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My Journey with Linear Induction Motor
Dr. S. N. MAHENDRA*
More than 4-decades agoR&D related to Linear
Induction Motor based propulsion was started in the
Department of Electrical Engineering. Initially it started
as a working model for Engineering Models
Exhibition.Later the activities covered a range of
applications like shuttle-propulsion in power-looms to
material-handling to surface/ overhead/underground/
people-mover transportation systems. The applications
developed and the R&D activities in chronological
order have been as follows:
• Shuttle-propulsion for weaving looms (1971-73) [1]
• Design & analysis methodologies standardization
(1973-97)[11]
• Surface-transportsystem (1980 continuing)[3, 12]
• Testing-methodologies & test-rigs (1980-87)
• Overhead-transportsystems (1983 continuing)[9]
• Conveyor-belt/material handling (1986 continuing)[9]
• LIM Powered People Mover system for closed-loop
circular track for Connaught Place people transport
system (1986-2013[4, 5]
• Malaviya Center for low cost LIM metro system (1997
continuing)[3, 9, 11]
• Independent control of forces of propulsion &
attraction (2003 continuing)[12]
• LIM powered sieving system for sorting ore near mines
(2003 continuing)
• LIM based traction elevator for vehicle parking (2012
continuing)[7]
• Linear Switched reluctance motor (2014 continuing)
• Segmented linear motor based propulsion for circular
looms (2014 continuing)[4]
The present article is based on the experiences,
problems-faced and developments made during the
journey of the author with Linear Induction Motor
(LIM).
The Journey Begins
The journey started in an interesting manner
during MODEX-70. Professor S. K. Kak, formerVice
Chancellor GoutamBudh Technical University, Noida,
was the student Convener of the famous Engineering
Models Exhibition and I was a member of his core
organization team. He asked me tomake and present
a model in the exhibition. He was himself heading
a huge team of dedicated students in making
a working model of Musical Fountain (similar to the
first of its type made and exhibited during EXPO-70
in Japan). When I asked him what shouldI make? He
suggested me to make a set of U-cores with DC coils
which are excited in a sequence such that a horizontal
component of the attraction force is produced in the
iron plates fixed to the moving member facing the cores
resulting innecessary force for linear motion (similar to
that inalinear stepper motor).
With detailed diagrams and design I met
Professor M. Bhattacharrya in the Electrical Machines
Lab for his suggestions and advice. He patiently
listened to the whole idea and encouraging me (as if I
was in the process of inventing something new and
great) said „why not give A.C. supply instead of D.C.
supply‟. To this I said „Sir, why not provide a 3-phase
distributed winding in the core like in an induction
motor and energies the three-phases with 3-phase
A.C.‟. He just said „Good. Go ahead.‟ Thus
unknowingly my journey with Linear Induction Motor
(LIM) started. The working model was made and
exhibited in room no. F-5 (Rampur Hall) near the first
pillar on the left side. Objects of different shapes made
of aluminum were shown moving from one end of the
core to the other in a linear direction along the length of
the core when the winding was energized. I was feeling
great as if I have done something really great, till a
visitor after seeing the exhibit said that a similar
machine was made by Professor E. R. Laithwaite long
back. I met Professor Bhattacharryathe next day and
asked him „Sir,do you know this fact‟. He coolly said
„Yes‟. I was pained (I do not know why) and
complained „Sir why did you not tell me this during the
first meeting itself so that I would not have exhibited my
ignorance and felt embarrassed‟. The words he spoke
after this have inspired me and encouraged me during
all the development work that I have done and narrated
in this article. He said, “If I had told you earlier you
would not have experienced in you the ability to
create/invent something new. Now you have
confidence that you can also think original and may
be in future you may make new things”. I can say that
this is a true quality of a teacher wherein a teacher not
only teaches but creates opportunity in his student to
realize the inherent strengths/weaknesses in him/her.
His words did come true at many occasions whenever
*Professor, Department of Electrical Engineering, IIT (BHU), Varanasi-221005
a new machine was made and for all this I give credit
to him.
Now I will take you along with this journey from
1971 till date highlighting milestones and pitfalls and
also the positive effect of a good teacher.
Period 1971 to 1972
During this period I continued with development of
LIM for shuttle propulsion in power looms as one of
the industrialist of Varanasi showed interest and offered
to support for development of handloom propelled by
LIM. During implementation shortcomings were
observed and three modified versions of the system
were made as shown in Figs.1-3. Fig. 3 shows a novel
geometry conceived and made by the author. It consists
of a Single Primary Double Secondary LIM (1972).
This was modified later by fitting bearings for
movement and lateral guidance of an Overhead
transport system. The running-rails apart from
mechanical strength to the overhead system also
provided return-path for magnetic flux, thusthere was
additional requirement of Aluminum Reaction Rail
only (1983) and a net saving of backing iron along the
length of track which would have been provide
otherwise for strengthening the magnetic circuit.
Fig.1 Back to back 3-phase LIM for automatic
shuttle propulsion (1971)
Fig.2 single phase LIM with starting windings at the
ends for producing starting force (1972)
Fig.3Single Primary Double Secondary LIM (fitted
with bearings for movement and lateral guidance of
OH transport system) [1972, 1983]
The small motor has carried the load of 1-adult/2-
children and has application in over-head transport
system.
The 1972 M. Tech. project report based on the work
concluded as follows:
“The study of various types of linear oscillating
induction motors made has clearly shown the
possibility of developing self-oscillating/switch-
oscillating linear motors operating on three-
phase/single-phase supply systems. The conclusions
drawn out by consideration of force/speed
characteristics and mathematical analysis of
respective machines clearly indicate a definite
possibility of developing a method of designing of
such machines. It must be realized that the perpetual
oscillation of these machines and their constructional
features make them one of the most complex of the
electromagnetic devices and these are, therefore, not
amenable to any simple analytical treatment.
Moreover, the basic shortcoming of such
machines is the existence of an inherent mechanical
friction and the problem of perfect alignment. The
ideal arrangement will be one in which the runner
moves in air under the influence of electromagnetic
field developed in such machines, without touching the
stationary member. The above motion must always
maintain a constant „air-gap length‟ through its
MY JOURNEY WITH LINEAR INDUCTION MOTOR 179
length of traverse. Another requirement to make an
ideal machine is a long bed of traverse – preferably
lying between -∞ and +∞. Although none of the above
requirements are practical, they do point towards
definite possibility of further development.”
Period 1973 to 1978
The concluding remarks of the report were
challenging hence I got registered with Professor M.
Bhattacharrya in 1973 to work further on this problem.
We had long sittings in the Department and in his
RajputanaHostel warden quarter. Then one day he said,
“Som now the time has come that you go out and get
far better environment, facilities and exposure”. This
again exhibited the greatnesses of Professor M.
Bhattacharrya because normally not many Ph.D.
supervisors will tell this to their research scholars. I was
bit disturbed but then the „Government of India‟s
National Scholarship for Study Abroad‟ award letter
indicating that with this scholarship I could go to any
part of the world to work in the field of LIM. I was
excited and contacted the giants in this subject at that
time - Professor E. R. Laithwaite at Imperial College
of Science & Technology, London, and through him
Professor A. J. Ellision, Head of Electrical
Engineering Department, The City University, London,
Professor SakaeYammamura of Tokyo University,
Japan, and Professor S. A. Nasar of University of
Kentucky, USA. I got encouragement and positive
response from all three of them.
Now came the problem of choosing a country
from these three countries for which I got the guidance
from Professor R. J. Galgali, Department of Chemistry,
BHU – a God gifted person who helped so many in so
many ways during his stay in BHU.Based on his
analysis and intuition he said „you go to London, the
UK - a country which has the roots of the subject and
Professor E. R. Laithwaite is known as the father of
Linear Induction Motors‟.
My correspondences with Professor E. R.
Laithwaite, Professor S. A. Nasar, Professor Sakae
Yammauraand Professor A. J. Ellisionfor seeking
possibility of doing research under them have been a
memorable part of my journey with LIM. It is
memorable because these correspondences reflect the
nature and seriousness which these professors had for
the prospective research scholars – and this is essential
even now. Excerpts from the lettersof Professor E. R.
Laithwaite are given below to show how helpful and
considerate he has been in his correspondence.
“….All these things are indicative of toils and
troubles of a professor at Imperial College. If you were to
register for Ph. D. you will be supervised by me, as Dr.
Eastham is leaving, and I have already so little time for
casual visitors, it would not be fair to ask you to work with
me at this time.”
April 4, 1973
“….May I first offer you my sincere congratulations
on being awarded the National Scholarship for Study
Abroad. What I said earlier is still true. It would be unfair
for someone like yourself to be under my direct supervision,
as my outside commitments are so heavy that it could well be
that we will talk to each other only twice a year.
However, we have very close ties with City
University…..there my personal friend Professor A. J. Ellison
is working on linear motors……would be willing to accept
you…..and it would mean that you still have access to me,
probably for longer than if you worked in my
department………..
I hope you will do this and I will have the pleasure of
meeting you before the end of this year.” May 17, 1973
The net outcome of the correspondence was that I
joined The City University (TCU), London, and after
meeting my guide Professor A. J. Ellision I visited
Imperial College of Science & Technology, London,
to report to Professor E. R. Laithwaite and take his
advice and direction for my research in TCU. The few
hours meeting was a memorable one as every word of
his within a short time had enchanted me with the
greatness of linear induction motors as experienced by
him. He demonstrated so many working systems he
had made to understand „what is induction motor‟ (as
he had often repeated during his class lectures that he
has not been able to understand what induction is). He
also demonstrated his famous transverse flux linear
induction motor. I was asked to hold a small „vehicle‟
(with secondary aluminum plate underneath) from one
end of the transverse flux linear induction motor
primary member and leave it when he tells me. To my
surprise the vehicle left by me on the track „flew‟ over
the entire length of transverse flux linear induction
motor primary member without touching the track
or falling sideways due to the presence of
electromagnetic forces of levitation and lateral
guidance produced in what he called the „magnetic-
river‟ created by him. The vehicle was caught by him
at the other end. During this meeting Professor
Laithwaite also told me not to rush for a quick degree
180 PRAJÑĀ : Vol. 60, Part-02, Year 2014-15 : Special Issue on "Science & Technology"
but do a good work. He also told me that it took him
seven years to obtain his Ph.D. degree. Perhaps he
observed some reaction on my face and reacted
immediately, „It‟s not that I did not do much during this
period. It got delayed because I did not have time to put
all my work in a thesis form.‟ After this I met him
many times without any problem, attended his inspiring
lectures and watched his BBC Christmas Special
Lectures. I remember each and every bit of it.
My Stay at the City University, London
My guide Professor A. J. Ellision right from
day one had been very kind to me and gave me time
whenever I wanted to discuss my research progress and
take his advice. By nature he was also very friendly and
kind to everyone and this quality of his benefitted me a
lot as whenever (while meeting a person from
universities and industriesin and around London) I told
that I am working with Professor A. J. Ellision he/she
would offer to help me in my research work in
whatever way it was possible for him/her. I was thus
able to effectively integrate the rich academic and
industrial exposure which I received in the UK and also
in European citieswhich I visited with IEE and IEEE
Students Travel Scholarships.
During one of the initial meetings when I told
him that I understand the inputs and outputs of an
electromagnetic system but not what is happening in
the electromagnetic system. He said do you want to go
inside this black-box? Do you have the courage? My
reply was „yes‟as I wanted to explore the links between
the electrical input and mechanical output of an
electromagnetic system. I knew that till I do not
understand this I will never be able to effectively design
these electromagnetic systems by providing a balance
between all the five basic circuits of electromagnetic
device viz. electrical, magnetic, mechanical, thermal
and dielectric circuits of an electromagnetic system. He
gave me green signal.
In yet another meeting after about six
months when I approached him with a proposal to
make circular transverse flux induction motor so
that one can test transverse flux induction motor
under dynamic conditions (as the set-up at Imperial
College of Science & Technology, London, was
good for standstill tests only). I had located
U-shaped stampings in the Department store and
had drawn a diagram also. He patiently listened
to me and said „OK you play with this till we
finalize your research plan‟. This resulted in
development of Basic transverse Flux Circular
Motor. When it was shown to the professors of
Imperial College of Science & Technology, London,
one of them - Professor Freeman - remarked „Oh God
this is a missing link between all the electric motors
made so far‟. Later BTFCM was placed as an exhibit
during IEEE INTERMAG-75 at Imperial College of
Science & Technology, London, - the only exhibit
from a research scholar as all other exhibits were of
senior professors.
Through research a link between the electrical
inputs and mechanical outputs via magnetic circuit was
thoroughly analyzed using the Maxwell‟s equations and
Maxwell‟s Second Stress Tensor. The predicted 3-
components of flux densities, forces and the
performance closely matched with the experimental
results obtained from BTFCM under dynamic
conditions. The work was appreciated by IEE (UK)
through “IEE Student Premium Award‟.
Back in BHU1978 onwards – activities &
milestones
On return I had planned to integrate the
knowledge gathered in London to remove the
weaknesses of the working system developed before
going to London. In achieving this objective the
encouragement and support received from Professor
G. Rajsekar needs special mention. He, after looking at
my thesis, asked me „Can you translate your research
into working systems to demonstrate the principle?‟
My reply was in affirmative. I told him that the main
difficulty was in the laying of track along which the
system has to move. He took this as a challenge and in
his own dynamic way persuaded his friend Mr. K. P.
Jairam, the then General Manger, DLW, Varanasi, to
extend support for making the working system. I am
grateful to DLW, its Officers and workers who whole
heartedly extended help to make the whole system as it
was unconventional in many ways. The 1:15 scale
LIM based BHU-DLW surface transport model
moving along 33-m oval track was later exhibited
number of times in the Railway Pavelion of India
International Fairs at Pragati Maidan, New Delhi.
Being the only working system of its type in the
country, it attracted attention of the visitors including
the then Prime Minister of India Shri Rajeev Gandhi
who remarked to ShriMadhaoRaoScindia, the then
Railway minister that „this could be the future
transport system for India‟.
Since then a large number of LIM based
working systems including a full-scale system carrying
MY JOURNEY WITH LINEAR INDUCTION MOTOR 181
about 20-adults moving along 65-m meter-gauge track
has been made with the help of UG/PG students and
financial support from organizations like AICTE.
To cut the long story short I willnarrate my journey
through photographs and brief description of some of
the working systems developed along withtheir
usefulness.
(a) 1:15 scale LIM based BHU-DLW Surface
Transport working System moving along 33m
oval track [1981, 2001]
Fig 4 ShriDigvijay Singh, Min of State for Railways,
Professor YC Simadhari, VC-BHU &Shri O. P.
Gupta, GM, DLW, inspecting 15:1 BHU-DLW
LIM Surface Transport System [2001]
The trolley safely moves along very sharp curves
(with about 6-m diameter even at 16kmph) due to the
presence of force of attraction between the moving
primary iron & the secondary reaction rail. A unique
feature of LIM based system in contrast to any other
conventional wheel-rail/road systems wherein (with
increase in speed) the wheel-rail/road grip becomes
poor leading to accidents.
The working system effectively bridges the gap
between the technology & decision makers as it
explains the principle of operation and the inherent
advantages easily.
(b) LIM based surface transport system for
underground metro moving along 65-m
meter-gauge track at Malaviya Center for
Development of LIM Propelled Rail Metro
System: [1997, 1998, 2001]
Working system was primarily made to verify
the developed design methodology. It also
demonstrated the indigenous capabilities developed in
the design/fabrication of LIM based systems as per
specifications.
Fig 5 Trolley with LIM Primary lifted-up to show the
underside arrangement
Fig 6 Trolley fitted with LIM Primary operating on 65m
meter-gauge track &Shri. S.K.Khanna, MEL, IR Board,
Shri O. P. Gupta, GM, DLW, &Shri J. Upadhyay, Ex-
MEL, IR Board doing foot-plate inspection of the LIM
Propelled Rail Metro System
Fig 7 ShriDigvijay Singh, Min of State for Railways,
Professor Y.C. Simadhari, VC-BHU & Prof. P. C.
Upadhyay, Registrar BHU, doing foot-plate inspection
[2001]
182 PRAJÑĀ : Vol. 60, Part-02, Year 2014-15 : Special Issue on "Science & Technology"
The working system attracted attention of
decision makers like the then Minister of State for
Railways, present & former Indian Railway Board
Members (Elect.).
The system also attracted attention of press & TV
media and its working along with the Institute R&D has
been widely reported by many TV channels including
„Imaging Sciences‟ programme of national DD TV.
The working system has acted as an effective
bridge between the technology and prototype stage for
adoption.
(c) LIM Powered People Mover system for closed-
loop circular track for Connaught Place people
transport system. (The moving platform at 5-10
kmph can complete one circle in 15-30 min)
[1986, 2013]
Fig 8 LIM Powered People Mover system for closed-loop
circular track for Connaught Place people transport
system
The model demonstrates feasibility of integration
between metro terminals and other public transport
modes as well as the shopping points in city-centers
like Connaught Place. The cost analysis has been done
and the proposal has been recently presented in two
international conferences. International reactions are
being received
(d) LIM based ropeways in which the rope is
stationery [2010, 2011]
Made primarily to demonstrate the principle of
ropeways in which the rope is stationery and the
trolley moves due to linear force produced by LIM
mounted on the trolley.
Since moving parts are only the wheels on bearings
(with no drum/gears connecting to the electric motor or
the moving-ropes) the maintenance will be bare
minimum. It has provision for remote monitoring
and control.
The proposal can be implemented in regions
where other modes of transport are neither feasible nor
economical and the ropeways are the only choice.
Fig 9 LIM based ropeways in which the rope is stationery
Concluding remarks & suggestion for further work
One important thing brought out in this article needs
special mention again. The role of teachers like
Professor M. Bhattacharrya, Professor G. Rajsekar,
Professor E. R. Laithwaite, Professor A. J. Ellison, who
had so coolly played their role in shaping me and my
work on LIM needs to be appreciated for the fact that
the role of a good teacher is the most essentialfactor in
shaping the „future-components‟ of the society viz. the
Man. The technological developments may assist a
teacher but these shall never be able to become a
substitute for the qualities of a good teacher.
Another point which I would like to highlight here
is the international interest shown in LIM activities
by countries like Japan. In February 2007 Mr.
Masahiro Ando, P.E. Professional Engineer as
Authorized by the Japanese Government &Dr. Vijay
Kumar Jatiya Funakawa Information & Environment
Technology Co. Ltd., Tokyo, and Manager dealing
in Business Planning & International Business
Operations, visited for discussions for providing
an effective solution to the ever-growing
MY JOURNEY WITH LINEAR INDUCTION MOTOR 183
urban transportation problem in the Indian cities.
In Japan the technology has been adopted
through a consortium (Japanese Subway Association)
approach which included people from
Academic/Associations, Subway Operators,
Development Components and Administration
(supportive organizations). Figures [13]
below show the
usage up to 2006 and distinct advantages observed by
JSA.
Copyright © Japan Subway Association. 2007.All rights reserved 6
Number of passengers in Japan
◆ Up to March 2006 since the first introduction in 1990
in Osaka, Japan the Linear Metro systems carried safely
more than around 2.2 billion passengers in total.
400 (million passengers / year)
300
200
100
0
330 million
2.2 Billion Passengers (1990~2006)
1990 2000 2006 2010 (year)
Copyright © Japan Subway Association. 2007. All rights reserved 10
Merit of Linear Metro
Steep gradient
Non-adhesion drive allows even inclines of
over 60‰ to be negotiated .
Copyright © Japan Subway Association. 2007. All rights reserved 11
Merit of Linear Metro
Sharp curve
The Linear Metro
handles sharp
curves effortlessly.
Quiet,smooth
operation,with no
squealing.
Copyright © Japan Subway Association. 2007. All rights reserved 18
Merit of Linear Metro
Conventional subway
Comfortable
interior
Diameter
Linear Metro
Interior height
Floor height
Linear motor
Small-diameter
wheels
Reaction plate
◆Lower than a conventional subway car floor height by 30 cm,
the Linear Metro uses limited space more effectively.
Compact & Comfort
On the basis of experiences gathered from linear
metros operating in Japan the Japanese have taken a
blanket decision to make all future metros in the
country Linear Motor based only. Two typical metros
in operation in Japan are shown below.
Copyright © Japan Subway Association. 2007. All rights reserved 25
Application example1
Osaka City
Copyright © Japan Subway Association. 2007. All rights reserved 29
Application example2
Tokyo Metropolitan
My presentation in February 2007 was followed by
that of Mr. Ando [13]
and the two presentations received
lot of interest followed by discussion from the audience
in the lecture hall as well from the media.
Prof. G Rajsekhar, former Dean Faculty of
184 PRAJÑĀ : Vol. 60, Part-02, Year 2014-15 : Special Issue on "Science & Technology"
Engineering and Technology and Professor
Department Electrical Engineering IT–BHU, traced
the history of LIM R&D activities in the Department.
He wondered that if the country had implemented the
Departmental proposal made in early 80‟s, India would
have been leaders in this field by now. He was hopeful
that now thevisit of Mr. Ando and Dr. Jatiya will lead
to an effective integration of the „rich experience of
Japanese Subway Association (JSA) in the
implementation of Linear Metro in Japan‟ with the
„fundamental LIM based R&D achievements of IT–
BHU‟.He was optimistic and confident that jointly the
two organizations can provide a solution for the urban
transportation problem in India and all over the world.
Mr. Ando who is „father of linear metro in
Japan‟ appreciated the R&D in BHU and felt a need
for exploring the possibility of solving the urban
transportation problem in Indian cities through linear
metro. There was a general consensus that the
Government of India and the Government of Japan
may be requested to initiate steps for joint
ventures/participation in making Linear Metro based
joint project proposals for Indian cities. To start with
the first Linear Metro may be made operational in
Varanasi as it would be a fitting tribute to
Mahamana Pandit Madan Mohan Malaviyaji – the
founder of Banaras Hindu University. The other
reasons being that:
Due to Sarnath many Japanese visit Varanasi and
this will help them in moving around comfortably
Any activity in Varanasi catches attention the
world-over, and
The R&D at BHU can be easily integrated.
Since then efforts were made at many levels to
initiate the activity between Japan and Varanasi but
with no success so far. It is expected that with renewed
efforts being made with the new ministry at the center
wherein Varanasi happens to be the Prime Minister‟s
constituency, the proposal may come through.
During the years a large number of
technologies/working-systems have been developed
and are ready for adoption by the user industries.
These are:
a. LIM powered systems for:
(i) Overhead/Underground/Surface transportation,
(ii) Material Handling,
(iii) Ropeways in which the rope does not move,
(iv) Vertical elevators for vehicle parking,
(v) People mover system for Connaught Place
b. Control strategies for energy saving in LIM
based systems including independent control of
propulsion & attraction forces produced
c. Handloom for visually handicapped.
Journey with a subject never ends.
People/researchers may change but so far as the R&D
in the subject is concerned it continues and I have all
hope that this will happen in our Department also. In
this regard it is worthwhile now to explore the
possibility of industry/academic-institution
participation for further development and effective
absorption of Linear Induction Motor (LIM) based
systems which have been developed & tested in the
Department.
Acknowledgement
Following individuals & Agencies support is
gratefully acknowledged:
MHRD/AICTE 1994-2000: For R&D Grants
to develop LIM propelled transport system operating
with 15-adult load on a 65-m meter-gauge track for
demonstrating the technical feasibility
Prof. Hari Gautam 1996(the then VC BHU &
later Chairman UGC): For supporting creation of
Malaviya Centre for “Development and Evaluation
of Low Cost LIM Propelled Rail Metro System” in
IT-BHU.
Shri Jagdish Upadhyay 1994-2000(Former
Member Electrical Railway Board, Visiting Professor
& Advisor AICTE project entitled LIM Propelled Rail
Metro System): For giving a practical shape to LIM
traction R&D activities and projecting it for its
adoption in India.
Professor M. Bhattacharrya (since 1973) for
starting my journey with LIM and Professor G.
Rajsekar (since 1977) for providing the necessary
thrust which was a great helped in making of BHU-
DLW model that helped in bridging the gap between
the technology and the decision makers.
„Government of India‟s National
Scholarship for Study Abroad‟ (1973-77) that helped
in acquiring advanced knowledge related to LIM
technology from abroad.
MY JOURNEY WITH LINEAR INDUCTION MOTOR 185
Graduate, Post-graduate & Research
Scholars 1977 till date: For assistance in fabricating
LIM powered working models of various applications
to demonstrate principle of LIM propulsion.
References
[1] S. N. Mahendra: Linear oscillating induction
motors, M. Tech. Project under Professor M.
Bhattacharry submitted in Dept of Elect. Engg.,
IT-BHU, 1982
[2] Mahendra, S.N. &Upadhyay, J.:Low-Cost LIM
Propelled Metro System for Indian Cities, Urban
Railways, v 2, Issue II, Nov. 1999, p 15-21.
[3] S.N. Mahendra, and J. Upadhyay, R&D Project
at IT-BHU for Development of LIM Propelled
Rail Metro for Medium Size Indian Cities,8th
World Conference on Transport Research
(WCTR-98), Antwerp, Belgium, July 12-17, 1998.
Special Interest Group (SIG-1): Urban
Development Problems.
[4] S. N. Mahendra, Ayan Das, Shailendra. N
Jaiswal:„Segmented LIM based Passenger
Conveyor System for Circular Route: A Case
Study‟, Research SymposiumUrban Mobility
India (UMI) Conference and Expo, New Delhi,
2013http://www.scribd.com/doc/189741371/Linea
r-Induction-Motor-based-Passenger-Conveyor-
System
[5] S N Mahendra & S Jaiswal,“Linear Induction
Motor Propelled Pms For Closed Loop Circular
Track”, International Conference on Transportation
system studies, IIT Delhi, 1986
[6] Raj Kumar Sinha& Naidu VenkatramanaRao:
„LIM based ropeways‟, B. Tech. Project submitted
under Professor S. N. Mahendra in Dept of Elect.
Engg., IIT (BHU), 2010
[7] Anuj Kumar:„Design and Analysis of Traction
Elevators‟,M. Tech. dissertation submitted under
Professor S. N. Mahendra in Dept of Elect. Engg.,
IIT (BHU), 2013
[8] LakshmareddyDondeti:„Performance analysis of
LIM based ropeway system operating under
various supply conditions‟, M. Tech. dissertation
submitted under Professor S. N. Mahendra in Dept
of Elect. Engg., IIT (BHU), 2011
[9] S. N. Mahendra, LakshmareddyDondeti, U.
Ram GopalVarma: Linear Induction Motor
Based Material Handling Systems for Saving
Clean Energy, IEI International Conference on
“Green Power Generation: Vision 2020”, IEI
Anpara Local Centre, Sonebhadra, Renusagar, 10th
to 12th
December, 2010
[10] S. N. Mahendra: Current & flux distributions,
forces &stiffnesses in Linear Induction
Machines Ph. D. thesis submitted under AJ
Ellision at The City University, London, 1977.
[11] S.N. Mahendra: LIM Based Traction:
Philosophy, Selection, Design-aspects &
Application to Transport Sector, International
Workshop on „LIM Propelled Rail Metro System‟
Department of Electrical Engineering, IT-BHU,
January 8-9, 1999, pA-1 to A21.
[12] S. N. Mahendra, SrihariVelisetti, Kunwar
Aditya: „Implementation of VVVF, CVVF
&CFVV Control Strategies for Control of
LIM‟,IEEE 3rd
International Conference on
Sustainable Energy Technologies (ICSET 2004),
Kathmandu, Nepal, pp 141-145.
[13] Power point presentation of Mr. Masahiro Ando,
P.E. Professional Engineer as Authorized by the
Japanese Government in February 2007 in
Department of Electrical Engineering, IT-BHU,
Varanasi.
186 PRAJÑĀ : Vol. 60, Part-02, Year 2014-15 : Special Issue on "Science & Technology"

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Jan 28, 2016 As printed in Pragya

  • 1.
  • 2. My Journey with Linear Induction Motor Dr. S. N. MAHENDRA* More than 4-decades agoR&D related to Linear Induction Motor based propulsion was started in the Department of Electrical Engineering. Initially it started as a working model for Engineering Models Exhibition.Later the activities covered a range of applications like shuttle-propulsion in power-looms to material-handling to surface/ overhead/underground/ people-mover transportation systems. The applications developed and the R&D activities in chronological order have been as follows: • Shuttle-propulsion for weaving looms (1971-73) [1] • Design & analysis methodologies standardization (1973-97)[11] • Surface-transportsystem (1980 continuing)[3, 12] • Testing-methodologies & test-rigs (1980-87) • Overhead-transportsystems (1983 continuing)[9] • Conveyor-belt/material handling (1986 continuing)[9] • LIM Powered People Mover system for closed-loop circular track for Connaught Place people transport system (1986-2013[4, 5] • Malaviya Center for low cost LIM metro system (1997 continuing)[3, 9, 11] • Independent control of forces of propulsion & attraction (2003 continuing)[12] • LIM powered sieving system for sorting ore near mines (2003 continuing) • LIM based traction elevator for vehicle parking (2012 continuing)[7] • Linear Switched reluctance motor (2014 continuing) • Segmented linear motor based propulsion for circular looms (2014 continuing)[4] The present article is based on the experiences, problems-faced and developments made during the journey of the author with Linear Induction Motor (LIM). The Journey Begins The journey started in an interesting manner during MODEX-70. Professor S. K. Kak, formerVice Chancellor GoutamBudh Technical University, Noida, was the student Convener of the famous Engineering Models Exhibition and I was a member of his core organization team. He asked me tomake and present a model in the exhibition. He was himself heading a huge team of dedicated students in making a working model of Musical Fountain (similar to the first of its type made and exhibited during EXPO-70 in Japan). When I asked him what shouldI make? He suggested me to make a set of U-cores with DC coils which are excited in a sequence such that a horizontal component of the attraction force is produced in the iron plates fixed to the moving member facing the cores resulting innecessary force for linear motion (similar to that inalinear stepper motor). With detailed diagrams and design I met Professor M. Bhattacharrya in the Electrical Machines Lab for his suggestions and advice. He patiently listened to the whole idea and encouraging me (as if I was in the process of inventing something new and great) said „why not give A.C. supply instead of D.C. supply‟. To this I said „Sir, why not provide a 3-phase distributed winding in the core like in an induction motor and energies the three-phases with 3-phase A.C.‟. He just said „Good. Go ahead.‟ Thus unknowingly my journey with Linear Induction Motor (LIM) started. The working model was made and exhibited in room no. F-5 (Rampur Hall) near the first pillar on the left side. Objects of different shapes made of aluminum were shown moving from one end of the core to the other in a linear direction along the length of the core when the winding was energized. I was feeling great as if I have done something really great, till a visitor after seeing the exhibit said that a similar machine was made by Professor E. R. Laithwaite long back. I met Professor Bhattacharryathe next day and asked him „Sir,do you know this fact‟. He coolly said „Yes‟. I was pained (I do not know why) and complained „Sir why did you not tell me this during the first meeting itself so that I would not have exhibited my ignorance and felt embarrassed‟. The words he spoke after this have inspired me and encouraged me during all the development work that I have done and narrated in this article. He said, “If I had told you earlier you would not have experienced in you the ability to create/invent something new. Now you have confidence that you can also think original and may be in future you may make new things”. I can say that this is a true quality of a teacher wherein a teacher not only teaches but creates opportunity in his student to realize the inherent strengths/weaknesses in him/her. His words did come true at many occasions whenever *Professor, Department of Electrical Engineering, IIT (BHU), Varanasi-221005
  • 3. a new machine was made and for all this I give credit to him. Now I will take you along with this journey from 1971 till date highlighting milestones and pitfalls and also the positive effect of a good teacher. Period 1971 to 1972 During this period I continued with development of LIM for shuttle propulsion in power looms as one of the industrialist of Varanasi showed interest and offered to support for development of handloom propelled by LIM. During implementation shortcomings were observed and three modified versions of the system were made as shown in Figs.1-3. Fig. 3 shows a novel geometry conceived and made by the author. It consists of a Single Primary Double Secondary LIM (1972). This was modified later by fitting bearings for movement and lateral guidance of an Overhead transport system. The running-rails apart from mechanical strength to the overhead system also provided return-path for magnetic flux, thusthere was additional requirement of Aluminum Reaction Rail only (1983) and a net saving of backing iron along the length of track which would have been provide otherwise for strengthening the magnetic circuit. Fig.1 Back to back 3-phase LIM for automatic shuttle propulsion (1971) Fig.2 single phase LIM with starting windings at the ends for producing starting force (1972) Fig.3Single Primary Double Secondary LIM (fitted with bearings for movement and lateral guidance of OH transport system) [1972, 1983] The small motor has carried the load of 1-adult/2- children and has application in over-head transport system. The 1972 M. Tech. project report based on the work concluded as follows: “The study of various types of linear oscillating induction motors made has clearly shown the possibility of developing self-oscillating/switch- oscillating linear motors operating on three- phase/single-phase supply systems. The conclusions drawn out by consideration of force/speed characteristics and mathematical analysis of respective machines clearly indicate a definite possibility of developing a method of designing of such machines. It must be realized that the perpetual oscillation of these machines and their constructional features make them one of the most complex of the electromagnetic devices and these are, therefore, not amenable to any simple analytical treatment. Moreover, the basic shortcoming of such machines is the existence of an inherent mechanical friction and the problem of perfect alignment. The ideal arrangement will be one in which the runner moves in air under the influence of electromagnetic field developed in such machines, without touching the stationary member. The above motion must always maintain a constant „air-gap length‟ through its MY JOURNEY WITH LINEAR INDUCTION MOTOR 179
  • 4. length of traverse. Another requirement to make an ideal machine is a long bed of traverse – preferably lying between -∞ and +∞. Although none of the above requirements are practical, they do point towards definite possibility of further development.” Period 1973 to 1978 The concluding remarks of the report were challenging hence I got registered with Professor M. Bhattacharrya in 1973 to work further on this problem. We had long sittings in the Department and in his RajputanaHostel warden quarter. Then one day he said, “Som now the time has come that you go out and get far better environment, facilities and exposure”. This again exhibited the greatnesses of Professor M. Bhattacharrya because normally not many Ph.D. supervisors will tell this to their research scholars. I was bit disturbed but then the „Government of India‟s National Scholarship for Study Abroad‟ award letter indicating that with this scholarship I could go to any part of the world to work in the field of LIM. I was excited and contacted the giants in this subject at that time - Professor E. R. Laithwaite at Imperial College of Science & Technology, London, and through him Professor A. J. Ellision, Head of Electrical Engineering Department, The City University, London, Professor SakaeYammamura of Tokyo University, Japan, and Professor S. A. Nasar of University of Kentucky, USA. I got encouragement and positive response from all three of them. Now came the problem of choosing a country from these three countries for which I got the guidance from Professor R. J. Galgali, Department of Chemistry, BHU – a God gifted person who helped so many in so many ways during his stay in BHU.Based on his analysis and intuition he said „you go to London, the UK - a country which has the roots of the subject and Professor E. R. Laithwaite is known as the father of Linear Induction Motors‟. My correspondences with Professor E. R. Laithwaite, Professor S. A. Nasar, Professor Sakae Yammauraand Professor A. J. Ellisionfor seeking possibility of doing research under them have been a memorable part of my journey with LIM. It is memorable because these correspondences reflect the nature and seriousness which these professors had for the prospective research scholars – and this is essential even now. Excerpts from the lettersof Professor E. R. Laithwaite are given below to show how helpful and considerate he has been in his correspondence. “….All these things are indicative of toils and troubles of a professor at Imperial College. If you were to register for Ph. D. you will be supervised by me, as Dr. Eastham is leaving, and I have already so little time for casual visitors, it would not be fair to ask you to work with me at this time.” April 4, 1973 “….May I first offer you my sincere congratulations on being awarded the National Scholarship for Study Abroad. What I said earlier is still true. It would be unfair for someone like yourself to be under my direct supervision, as my outside commitments are so heavy that it could well be that we will talk to each other only twice a year. However, we have very close ties with City University…..there my personal friend Professor A. J. Ellison is working on linear motors……would be willing to accept you…..and it would mean that you still have access to me, probably for longer than if you worked in my department……….. I hope you will do this and I will have the pleasure of meeting you before the end of this year.” May 17, 1973 The net outcome of the correspondence was that I joined The City University (TCU), London, and after meeting my guide Professor A. J. Ellision I visited Imperial College of Science & Technology, London, to report to Professor E. R. Laithwaite and take his advice and direction for my research in TCU. The few hours meeting was a memorable one as every word of his within a short time had enchanted me with the greatness of linear induction motors as experienced by him. He demonstrated so many working systems he had made to understand „what is induction motor‟ (as he had often repeated during his class lectures that he has not been able to understand what induction is). He also demonstrated his famous transverse flux linear induction motor. I was asked to hold a small „vehicle‟ (with secondary aluminum plate underneath) from one end of the transverse flux linear induction motor primary member and leave it when he tells me. To my surprise the vehicle left by me on the track „flew‟ over the entire length of transverse flux linear induction motor primary member without touching the track or falling sideways due to the presence of electromagnetic forces of levitation and lateral guidance produced in what he called the „magnetic- river‟ created by him. The vehicle was caught by him at the other end. During this meeting Professor Laithwaite also told me not to rush for a quick degree 180 PRAJÑĀ : Vol. 60, Part-02, Year 2014-15 : Special Issue on "Science & Technology"
  • 5. but do a good work. He also told me that it took him seven years to obtain his Ph.D. degree. Perhaps he observed some reaction on my face and reacted immediately, „It‟s not that I did not do much during this period. It got delayed because I did not have time to put all my work in a thesis form.‟ After this I met him many times without any problem, attended his inspiring lectures and watched his BBC Christmas Special Lectures. I remember each and every bit of it. My Stay at the City University, London My guide Professor A. J. Ellision right from day one had been very kind to me and gave me time whenever I wanted to discuss my research progress and take his advice. By nature he was also very friendly and kind to everyone and this quality of his benefitted me a lot as whenever (while meeting a person from universities and industriesin and around London) I told that I am working with Professor A. J. Ellision he/she would offer to help me in my research work in whatever way it was possible for him/her. I was thus able to effectively integrate the rich academic and industrial exposure which I received in the UK and also in European citieswhich I visited with IEE and IEEE Students Travel Scholarships. During one of the initial meetings when I told him that I understand the inputs and outputs of an electromagnetic system but not what is happening in the electromagnetic system. He said do you want to go inside this black-box? Do you have the courage? My reply was „yes‟as I wanted to explore the links between the electrical input and mechanical output of an electromagnetic system. I knew that till I do not understand this I will never be able to effectively design these electromagnetic systems by providing a balance between all the five basic circuits of electromagnetic device viz. electrical, magnetic, mechanical, thermal and dielectric circuits of an electromagnetic system. He gave me green signal. In yet another meeting after about six months when I approached him with a proposal to make circular transverse flux induction motor so that one can test transverse flux induction motor under dynamic conditions (as the set-up at Imperial College of Science & Technology, London, was good for standstill tests only). I had located U-shaped stampings in the Department store and had drawn a diagram also. He patiently listened to me and said „OK you play with this till we finalize your research plan‟. This resulted in development of Basic transverse Flux Circular Motor. When it was shown to the professors of Imperial College of Science & Technology, London, one of them - Professor Freeman - remarked „Oh God this is a missing link between all the electric motors made so far‟. Later BTFCM was placed as an exhibit during IEEE INTERMAG-75 at Imperial College of Science & Technology, London, - the only exhibit from a research scholar as all other exhibits were of senior professors. Through research a link between the electrical inputs and mechanical outputs via magnetic circuit was thoroughly analyzed using the Maxwell‟s equations and Maxwell‟s Second Stress Tensor. The predicted 3- components of flux densities, forces and the performance closely matched with the experimental results obtained from BTFCM under dynamic conditions. The work was appreciated by IEE (UK) through “IEE Student Premium Award‟. Back in BHU1978 onwards – activities & milestones On return I had planned to integrate the knowledge gathered in London to remove the weaknesses of the working system developed before going to London. In achieving this objective the encouragement and support received from Professor G. Rajsekar needs special mention. He, after looking at my thesis, asked me „Can you translate your research into working systems to demonstrate the principle?‟ My reply was in affirmative. I told him that the main difficulty was in the laying of track along which the system has to move. He took this as a challenge and in his own dynamic way persuaded his friend Mr. K. P. Jairam, the then General Manger, DLW, Varanasi, to extend support for making the working system. I am grateful to DLW, its Officers and workers who whole heartedly extended help to make the whole system as it was unconventional in many ways. The 1:15 scale LIM based BHU-DLW surface transport model moving along 33-m oval track was later exhibited number of times in the Railway Pavelion of India International Fairs at Pragati Maidan, New Delhi. Being the only working system of its type in the country, it attracted attention of the visitors including the then Prime Minister of India Shri Rajeev Gandhi who remarked to ShriMadhaoRaoScindia, the then Railway minister that „this could be the future transport system for India‟. Since then a large number of LIM based working systems including a full-scale system carrying MY JOURNEY WITH LINEAR INDUCTION MOTOR 181
  • 6. about 20-adults moving along 65-m meter-gauge track has been made with the help of UG/PG students and financial support from organizations like AICTE. To cut the long story short I willnarrate my journey through photographs and brief description of some of the working systems developed along withtheir usefulness. (a) 1:15 scale LIM based BHU-DLW Surface Transport working System moving along 33m oval track [1981, 2001] Fig 4 ShriDigvijay Singh, Min of State for Railways, Professor YC Simadhari, VC-BHU &Shri O. P. Gupta, GM, DLW, inspecting 15:1 BHU-DLW LIM Surface Transport System [2001] The trolley safely moves along very sharp curves (with about 6-m diameter even at 16kmph) due to the presence of force of attraction between the moving primary iron & the secondary reaction rail. A unique feature of LIM based system in contrast to any other conventional wheel-rail/road systems wherein (with increase in speed) the wheel-rail/road grip becomes poor leading to accidents. The working system effectively bridges the gap between the technology & decision makers as it explains the principle of operation and the inherent advantages easily. (b) LIM based surface transport system for underground metro moving along 65-m meter-gauge track at Malaviya Center for Development of LIM Propelled Rail Metro System: [1997, 1998, 2001] Working system was primarily made to verify the developed design methodology. It also demonstrated the indigenous capabilities developed in the design/fabrication of LIM based systems as per specifications. Fig 5 Trolley with LIM Primary lifted-up to show the underside arrangement Fig 6 Trolley fitted with LIM Primary operating on 65m meter-gauge track &Shri. S.K.Khanna, MEL, IR Board, Shri O. P. Gupta, GM, DLW, &Shri J. Upadhyay, Ex- MEL, IR Board doing foot-plate inspection of the LIM Propelled Rail Metro System Fig 7 ShriDigvijay Singh, Min of State for Railways, Professor Y.C. Simadhari, VC-BHU & Prof. P. C. Upadhyay, Registrar BHU, doing foot-plate inspection [2001] 182 PRAJÑĀ : Vol. 60, Part-02, Year 2014-15 : Special Issue on "Science & Technology"
  • 7. The working system attracted attention of decision makers like the then Minister of State for Railways, present & former Indian Railway Board Members (Elect.). The system also attracted attention of press & TV media and its working along with the Institute R&D has been widely reported by many TV channels including „Imaging Sciences‟ programme of national DD TV. The working system has acted as an effective bridge between the technology and prototype stage for adoption. (c) LIM Powered People Mover system for closed- loop circular track for Connaught Place people transport system. (The moving platform at 5-10 kmph can complete one circle in 15-30 min) [1986, 2013] Fig 8 LIM Powered People Mover system for closed-loop circular track for Connaught Place people transport system The model demonstrates feasibility of integration between metro terminals and other public transport modes as well as the shopping points in city-centers like Connaught Place. The cost analysis has been done and the proposal has been recently presented in two international conferences. International reactions are being received (d) LIM based ropeways in which the rope is stationery [2010, 2011] Made primarily to demonstrate the principle of ropeways in which the rope is stationery and the trolley moves due to linear force produced by LIM mounted on the trolley. Since moving parts are only the wheels on bearings (with no drum/gears connecting to the electric motor or the moving-ropes) the maintenance will be bare minimum. It has provision for remote monitoring and control. The proposal can be implemented in regions where other modes of transport are neither feasible nor economical and the ropeways are the only choice. Fig 9 LIM based ropeways in which the rope is stationery Concluding remarks & suggestion for further work One important thing brought out in this article needs special mention again. The role of teachers like Professor M. Bhattacharrya, Professor G. Rajsekar, Professor E. R. Laithwaite, Professor A. J. Ellison, who had so coolly played their role in shaping me and my work on LIM needs to be appreciated for the fact that the role of a good teacher is the most essentialfactor in shaping the „future-components‟ of the society viz. the Man. The technological developments may assist a teacher but these shall never be able to become a substitute for the qualities of a good teacher. Another point which I would like to highlight here is the international interest shown in LIM activities by countries like Japan. In February 2007 Mr. Masahiro Ando, P.E. Professional Engineer as Authorized by the Japanese Government &Dr. Vijay Kumar Jatiya Funakawa Information & Environment Technology Co. Ltd., Tokyo, and Manager dealing in Business Planning & International Business Operations, visited for discussions for providing an effective solution to the ever-growing MY JOURNEY WITH LINEAR INDUCTION MOTOR 183
  • 8. urban transportation problem in the Indian cities. In Japan the technology has been adopted through a consortium (Japanese Subway Association) approach which included people from Academic/Associations, Subway Operators, Development Components and Administration (supportive organizations). Figures [13] below show the usage up to 2006 and distinct advantages observed by JSA. Copyright © Japan Subway Association. 2007.All rights reserved 6 Number of passengers in Japan ◆ Up to March 2006 since the first introduction in 1990 in Osaka, Japan the Linear Metro systems carried safely more than around 2.2 billion passengers in total. 400 (million passengers / year) 300 200 100 0 330 million 2.2 Billion Passengers (1990~2006) 1990 2000 2006 2010 (year) Copyright © Japan Subway Association. 2007. All rights reserved 10 Merit of Linear Metro Steep gradient Non-adhesion drive allows even inclines of over 60‰ to be negotiated . Copyright © Japan Subway Association. 2007. All rights reserved 11 Merit of Linear Metro Sharp curve The Linear Metro handles sharp curves effortlessly. Quiet,smooth operation,with no squealing. Copyright © Japan Subway Association. 2007. All rights reserved 18 Merit of Linear Metro Conventional subway Comfortable interior Diameter Linear Metro Interior height Floor height Linear motor Small-diameter wheels Reaction plate ◆Lower than a conventional subway car floor height by 30 cm, the Linear Metro uses limited space more effectively. Compact & Comfort On the basis of experiences gathered from linear metros operating in Japan the Japanese have taken a blanket decision to make all future metros in the country Linear Motor based only. Two typical metros in operation in Japan are shown below. Copyright © Japan Subway Association. 2007. All rights reserved 25 Application example1 Osaka City Copyright © Japan Subway Association. 2007. All rights reserved 29 Application example2 Tokyo Metropolitan My presentation in February 2007 was followed by that of Mr. Ando [13] and the two presentations received lot of interest followed by discussion from the audience in the lecture hall as well from the media. Prof. G Rajsekhar, former Dean Faculty of 184 PRAJÑĀ : Vol. 60, Part-02, Year 2014-15 : Special Issue on "Science & Technology"
  • 9. Engineering and Technology and Professor Department Electrical Engineering IT–BHU, traced the history of LIM R&D activities in the Department. He wondered that if the country had implemented the Departmental proposal made in early 80‟s, India would have been leaders in this field by now. He was hopeful that now thevisit of Mr. Ando and Dr. Jatiya will lead to an effective integration of the „rich experience of Japanese Subway Association (JSA) in the implementation of Linear Metro in Japan‟ with the „fundamental LIM based R&D achievements of IT– BHU‟.He was optimistic and confident that jointly the two organizations can provide a solution for the urban transportation problem in India and all over the world. Mr. Ando who is „father of linear metro in Japan‟ appreciated the R&D in BHU and felt a need for exploring the possibility of solving the urban transportation problem in Indian cities through linear metro. There was a general consensus that the Government of India and the Government of Japan may be requested to initiate steps for joint ventures/participation in making Linear Metro based joint project proposals for Indian cities. To start with the first Linear Metro may be made operational in Varanasi as it would be a fitting tribute to Mahamana Pandit Madan Mohan Malaviyaji – the founder of Banaras Hindu University. The other reasons being that: Due to Sarnath many Japanese visit Varanasi and this will help them in moving around comfortably Any activity in Varanasi catches attention the world-over, and The R&D at BHU can be easily integrated. Since then efforts were made at many levels to initiate the activity between Japan and Varanasi but with no success so far. It is expected that with renewed efforts being made with the new ministry at the center wherein Varanasi happens to be the Prime Minister‟s constituency, the proposal may come through. During the years a large number of technologies/working-systems have been developed and are ready for adoption by the user industries. These are: a. LIM powered systems for: (i) Overhead/Underground/Surface transportation, (ii) Material Handling, (iii) Ropeways in which the rope does not move, (iv) Vertical elevators for vehicle parking, (v) People mover system for Connaught Place b. Control strategies for energy saving in LIM based systems including independent control of propulsion & attraction forces produced c. Handloom for visually handicapped. Journey with a subject never ends. People/researchers may change but so far as the R&D in the subject is concerned it continues and I have all hope that this will happen in our Department also. In this regard it is worthwhile now to explore the possibility of industry/academic-institution participation for further development and effective absorption of Linear Induction Motor (LIM) based systems which have been developed & tested in the Department. Acknowledgement Following individuals & Agencies support is gratefully acknowledged: MHRD/AICTE 1994-2000: For R&D Grants to develop LIM propelled transport system operating with 15-adult load on a 65-m meter-gauge track for demonstrating the technical feasibility Prof. Hari Gautam 1996(the then VC BHU & later Chairman UGC): For supporting creation of Malaviya Centre for “Development and Evaluation of Low Cost LIM Propelled Rail Metro System” in IT-BHU. Shri Jagdish Upadhyay 1994-2000(Former Member Electrical Railway Board, Visiting Professor & Advisor AICTE project entitled LIM Propelled Rail Metro System): For giving a practical shape to LIM traction R&D activities and projecting it for its adoption in India. Professor M. Bhattacharrya (since 1973) for starting my journey with LIM and Professor G. Rajsekar (since 1977) for providing the necessary thrust which was a great helped in making of BHU- DLW model that helped in bridging the gap between the technology and the decision makers. „Government of India‟s National Scholarship for Study Abroad‟ (1973-77) that helped in acquiring advanced knowledge related to LIM technology from abroad. MY JOURNEY WITH LINEAR INDUCTION MOTOR 185
  • 10. Graduate, Post-graduate & Research Scholars 1977 till date: For assistance in fabricating LIM powered working models of various applications to demonstrate principle of LIM propulsion. References [1] S. N. Mahendra: Linear oscillating induction motors, M. Tech. Project under Professor M. Bhattacharry submitted in Dept of Elect. Engg., IT-BHU, 1982 [2] Mahendra, S.N. &Upadhyay, J.:Low-Cost LIM Propelled Metro System for Indian Cities, Urban Railways, v 2, Issue II, Nov. 1999, p 15-21. [3] S.N. Mahendra, and J. Upadhyay, R&D Project at IT-BHU for Development of LIM Propelled Rail Metro for Medium Size Indian Cities,8th World Conference on Transport Research (WCTR-98), Antwerp, Belgium, July 12-17, 1998. Special Interest Group (SIG-1): Urban Development Problems. [4] S. N. Mahendra, Ayan Das, Shailendra. N Jaiswal:„Segmented LIM based Passenger Conveyor System for Circular Route: A Case Study‟, Research SymposiumUrban Mobility India (UMI) Conference and Expo, New Delhi, 2013http://www.scribd.com/doc/189741371/Linea r-Induction-Motor-based-Passenger-Conveyor- System [5] S N Mahendra & S Jaiswal,“Linear Induction Motor Propelled Pms For Closed Loop Circular Track”, International Conference on Transportation system studies, IIT Delhi, 1986 [6] Raj Kumar Sinha& Naidu VenkatramanaRao: „LIM based ropeways‟, B. Tech. Project submitted under Professor S. N. Mahendra in Dept of Elect. Engg., IIT (BHU), 2010 [7] Anuj Kumar:„Design and Analysis of Traction Elevators‟,M. Tech. dissertation submitted under Professor S. N. Mahendra in Dept of Elect. Engg., IIT (BHU), 2013 [8] LakshmareddyDondeti:„Performance analysis of LIM based ropeway system operating under various supply conditions‟, M. Tech. dissertation submitted under Professor S. N. Mahendra in Dept of Elect. Engg., IIT (BHU), 2011 [9] S. N. Mahendra, LakshmareddyDondeti, U. Ram GopalVarma: Linear Induction Motor Based Material Handling Systems for Saving Clean Energy, IEI International Conference on “Green Power Generation: Vision 2020”, IEI Anpara Local Centre, Sonebhadra, Renusagar, 10th to 12th December, 2010 [10] S. N. Mahendra: Current & flux distributions, forces &stiffnesses in Linear Induction Machines Ph. D. thesis submitted under AJ Ellision at The City University, London, 1977. [11] S.N. Mahendra: LIM Based Traction: Philosophy, Selection, Design-aspects & Application to Transport Sector, International Workshop on „LIM Propelled Rail Metro System‟ Department of Electrical Engineering, IT-BHU, January 8-9, 1999, pA-1 to A21. [12] S. N. Mahendra, SrihariVelisetti, Kunwar Aditya: „Implementation of VVVF, CVVF &CFVV Control Strategies for Control of LIM‟,IEEE 3rd International Conference on Sustainable Energy Technologies (ICSET 2004), Kathmandu, Nepal, pp 141-145. [13] Power point presentation of Mr. Masahiro Ando, P.E. Professional Engineer as Authorized by the Japanese Government in February 2007 in Department of Electrical Engineering, IT-BHU, Varanasi. 186 PRAJÑĀ : Vol. 60, Part-02, Year 2014-15 : Special Issue on "Science & Technology"