Distributed Drives Monitoring and Control: A Laboratory Setup

Abstract

A laboratory setup of distributed drives system comprising a three-phase induction motor (IM) drive and a permanent magnet synchronous motor (PMSM) drive is modeled, designed, and developed for the monitoring and control of the individual drives. The integrated operation of IM and PMSM drives system has been analyzed under different operating conditions, and their performance has been monitored through supervisory control and data acquisition (SCADA) system. The necessary SCADA graphical user interface (GUI) has also been created for the display of drive parameters. The performances of IM and PMSM under parametric variations are predicted through sensitivity analysis. An integrated operation of the drives is demonstrated through experimental and simulation results.

Full text

Hindawi Publishing Corporation
Journal of Engineering
Volume , Article ID ,  pages
http://dx.doi.org/.//
Research Article
Distributed Drives Monitoring and Control: A Laboratory Setup
Mini Sreejeth, Parmod Kumar, and Madhusudan Singh
Department of Electrical Engineering, Delhi Technological University, Bawana Road, New Delhi 110042, India
Correspondence should be addressed to Mini Sreejeth; minisreejeth@dce.ac.in
Received  November ; Revised  December ; Accepted  December 
Academic Editor: Paolo Colantonio
Copyright ©  Mini Sreejeth et al. is is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
A laboratory setup of distributed drives system comprising a three-phase induction motor (IM) drive and a permanent magnet
synchronous motor (PMSM) drive is modeled, designed, and developed for the monitoring and control of the individual drives. e
integrated operation of IM and PMSM drives system has been analyzed under dierent operatingconditions, and their performance
has been monitored through supervisory control and data acquisition (SCADA) system. e necessary SCADA graphical user
interface (GUI) has also been created for the display of drive parameters. e performances of IM and PMSM under parametric
variations are predicted through sensitivity analysis. An integrated operation of the drives is demonstrated through experimental
and simulation results.
1. Introduction
Monitoring and control of drives is a necessary prerequisite
forqualitycontrolofaproductaswellasforenergycon-
servation in automated process plants. Electrical energy is
supplied to the motors through power electronic converter
to get the desired torque/speed characteristics of the motors
for motion control in industrial processes. is is achieved
through modern motor drives, advance control algorithms,
and intelligent devices such as programmable logic controller
(PLC), digital signal processor (DSP), and microcontroller.
is makes the operation of drives complex, sophisticated,
and expensive []. Further, in production plant, the process
isdistributedatshoplevelbasedonfunctionalrequire-
ments, which results in distribution of the various drives
for dierent process operations. In distributed drives system,
the processing tasks are physically distributed among the
various drives, which requires placement of the necessary
computing, with optimal volume of data, close to the process.
Such system also provides fault tolerant and self-diagnostic
capability and enhances the reliability of overall system. us,
a distributed drives system has partially autonomous local
computing devices with input, output, and storage capabil-
ity, interconnected through a digital communication link
coordinated by a supervisory control and data acquisition
system. e distributed system has the advantages of local
as well as centralized control. In such cases, the SCADA
and programmable logic controller coordinate the local
controllers through a communication link [].
In the past few decades, limited literatures are available on
distributed drives control using PLC. Applications of PLC
have been reported for monitoring control system of an
induction motor [,]. PLC has been also used as a power
factor controller for power factor improvement and to keep
the voltage to frequency ratio of a three-phase IM, constant
under all control conditions []. Also, a vector-oriented con-
trol scheme, for the regulation of voltage and current of three-
phase pulse width modulation inverter, which uses a complex
programmable logic device (CPLD) [], has been reported.
Remote control and operation of electric drive need a large
amount of data to be acquired, processed, and presented by
the SCADA system [,]. In this paper, distributed control
for a three-phase IM drive and a three-phase PMSM drive is
congured, designed, and developed for experimental work,
and integrated control operation is demonstrated through
experimental and simulation results. e application of
adjustable speed drives (ASDs) for fans, pumps, blowers, and
compressors do not require very precise speed control. Speed
sensor in a drive adds cost and reduces the reliability of the
drive. erefore, for applications requiring moderate per-
formance, sensorless drive is a better option, and, hence,
sensorless vector control is used for IM control [–]. On the

Journal of Engineering
other hand, PMSMs are generally used for low-power servo
applications where very precise position control is required.
A PID controller is applied [] to the position control, and a
model reference adaptive control has been implemented for
the PMSM []. As speed estimators and observers rely on
the knowledge of motor parameters, they are inadequate for
accurate position estimation. In the present work, a position
feedback encoder is used for PMSM, and an indirect eld-
oriented control is employed for its control [–].
A detailed study on distributed drives including design,
development, and testing of prototype distributed drives is
demonstrated. e monitoring and supervisory control of
IM and PMSM drives, thereby validating the concept of
distributed drives, is also described. Further, the developed
experimental setup enables and facilitates imparting training
and providing the facilities with hands of experimentation,
research, and practical training. e necessary SCADA GUI
has also been created for the display of drive parameters such
as speed. e performances of IM and PMSM are predicted
by sensitivity analysis.
2. Control Algorithm
Sensorless control for IM and indirect eld-oriented control
for the PMSM have been used in distributed control of the
drives.
2.1. Sensorless Control of ree-Phase IM Drive
2.1.1. Flux Estimator. e direct and quadrature rotor ux
components (𝑠
𝑑𝑟 and 𝑠
𝑞𝑟) are estimated from the IM ter-
minal voltages (𝑎,𝑏,and𝑐), currents (𝑎,𝑏,and𝑐),
stator resistance of the motor, 𝑠, the stator and rotor self-
inductances 𝑠and 𝑟, respectively, and their mutual induc-
tance 𝑚, which are described in ()to(); [], consider
𝑠
𝑑𝑠 =𝑠
𝑑𝑠 −𝑠𝑠
𝑑𝑠,
𝑠
𝑞𝑠 =𝑠
𝑞𝑠 −𝑠𝑠
𝑞𝑠, ()
where
𝑠
𝑞𝑠 =2
3𝑎−1
3𝑏−1
3𝑐,
𝑠
𝑑𝑠 =−1
3𝑏+1
3𝑐,
𝑠
𝑞𝑠 =2
3𝑎−1
3𝑏−1
3𝑐,
𝑠
𝑑𝑠 =−1
3𝑏+1
3𝑐,
𝑠
𝑑𝑟 =𝑟
𝑚𝑠
𝑑𝑠 −𝑠𝑠
𝑑𝑠,
𝑠
𝑞𝑟 =𝑟
𝑚𝑠
𝑞𝑠 −𝑠𝑠
𝑞𝑠,
()
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F : Phasors showing rotor ux orientation.
where
=1− 2
𝑚
𝑟𝑠
()
and 𝑠
𝑑𝑠,𝑠
𝑞𝑠,𝑠
𝑑𝑠,and𝑠
𝑞𝑠 arestatordirectandquadratureaxis
currents and uxes, respectively.
Also,
𝑟=𝑠
𝑞𝑟2+𝑠
𝑑𝑟2.()
e correct alignment of current, 𝑑𝑠,inthedirectionof
ux, 𝑟,andthecurrent,𝑞𝑠, perpendicular to it are needful
requirements in vector control. is alignment is depicted
in Figure  using rotor ux vectors 𝑠
𝑑𝑟 and 𝑠
𝑞𝑟,where𝑒-
𝑒frame is rotating at synchronous speed with respect to
stationary frame 𝑠-𝑠, and at any instance, the angular
position of 𝑒axis with respect to the 𝑠axis is 𝑒,where
𝑒=𝑒, cos 𝑒=𝑠
𝑑𝑟
𝑟,
sin 𝑒=𝑠
𝑞𝑟
𝑟.()
2.1.2. Speed Estimator. e speed is estimated by using the
data of the rotor ux vector (𝑟), obtained in a ux estimator
as follows.
e rotor circuit equations []of𝑠-𝑠frame are writ-
ten as 𝑠
𝑑𝑟
 +𝑟𝑠
𝑑𝑟 +𝑟𝑠
𝑞𝑟 =0,
𝑠
𝑞𝑟
 +𝑟𝑠
𝑞𝑟 −𝑟𝑠
𝑑𝑟 =0. ()

Journal of Engineering 
Adding terms (𝑚𝑟/𝑟)𝑠
𝑑𝑠 and (𝑚𝑟/𝑟)𝑠
𝑞𝑠,respec-
tively,onbothsidesofthepreviousequation,weget
𝑠
𝑑𝑟
 +𝑟
𝑟𝑚𝑠
𝑑𝑠 +𝑟𝑠
𝑑𝑟+𝑟𝑠
𝑞𝑟 =𝑚𝑟
𝑟𝑠
𝑑𝑠,()
𝑠
𝑞𝑟
 +𝑟
𝑟𝑚𝑠
𝑞𝑠 +𝑟𝑠
𝑞𝑟−𝑟𝑠
𝑑𝑟 =𝑚𝑟
𝑟𝑠
𝑞𝑠,()
𝑠
𝑑𝑟
 =𝑚
𝑟𝑠
𝑑𝑠 −𝑟𝑠
𝑞𝑟 −1
𝑟𝑠
𝑑𝑟,()
𝑠
𝑞𝑟
 =𝑚
𝑟𝑠
𝑞𝑠 +𝑟𝑠
𝑑𝑟 −1
𝑟𝑠
𝑞𝑟,()
where
𝑚𝑠
𝑑𝑠 +𝑟𝑠
𝑑𝑟 =𝑠
𝑑𝑟,
𝑚𝑠
𝑞𝑠 +𝑟𝑠
𝑞𝑟 =𝑠
𝑞𝑟,()
and 𝑟(i.e., 𝑟/𝑟) is the rotor time response. Also, from (),
𝑒=tan−1 𝑠
𝑞𝑟
𝑠
𝑑𝑟 .()
Dierentiating the aforementioned, we get
𝑒
 =𝑠
𝑑𝑟󸀠𝑠
𝑞𝑟 −𝑠
𝑞𝑟󸀠𝑠
𝑑𝑟
2
𝑟.()
Combining (), (), and () and simplifying, one yields
𝑟=𝑒
 −𝑚
𝑟𝑠
𝑑𝑟𝑠
𝑞𝑠 −𝑠
𝑞𝑟𝑠
𝑑𝑠
2
𝑟,
𝑟=1
2
𝑟𝑠
𝑑𝑟󸀠𝑠
𝑞𝑟 −𝑠
𝑞𝑟󸀠𝑠
𝑑𝑟−𝑚
𝑟𝑠
𝑑𝑟𝑠
𝑞𝑠 −𝑠
𝑞𝑟𝑠
𝑑𝑠,
()
where 󸀠𝑠
𝑞𝑟 and 󸀠𝑠
𝑑𝑟 are rst derivatives of s
𝑞𝑟 and 𝑠
𝑑𝑟,respec-
tively.
e torque component of current ∗
𝑞𝑠 and the ux compo-
nent of current ∗
𝑑𝑠 are evaluated from the speed control loop
andtheuxcontrolloop,respectively,asfollows:
∗
𝑞𝑠 =𝑟−∗
𝑟1,
∗
𝑑𝑠 =Ψ
𝑟−Ψ∗
𝑟2,()
where ∗
𝑟and ∗
𝑟are the reference speed and ux; 1and
2are the gain of speed loop and ux loop; 𝑟and 𝑟are
computed using the ux and speed estimators, respectively,
as explained earlier.
e principal vector control parameters, ∗
𝑑𝑠 and ∗
𝑞𝑠,which
are DC values in synchronously rotating frame, are converted
to stationary frame with the help of unit vectors (sin and
cos ) generated from ux vectors 𝑠
𝑑𝑟 and 𝑠
𝑞𝑟 as given by ().
e resulting stationary frame signals are then converted to
phase current commands for the inverter []. e torque is
estimated using ()as
𝑒=3
2
2𝑚
𝑟𝑠
𝑑𝑟𝑠
𝑞𝑠 −𝑠
𝑞𝑟𝑠
𝑑𝑠. ()
e block diagram of the sensorless vector control for the
IM drive is shown in Figure .
2.2. Control Scheme for ree-Phase PMSM Drive. e rotor
of PMSM is made up of permanent magnet of Neodymium-
iron-boron, which oers high energy density. Based on the
assumptions that (i) the rotor copper losses are negligible, (ii)
there is no saturation, (iii) there are no eld current dynamics,
and (iv) no cage windings are on the rotor, the stator -
equationsofthePMSMintherotorreferenceframeareas
follows [,]:
𝑞𝑠 =𝑠𝑞𝑠 +
𝑞𝑠 +𝑠𝑑𝑠,
𝑑𝑠 =𝑠𝑑𝑠 +
𝑑𝑠 −𝑠𝑞𝑠,()
where 𝑞𝑠 =𝑞𝑠𝑞𝑠,
𝑑𝑠 =𝑑𝑠𝑑𝑠 +𝑓.()
𝑑𝑠 and 𝑞𝑠 are the ,axis voltages, 𝑑𝑠 and 𝑞𝑠 are the ,
axis stator currents, 𝑑𝑠 and 𝑞𝑠 are the ,axis inductance,
𝑑𝑠 and 𝑞𝑠 are the ,axis stator ux linkages, 𝑓is the
ux linkage due to the rotor magnets linking the stator, while
𝑠and 𝑠are the stator resistance and inverter frequency,
respectively. e inverter frequency 𝑠is related to the rotor
speed 𝑟as follows:
𝑠=
2𝑟,()
where isthenumberofpoles,andtheelectromagnetic
torque 𝑒is
𝑒=3
2
2𝑓𝑞𝑠 +𝑑𝑠 −𝑞𝑠𝑑𝑠𝑞𝑠. ()
is torque, 𝑒, encounters load torque, moment of
inertia of drive, and its damping constant. us, the equation
for the motion is given by
𝑒=
𝐿+𝑟+
𝑟,()
where 𝐿is the load torque, moment of inertia, and 
damping coecient.
Figure  shows the typical block diagram of a PMSM
drive. e system consists of a PMSM, speed/position feed-
back, an inverter, and a controller (constant torque and ux
weakening operation, generation of reference currents, and
PI controller). e error between the commanded and actual

Journal of Engineering
Inverter
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F : Block diagram of three-phase PMSM drive.
speed is operated upon by the PI controller to generate the
reference torque.
e ratio of torque reference and motor torque constant
is used during constant torque operation to compute the
reference quadrature axis current, 𝑞𝑠.Foroperationupto
rated speed, the direct axis current is made equal to zero.
From these –axes currents and the rotor position/speed
feedback, the reference stator phase currents are obtained
using Park’s inverse transformation as given in ()

𝑎
𝑏
𝑐
=





cos 𝑟sin 𝑟1
cos 𝑟−2
3sin 𝑟−2
31
cos 𝑟+2
3sin 𝑟+2
31







𝑞𝑠
𝑑𝑠
0𝑠
,()
where 0𝑠 isthezerosequencecurrent,whichiszerofora
balanced system.
e hysteresis PWM current controller attempts to force
the actual motor currents to reference current values using
stator current feedback. e error between these currents is
usedtoswitchthePWMinverter.eoutputofthePWM
is supplied to the stator of the PMSM, which yields the
commanded speed. e position feedback is obtained by an
optical encoder mounted on the machine sha.
In order to operate the drive in the ux weakening mode,
itisessentialtondthemaximumspeed.emaximum
operating speed with zero torque can be obtained from the
steady state stator voltage equations. e ux weakening
controller computes the demagnetizing component of stator
current, 𝑑𝑠,satisfyingthemaximumcurrentandvoltage
limits. For this direct axis current and the rated stator current,
the quadrature axis current can be obtained from ()
𝑠=2
𝑑𝑠 +2
𝑞𝑠.()

Journal of Engineering 
HMI
Modbus
RTU PLC
Servodrive IM drive
Modbus
RTU
Ethernet
SCADA PC
Profibus DP
F : Schematic layout of distributed drives laboratory setup.
ese –axes currents and the rotor position/speed can be
utilized to obtain the commanded speed.
3. Sensitivity Analysis of IM and PMSM
Sensitivity analysis is used by designers of machines for
the prediction of the eect of parameter of interest on the
performance variables of the motor. In the present study, sen-
sitivity values of the performance variables like power input,
power output, eciency, power factor, stator current, starting
current, magnetizing current, developed torque, and starting
torque, with respect to the equivalent circuit parameters, are
obtained for the IM. e sensitivity is computed by (), as
sensitivity of a variable with respect to a parameter can
be represented as
𝑁
𝛼= 100⋅ 𝑐−𝑛
𝑛,()
where 𝑛is the performance variable with nominal param-
eters, and 𝑐is the value of the performance variable when
the value of the parameter is increased by dened deviation
value. A similar analysis is also carried out for PMSM.
4. Laboratory Setup of the
Distributed Drives System
To analyse the utility of distributed drive system, a labo-
ratory setup has been designed and developed for research
and development activities. Figure  shows laboratory setup
which incorporates industry standard networking. It has an
IEEE . complaint Ethernet data highway and is currently
supporting a network of two-operator consoles, a PLC, and
two drives (IM drive and PMSM drive) all connected in
star topology. e PLC (GE Fanuc -) coordinates the
operation of these drives. e PLC passes real-time data to
the operator console via Ethernet interface using customized
soware, namely, VersaMotion, for PMSM drive and DCT
soware for the IM drive. e input/output (I/O) units of
PLC and drives communicate using Probus-DP [,]. e
communication between individual drives and PCs, SCADA,
is through Modbus protocol.
4.1. PLC in Distributed Drive System. ePLCusedinthe
laboratory setup consists of several modules, namely, Power
Supply, CPU, Digital Input, Digital Output, and Network
Modules. e digital input module is a – V DC,  mA
with positive/negative logic and  input points. is module
is used to read ON/OFF position of dierent contacts used
to control the drives. ere are two output modules with
 points operating at  V DC, which are used to output
the status of the individual drive, alarm signal, and so forth
basedonthedecisionmadebythecontrolstrategythat
is written as ladder logic program in the PLC. e power
supply of PLC is capable of supporting – V AC or  V
DC. e CPU has a user logic memory of  Kbytes. e
communication module includes Probus module operating
at baud rate of . Mbps with a power requirement of  V
DC. Procy Machine Edition . provides soware utilities
for PLC programming. e PLC is programmed in ladder
diagrams, and program is downloaded in the PLC from a
personal computer through RS C serial interface. A ladder
diagram consists of graphic symbols like contacts, coils,
timers, counters, and so forth which are laid out in networks

Journal of Engineering
1
2
3
4
5
6
M00001
Q00013
Q00014
Q00001
Q00015
Q00013
Q00016
Q00014
Q00017
Q00001
Q00003
Q00004
Q00013
Q00014
Q00015
ONDTR
TENTHS
45
R00001
R
PV
30
ONDTR
TENTHS
15
R00004
R
PV60
ONDTR
TENTHS
0
R00007
R
(a)
Speed control of motors
Induction motor Control switch
OFF ON
PMSM
On-state
Speed mode Position mode Torque mode
1037
Speed mode 1
500
(b)
F : (a) Ladder logic for integrated operation of IM and PMSM drives. (b) SCADA GUI developed for the speed controlof the distributed
drives.
similar to a rung of a relay logic diagram. e PLC stores the
inputs (ON/OFF status of coils), execute, the user program
cyclically, and nally writes the outputs (energizing a coil
for actual opening/closing of contacts) to the output status
table. is read-execute-write cycle is called a scan cycle. e
ladder logic diagram for the integrated operation of the IM
andPMSMdrivesisshowninFigure (a).
4.2. SCADA. For the remote monitoring and control of the
drives, GE Fanuc SCADA Cimplicity . soware is used.
e SCADA soware is loaded on the server PC which
provides supervision in the form of graphical animation and
data trends of the processes on the window of PC or screen
of HMI. e Cimplicity project wizard window is used to
congure various communication ports and the controller
type and also to create new points corresponding to addresses
used in the controller. is graphical interactive window is
used to animate the drive system. At present, controls like
start, stop, speed control, and so forth are developed on the
soware window to control the drives remotely. Each drive
canbecontrolledlocallyattheeldlevel,throughthePLC,
or through the SCADA interface. e SCADA GUI developed
for the speed control of the distributed drives is shown in
Figure (b). e control algorithm has been implemented
and tested for a three-phase squirrel cage induction motor
and three-phase PMSM drive. e technical specications for
these drives are presented in Tables and .
5. Results and Discussions
A three-phase sensorless induction drive and a three-phase
PMSM drive are congured in the SCADA system. e
0
50
100
150
200
250
300
350
400
450
0 2 4 6 8 101214161820
Voltage (V)
Time (s)
Motor voltage at no load
Motor voltage at 25% load
F : Voltage variation of IM drive during starting at dierent
loads and  rpm speed.
operation and performance characteristics of the drives are
monitored and studied under varying torque and speed
conditions. Simulation results are also described. In order to
study the eect of parametric variation on the motor per-
formance variable, sensitivity analysis is carried out for both
IM and PMSM with respect to their respective equivalent
circuits.
5.1. Performance of ree-Phase IM Drive under Dierent
Load Conditions. Figure  to Figure  show the variation
of various parameters of sensorless control induction motor
drive during starting at no load and % load conditions.
Figures and show the variation of voltage and frequency.
Both the voltage and frequency increase linearly till they
attain a value of  V and  Hz, respectively, at rated speed

Journal of Engineering 
T : Technical specications of three-phase induction motor.
Connection type 
Input volt age  V ±%
Input current  A
Rated power . kW
Input frequency  Hz
Pole number 
Rated speed  rpm
T : Technical specications of three-phase PMSM.
Parameter Value
Rated output . kW
Rated torque . Nm
Motor voltage  V
Rated current . A
Maximum current . A
Encoder position feedback  ppr
Peak torque . Nm
Rated speed  rpm
Moment of inertia . kg⋅m
Armature resistance . 
Armature inductance  mH
under no load starting condition. While the machine is
started with a load of %, the variations in voltage and
frequency are almost similar to that of the previous case.
Figure  shows the variation of current during starting
under no load and % load conditions. e starting current
was . A during starting which is settled down to a steady
state value of . A in  s under no load case. While with %
load, the starting current was . A which is settled down to
steady state value of . A in about  s.
Figure  shows the variation of torque during starting
with no load and % load. At no load starting, it is observed
that the negative peak torque value is . Nm at the rst
instance, and then it reaches a positive peak value of .Nm
and nally settles down to a steady state value of .Nm in
about s. While with % load starting, the negative peak
torque value at the rst instance is  Nm, and the positive peak
value is . Nm which nally settles down to a steady value of
. Nm in  s. Figure  shows the power variation at starting
with no load and % load. e power drawn during transient
period is . kW, which decreases to a value of . kW, then it
increases linearly to a value of . kW and nally settles down
to a value of . kW in  s. When the machine is started
with % load, the initial power drawn is . kW, which then
increases to a value of . kW and nally settles down to a
value of . kW in  s.
Figure  shows the speed response of IM during starting
at no load and % load. It is observed that the motor reaches
its rated speed that is,  rpm in about  s under no load
starting and in about  s under % load at starting. Figure 
shows simulated dynamic performance of IM drive under no
0
10
20
30
40
50
60
Frequency (Hz)
Frequency at no load
Frequency at 25% load
0 2 4 6 8 10 12 14 16 18 20
Time (s)
F : Frequency variation of IM drive during starting at
dierent loads and  rpm speed.
0
1
2
3
4
5
6
Motor current (A)
Current at no load (A)
Current at 25% load (A)
02 4 6 8 10 12 14 16 18 20
Time (s)
F : Current variation of IM drive during starting at dierent
loads and  rpm speed.
3
8
13
18
23
Torque (Nm)
Torque at no load
Torque at 25% load
0 2 4 6 8 10 12 14 16 18 20
Time (s)
−2
−7
F : Torque variation of IM drive during starting at dierent
loads and  rpm speed.
load and at rated speed of  rpm. e motor attains the
desired speed of rpm in about . s.
5.2. Starting Performance of ree-Phase PMSM Drive under
No Load Condition. Figure  shows the dynamic perfor-
mance of PMSM under no load with a reference speed of
 rpm. e motor attains the set synchronous speed of
 rpm in about  ms. Figure  shows simulated dy-
namic performance of PMSM at no load with a reference

Journal of Engineering
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Power (kW)
Power at no load
Power at 25% load
02 4 6 8 10 12 14 16 18 20
Time (s)
F : Power variation of IM drive during starting at dierent
loads and  rpm speed.
0
200
400
600
800
1000
1200
1400
1600
Speed (rpm)
Speed at no load
Speed at 25% load
024681012141618
20
Time (s)
F : Speed variation of IM drive during starting at dierent
loads and  rpm speed.
012 3 4 5 6 7 8 9 10
200
400
600
800
1000
1200
1400
Time (s)
Speed (rpm)
Set speed
Actual speed
F : Simulated speed response of three-phase IM drive at no
load and rated speed.
speed of  rpm. e motor attains the set synchronous
speed of  rpm in about  ms.
5.3. Sensitivity Analysis for Performance Variables of PMSM.
Motor parameters like stator resistance and inductance vary
depending on operating conditions, mainlymotor duty cycle,
eect of magnetic saturation, and so forth. e eect of
3138
Time (ms)
2823.7
2509.4
2195.1
1880.8
1566.5
1252.2
937.9
623.6
309.3
0
53.8
107.6
161.4
215.2
269
322.8
376.6
430.4
484.2
538
Speed (rpm)
Speed input
Motor rotation speed
command
−5
F : Experimental starting response of three-phase PMSM at
no load and rated speed.
00.05 0.1 0.15 0.2 0.25 0.3 0.35
0
500
1000
1500
2000
2500
3000
3500
Time (s)
Speed (rpm)
Set speed
Actual speed
F : Simulated starting response of three-phase PMSM at no
load and rated speed.
parametric variations on the eciency of PMSM has been
analyzed and is shown in Figure  for rated speed and rated
torque conditions, where represents the parameter variation
coecient and is dened as the ratio of new parameter value
to the actual parameter value. at is,
=󸀠
𝑠
𝑠=󸀠
𝑠
𝑠,()
where 󸀠
𝑠and 󸀠
𝑠are the new stator resistance and stator
inductance, respectively. In the present analysis, is deter-
minedfor%deviationinmotorparameters.
It is observed from Figure  that the variation in the
eciency is negligibly small with variation in 𝑠and 𝑠,and
it follows a Gaussian distribution. e variation in eciency
duetochangein𝑠and 𝑠is expressed as a fourth order
polynomial using best t curve in Figure ,where
|𝑅𝑠=0.384−1.583+2.072−0.91+0.04,
|𝐿𝑠=0.16 4−0.593+0.552+0.01−0.13. ()
5.4. Sensitivity Analysis for Performance Variables of IM.
Table  shows the sensitivity of dierent performance vari-
ables of three-phase IM with respect to its equivalent circuit

Journal of Engineering 
T : Sensitivity of performance variables of three-phase IM.
(Outputpower=fullload=.kW. = 0.043)
Parameters 𝑠𝑟𝑠𝑟𝑚
Power input −. −. −. −. . . −.
Power output −. −. −. −. . . −.
Eciency −. . −. −. . . .
Power factor . −. −. −. . . .
Stator current −. −. −. . −. . −.
Starting current −. −. −. −. −. . −.
Magnetizing current −. . −. −. −. . −.
Torq u e −. −. −. −. . . −.
Starting torque −. . −. −. . . −.
00.25 0.5 0.75 1 1.25 1.5 1.75 2
−0.02
−0.04
−0.06
−0.08
−0.1
−0.12
3FEVDUJPO JO FďDJFODZ য
1BSBNFUFS WBSJBUJPO DPFČDJFOU ব
7BSJBUJPO PG ॗॱ
7BSJBUJPO PG ॑ॱ
F : Eect of parametric variations on the eciency of PMSM
for rated speed and rated torque.
parameters. e sensitivity of the power input and power
output with respect to 𝑟is the highest and is the lowest
with respect to 𝑟. Motor eciency is less sensitive to all
the equivalent circuit parameters, with variation in 𝑠and
𝑚aecting it more compared to other parameters. e
power factor is more aected by variation in 𝑚and 𝑟,
while variations in other parameters have less eect on it. e
stator current is more aected by variation in 𝑟and least by
variation in 𝑟. e sensitivity of starting current with respect
to 𝑠and 𝑟isthehighestwhilewithrespectto𝑚is the
lowest. Magnetizing current is more sensitive to changes in
𝑚and less sensitive to changes in 𝑟.edevelopedtorque
and starting torque are mainly aected by variations in 𝑟.
e sensitivity of developed torque is the least with respect to
𝑟and 𝑚,respectively.
e sensitivity of the performance variables with respect
to frequency and supply voltage is also obtained. It is observed
that the frequency variation has maximum eect on starting
torqueandmagnetizingcurrentfollowedbystartingcurrent.
e sensitivity of developed torque with respect to frequency
istheleast.esensitivityofpowerinput,poweroutput,
developed torque, and starting torque with respect to supply
voltage is % each. Similarly, the stator current, starting
current, magnetizing current, and so forth change by % with
respect to variation in supply voltage. e supply voltage
variation has negligible eect on eciency, while power
factor is not aected by supply voltage variation.
6. Conclusion
A prototype of distributed drives system, consisting of a
three-phase IM drive and a PMSM drive, is designed, devel-
oped, and implemented as a laboratory setup. is prototype
system demonstrates the operation and control of distributed
drives through PLC and SCADA. e operation, control, and
monitoring of various performance parameters of PMSM and
IM under dierent operating conditions are carried out in
detail. A detailed sensitivity analysis is also carried out to
observe the eect of parametric variations on performance
of the motors.
Conflict of Interests
In this research work, GE Fanuc - Series PLC has been
used for creation of the laboratory setup. e said PLC
uses Probus DP protocol for communication between the
input/output modules and the drives. e selection of the
PLC is intended solely to facilitate research and development
workandisnotbasedonanycommercialinterest.
Acknowledgments
is work was supported in part by the MODROB Scheme
of AICTE, India. e authors gratefully acknowledge the
support provided by AICTE, India, and GE Fanuc in setting
up the laboratory infrastructure in the Electrical Engineering
Department at Delhi Technological University, New Delhi,
India.

 Journal of Engineering
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