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Ward Leonard 01
Ward Leonard 01
::2011/04/07::
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Ward Leonard Corporate
Ward Leonard Corporate
::2013/04/30::
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Ward Leonard Varistat Dimmer
Ward Leonard Varistat Dimmer
::2012/06/15::
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WARD LEONARD - Allons enfants @ Tous en Seine
WARD LEONARD - Allons enfants @ Tous en Seine
::2012/03/29::
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Barbe Rousse Chante Les Ward Leonard
Barbe Rousse Chante Les Ward Leonard
::2007/02/03::
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Schindler Ward Leonard gearless machines with Aconic controllers
Schindler Ward Leonard gearless machines with Aconic controllers
::2011/01/13::
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Ward Leonard - Allons Enfants - Rock
Ward Leonard - Allons Enfants - Rock
::2012/02/28::
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Lecture - 21 DC Motor Speed Control Controller Design 3
Lecture - 21 DC Motor Speed Control Controller Design 3
::2008/04/03::
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Ward Léonard : Présentation + Intro + Les Costards (Live Montereau Confluence 2012)
Ward Léonard : Présentation + Intro + Les Costards (Live Montereau Confluence 2012)
::2012/06/10::
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Aufzug Antrieb  Ward Leonard
Aufzug Antrieb Ward Leonard
::2013/11/11::
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Ward Leonard - Paroles en l
Ward Leonard - Paroles en l'air - live - Montereau Confluences 2012
::2012/10/11::
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Ward Leonard - La Ruelle des Morts (Hubert-Félix Thiefaine cover).
Ward Leonard - La Ruelle des Morts (Hubert-Félix Thiefaine cover).
::2013/08/12::
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Conexion Ward leonard... sencillamente explicado
Conexion Ward leonard... sencillamente explicado
::2013/07/17::
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Dicky Eklund ward knocks down Sugar Ray Leonard the fighter real !!!
Dicky Eklund ward knocks down Sugar Ray Leonard the fighter real !!!
::2011/01/02::
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Ward Léonard : L
Ward Léonard : L'Étoile (Live Montereau Confluence 2012)
::2012/06/10::
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lecture(13):motor protection.WMV
lecture(13):motor protection.WMV
::2011/11/18::
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Ward Leonard 02
Ward Leonard 02
::2011/04/07::
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Mais qu
Mais qu'est-ce qu'il fout ? - Ward Leonard
::2012/02/08::
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Funicular Mountain Tram Elevator in Prague of Europe
Funicular Mountain Tram Elevator in Prague of Europe
::2014/01/14::
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Ward Churchill Interview on Leonard Peltier
Ward Churchill Interview on Leonard Peltier
::2012/06/25::
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Sugar Ray Leonard vs Dick Ecklund Part 1 of 4
Sugar Ray Leonard vs Dick Ecklund Part 1 of 4
::2013/01/29::
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BOXING Micky Ward VS Alfonso Sanchez Round 7
BOXING Micky Ward VS Alfonso Sanchez Round 7
::2010/12/04::
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First Days with Monarch 10ee made in USA   Chinese- rejected part#1
First Days with Monarch 10ee made in USA Chinese- rejected part#1
::2012/12/09::
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Sugar Ray Leonard vs Dick Eklund
Sugar Ray Leonard vs Dick Eklund
::2013/01/29::
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Ward Léonard - Tête de fou
Ward Léonard - Tête de fou
::2010/03/20::
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Legendary Nights Sugar Ray Leonard vs Thomas Hagler The Super Fight
Legendary Nights Sugar Ray Leonard vs Thomas Hagler The Super Fight
::2013/11/30::
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Sta Ge Hellas Lift Control Panel - Smart
Sta Ge Hellas Lift Control Panel - Smart
::2009/03/02::
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Danube Tower Elevator
Danube Tower Elevator
::2009/04/09::
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Sugar Ray Leonard vs Thomas Hearns II
Sugar Ray Leonard vs Thomas Hearns II
::2013/01/29::
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Sugar Ray Leonard vs Dick Ecklund Part 3 of 4
Sugar Ray Leonard vs Dick Ecklund Part 3 of 4
::2013/01/29::
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The Big Bankers Never Lose: Control Over Money and the Federal Reserve Ron Paul
The Big Bankers Never Lose: Control Over Money and the Federal Reserve Ron Paul
::2014/04/14::
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The God That Failed Transition and Control of the Public Mind Noam Chomsky
The God That Failed Transition and Control of the Public Mind Noam Chomsky
::2014/04/14::
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BluesTune: Mark Leonard & Bill Champlin, Bruce Gaitsch, B. Ward
BluesTune: Mark Leonard & Bill Champlin, Bruce Gaitsch, B. Ward
::2011/04/16::
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Leonard Luizzi hopes for a seat in the 5th Ward Council of Hoboken
Leonard Luizzi hopes for a seat in the 5th Ward Council of Hoboken
::2011/04/22::
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Dialog with Gun Appreciation Day founder Larry Ward
Dialog with Gun Appreciation Day founder Larry Ward
::2012/12/23::
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KLEEMAN HYDRAULISCHE AUFZUGE with MOTION CONTROLLER
KLEEMAN HYDRAULISCHE AUFZUGE with MOTION CONTROLLER
::2011/04/29::
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JACK WHITE & ALICIA KEYS - Another Way to Die (Drum Cover by Jeremy Barthelemy)
JACK WHITE & ALICIA KEYS - Another Way to Die (Drum Cover by Jeremy Barthelemy)
::2012/10/20::
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ANCIENT BIBLE CODES: DNA and Bio Spiritual Warfare - 4-HOUR MOVIE MARATHON
ANCIENT BIBLE CODES: DNA and Bio Spiritual Warfare - 4-HOUR MOVIE MARATHON
::2013/10/09::
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ANDRE WARD NO FIGHTS IN 2014? PROMOTER GOOSSEN BEEF DESTROYING P4P CAREER LEGACY! CHAVEZ JR GGG?
ANDRE WARD NO FIGHTS IN 2014? PROMOTER GOOSSEN BEEF DESTROYING P4P CAREER LEGACY! CHAVEZ JR GGG?
::2014/03/06::
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Side Control Escape Far Side Arm Isolated
Side Control Escape Far Side Arm Isolated
::2014/04/04::
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Former NFL stars Tony Dorsett, Leonard Marshall, Joe DeLameilleure show indicators of CTE resulting
Former NFL stars Tony Dorsett, Leonard Marshall, Joe DeLameilleure show indicators of CTE resulting
::2013/11/07::
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Granville Taylor Woods Patent No 373383 Video Segment 3
Granville Taylor Woods Patent No 373383 Video Segment 3
::2012/01/02::
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2011, Retour en Images
2011, Retour en Images
::2012/01/04::
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DDR Aufzug Schachtfahrt
DDR Aufzug Schachtfahrt
::2014/02/02::
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What Is It Like to Work for the CIA?
What Is It Like to Work for the CIA?
::2014/04/14::
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Doing Time: The Politics of Imprisonment - Lecture by Ward Churchill (Part 1)
Doing Time: The Politics of Imprisonment - Lecture by Ward Churchill (Part 1)
::2011/06/02::
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HON Ward And Counter Warding Guide for 1650-1750 part 1 of 2
HON Ward And Counter Warding Guide for 1650-1750 part 1 of 2
::2011/03/29::
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Sugar Ray Leonard vs Dick Ecklund Part 2 of 4
Sugar Ray Leonard vs Dick Ecklund Part 2 of 4
::2013/01/29::
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TOP SIDE CONTROL Paper Cutter Choke with Matt Andrews
TOP SIDE CONTROL Paper Cutter Choke with Matt Andrews
::2014/04/04::
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Tiro Interviews ref Jack Rees on Ward/Rodriguez
Tiro Interviews ref Jack Rees on Ward/Rodriguez
::2013/11/17::
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From Wikipedia, the free encyclopedia
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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] An outstanding contribution to the war effort was the use of Ward-Leonard Control systems in antiaircraft radars. 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]

A Ward Leonard drive is a high-power amplifier in the multi-kilowatt range, built from rotating electrical machinery. A Ward Leonard drive unit consists of a motor and generator with shafts coupled together. The motor, 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.[2]

A more technical description[edit]

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

The speed of motor is controlled by varying the voltage fed to the generator, 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 of the right shows the Ward Leonard control system, with the Vgf feeding the generator and Vmf feeding the motor.[3]

Mathematical approach[edit]

Among many ways of defining the characteristic of a system, obtaining a transfer characteristic is one of the most commonly used methods. Below are the steps to obtain the transfer function, eq. 4.

Before going into the equations, first conventions should be set up, which will follow the convention data used. The first subscripts 'g' and 'm' each represents generator and motor. The superscripts 'f', 'r',and 'a', correspond to field, rotor, and armature.

  • W_i = plant state vector
  • K = gain
  • t = time constant
  • J = polar moment of inertia
  • D = angular viscous friction
  • G = rotational inductance constant
  • s = Laplace operator

Eq. 1: The generator field equation

V_g^f = R_g^f I_g^f + L_g^f I_g^f

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

-G_g^fa I_g^f W_g^r + (R_g^a + R_m^a) I^a + (L_g^a + L_m^a) I^a + G_m^fa I_m^f W_m^r = 0

Eq. 3: Motor torque equation

-T_L = J_m W_m^r + D_mW_m^r

With total impedance, L_g^a + L_m^a, neglected, the transfer function can be obtained by solving eq 3 T_L = 0.

Eq. 4: Transfer function

\frac{W_m^r(S)}{V_g^f(S)} = \cfrac{K_BK_v/D_m}{\left(t_g^fs + 1\right)\left(t_ms + \frac{K_m}{D_m}\right)}[3]

with the constants defined as below:

K_B = \frac{G_m^fa V_m^f}{R_m^f(R_g^a + R_m^a)}
K_v = \frac{G_g^fa W_g^r}{R_g^f}
t_m = \frac{J_m}{D_m}
t_g^f = \frac{L_g^f}{R_g^f}
K_m = D_m + K_B^2(R_g^a + R_m^a)

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. ^ Shinners, Stanley M (1998). Modern Control System Theory. Wiley and Sons. p. 202. ISBN 978-0471249061. 
  3. ^ 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
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