moves under the
pull of stator flux vector.
81. But if speed of stator flux vector is suddenly increased then because of inertia of
rotor and its connected load, the rotor flux vector cannot respond to sudden
change in the speed of stator flux vector.
As a result it falls further behind the stator flux vector. The load angle i.e. the angle
between stator flux vector and rotor flux vector thus gets increased.
Motor torque thus increases for the time being. We can similarly reduce the torque
angle by sudden decrease in the speed of stator flux vector.
82.
83.
84. The magnitude of desired Stator flux and actual stator flux as well as the
magnitude of motor torque and actual motor torque are also compared through
different comparator.
Stator flux and rotor flux vectors are assumed to rotate 360 degrees for every
rotation.
One complete rotation can be subdivided into in six parts or sectors. Each sector
will thus cover 60 degrees
86. The outputs of these two comparators and sector position of stator flux vector are
used to decide an appropriate voltage vector.
The selected voltage vector is used to decide the set of IGBTs which are required to
be triggered for meeting with torque and flux requirement.
The desired values are set by controllers and actual values are calculated by an
intelligent motor model. This motor model contains a set of programs and it can
calculate actual motor torque and stator flux very precisely every 25 us.
89. CONCLUSION
Under the guidance of Mr. Shankar Banerjee we made the following conclusions,
• Drive is system which fulfills requirement of both User and Process by adjusting TORQUE and SPEED of the motor.
• Drives are two types
A. AC Drive
B. DC Drive
• AC Drive is a device that is used to control the speed and torque of a motor depending upon the requirement of
user or operator.
• Dc drives are Dc motor speed control system . Since the speed of dc motor is directly proportional to armature
voltage and inversely proportional to motor flux (which is a function of field current), either armature voltage or
field current can be used to control speed.
• ASTAT is a highly developed, well proven system for speed control of heavy duty motors in cranes and other heavy
industrial machinery
• Direct Torque Control (DTC) developed by ABB has improved motor control accuracy without the requirement of
speed feedback device.
At last I would like to thanks all those who have helped me in improving these very important
knowledge which in future I know will be very helpful to me.
