Volume 3 of 4 module 7 basic ac theory this module describes the basic concepts of alternating current ac electrical circuits and discusses the associated terminology. Module 2 basic dc theory this module describes the basic concepts of direct current dc electrical circuits and discusses the associated terminology. To obtain the performance characteristics of a dc shunt motor by load test. In this report, we have implemented a dc motor speed control system. A dc motors speed can be controlled over a wide range, using either a variable supply voltage or by changing the strength of current in its field windings. The direction of the mechanical force is given by flemings lefthand rule and its magnitude is given by f bil newton. Each part of those has its identity and great importance, advantage and sometimes problems, now we will separately explain each part. Working principle of a dc motor an electric motor is an electrical machine which converts electrical energy into mechanical energy. Construction of ac circuits and working of ac circuits. A brushless dc motor is similar to a brushed dc motor but as the name suggests, a bldc doesnt use brushes for commutation but rather they are electronically commutated. The purpose of this experiment is to design and implement a closeloop speed control of a dcmotor drive. Earlier, the variable dc voltage for the speed control of an industrial dc motor was generated by a dc generator.
March16,20 onthe28thofapril2012thecontentsoftheenglishaswellasgermanwikibooksandwikipedia projectswerelicensedundercreativecommonsattributionsharealike3. Circuit theory i superposition steps to apply superposition principle. A circuit that has capacitive or inductive characteristics is referred to as being a reactive circuit. This application note will discuss how a bdc motor works, how to drive a bdc motor, and how a drive circuit can be interfaced to a pic microcontroller. When power for the stator electromagnet is supplied by a separate dc source, either. Simplified dc motor with an electromagnet as stator. First, a look at an incredibly simpli ed motor, a square loop in a magnetic eld, as shown in figure 1. An905 ds00905bpage 2 2010 microchip technology inc. This thesis mainly deals with controlling dc motor.
Pdf the pid controller design and choosing pid parameters according to system response are proposed in this paper. Dc servo motors theory of dc servo motor electrical4u. In conventional brushed dc motors, the brushes are used to transmit the power to the rotor as they turn in a fixed magnetic field. Dc motor dc motor theory the dc motor has two basic parts. Share on tumblr simple circuit using timer ic 555 and mosfet irf 540 given for dc motor speed control, some dc motors have unfit rpm rotation per minute for projects to control speed of dc motor this simple circuit can be used. May 15, 2018 from general torque equation of dc motor it is found that, torque t.
The direction of the force is given by flemings left hand rule. Dc drive is basically a dc motor speed control system that supplies the voltage to the motor to operate at desired speed. An introduction to brushless dc motor control digikey. In a linear circuit of fixed resistance, if we increase the voltage, the current goes up, and similarly, if we decrease the voltage, the current goes down. Implement a transistor circuit and arduino program for pwm control of the 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 control is required. An electric motor is an electrical machine which converts electrical energy into mechanical energy. Types of dc motor a direct current motor, dc is named according to the connection of the field winding with the armature. Many dc motors use an electromagnet for the stator, as illustrated in figure 27. Dc generators will act as dc motors if connected to a dc power source and not spun at a sufficient speed.
The basic idea of an electric motor is to generate two magnetic fields. Circuit theory i important properties of capacitors. Speed control of dc shunt motor with field and armature rheostat control 79 2. Induction motor theory jerry bednarczyk, pe course content introduction the ac induction motor is well suited to applications requiring constant speed operation. Another name for a coil or loop of wire inductors oppose the change in current. Pdf dc motor dc motor theory cahtayu cahtayu academia. Brushless dc motor bldc and permanent magnet ac synchronous motors drives have many. Relationship between voltage current and resistance. Target motor theory 3phase ac motor control with vhz speed closed loop, rev. It works on the principle of lorentz law, which states that the current carrying conductor placed in a magnetic and electric field experience a force. This is a problem in dc power systems, as the generator will act as a load, drawing energy from the battery, when the engine or other prime mover device stops moving. 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.
This portable document format \pdf\ file contains bookmarks, thumbnails, and hyperlinks to help you navigate through the document. Speed control of dc shunt motor with field and armature. In general, the induction motor is cheaper and easier to maintain compared to other alternatives. A brushless dc motor known as bldc is a permanent magnet synchronous electric motor which is driven by direct current dc electricity and it accomplishes electronically controlled commutation system commutation is the process of producing rotational torque in the motor by changing phase currents through it at appropriate times instead of a. Its operation is based on the principle that when a current carrying conductor is placed in a magnetic field, the conductor experiences a mechanical force. Motor current is inversely proportional to speed, due to the counteremf produced by the armature as it rotates. Brushes and commutator unlike other electric motor types i. Their rapid gain in popularity has seen an increasing range of applications in the fields of consumer appliances, automotive industry, industrial automation, chemical and medical, aerospace and instrumentation. The idea of a speed control system is to maintain the speed of the motor at the desired value under various condition. The induction motor is made up of the stator, or stationary windings, and the rotor. Construction of dc motor all parts of dc motor in details.
The drive circuits discussed in this section allow the controller to pulsewidth modulate the. Module 6 dc motors this module describes the types of dc motors and includes discussions of speed control, applications, and load characteristics. Power low in dc motor copper loss in armature, field and series windings brush loss is sometimes included v brushi a equivalent circuit of series motor 2. Find the total contribution by adding algebraically. The inverter converts dc power to ac power at required frequency and amplitude.
Previously, you saw that a dc motor is made up basically of a fixed magnet stator and a rotating magnet rotor. The motors which are utilized as dc servo motors, generally have separate dc source for field winding and armature winding. Field control has some specific advantages over armature control and on the other hand armature control has also some. Repeat step 1 for each of the other independent sources. Induced voltage opposes applied voltage and limits current.
Therefore, theoretically, construction of a dc motor is same as that of a dc generator. Principles of operation the construction of a simple bdc motor is shown in figure 1. The relationship between voltage, current and resistance forms the basis of ohms law. Dc motors, where dc stands for direct current and ac motors where ac stands for alternating current. In fact, a bldc motor can be set up to run in a basic. Article library an introduction to brushless dc motor control an introduction to brushless dc motor control. The same dc machine can be used as a motor or generator. Dc motors were the first form of motor widely used, as they could be powered from existing direct current lighting power distribution systems. A machine that converts dc power into mechanical energy is known as dc motor. Find the output voltage or current due to that active source using nodal or mesh analysis. Volume 2 of 4 module 3 dc circuits this module introduces the rules associated with the reactive components of inductance and capacitance and how they affect dc circuits. Equivalent circuit of compound excited dc motor differential compound torque. The typical 3phase inverter is illustrated in figure 32.
While dc motors require the use of brushes to make electrical contact with moving coils of wire, ac motors do not. Brushed dc motor fundamentals microchip technology. The working principle of the dc motor is based on the principle that the current carrying conductor is. The design of motor drive for brushless dc motor intechopen. But the dc motor has the wide range of speed and good speed regulation which in electric traction. The high performance of control and fast dynamic response of electric machines can be achieved via motor drive because of high development of semiconductors such as the microcontroller and power transistors.
The 3phase set of currents, each of equal magnitude and with a phase. If v is abruptly changed, then the current will have an infinite value that is practically impossible. This simple generatorbattery circuit, for example, would not be. A dc motor is an electrical machine that converts electrical energy into mechanical energy the working of dc motor is based on the principle that when a current carrying conductor is placed in a magnetic field, it experiences a mechanical force. In a brushed dc motor, the coils on the rotor utilize the motors magnetic eld. Capacitors and inductors 1 a capacitor is an open circuit to dc. Dc motorgenerator module to demonstrate and explain the operation of dc motors and generators. Dc motors although ac motors are used in most of the cases, dc motors have many applications and used for multipurpose applications. Brushed dc motor theory and operation chris joyce, shane skikne, evan simpson, james nee january 8, 2014 abstract this study looked into the e ect of changing the material within the rotor of an electric motor. Electrical4u is dedicated to the teaching and sharing of all things related to.
The construction of the dc motor and generator are same. The rotor will constantly be turning to align its magnetic field with that of the stator field. Question 1 if the ends of a wire loop are attached to two halfcircular metal strips, arranged so that the two strips almost form a complete circle, and those strips are contacted by two brushes which connect to opposite poles of a battery, which way will the wire loop rotate. The ampl itude of the appl ied voltage is adjusted using the pwm technique. Electrical circuit theory and technology revised second edition john bird, bschons, ceng, miee, fieie, cmath, fima, fcollp newnes oxford amsterdam boston london new york paris. Brushless dc motors or bldc motors have become a significant contributor of the modern drive technology. Turn off all independent sources except one source. Dc motor principle a machine that converts dc power into mechanical energy is known as dc motor. Sep 22, 2014 the working of a dc motor is well explained in this video with the help of animation. We explain basic circuit theory and networks, circuit analysis, two port networks, matrixes, rl circuits, and more. However, the proliferation of inexpensive, robust electronic devices specially designed for motor control means that designing a circuit is relatively simple and inexpensive. A good material for the poles of a pmdc motor should have the apposite of the above. Speed control dc motor using chopper pdf eee322 course project dc motor speed control by using chopper circuit 2. Dc machines 1 dc machines transformsmechanicalenergyintoelectric energywithdc voltage and current dc generatoror dynamo, or conversely dc motor.
The control can be archived either by controlling the field current or armature current. Separately excited dc servo motor dc servo motor theory. We shall use the same dcmotor for which the parameters were calculated in the. A 3phase, y connected, 460 volt line to line, 25 horsepower, 60 hz, 8 pole induction motor has the following constants, in ohms per phase referred to the stator. Motor property 1 torque is proportional to current question. The variable dc voltage is controlled by varying the on.
This means that if the voltage is high the current is high, and if the voltage is low the current is low. First, one is separately excited dc motor and selfexcited dc motor. Experiment 5 dc motor speed control walter scott, jr. The purpose of a drive circuit is to give the controller a way to vary the current in the windings of the bdc motor. In fact, ac and dc motor designs are very similar to their. The working of a dc motor is well explained in this video with the help of animation. Working principle of a dc motor the dc motor is the device which converts the direct current into the mechanical work. The armature is made of coils of wire wrapped around the core, and the core has an extended shaft that rotates on bearings. Its operation is based on the principle that when a current carrying conductor is placed in a. Dc generator theory worksheet dc electric circuits.
Dc machines 1 dc machines transformsmechanicalenergyintoelectric energywithdc voltage and currentdc generatoror dynamo, or converselydc motor. In fact, ac and dc motor designs are very similar to their generator counterparts identical for the sake of this tutorial, the ac motor being dependent. The selfexcited motors are further classified as shunt wound or shunt motor, series wound or series motor and compound wound or compound motor. Circuit theory i superposition the superposition principle states that the voltage across or current through an element in a linear circuit is the algebraic sum of the voltages across or currents through that element due to each independent source acting alone. The dc motor converts the electrical power into mechanical power is known as dc motor. Theory dc motors are widely used in robotics for their small. But in field controlled dc servo motor, the armature is excited by constant current source, hence i a is constant here. All bdc motors are made of the same basic components. For this example, refer to the motor equivalent circuit and calculations described above.