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MAM SCHOOL OF ENGINEERING trichy, WARD-LEONARD CONTROL
MAM SCHOOL OF ENGINEERING trichy, WARD-LEONARD CONTROL
Published: 2017/01/12
Channel: MAM SCHOOL OF ENGINEERING trichy
Ward Leonard Operation
Ward Leonard Operation
Published: 2015/12/11
Channel: macgeorge
Ward Leonard 2,000 HP AC Induction Motor Video
Ward Leonard 2,000 HP AC Induction Motor Video
Published: 2016/09/29
Channel: Info Terkini
Speed Control of DC Motor
Speed Control of DC Motor
Published: 2016/05/02
Channel: sumit maitra
Ward Leonard - Excellence in Motor & Control Solutions
Ward Leonard - Excellence in Motor & Control Solutions
Published: 2014/01/23
Channel: Ward Leonard
Ward leonard method
Ward leonard method
Published: 2015/10/23
Channel: borisagar sameer
Schindler Ward Leonard gearless machines with Aconic controllers
Schindler Ward Leonard gearless machines with Aconic controllers
Published: 2011/01/13
Channel: joris3842
Speed control of Electrical Drives Lecture, BTech by Ms. Apoorva Gupta.
Speed control of Electrical Drives Lecture, BTech by Ms. Apoorva Gupta.
Published: 2013/07/19
Channel: Guru Kpo
15112012034 grupo ward leonard
15112012034 grupo ward leonard
Published: 2013/02/07
Channel: CELESTINOJOSEGARCIA
Dicky Eklund ward knocks down Sugar Ray Leonard the fighter real !!!
Dicky Eklund ward knocks down Sugar Ray Leonard the fighter real !!!
Published: 2011/01/02
Channel: Living the Dream
High Power Density AC Drilling Motors from Ward Leonard
High Power Density AC Drilling Motors from Ward Leonard
Published: 2015/05/18
Channel: Ward Leonard
Who control the American military? Who owns their allegience? Who
Who control the American military? Who owns their allegience? Who's order have priority?
Published: 2012/06/21
Channel: TargetedSalesPitch
Speed control of DC shunt motor
Speed control of DC shunt motor
Published: 2016/05/18
Channel: Sanjeev Jamge
Mod-01 Lec-32 Lecture-32-Speed Control of DC Shunt Motors
Mod-01 Lec-32 Lecture-32-Speed Control of DC Shunt Motors
Published: 2012/07/11
Channel: nptelhrd
Otis 1970
Otis 1970's Highspeed, Gearless, relay controlled Elevators (A semi showcase + cheeky manual call)
Published: 2011/05/18
Channel: produKtNZ
Ward Leonard 01
Ward Leonard 01
Published: 2011/04/07
Channel: Pablo singh
Ward Leonard Varistat Dimmer
Ward Leonard Varistat Dimmer
Published: 2012/06/15
Channel: general0ne
wardleonard method part 1
wardleonard method part 1
Published: 2017/02/10
Channel: ishwar nakum
Lec-6 DC Motor Speed Control
Lec-6 DC Motor Speed Control
Published: 2008/08/25
Channel: nptelhrd
Ward Leonard Dyno Testing
Ward Leonard Dyno Testing
Published: 2016/04/28
Channel: Ward Leonard
Speed Control of Dc Motor
Speed Control of Dc Motor
Published: 2015/11/27
Channel: NewTrendZ
Conexion Ward leonard... sencillamente explicado
Conexion Ward leonard... sencillamente explicado
Published: 2013/07/17
Channel: Facundo Bragaioli Servetto
Ward Churchill Interview on Leonard Peltier
Ward Churchill Interview on Leonard Peltier
Published: 2012/06/25
Channel: The Film Archives
SPEED CONTROL OF DC SHUNT MOTOR BY DR.SURESH.S/KIT/CBE
SPEED CONTROL OF DC SHUNT MOTOR BY DR.SURESH.S/KIT/CBE
Published: 2017/01/30
Channel: suresh seetharaman
Lecture - 16 Dc Motor Speed Control - Introduction
Lecture - 16 Dc Motor Speed Control - Introduction
Published: 2008/04/17
Channel: nptelhrd
DC Motor, How it works?
DC Motor, How it works?
Published: 2014/09/23
Channel: Learn Engineering
MIKE TYSON ANGRY!
MIKE TYSON ANGRY!
Published: 2013/12/30
Channel: mikschumans
Ward Leonard MotorCare™
Ward Leonard MotorCare™
Published: 2015/05/15
Channel: Ward Leonard
SPEED CONTROL OF DC SHUNT MOTOR
SPEED CONTROL OF DC SHUNT MOTOR
Published: 2016/12/13
Channel: Rajasekar M
TO STUDY THE SPEED CONTROL OF D C  SHUNT MOTOR
TO STUDY THE SPEED CONTROL OF D C SHUNT MOTOR
Published: 2014/06/20
Channel: Ambalika Institute Of Management & Technology
speed control of dc shunt motor
speed control of dc shunt motor
Published: 2017/05/09
Channel: tarequlislam tarek
speed control of dc shunt motor - description in hindi
speed control of dc shunt motor - description in hindi
Published: 2016/10/24
Channel: Anmol Parasar
Ward Leonard 02
Ward Leonard 02
Published: 2011/04/07
Channel: Pablo singh
2003 Cedar Fire - Movie made by David Russell
2003 Cedar Fire - Movie made by David Russell
Published: 2010/09/18
Channel: Jim F
Ward Leonard  DynoTesting
Ward Leonard DynoTesting
Published: 2015/07/10
Channel: Patagonia Consult SRL
Aufzug Antrieb  Ward Leonard
Aufzug Antrieb Ward Leonard
Published: 2013/11/11
Channel: Oliver Hötzel
L
L'Étoile - Ward Leonard - Live Festival Montereau Confluences 2014
Published: 2014/06/12
Channel: Ward Leonard
Ward Churchill Interview on Leonard Peltier
Ward Churchill Interview on Leonard Peltier
Published: 2016/06/26
Channel: Sven Peters
SPEED CONTROL OF DC SHUNT MOTOR
SPEED CONTROL OF DC SHUNT MOTOR
Published: 2016/05/28
Channel: Atish Peshattiwar
speed control of dc motor using scr triggered by ujt
speed control of dc motor using scr triggered by ujt
Published: 2015/10/08
Channel: Lightening vipra
Lecture 6: DC motor Control Dr. Omar Elobidy @PSUT.
Lecture 6: DC motor Control Dr. Omar Elobidy @PSUT.
Published: 2017/03/02
Channel: PSUT University Official Channel
Ward Leonard - Paroles en l
Ward Leonard - Paroles en l'air - live - Montereau Confluences 2012
Published: 2012/10/11
Channel: Ward Leonard
Ward Leonard - Tout se barre (Live au "Le cri de la betterave")
Ward Leonard - Tout se barre (Live au "Le cri de la betterave")
Published: 2016/12/25
Channel: L'armée des ombres
Electrical Machines & Industrial Automation Realistic Interview, or Viva Voce
Electrical Machines & Industrial Automation Realistic Interview, or Viva Voce
Published: 2016/11/01
Channel: EspoirLive
Production Engineering Mock Interview 10 of 28
Production Engineering Mock Interview 10 of 28
Published: 2017/02/28
Channel: EspoirLive
Гейнер до и после в домашних условиях своими руками, или протеин как принимать для набора массы
Гейнер до и после в домашних условиях своими руками, или протеин как принимать для набора массы
Published: 2015/03/06
Channel: ПРОКАЧКА
Funicular Mountain Tram Elevator in Prague of Europe
Funicular Mountain Tram Elevator in Prague of Europe
Published: 2014/01/14
Channel: epSos.de
Ward Leonard
Ward Leonard
Published: 2017/02/04
Channel: Manuel Ludueña
House - Broken, Part 2
House - Broken, Part 2
Published: 2012/08/17
Channel: NBCUniversalShows
House - Broken, Part 1
House - Broken, Part 1
Published: 2012/08/17
Channel: NBCUniversalShows
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WIKIPEDIA ARTICLE

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Ward Leonard Control, also known as the Ward Leonard Drive System, was a widely used DC motor speed control system introduced by Harry Ward Leonard in 1891. In early 1900s, the control system of Ward Leonard was adopted by the U.S. Navy and also used in passenger lift of large mines. It also provided a solution to a moving sidewalk at the Paris Exposition of 1900, where many others had failed to operate properly.[citation needed] It was applied to railway locomotives used in World War I, and was used in anti-aircraft radars in World War II. Connected to automatic anti-aircraft gun directors, the tracking motion in two dimensions had to be extremely smooth and precise. The MIT Radiation Laboratory selected Ward-Leonard to equip the famous radar SCR-584 in 1942. The Ward Leonard control system was widely used for elevators until thyristor drives became available in the 1980s, because it offered smooth speed control and consistent torque. Many Ward Leonard control systems and variations on them remain in use.[1]

Basic concept[edit]

The key feature of the Ward Leonard control system is the ability to smoothly vary the speed of a DC motor, including reversing it, by controlling the field windings and hence the output voltage of a DC generator. As the speed of a DC motor is dictated by the supplied voltage, this gives simple speed control. The DC generator could be driven by any means, provided that also supplied a voltage source for the field windings. This 'prime mover' could be an AC motor, or it could be an internal combustion engine (its application to vehicles was patented by H.W. Leonard in 1903[2]).

A Ward Leonard drive can be viewed as a high-power amplifier in the multi-kilowatt range, built from rotating electrical machinery. Where the 'prime mover' is electrical, a Ward Leonard drive unit consists of a motor and generator with shafts coupled together. The prime mover, which turns at a constant speed, may be AC or DC powered. The generator is a DC generator, with field windings and armature windings. The input to the amplifier is applied to the field windings, and the higher power output comes from the armature windings. (See Excitation (magnetic)#Amplifier principle for how a generator can act as an amplifier.) The amplifier output is usually connected to a second motor, which moves the load, such as an elevator. With this arrangement, small changes in current applied to the input, and thus the generator field, result in large changes in the output, allowing smooth speed control.[3]

A flywheel may be used to reduce voltage fluctuations during sudden load changes. The Ward Leonard system with this modification is known as Ward Leonard Ilgner Control.[4]

A more technical description[edit]

A Ward Leonard Control system with generator and motor connected directly.

The speed of a DC motor is controlled by varying the voltage fed to the generator field windings, Vgf, which varies the output voltage of the generator. The varied output voltage will change the voltage of the motor, since they are connected directly through the armature. Consequently, changing the Vgf will control the speed of the motor. The picture on the right shows the Ward Leonard control system, with the Vgf feeding the generator and Vmf feeding the motor.[5]

Transfer function[edit]

The first subscripts 'g' and 'm' each represents generator and motor. The superscripts 'f', 'r',and 'a', correspond to field, rotor, and armature.

  • = plant state vector
  • = gain
  • = time constant
  • = polar moment of inertia
  • = angular viscous friction
  • = rotational inductance constant
  • = Laplace operator

Eq. 1: The generator field equation

Eq. 2: The equation of electrical equilibrium in the armature circuit

Eq. 3: Motor torque equation

With total impedance, , neglected, the transfer function can be obtained by solving eq 3 .

Eq. 4: Transfer function

[5]

with the constants defined as below:

See also[edit]

References[edit]

Citations
  1. ^ Kulkarni, A.B. (Oct 2000). "Energy consumption analysis for geared elevator modernization: upgrade from DC Ward Leonard system to AC vector controlled drive". Conference Record of the 2000 IEEE Industry Applications Conference. 4. Institute of Electrical and Electronics Engineers. pp. 2066–2070. 
  2. ^ "Electrically propelled Vehicle", H.W. Leonard, US Patent 1121382, originally filed March, 1903
  3. ^ Shinners, Stanley M (1998). Modern Control System Theory. Wiley and Sons. p. 202. ISBN 978-0471249061. 
  4. ^ Rajput, R.K. (2005). Basic Electrical Engineering. Laxmi Publications Pvt Limited. p. 571. ISBN 9788170081203. Retrieved 2014-06-14. 
  5. ^ a b Datta, A.K. (1973). "Computerless optimal control of Ward Leonard drive system". International Journal of Systems Science. 4 (4): 671–678. doi:10.1080/00207727308920047. 
General references
  • The Editors (Nov 1989). "Technology for Electrical Components". Power Transmission Design: 25–27. 
  • Ward Leonard, H. (1896). "Volts versus ohms - the speed regulation of electric motors". AIEE Trans. 13: 375–384. 
  • Gottlieb, I.M. (1994). "Electric Motors & Control Techniques 2nd Edition". TAB Books. 
  • Malcolm Barnes (2003). Practical Variable Speed Drives and Power Electronics. Oxford: Newnes. pp. 20–21. ISBN 978-0-7506-5808-9. 

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