Types of dc generatorseparately excited and self excited. Speed control of separately excited dc motor and performance analysis by software simulation has been done. Analysis and simulation of commonmode conducted interference source in separately excited dc motor. Direct current motors can be divided into separately excited dc motors, shuntwound dc motors, serieswound dc motors and compoundwound dc motor s. The most common types rely on the forces produced by magnetic fields. Small servotype dc motors normally have permanentmagnet pm excitation for the field, whereas larger size motors tend to have separate field supply, v f, for excitation. Dc motor ieee conferences, publications, and resources. In a separately excited dc generator the field coils are energised from an independent source. A separately excited dc motor fed through single phase half wave converter 26 is shown in fig.
Selfexcited field motors can be series, shunt, or compound wound connected to the armature. The main distinguishing fact in these types of dc motor is that, the armature current does not flow through the field windings, as the field winding is energized from a separate external source of dc current as shown in the figure beside. The current flowing in the stator electromagnet is often called. Separately excited dc motor electronic components systems. A 50 hp, 240 vdc separately excited motor is operating at rpm. But since the output voltage may be controlled more easily and over a wide range from zero to a maximum, this type of excitation finds many applications.
Construction of dc motor in detail, there is a yoke magnetic frame, pole core and pole shoes, the armature core, armature winding conductor, commutator, and brushes and bearings. Types of dc generator separately excited and self excited the dc generator converts the electrical power into electrical power. The same dc machine can be used as a motor or generator. Optimization filter of speed is obtained using modulus hugging approach. This paper describes speed control of separately excited dc motor using chopper as power converter and pi as speed and current controller.
If a small perturbation around a dc operating point is introduced, these equations can be written as 79. However, if the generator is operated at the knee point in the magnetization. Pdf speed control of separately excited dc motor and performance analysis by software simulation has been done. Pdf speed control of separately excited dc motor with efficiency. The selfexcited motors are further classified as shunt wound or shunt motor, series wound or series motor and compound wound or. Pdf speed control of separately excited dc motor using. In the separate motor, we supply the field winding from a separate dc power source. In a shunt motor the field is connected in parallel shunt with the armature windings. Separately excited dc motors sedc in every dc motors, there is a stator that refers to the static part consisting of the field winding, and the rotor which is the moving part consisting of the armature winding. After obtaining the complete model of dc drive system, the model is simulated by matlab. The main distinguishing fact in these types of dc motor is that, the armature current does not flow through the field windings, as the field windin. A dc shunt motor rotates due to the torque developed in the armature when the armature and field terminals are connected to the dc supply. The shuntconnected motor offers good speed regulation. Types of dc motor self excited, separately excited dc motor.
Speed control of a separately excited dc motor engineering. For this converter the average output voltage can be calculated versus the firing angle. The objective of this paper is to describe the principle of dc motor speed control using nonlinear combined control armature voltage and field current and proportional integral derivative pid controller for dc motor drives. Sometimes the term independentfield dc motor is also used. As the name suggests, in case of a separately excited dc motor the supply is given separately to the field and armature windings. Load characteristics of dc compound generator with differential and cumulative connection. Described in articlethis is the simulation of a separately excited motor, includingdc starting, speed control and. Working principle of a dc motor an electric motor is an electrical machine which converts electrical energy into mechanical energy. In a separately excited dc motor, separate power is given to the field and the armature windings.
Dc motor is still the most common choice if wide range of adjustable speed drive operation is specified. Previously, you saw that a dc motor is made up basically of a fixed magnet stator and a rotating magnet rotor. Field current and to obtain the performance characteristics t. The external characteristic of the separately excited dc generator is obtained by subtracting the drops due to ohmic loss i a r a in the armature from generated voltage e g. Identify and utilize equations that represent motor performance to solve separately excited dc motor problems. To access complete course of basic electrical engineering basic. The field winding can be separately excited or connected to the same source as the armature. A separately excited dc motor and a dc shunt motor are similar in construction and in all aspects except the way in which the field winding is excited in both the machines. The field of them does not need any separate excitation. The separately excited dc motors represented in fig. To study the methods of controlling the speed of separately excited dc motor. Swinburnes test and speed control of dc shunt motor. It is one of the most popular converter circuits and is widely used in the speed control of separately excited dc machines. Direct current dc motors are power core of electric industrial trucks, such as forklift and van.
Separately excited motor the rotor and stator are each connected from a different power supply. We will consider three types of wound field dc machine. Fuzzy speed control of separately excited dc motor using. Construction of dc motor all parts of dc motor in details. 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. Open circuit and load characteristics of separately and self excited dc shunt generators. The field winding is replaced by a permanent magnet, resulting in simpler construction. The separately excited dc motor is typical and always taught at universities. Video lecture types of dc motor of chapter dc machine of subject basic electrical engineering for firstyear engineering students. Indeed, the rle load shown in this figure may represent the electrical. The motor speed if the terminal voltage is reduced by 20% and the power drawn remains the same. The magnetic flux in a dc machine is produced by the field coils carrying current. Dc motors, generators and energy conversion devices.
If the armature reaction is neglected, decrease in v a should be linear and equal to the voltage drop across r a and carbon brushes. Different speed can be obtained by changing the armature voltage and the field voltage. Pdf speed control of separately excited dc motor with. The speed control techniques in separately excited dc motor are 2. Speed of the motor can be controlled by varying v a and holding v f constant at its rated value. Usually, in other dc motors, the field coil and the armature coil both are energized from a single source. Four quadrant operation of chopper fed separately excited. The fourth connection, separatelyexcited, can be made to respond like any of the other three by proper control of the excitation voltage. A separately excited dc motor is a motor whose field circuit is supplied from a separate constantvoltage power supply. Nearly all types of dc motors have some internal mechanism, either electromechanical or electronic, to periodically change the direction of current in part of the motor. Hey guys in this lecture i discuss introduction to magnetisation curve and intro to dc seperately excited and shunt motor pdf summary. The direction of rotation can be explained with help of flemings left hand principle. What are the applications of a separately excited dc motor. Equivalent circuit of a separately excited dc generator as the load current i l increases, the terminal voltage decreases as indicated by solid line.
The separately excited dc motor can be controlled from below and up to rated speed. A same dc machine can be used as a motor or generator. Each part of those has its identity and great importance, advantage and sometimes problems, now we will separately explain each part. Types of dc motor a direct current motor, dc is named according to the connection of the field winding with the armature. Torque speed characteristics of a separately excited dc motor introduction. Pdf control of separately excited dc motor researchgate. Speed control of separately excited dc motor with efficiency maximization propensity. The name suggests the construction of this type of motor. For a dc drive, it is important to study the torquespeed characteristics of a dc motor since the motor characteristics should match with that of the load to which the drive is going to connect. A dc motor is any of a class of rotary electrical motors that converts direct current electrical energy into mechanical energy. The separately excited dc motors are most often used. Learn about the different types of dc motor and their applications.
Dc motors although ac motors are used in most of the cases, dc motors have many applications and used for multipurpose applications. Simulation used in education for a separately excited dc motor. Types of dc motors and their applications electrical4u. Single phase half wave converter feeding a dc motor offers only one quadrant drive.
But they have become the serious inner interference source because its structure and control has changed significantly. What is the practical difference between a separately. In the motor, the emf of rotation can be called as counter or back emf, and ereb. In a separately excited dc motor the supply is given separately to the field and armature windings. The equivalent circuits of these two dc motors are shown in fig. Separately excited dc motor has field coils similar to that of shunt wound dc motor. First, one is separately excited dc motor and selfexcited dc motor. This curve gives the relation between the terminal voltage v and load current.
The circulating current in the field windings produces a magnetic flux, and the phenomenon is known as excitation. Singleinput fuzzy logic controllers for efficiency maximized separately excited dc. Its operation is based on the principle that when a current carrying conductor is placed in a. Therefore, theoretically, construction of a dc motor is same as that of a dc generator. A good material for the poles of a pmdc motor should have the apposite of the above. In a pm dc machine, the armature circuit model is the complete circuit model. Shunt motor is the most common types of dc motor where we connect the field winding parallel with the armature windings so this motor can be selfexcited from the armature windings and this gives it the feature of greatest speed regulation, simplified reversing control and low starting torque, so shunt motor is suitable for beltdriven. So, any change in armature current ia has no effect on field current if direction of rotation of motor can be reverse by reversing voltage. This gives another degree of freedom for controlling the motor over the shunt. Dc motor principle a machine that converts dc power into mechanical energy is known as dc motor. Draw a circuit model of a separately excited dc motor. Dc motor is mainly constructed from two main parts, the stator and the rotor as shown in fig. When power for the stator electromagnet is supplied by a separate dc source, either fixed or variable, the motor is known as a separatelyexcited dc motor.
Separately excited motor have separate field winding means supply to armature is different and supplied to field is different. Dc machine construction, working, types, emf equation. The external characteristic curve lies below the internal characteristic curve. A simple explanation of the different types of dc motors. The disadvantage of a separately excited dc generator is the same that we require an external dc source for excitation. Nevertheless, the fast dynamics of dc machines are. Speed control of separately excited dc motor by ppt 2 free download as powerpoint presentation. Many dc motors use an electromagnet for the stator, as illustrated in figure 27. When a separately excited motor is excited by a field current of if and an armature current of ia flows in the circuit, the motor develops a back emf and a torque to balance the load torque at a particular speed. Simplified dc motor with an electromagnet as stator. The separately excited brushed dc motor lends easily to simple control, by virtue of the brush. Separately excited dc motor can operate above base speed. Direct current dc motors have been dominating the field of adjustable speed drives for over a century. Characteristics of separately excited dc generators.