Speed Control of Separately Excited DC Motor Using Chopper

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056
Volume: 04 Issue: 01 | Jan -2017 www.irjet.net p-ISSN: 2395-0072
© 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 799
Speed Control of Separately Excited DC Motor Using Chopper
Kaustubh S. Deshmukh, Master in Technology, Electrical Engineering, G H Raisoni College of Engineering
and Technology, Nagpur, Maharashtra, India
Prof. Rutuja S Hiware, Electrical Engineering, G H Raisoni College of Engineering and Technology, Nagpur,
Maharashtra, India
--------------------------------------------------------------------------------------------------------------------------------------------------------------
Abstract - The Aim of the paper is to control the separately excited dc motor by using the IGBT based chopper. The
speed of separately excited dc motor can be control by changing the armature voltage and changing field flux. Due
to this the speed can be controlled for below rated speed and speed above the rated speed, respectively. In this
paper, the motor speed below and upto the rated speed can be achieved by Changing the Armature voltage. The
Armature voltage can be controlled by Using IGBT based chopper. The IGBT chopper receives signal from
controller and Adjustable voltage is given to the armature of dc motor according to the wanted speed. The
advantages to employed this technique is that the Speed varies proportionally with armature voltage and varies
inversely with field voltage by keeping field and armature voltage constant respectively. The IGBT employed
chopper i.e. power module gives smoother control as compared with the SCR based circuit. By employing this
system, we can chop the frequency and speed of DC motor can be control. The two controllers are employed here,
speed controller and current controller. Here, we are employing the PI type controller i.e. proportional-integral
type. The aim of using PI type controller is it eliminates the delay and provide fast control. It give a very fast
response to sudden changes in motor speed. The simulation of model is done and analyzed in MATLAB (Simulink)
under Different renge speed and torque condition.
1. Introduction
Demanding of Industrial Sector for high
performance electrical drives is increases nowadays.
Variable speed applications are gradually increases in
industrial sector. Therefor it is needed to create high
performance, high flexible electrical drives. Electrical
motor, Power controller and energy transmitting
medium are the main Constituents of Electrical
drives. Nowadays, power electronics converter are
cast instates of power controller. High performance
motor drive system has special features such as good
dynamic speed command and load regulating
reaction Electric drives are categories as: DC drives
system and AC drives system. DC drives are widely
used than AC drives, in applications such as, good
speed regulation adjustable speed control, braking
and reversing frequent starting. Some important
applications are mine winders, paper mills, hoists,
rolling mills, printing presses, traction, machine tools,
textile mills, cranes, excavators. DC motors are used
widely in position control system and variable speed
drives. DC motors has excellent control of speed for
speeding up and slowing down. In a DC motor the
supply is directly connects to the field of the motor
and as results a specific voltage control is obtained,
which is necessary for control of speed and torque.
DC drives are backbone of industrial applications due
its advantages like simplicity Reliable, low cost,
flexible etc. DC drives are cheaper for low
horsepower ratings. DC motors are generally
consider as flexible speed machines and a wide range
of options have developed for this purpose.
There are several techniques of speed
control of DC drives – armature voltage control,
armature resistance control and field flux control. In
this paper, the motor speed under and upto the rated
speed can be achieved by Changing the Armature
voltage. The Armature voltage can be controlled by
Using IGBT based chopper. Using Chopper as power
converter and PI as speed and current controller,

controlling of DC motor speed is examined. The
purpose of controller is to reduce the error and the
error is calculated by Equaling output value with the
set point. A chopper is a static power electronic
device used to converts stable dc input voltage to a
adjustable dc voltage as output. Here we use IGBT
Chopper systems which have fast in response,
smooth control capability and are very efficient. A
IGBT chopper is used to step down or step up the
stable dc input voltage.
2. Chopper
A chopper is a static power electronic device
which changes stable dc input voltage to a adjustable
dc voltage. chopper is used to step down or step up
the stable dc input voltage. Chopper systems offer
high efficiency, regeneration facility, smooth control,
and faster response. There are some power
semiconductor devices used in a chopper circuit.
They are force commutated thyristor, MOSFET, BJT,
GTO and IGBT But from the above switching devices,
GTO and IGBT are broadly used. These
semiconductor devices are generally denoted by a
switch. No current will flow, when the switch is OFF,
and when switch is ON, the Current will flows
through the load. In this paper, we cast the IGBT as
switch in chopper circuit. IGBT employed chopper
gives fast Switching, more efficiency, less switching
losses. The ON and OFF state of semiconductor
switch i.e. IGBT switch which is high in speed. It
connects and disconnect, the source to load and the
load from source respectively, at a fast speed. As
shown in Fig1. When the switch is turning ON state
i.e. Ton, chopper is turn ON and Output voltage and
source voltage are equal. When the switch is turn OFF
i.e. Toff, chopper is off and load voltage is zero. In this
way, we obtaind the chopped dc voltage at the load
terminals.
2.1 Chopper circuit diagram and its voltage and
current waveform
3. Separately Excited DC Motor
The major use of DC motors are in position
control and changeable-speed applications. The
techniques of speed control for DC motors are less
expensive and simpler than the AC motors. When the
wide speed range of control is needed, the DC motors
are employed Separately excited dc motor has
armature and field winding. It requires separate
supply voltage. Field flux is supplied by field winding
to armature. The current immediately flows to the
armature winding, when the DC voltage is applied to
the motor, through the brushes and commutator. The
rotor is positioned in magnetic field and it is also
carrying current. The back EMF and a torque are
produced by motor, a torque stabilizes the load
torque at specific speed. When the field current and
armature current flows in circuit, it excites the DC

motor, thus develops the back EMF and torque. The
armature current is independent of The field current.
The field and armature winding are supplied
separately. Any variation in the armature current has
no influence on the field current. The field current are
generally minimum than armature current. Suppose,
Ia is the armature current in ampere, Va is the
armature voltage in volt, Eg is the motor back emf in
volt, Ra is the armature resistance in ohm, La is the
armature inductance in Henry.
The armature voltage equation is shown below:
The Torque equation is given as,
Equation for back EMF of motor is given as,
Thus from the above equations, we observe that the
speed of DC motor be influenced by armature
current, applied voltage, field flux, and armature
resistance. So we can control the speed of motor by-
armature resistance control, armature voltage
control, and field flux control.
4. Modeling Of DC Motor
The basic principle of speed control of DC
motor is that the output speed of DC motor can be
change by changing the armature voltage for speed
under and upto the rated speed. The field voltage is
kept stable. The output speed is matched with the
reference speed and if error is occurred than error
signal is fed to speed controller. Controller will
compare the result, and thus output will Vary
whenever there is a change in the base speed and the
speed feedback. The control voltage that controls the
operation duty cycle of converter, which is control by
speed controller. The converter output provides the
variable voltage essential to bring motor back to the
desired speed. The Reference speed is delivered
through a potential divider. The voltage from
potential divider is linearly linked to the speed of the
DC motor. The output speed of motor is shown by
Tachogenerator. Result of Tacho will not be perfectly
dc and contains some ripple. So, we employed a filter
to bring Tacho output controller level. The block
diagram for DC motor speed control is show below:
5. MATLAB Simulation And Results
In this paper, we analyzed the speed control of
D.C.MOTOR by using current and speed controller. In
the open loop model the output speed is uncontrolled
as shown in below fig.
5.1 Simulink model of open loop model of
chopper with dc machine

5.1.1 Simulation result for Speed
5.1.2 Simulation result for Torque
5.1.3 Simulation result for Current.
5.2 Simulation of closed loop model of chopper
with dc machine
5.2.1 Result for Speed
5.2.2 Result for Current

5. Conclusion
The DC motor speed control has been
successfully analyzed using chopper as a power
controller and Speed and Current controller
(Proportional-Integral type) based on the closed loop
model of DC motor. Initially a simplified open loop
model for DC motor is studied and then closed loop
model is considered and required of current
controller is studied. Then a generalized modelling
for speed control of dc motor is done and analyzed.
The simulation is done in MATLAB under changing
load condition, changing reference speed condition
and changing input voltage. The results obtained are
analyzed. The DC motor speed control is completed,
for rated and under rated speed by changing the
armature voltage.
6. References
[1] Amir Faizy, Shailendra Kumar, DC motor control
using chopper, NIT Rourkela 2011.
[2] Saffet Ayasun, Gultekin Karbeyaz, DC motor speed
control methods using MATLAB/ SIMULINK and their
integration into undergraduate courses, 2008.
[3] Bose B.K., Power electronics and motor drives
recent technology advances,” Proceedings of the IEEE
International Symposium on Industrial Electronics,”
IEEE, 2002, p 22-25.
[4] SIMULINK, Model-based and system-based
design using Simulink, Maths works, Inc, Natick, MA,
2000.
[5] MATLAB SIMULINK, version 2009,
SimPowerSystem, One quadrant chopper DC drive.
[6] Chinnaiyan V. Kumar, Jerome Joritha, Karpagam, J.
S.Sheikh Mohammed, Design and Implementation of
High Power DC-DC converter and speed control of dc
motor using TMS 320F240DSP, Proceedings of India
International Conference on Power Electronics, 2006.
[7] Rashid, M.H., Power Electronics, Prentice Hall of
India, New Delhi, 1993.
[8] Ogata, K., Modern Control Engineering.
Englewood Cliffs, NJ: Prentice Hall, 2001.
[9] Dubey, G.K., Fundamentals of Electrical Drives.
New Delhi, Narosa Publishing House, 2009

Speed Control of Separately Excited DC Motor Using Chopper

More Related Content

What's hot (20)

Similar to Speed Control of Separately Excited DC Motor Using Chopper (20)

More from IRJET Journal (20)

Recently uploaded (20)

Speed Control of Separately Excited DC Motor Using Chopper