The different methods of speed control in dc shunt motors are 1. The field of shunt motor is supplied from a constant voltage exciter. 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. We can use thyristors controlled rectifier or converters. The shunt field of the motor m1 is connected across the dc.
Us3108214a wardleonard motor current overload control. 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 fig above shows the typical wardleonard system. The different methods of speed control in dc shunt motors are explained below, flux control method. In this type figure 1 the field is in series with the armature. 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. 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. The converters used are choppers in case of dc supply or controlled rectifiers in case of ac supply. This method is not suitable for intermittent loads. 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. In the ward leonard method, we get full range from 0 to normal speed of the motor. Merits and demerits of rheostatic control method 1.
Speed control methods of dc motor shunt, series motors. One for controlling the armature voltage of the dc motor by means of controlling the. The speed of motor m1 is to be controlled which is powered by the generator g. In armature voltage control method or rheostatic control method for speed control in d. To obtain speed control of dc shunt motor using a armature resistance control b.
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. Speed control of dc motor using pulse wi authorstream. This control system is consisting of a dc motor m 1 and powered by a dc generator g. Digital ward leonard speed control is operated with two pid controllers. Explain the experiment on ward leonard method of speed. The arrangement of this system is as shown in the figure at right. Armature control of dc shunt motor motor speed is directly proportional to back emf e b, e b v i r a. 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. The field of the generator is supplied from the exciter e. The control system 10 is shown as used in connection with an electrical driving apparatus 12 comprising specifically a dc.
Flux control method speed is inversely proportional to. Speed control methods of dc shunt motor my tech info. This paper discusses the speed and torque control of a shunt dc motor through matlab simulink simulations. 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. In this method an external variable resistance r x is connected in series with the armature. 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. These methods as applied to shunt, compound and series motors will be discussed below. The armature of the shunt motor m whose speed is to be controlled is connected directly to a d. By varying the generator field current, its output voltage will. Therefore speed control of dc motor is two type armature control method field control method 3. Explain the experiment on ward leonard method of speed control of a dc shunt motor. But its cost is high, more losses and less efficiency.
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. 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. M2 is the motor, it controls the speed of the generator. The speed control below the rated speed control is not possible using this type of control. 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. 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 the past, wardleonard method is used for voltage control method. 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. The ward leonard system provides an alternative control method to expensive and. Static ward leonard drives are being used these days because of the drawbacks of the classical method. Speed control of dc motor full guide for controlling the. 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. Speed control of dc shunt motor with field and armature. The connection diagram of the ward leonard method of speed control of a dc shunt motor is shown in the figure below.
Ward leonard control, also known as the ward leonard drive system, was a widely used dc motor speed control system introduced by harry. Speed control of dc shunt motor your electrical guide. In this method the variable voltage is obtained from motorgenerator set. 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. At present, variable voltage is achieved by scr controlled ac to dc converter unit is used to. Increasing the shunt motor speed by reducing armature resistance armature control reduces the running cost but increases the efficiency from its original values to. As you know that the construction of any type of dc motor is very similar to a dc generator. M1 may be any ac motor or dc motor with constant speed. Before discussing the speed control of dc shunt motor, we have to find the factors affecting the speed of a dc motor. C shunt motor as a function of armature voltage, field current, and external. Pdf an investigation of the ward leonard system for use in a. He has 8 years of experience in customer support, operations and administration.
Such a fine speed control is generally not possible with a. Motor speed can be controlled by controlling armature voltage va armature current ia. The purpose of a motor speed controller is to take a signal representing the required speed, and to drive a motor at that speed. In this system the armature of the dc shunt motor is directly connected to a generator driven by a constant speed ac motor. This double dependence makes it impossible to keep the speed sensibly constant on rapidly changing loads. Speed control methods of dc motor speed control of shunt motor 1. This ward leonard system is used where very sensitive speed control of the motor is required e. View notes speedcontrolofdcshuntmotor from boston 6. Conventional wardleonardstatic ward leonard method. Therefore the voltage drops i a r a will be negligible as compared to the external supply voltage v. The wardleonard method of speed control of dc motor uses voltage control, i. As a very flexible, reliable means of motor speed control, the ward leonard speed control system is unmatched. Dc machines are usually classified on the basis of their field excitation method. Disadvantages are high maintenance and low lifespan for high intensity uses.
Ward leonard control system is introduced by henry ward leonard in 1891. Although the control system of the present invention is described with the above installation, it should be. Armature voltage control is used to control the motor speed below the rated speed. In fact, fine speed control is one of the reasons for the strong competitive position of d. This method is only applicable when we want speed which is higher than the normal speed of the motor. The connection diagram of the ward leonard method of. The arrangement of this system is as required in the figure shown below. The dc shunt motor is 120vdc with rated speed of 1800 revolutions per minute.
What are the methods of speed control of dc motors. 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. 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. 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. 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. Ward leonard speed control method of dc motor ward. Ward leonard method of speed control is used for controlling the speed of a dc motor. Dc motors dc motors 1 noload speed of which of the.
Speed control of dc motor the speed of a dc motor is given by i. 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. What are the applications of speed control of a motor. In armature voltage control method the speed control is achieved by varying the applied voltage in the armature winding of the motor. This project aims at achieving smooth speed control of dc motor in wide range of application. Tarun agarwal is the chief customer support officer at edgefx technologies pvt ltd. In this method the speed of the dc motor m 1 is controlled by applying variable voltage across its armature.
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. Ward leonard method speed control of dc motor youtube. This system is used where an unusually wide and very. Pdf digital speed control of dc motor for industrial. Rotating mg sets are replaced by solid state converters to control dc motor speed. An efficient method for speed control of dc shunt motor. The intermediate speeds can be obtained by adjusting the shunt field regulator. Operation the shunt field of the main motor dc shunt. Speed changes with every change in load, because speed variations depend not only on controlling resistance but on load current also. The speed of the dc shunt motor can be controlled by. What are the methods for controlling the speed of a dc.
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