In this system, m is the main dc motor whose speed is to be controlled, and g is a separately excited dc generator. But its cost is high, more losses and less efficiency. The motor, which turns at a constant speed, may be ac or dc powered. The field winding of this motor is permanently connected to d. Explain with neat circuit diagram the star delta starter. Closedloop control application for a wardleonard block c98a7066a511027619, 0620 5 4 selection of the components. The 4q version is required to obtain both polarities in the generator voltage. Why is stator voltage control suitable for speed control of induction motor in fan and pump drives. Why is a slip power recovery scheme suitable mainly for drives with a low speed. The ward leonard system provides an alternative control method to expensive and complex systems used today. Remote access and speed control of dc motor using ward leonard system abstract. Ac ward leonard drive systems illinois institute of.
Limited resources and requirement of regular maintenance of equipment in traditional laboratory supports idea of webaccessible laboratories which provides facility of online experimentation on real processes. M2 is the motor, it controls the speed of the generator. The system is made up of a driving motor which runs at almost constant speed and powers a dc generator as shown in the diagram. Ward leonard system of speed control works on this principle of armature voltage control. Today, you will find our products installed on virtually every surface and subsurface ship in the us navy. The armature of the dc generator is connected directly to tharmature of a dc motor, the dc motor drives the load equipment at an adjustable speed the motor. Speed control in dc motors was obtained by means of voltage control first in 1981 by ward leonard 1. Modeling of the thyristor controlled rectifiers for control of ward. Wardleonard speedcontrol system article about ward. The arrangement of this system is as required in the figure shown below. The connection diagram of the ward leonard method of speed control of a dc shunt motor is shown in the figure below. This control system is consisting of a dc motor m 1 and powered by a dc generator g. Ward leonard method of speed control electric motor electric.
Wardleonard method of speed control electrical concepts. Where the prime mover is electrical, a ward leonard drive unit consists of a motor and generator with shafts coupled together. A ward leonard drive system consists of a motor prime mover and a generator with shafts coupled together. As a very flexible, reliable means of motor speed control, the ward leonard speed control system is unmatched.
We usually use ward leonard method of speed control in. Speed control of dc motor dc motor speed control youtube. In this method the speed of the dc motor m 1 is controlled by applying variable voltage across its armature. Ward leonard method of speed control is used for controlling the speed of a the from psychology psych101 at high school summer program. 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.
The ward leonard method of dc variable speed control continued until the late 1960s when. In this paper, a control algorithm is proposed for ac drives without a speed sensor, building upon the idea of ac ward leonard drive systems developed recently. Currently famous and most frequent type of controller used in many industries is pid controller 2,3, but due to some hindrances, they face. By changing the injected voltage, the resistance and speed of an induction motor are controlled. Sinamics dcm for generator field the sinamics dcm for the generator field should be a 4q device. This project aims at achieving smooth speed control of dc motor in wide range of application. Closedloop control application for a wardleonard block. Speed control of dc series and shunt motorsarmature and field control, ward leonard control systemusing controlled rectifiers and dc choppers applications. Speed control methods of dc motor shunt, series motors. Ward leonard method of speed control is used for controlling the speed of a dc motor. The speed of a dc motor is controlled by varying the voltage fed to the generator field windings, v gf.
We can use thyristors controlled rectifier or converters. M1 is the main motor whose speed control is required. Ward leonard method of speed control is used for controlling the. Many ward leonard control systems and variations on them remain in use. At this meeting a wide range of papers on electric circuit theory, on power.
In the old days, a ward leonard system applied and used for the speed control of dc shunt electric motors was quite convenient to obtain a variety of speeds and reversing for industrial applications. The system is made up of a driving motor which runs at almost constant speed and powers a d. Ward leonard system of speed control your electrical home. The connection diagram of the ward leonard method of speed control. Pdf an investigation of the ward leonard system for use in a.
This method eliminates the need for series armature starting resistance. Metode speed control ini, dikenal sebagai sistem ward leonard, ditemukan di pabrik baja steel mills, lift bertingkat, pertambangan, dan pabrik kertas. As shown in the figure above, m is separately excited dc motor whose speed is to be controlled and g is separately excited dc generator driven by a three phase ac driving motor. Military electrical products and services ward leonard. A system for controlling the speed of a directcurrent motor in which the armature voltage of a separately excited directcurrent motor is controlled by a. Dalam instalasi modern, generator sering digantikan dengan highpower electronic converter yang mengubah ac power dari listrik ke dc. The ward leonard control system was widely used for elevators until thyristor drives became available in the 1. Wardleonard speed control as a very flexible, reliable means of motor speed control the wardleonard system is unmatched. Digital ward leonard speed control is operated with two pid.
By varying the generator field current, its output voltage will. This is also called scalar control because only the amplitude of the voltage is controlled. Describe the working of 3 point starter for dc shunt motor with neat diagram. Mention some of the drawbacks of conventional ward leonard scheme over static ward leonard scheme. Speed control of dc motor dc motor speed control speed control methods of a dc motor can be varied by varying flux, armature resistance or applied voltage. This system is used where an unusually wide and very sensitive speed control is required as for colliery winders, electric excavators, elevators and the main drives in steel mills and blooming and paper mills.
This ward leonard system is used where very sensitive speed control of the motor is required e. In ward leonard system, a prime mover drives a direct current dc generator at a constant speed. Ward leonard method of speed control of dc motor uses a motor generator set. Ward leonard specializes in the provision of stateoftheart motor, control, component and systems integration solutions for customers worldwide. The injected voltage increases the resistance of the rotor, thus controlled the speed of the motor. The speed of a dc motor is controlled by varying the voltage fed to the generator field windings, v gf, which varies the output voltage of the generator. Explain ward leonard method of speed control in dc motors. Ward leonard method of speed control is achieved by varying the applied voltage to the armature. Ward leonard speed control pdf documents a ward leonard drive can be viewed as a high power amplifier in the multi kilowatt range, built from rotating electrical machinery. The static kramerdrive is the method of controlling the speed of an induction motor by injecting the oppositephase voltage in the rotor circuit. In a control system of the ward leonard type, a leonard generator, a counter voltage machine in series with the field of said generator across a constant voltage slightly higher than the maximum voltage of said machine, a shunt motor driving the counter voltage machine at constant speed, means for manually switching in the said shunt motor.
The classical scheme of dc motor control developed by ward leonard. Wardleonard motor speed control system for ships machinery operation motor speed control. Draw and explain the mechanical characteristics of dc series and shunt motor. Ward leonard control system is introduced by henry ward leonard in 1891. Ward leonard method of speed control or armature voltage control. Ward leonard method of speed control free download as pdf file. Ward leonard drive systems, also known as ward leonard control, were widely used dc motor speed control systems introduced by harry ward leonard in 1891.
Abstract variable speed drive technology has advanced dramatically in the last 10 years with the advent of new power devices and. Find out information about wardleonard speedcontrol system. In early 1900s, the control system of ward leonard was adopted by the u. The ward leonard method of dc variable speed control continued until the late 1960s when electric regulator company brought to market a practical, general purpose, static, solid state controller that converted the ac line directly to rectified dc using scr. Explain with neat circuit diagram the star delta starter method of starting from ee 1205 at indian institute of technology, chennai. What links here related changes upload file special pages permanent link page information. Diesellocomotives, and so on where we require a very wide and sensitive speed control of dc motor in both directions of rotation. Ward leonard method of speed control or armature voltage.
Productsservices for ward leonard method of speed control speed controls 57 companies speed controls, including speed regulators and rate controllers, are used to decelerate and regulate the speed of loads such as moving carriages and machining feeds near the end of their travel. Ward leonard loop fundamental construction ac synchronous motor cemf emf k x i f speed k x cemf if. Loop current balance and setting electrical neutral dc machines ac method. Navy and also used in passenger lift of large mines. A ward leonard control system with generator and motor connected directly. Can the ward leonard system of speed control provide. Describe the working of 3 point starter for dc shunt motor. Lecture 16 dc motor speed control introduction duration.
98 1256 1544 362 1202 374 204 1354 1409 839 1355 820 1166 771 148 1289 208 352 544 18 900 435 1677 1558 1325 217 678 977 104 1034 429 1548 1302 1563 1285 506 114 1105 891 64 1081 1350 1261 711 1197 484 1427 917