To study the methods of controlling the speed of shunt dc motor. The arrangement of this system is as shown in the figure at right. The actual values for a given load, speed, and motor vary. Though there are separate branches for the flow of armature current and field current.
To control the speed of dc shunt motor by armature control method and field control method apparatus requirred. When a current carrying conductor is placed in a magnetic field, it experiences a force. Voltage can be applied to the terminals of the dc motor or external resistance can be applied in the armature. Though there are separate branches for the flow of. Examples of how a dc rectifier bridge operates are given on the next few pages. Ward leonard control smooth variation of voltage, on the other hand, produces a flat characteristic with. Brushed dc motor fundamentals microchip technology. With some products, velocity mode operation can include capacity for regeneration. Therefore speed of the 3 types of dc motors shunt, series and compound can be controlled by changing the quantities on the righthand side of the equation above hence the speed can be varied by changing. The dc shunt motor construction is the same as any type of dc motor. Speed control of shunt dc motor johurul islam academia.
Dc shunt motor speed control and analysis using ziegler nichols algorithm with pid controller yogesh sharma l,a shis patra 2 1, 2 electrical engineering department, m. The simple rheostatic method provides a speed torque characteristic dc shunt motor with little hardness and little stability. The shunt motor runs at a speed defined by the expressions. The dc shunt motor is 120vdc with rated speed of 1800 revolutions per minute. A machine that converts dc electrical power into mechanical power is known as dc motor. It is a machine which converts electrical energy into mechanical energy.
The voltage equation of a dc motor is where e b is the back emf, v is the supply voltage, i a the armature current, and r a is the armature resistance again, the expression of back emf in a dc motor is where. Speed control of dc motor using pulse width modulation, 555. Working principle from the above circuit diagram, we can conclude that if we want to increase the speed of the shunt motor, we will vary the field resistance. Speed control of dc shunt motor with field and armature rheostat. This equation is called the dc motor speed equation and is just a straight line with a negative slope. Working principle of dc shunt motor, dc series motor and all other dc motors can be stated as follows. Thus the speed of dc motor is given by, eb v i a r a. And the armature winding is connected to external supply voltage hence it plays the role of current carrying. If we add resistance in series with the armature, the armature current ia decreases and.
Thus flux can be controlled by adding a rheostat variable resistance in series with the. A simple explanation of how to control the speed of a dc motor. Control of motor torque and velocity or speed are operating mode selections available to most basic dc drives and to some flux vector type ac drives. Brake test also called as direct loading test of testing the motor. The concept of the speed regulation is different from the speed control. As such, the field windings and armature are connected in a parallel combination, and in electrical terminology a parallel combination is known as a shunt.
Dc shunt motor speed control and analysis using ziegler. The resulting torquespeed characteristic of a shunt dc motor is shown in fig. Disadvantages are high maintenance and low lifespan for high. Apparatus type range quantity 1 voltmeter mc 0300v 1 2 ammeter mc 020a 1 3 rheostat 1250. Dc starter face plate type suitable for above motor. Speedcontrolofdcshuntmotor page 1 experiment no 9 aim. Brake test is also a method of finding efficiency of dc motors. 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. 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 speed of a shunt motor can be changed by flux control method. Selfexcited field motors can be series, shunt, or compound wound connected to the armature. The characteristics of a shunt motor reveal that it is an approximately constant speed motor. M1 may be any ac motor or dc motor with constant speed.
Theory the back emf for a dc motor is given by, p nz back emf, e b 60 a the number of poles, p the armature conductors, z and the number of parallel paths, a are constant for a particular machine. 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. Speed control of a dc motor using controllers science. Simplified dc motor with an electromagnet as stator. Speed control of dc motor using pulsewidth modulation. This paper describes the speed control of a dc shunt motor using conventional controllers pid, imc and fuzzy logic controller based on matlab simulation program.
Ac induction motor speed control so what can we do to control the speed of an ac induction motor. By means of this method, the motor can be worked at any speed up to its maximum speed. Speed control of dc shunt motor with field and armature. To control dc motors torque, a dc drive will regulate armature current. The performance of a cwdc motor is a combination of swdc and shwdc motors. One of the most important features of the dc motor is that their speed can easily be control according to the requirement by using simple methods. Voltage values given in these examples are used for explanation only. The dc motor converts the mechanical power into dc electrical power. The torque developed by a dc motor is directly proportional to the armature current and the stator flux. The field of the shunt motor is supplied from a constantvoltage exciter e. Cwdc motors have higher torque than a shwdc motor while offering better speed control than a swdc motor. Speed control of dc shunt motor free download as pdf file.
Speed control of dc shunt motor your electrical guide. A shunt dc motor connects the armature and field windings in parallel or shunt with a common d. The flux of a dc motor can be changed by changing ish with help of a shunt field rheostat. Therefore the voltage drops i a r a will be negligible as compared to the external supply voltage v. Since they are connected in parallel, the armature and field windings are exposed to the same supply voltage. Lathes, drills, boring mills, shapers, spinning, and weaving machines series motor. Pdf this paper discusses the speed and torque control of a shunt dc motor through matlab simulink simulations.
A thyristor bridge is a technique commonly used to control the speed of a dc motor by varying the dc voltage. This system is used where very sensitive speed control of motor is required e. The flux is dependent on the current through the shunt field winding. Speed control methods of dc motor speed control of. Pulsewidth modulation pwm or dutycycle variation methods are commonly used in speed control of dc motors. By decreasing the flux, the speed can be increased and vice versa. Speed control methods of dc motor shunt, series motors. In this type figure 1 the field is in series with the armature. This type of motor has good speed regulation even as the load varies, but does not have the starting torque of a series dc motor. Compoundwound dc motors basic drive circuits drive circuits are used in applications where a controller of some kind is being used and speed.
We use dc motors in many systems in our day to day life. Speed control of dc shunt motor electric motor direct current. Speed control of dc shunt motor using microcontroller and. Before discussing the speed control of dc motor, let us first establish the expression of the speed of a dc motor. A dc shunt motor also known as a shunt wound dc motor is a type of selfexcited dc motor where the field windings are shunted to or are connected in parallel to the armature winding of the motor. Previously, you saw that a dc motor is made up basically of a fixed magnet stator and a rotating magnet rotor. As resistance increased, the value of the field current will reduce. A mathematical model of the process has been developed using real plant data and then conventional controllers and fuzzy logic controller has been designed.
The duty cycle is defined as the percentage of digital high to digital low plus digital high pulsewidth during a pwm period. When supply voltage v and armature resistance ra are kept constant, the speed is directly proportional to armature current ia. This motor can be constructed with the basic parts like field windings stator, a commutator and an armature rotor the working principle of a dc shunt motor is, whenever a dc motor is turned on, then dc flows throughout stator as well as the rotor. The armature of the shunt motor m whose speed is to be controlled is connected directly to a d. Many dc motors use an electromagnet for the stator, as illustrated in figure 27. Speed control can be achieved using dc drives in a number of ways. Before discussing the speed control of dc shunt motor, we have to find the factors affecting the speed of a dc motor. Speed control of dc motor shunt motor and series motor. For example, cpu fans, fume extinguishers, toy cars etc. Working principle of dc shunt motor your electrical guide. On occasion, a field regulator is contained within the field circuit of dc shunt motor for additional speed adjustment. In this article we are going to discuss about brake test on d. In the armature control method, the speed of the dc motor is directly proportional to the back emf eb and eb v iara. He has 8 years of experience in customer support, operations and.
In this project, i will show how speed control of dc motor can be implemented using 555 and pulse width modulation pwm. Electrical machinel dc laboratory manual grietelectrical and. A dc motors speed and torque characteristics vary according to three different magnetization sources, separately excited field, selfexcited field or permanentfield, which are used selectively to control the motor over the mechanical loads range. Speed control methods of dc shunt motor my tech info. Speed control of dc shunt motor with field and armature rheostat control 79 2. 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. Dc drives offer the ability to control the speed and torque of heavyduty dc motors in various industrial and other similar applications. The terminal voltage of the armature, v the external resistance in armature circuit, r a the flux per pole. Motors plays an important role in energy conversion process.