Dc machines are usually classified on the basis of their field excitation method. In this type figure 1 the field is in series with the armature. Speed changes with every change in load, because speed variations depend not only on controlling resistance but on load current also. Speed control of dc shunt motor your electrical guide. An efficient method for speed control of dc shunt motor. The shunt field of the motor m1 is connected across the dc. In armature voltage control method the speed control is achieved by varying the applied voltage in the armature winding of the motor. The brushed dc electric motor generates torque directly from dc power supplied to the motor by using internal commutation, stationary magnets permanent or electromagnets, and rotating electromagnets advantages of a brushed dc motor include low initial cost, high reliability, and simple control of motor speed. As you know that the construction of any type of dc motor is very similar to a dc generator. Although the control system of the present invention is described with the above installation, it should be. This speed control method is also known as ward leonard method, which is discussed in detail under the topic ward leonard method or armature voltage control. The control system 10 is shown as used in connection with an electrical driving apparatus 12 comprising specifically a dc.
Armature voltage control is used to control the motor speed below the rated speed. Static ward leonard drives are being used these days because of the drawbacks of the classical method. Increasing the shunt motor speed by reducing armature resistance armature control reduces the running cost but increases the efficiency from its original values to. The arrangement of this system is as shown in the figure at right. This project aims at achieving smooth speed control of dc motor in wide range of application. The high number of turns allows a strong magnetic field to be generated, but the smaller gauge wires provide a high resistance and limit the current flowing through the shunt coil. E b vi a r a here, eb back emf, in volts ia armature current, in amps ra armature resistance, in ohms v terminal voltage, in volts. As a very flexible, reliable means of motor speed control, the ward leonard speed control system is unmatched. Armature control of dc shunt motor motor speed is directly proportional to back emf e b, e b v i r a. Speed control methods of dc motor speed control of shunt motor 1. The armature of the shunt motor m whose speed is to be controlled is connected directly to a d. There are so many methods for controlling the speed of a dc shunt motor but field rheostat control method is most reliable, economic and independent of load on the motor.
But its cost is high, more losses and less efficiency. Dc motors dc motors 1 noload speed of which of the. This system is used where an unusually wide and very. To obtain speed control of dc shunt motor using a armature resistance control b. Rotating mg sets are replaced by solid state converters to control dc motor speed. Therefore speed control of dc motor is two type armature control method field control method 3.
The purpose of a motor speed controller is to take a signal representing the required speed, and to drive a motor at that speed. He has 8 years of experience in customer support, operations and administration. Therefore the voltage drops i a r a will be negligible as compared to the external supply voltage v. This type of dc motor is only used for direct coupling and other work where the load or part of the load is permanently coupled to the motor this will be seen from the speedtorque characteristic, which shows that on no load or light load the speed will be very high and therefore dangerous. Tarun agarwal is the chief customer support officer at edgefx technologies pvt ltd. One for controlling the armature voltage of the dc motor by means of controlling the. Working of control panel for the speed control through armature control and field control we will be using face plate type starter also in order to limit the starting current, also otherwise higher capacity of armature control rheostat will be required. Speed control of dc motor using pulse wi authorstream.
View notes speedcontrolofdcshuntmotor from boston 6. The field of shunt motor is supplied from a constant voltage exciter. At present, variable voltage is achieved by scr controlled ac to dc converter unit is used to. Speed control methods of dc shunt motor my tech info. Ward leonard method of speed control or armature voltage. Shunt wound dc motor or dc shunt motor is a selfexcited dc motor whereas we said before at previous article types of dc motor that it operates on direct current and the field winding is connected in parallel to the armature winding so both windings exposed to the same power supply voltage, and this motor able to maintain at a.
Before discussing the speed control of dc shunt motor, we have to find the factors affecting the speed of a dc motor. The dc shunt motor is 120vdc with rated speed of 1800 revolutions per minute. As the rotating speed of dc shunt motor depends on armature voltage and field current applied to the shunt motor, therefore, these two process parameters were varied during experimentation. Speed control by ward leonard method gives uniform speed variation a in one direction b in both directions c below normal speed only d above normal speed only. The speed of the dc shunt motor can be controlled by. Disadvantages are high maintenance and low lifespan for high intensity uses.
It has been shown earlier that the speed of a motor is given by the relation it is obvious that the speed can be controlled by varying i fluxpole, f flux control ii resistance ra of armature circuit rheostatic control and iii applied voltage v voltage con trol. Speed control of dc shunt motor with field and armature. Motor speed can be controlled by controlling armature voltage va armature current ia. The intermediate speeds can be obtained by adjusting the shunt field regulator. If the field of a dc shunt motor gets opened while motor is running a the speed of motor will be reduced b the armature current will reduce c the motor will attain dangerously high speed d the motor will continue to constant speed 10. Conventional wardleonardstatic ward leonard method. Speed control of dc motor the speed of a dc motor is given by i.
This paper discusses the speed and torque control of a shunt dc motor through matlab simulink simulations. In this system the armature of the dc shunt motor is directly connected to a generator driven by a constant speed ac motor. We cant imagine our life without speed control of a motor, because nowadays all moving equipment works with the help of motor, it may be a ac motor,dc motor or a servomotor. In fact, fine speed control is one of the reasons for the strong competitive position of d. Ward leonard speed control method of dc motor ward. What are the methods of speed control of dc motors. In this method the variable voltage is obtained from motorgenerator set. M1 may be any ac motor or dc motor with constant speed. The arrangement of this system is as required in the figure shown below.
Ward leonard control system is introduced by henry ward leonard in 1891. M2 is the motor, it controls the speed of the generator. Operation the shunt field of the main motor dc shunt. Merits and demerits of rheostatic control method 1. Ward leonard method speed control of dc motor youtube.
Pdf an investigation of the ward leonard system for use in a. The wardleonard method of speed control of dc motor uses voltage control, i. Pdf digital speed control of dc motor for industrial. The connection diagram of the ward leonard method of speed control of a dc shunt motor is shown in the figure below.
Us3108214a wardleonard motor current overload control. Central composite design of experiments based experimental designed has been applied and number of experiments have been performed. The speed of motor m1 is to be controlled which is powered by the generator g. Ward leonard control, also known as the ward leonard drive system, was a widely used dc motor speed control system introduced by harry. This is also well known that the dc machines can be used as a generator as well as as a motor, their is the difference of operation in both case i. The different methods of speed control in dc shunt motors are explained below, flux control method armature control method voltage control method multiple voltage control ward leonard system. Digital ward leonard speed control is operated with two pid controllers. The speed control below the rated speed control is not possible using this type of control. These methods as applied to shunt, compound and series motors will be discussed below. The connection diagram of the ward leonard method of. Speed control of dc motor full guide for controlling the.
The different methods of speed control in dc shunt motors are 1. In this post, we will discuss about various speed control methods of dc shunt motor. The fig above shows the typical wardleonard system. 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. Explain the experiment on ward leonard method of speed. The ward leonard system provides an alternative control method to expensive and. In this wardleonard method, the adjustable voltage for the armature is obtained from an adjustablevoltage generator while the field circuit is supplied from a separate source. By varying the generator field current, its output voltage will. 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. We control the speed by adding a variable resistance in series with the shunt field, when we increase the resistance the field current reduces and by the way, the flux reduces and the speed increases.
Ward leonard method of speed control or armature voltage control ward leonard method of speed control is achieved by varying the applied voltage to the armature. This method is only applicable when we want speed which is higher than the normal speed of the motor. The field of the generator is supplied from the exciter e. In the ward leonard method, we get full range from 0 to normal speed of the motor. C shunt motor as a function of armature voltage, field current, and external. This control system is consisting of a dc motor m 1 and powered by a dc generator g. Such a fine speed control is generally not possible with a. The shunt field windings of a dc shunt motor are made of smaller gauge wire, but they have many more turns than a serieswound dc motor. In the past, wardleonard method is used for voltage control method. When we talk about speed control of dc motor we said that there is ward leonard method of speed control which based on varying the applied voltage to the armature, in this system we have a dc motor m powered by a dc generator g and we use a motor generator set which consists of either ac or dc motor to have the variable voltage we need, and that.
In this method the speed of the dc motor m 1 is controlled by applying variable voltage across its armature. What are the methods for controlling the speed of a dc. This method is not suitable for intermittent loads. Flux control method speed is inversely proportional to. What are the applications of speed control of a motor.
Ward leonard method of speed control is used for controlling the speed of a dc motor. This double dependence makes it impossible to keep the speed sensibly constant on rapidly changing loads. The different methods of speed control in dc shunt motors are explained below, flux control method. Explain the experiment on ward leonard method of speed control of a dc shunt motor. In armature voltage control method or rheostatic control method for speed control in d. We can use thyristors controlled rectifier or converters.
905 637 1081 929 466 96 694 670 36 1011 507 1423 488 1217 1330 1517 13 1564 967 544 634 607 753 592 1418 1423 605 1037 1467 1367 1063 1026 14