Dc motor principle a machine that converts dc power into mechanical energy is known as dc motor. The overhauling load has a constant torque of 700 nm. The power loss due to the resistance of the armature b. These notes has been made by me after watching nptel lectures given by dr. Ee 361 laboratory manual and lecture notes, middle east technical.
In this lecture we shall consider mainly the separately excited and the shunt dc motors. An905 ds00905bpage 2 2010 microchip technology inc. As shown in figure 3, when a pulley with radius r is attached to the motor and force of f is applied to the pulley,s circumference, the torque generated, tl, can be derived by multiplying f and r f. The motor of problem 12 is used to brake an overhauling load regeneratively. It is a machine which convert electrical energy into mechanical energy. The most common types rely on the forces produced by magnetic fields. Introduction a series dc motor is a motor whose filed windings consists of a relatively few turns connected in. The system structure of a dc motor is depicted in figure22, including the. As shown in figure 3, when a pulley with radius r is attached to the motor and force of f is applied to the pulley,s circumference, the torque generated, tl. Ee301 dc motors i learning objectives basic dc motor. The electrical power flowing into a dc motor, or the electrical power flowing out. Since ish is relatively small, shunt field rheostat has to carry only a. The successive sections explain the implementation of code drivers using the mpc5604b mcu. The load angle is almost constant and it is about 90allowing the maximum efficiency.
Too low a frequency will result in a noisy motor at low speeds and sluggish response to changes in duty cycle. In this particular case, notice that the ux owing in the coil is given by equation 3 substituting with the angle t of the motor and a with the area of the internal surface of the coil. Jongeun choi department of mechanical engineering michigan state university lecture 9 modeling of dc motors 2 course roadmap laplace transform transfer function models for systems electrical mechanical electromechanical block diagrams linearization modeling analysis design time. What is common to all the members of this family is that the basic physical process involved in their operation is the conversion. Dc motor propeller matching 3 mar 05 lab 5 lecture notes nomenclature t prop thrust q prop torque qm motor torque pshaft shaft power pelec electrical power ct thrust coe. Experiment 7 series dc motor i objectives to determine the torquespeed characteristic curve. Brushes and commutator unlike other electric motor types i. Motor control electrical engineering and computer science. Other members of the family are the directcurrent dc motor or generator, the induction motor or generator, and a number of derivatives of all these three.
Craig 4 in rotational electromechanical devices other than dc machines, torque is produced as a result of one or more magnetic fields which rotate about the air gap of the device. Reluctance machines, induction machines, synchronous machines, stepper motors, and brushless dc motors. The purpose of this project was to control the angular rate of the load shaft position of a dc motor by varying the applied input voltage. The electronic circuits created to control these motors and schematics for pcbs, tips to reduce noise over important signals can also be found in this application note. Torque exerted by the motor, when a multiple segments commutator is used. Experiment 5 dc motor speed control walter scott, jr. For example, if a bdc motor is rated to turn at 15000 rpm at 12v, the motor will ideally turn at 7500 rpm when a 50% duty cycle waveform is applied across the motor. Transistors the small dc motor, is likely to use more power than an arduino digital output can handle directly. Lecture series on basic electrical technology by prof. Another name for a coil or loop of wire inductors oppose the change in current. In general, a dc motor,s stalling torque is equal to its starting torque. Raju,assistant professor chadalawada ramanamma engineering college autonomous. Transforms mechanical energy into electric energy with dc voltage and current dc generator or dynamo, or conversely dc motor.
Reluctance machines, induction machines, synchronous machines, stepper motors, and. There are three main varieties of dc motors, all of which make use of the relations above. The flux of a dc motor can be changed by changing ish with help of a shunt field rheostat. If we tried to connect the motor straight to an arduino pin, there is a good chance that it could damage the arduino. The speed in a dc motor can be adjusted through the intensity of its current. An4251, controlling dc motors and servo motors application. Understand the effect of multiple armature loops in a dc motor. Modeling of dc motor the most common device used as an actuator in mechanical control is the dc motor. Dc stands for direct current, and they were the first type of motors that were commonly used because they could be powered from a preexisting power distribution system.
Synchronous motor the synchronous motor runs at a constant speed re gardless of the load on the motor. Construction of a dc motor is same as that of a dc. Apr 01, 2008 lecture series on basic electrical technology by prof. Introduction a series dc motor is a motor whose filed windings consists of a relatively few turns connected in series with the armature circuit. A force is induced in a conductor that has a current going through it and placed in a magnetic field any dc machine can act either as a generator or. Smart funded by the national science foun dation dc motor dc motors are simple twolead electrically controlled the voltage range of the dc motor is 1. It has a maximum speed of 500 rads with a maximum current of 2 a. This combination is commonly known as electrical drives. We have learnt in the previous lecture 37, that for motor operation. Its operation is based on the principle that when a current carrying conductor is placed in a. For motors up to a few kilowatts the armature circuit of the motor. Motor parameters time constant, electrical te winding current to reach 63.
We shall use the same dcmotor for which the parameters were calculated in the. Explain the effect of motor reaction in a dc generator. The appropriate tool for studying transient response of the dc motor or any system is the transfer function of the system eecs461, lecture 6, updated september 24, 2014 6. The torque at which the kt rollsoff reduces by 10% as a function of. Dc machines 1 dc machines transformsmechanicalenergyintoelectric energywithdc voltage and currentdc generatoror dynamo, or converselydc motor. Massachusetts institute of technology department of electrical engineering and computer science 6. However, electrical drives can be classified as dc drives and ac drives. Smart funded by the national science foun dation dc motor. An emf voltage is induced in a conductor if it moves through a magnetic field. The equivalent circuit for the dc motor can be analyzed using any circuit technique learned earlier in this course.
Module 5 dc generators this module describes the types of dc generators and their application in terms of voltage production and load characteristics. Brush dc motor summary the magnetic field intensity is proportional to the current forced into the motor leads. 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. The principle of working of a dc motor is that whenever a current carrying.
Brushed dc motors, despite their mechanical complexity, are governed by only a few forces. The frequency of the pwm waveform is an important consideration. The electronic commutation switches the current back and forth to mimic ac current and keep the motor turning. Any dc machine can act either as a generator or as a motor. Continuous torque is the torque a motor can produce continuously without exceeding the thermal limit of the winding insulation peak torque.
Induced voltage opposes applied voltage and limits current. Ee301 dc motors part ii 3 112016 pin pout ploss pa as the motor speeds up, the contact arm moves to sequentially remove starting resistors from the circuit example. Dc motor speed control 1 when the voltage applied to a dc motor lower than nominal voltage motor runs slower higher than nominal voltage motor runs faster linear control connect a potentiometer in series with motor use a transistor bjtfet as a variable resistor. Figure 4 open loop transfer function of dc motor if we consider t load 0, s. For example, the control of a rotary inverted pendulum requires a dc motor to drive the arm and the pendulum as shown in figure 21.
It consists of an electric motor motors, a transfer mechanism, an electrical energy converter, and a control system. First, a look at an incredibly simpli ed motor, a square loop in a magnetic eld, as shown in figure 1. The principle of operation of a dc generator is similar to that of the ac generator, which was discussed previously. The power input to a dc motor is simply the input current multiplied by the applied voltage. This webseminar will focus on the basics of brushed dc motor construction and some common characteristics. Dc machine are the electromechanical energy conversion devices which converts either dc power to mechanical power or mechanical power to dc power. Module 6 dc motors this module describes the types of dc motors and includes discussions of speed control, applications, and load characteristics. A rotating armature coil passes through a magnetic field that develops between the north and. What is common to all the members of this family is that the basic. Dec 07, 2014 dc motor introduction, principle and working introduction. Dc motor introduction, principle and working my tech info. Speed control of the dc motor is primarily through the voltage v, either directly or through pulsewidth modulation, but the stator. Tutorial 1 drive fundamentals and dc motor characteristics. Brushless dc motors nyu tandon school of engineering.
Dc motor rotor construction commutator poles rotor winding fan bearing brushes. The induction motor is discussed in detail in this unit. The most common farm appli cation of a synchronous motor is in an electric clock or timer. May 25, 2016 a dc motor is an electrical machines that converts direct current electrical power into mechanical power. Motor property 1 torque is proportional to current question. Brushed dc motor fundamentals microchip technology.
The current is carried through an armature or stator. Dc machines 1 dc machines transformsmechanicalenergyintoelectric energywithdc voltage and current dc generatoror dynamo, or conversely dc motor. Electric motors rss technical lecture 2 friday, 10 feb 2012 prof. Dc motors are rarely utilized in normal applications as a result of all electrical supply firms furnish electrical energy but, for special applications like in steel mills, mines and electric traction, its advantageous to convert ac into dc so as to use dc motors. Term may also refer to the winding that is on the rotor. A good material for the poles of a pmdc motor should have the apposite of the above. Principles and working of dc and ac machines bits pilani. Dc drives this senior part of electrical engineering introduces the principles of combining electrical machines with power electronics converters. This is part 1 in a 4 part series of webseminars related to controlling a brushed dc motor using a microcontroller.
To find out how to reverse the direction of rotation of a series dc motor. Dc motor introduction, principle and working introduction. When current carrying conductor is placed in a magnetic field it. A linear differential equation describing the electromechanical properties of a dc motor to model transfer.
Due to electrical and mechanical losses in the motor, the. The purpose of this experiment is to design and implement a closeloop speed control of a dcmotor drive. Whence, computing the derivative in equation 12, the back electromotive. For a dc motor, the efficiency is the electrical output power divided by the mechanical input power, or for a dc generator, the efficiency is the electrical output power divided by the mechanical input power, or note that the efficiency of a dc machine will vary with. A dc motor is an electrical machines that converts direct current electrical power into mechanical power. The appropriate tool for studying transient response of the dc motor or any system is the transfer function of the system eecs461, lecture 6, updated september 17, 2008 6. Dc motors although ac motors are used in most of the cases, dc motors have many applications and used for multipurpose applications. An armaturecontrolled dc motor has the following ratings. Umanand, principal research scientist, power electronics group, cedt, iisc bangalore.
88 220 284 365 671 61 1041 225 226 1448 892 758 63 946 1187 393 580 746 674 1173 834 1258 791 1050 644 156 154 1077 385 751 311 742 406 723 183 304 1077 1034 2 396 1097 486 1483 780 100