What is Dc motor: Definition and 321 Discussions

A DC motor is any of a class of rotary electrical motors that converts direct current electrical energy into mechanical energy. The most common types rely on the forces produced by magnetic fields. 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.
DC motors were the first form of motor widely used, as they could be powered from existing direct-current lighting power distribution systems. A DC motor's 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. Small DC motors are used in tools, toys, and appliances. The universal motor can operate on direct current but is a lightweight brushed motor used for portable power tools and appliances. Larger DC motors are currently used in propulsion of electric vehicles, elevator and hoists, and in drives for steel rolling mills. The advent of power electronics has made replacement of DC motors with AC motors possible in many applications.

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  1. J

    If I wanted to create a hand crank to spin this dc motor

    If I wanted to create a hand crank to spin this dc motor... I want to create a handcrank to spin a DC motor at 24000 rpm. The DC motor is an 18V hobby motor from radioshack. Is this possible?
  2. B

    Engineering Dc motor + battery + solar panel

    i would like to design a solar assisted driving mechanism for my bicycle? What is the compatible battery specifications to power 24v 1hp dc motor and the necessary solar panel specification to charge the battery? I'm kinda clueless in this so any help would be deeply appreciated. Thanks
  3. T

    How many amps can I generate with a dc motor?

    I want to use a 12V DC Brushless permanent magnet motor as a wind powered electrical generator for a project. The motor is rated DC 12V and 1.20 amps. Once I reach an output of 12V does that means that I also have 1.2 Amps? Thank you.
  4. S

    Concept of dc motor and a.c. generator

    Homework Statement I want to ask how dc motor and ac generator work and how they are used. dc motor is a device that converts electrical energy into mechanical energy. dc motor consists of magnet, coil, split ring commutator, brush and dc supply. dc supply will give direct current to the...
  5. M

    12v dc motor speed self limited?

    Fellow Engineering Lovers, Being a mechanical with limited electrical I must turn to the electron masters for answers. I have a PM brushed DC 12 V fan motor on of a standard electric cooling fan on a car radiator. My calculation comes out to be about 90 watt. I also have PWM 12-24 power...
  6. S

    DC Motor Speed: Does it Reach Constant Rotation?

    For a simple DC motor like this: http://i1-news.softpedia-static.com/images/news2/How-Brushless-DC-Motors-Work-3.jpg Does it reach a constant rotational speed? I know that when a current flows through it, Flemmings Left HAnd rule causes a couple of forces that results in rotation. As...
  7. O

    Optimize DC motor to run on 2V?

    What would you do? Would you increase or lessen the turns of the coils? Would thinner or thicker wire be better? Would you increase the size of each of the iron cores of each pole of the armature? How do bearings assist the motor? Would simultaneously using both a perma magnet and an...
  8. G

    DC Motor Question: Change in Magnetic Flux

    Homework Statement A simple DC motor consists of an armature placed between two poles of a magnet. The armature is rectangular and has dimensions of 90mm in breadth and 100mm in length. Magnetic flux density produced by the magnet is 0.5T. Number of turns of armature winding is 500. What is...
  9. D

    Power a DC Motor: Steps & Solutions

    Hey guys, I'm working on a project involving a DC motor. I'm in school for mechanical engineering.. Electrical problems haven't really interested me so this is the first I've ever really looked into it apart from studying basic circuits in a physics course last year. Anywho, the project: I...
  10. M

    DC motor torque-speed chart in braking quadrant

    Hello, I would like to know what will be the shape of the torque-speed diagram in braking quadrant. Many thanks
  11. H

    What could be causing heavy sparking on load for this DC motor?

    Hey there... We are working on one DC motor after it was overhauled. DC Boom Motor 100 KW for Portrek Crane We have performed Servicing, Re varnishing,Commutator skimming undercutting Setting of Brush.and test the motor on no load.Motor was running perfect without sparking. When...
  12. S

    How can I prevent undervoltage in a DC motor powered electric vehicle?

    I am currently running a DC motor in an electric vehicle. A lithium polymer battery powers a motor controller which is connected to said DC motor to drive the car. The lithium polymer battery as you would imagine has a battery monitoring system on it. One of the conditions it protects against...
  13. E

    Efficiency of a DC Motor Gearbox

    Does the efficiency of a gearbox just reduce the torque output of the motor? Or does it also reduce the speed? For example I have a motor with 100 N*m torque at 100 RPM, it then goes into a gearbox with a 80% efficiency and a 2:1 ratio. So the torque would be 2*100*0.8 Nm and the RPM 100/2...
  14. M

    Welcome Engineer Designing a 30 W Brushless DC Motor

    Hi to everyone :-) I'm new to this forum. I'm an engineer working in a core field. I need to design brush less dc motor of 30 W power, Inout voltage-13.5 V. I'm struck in winding design . Could anyone help?
  15. J

    Torque vs Current of a DC motor

    Hello all, I hope you can fill a couple of holes in my understanding. As part of a school assignment I have investigated the relationship between torque and current in a DC motor. I have used linear regression and the linear fit is pretty good. I have done research on the relationship between...
  16. F

    Engineering  Modeling Optima 300 Brushless DC Motor 2208-1100KV

    This is not homework but I would consider it to fall in this category. I am working on a robotics project and wanted to simulate a PID controller before implementation. I need to find a transfer function for my motor for this to work. Homework Statement As mentioned above, I need to find...
  17. B

    DC Motor RPM Equation Confusion

    According to http://www.aveox.com/DC.aspx" The way to calculate the output of a DC motor in kRPMs is the formula RPM of motor: kRPM = (V - RmI) / Kb V= Voltage Rm = Terminal Resistance I = Current Kb = Voltage Constant (V/kRPMs) This insinuates that an increase in amperage...
  18. B

    Is There a Way to Calculate Gear Ratio Based on Torque and Outside Forces?

    Im working on a model in SIMULINK of an electric drivetrain with an automatic transmission.. The overall goal is to develop an algorithm controlling controlling a CVT via factors such as current, angular velocity, etc. This may seem very basic to most of you, but i know that Output torque =...
  19. O

    Position control for DC motor driven actuator

    I am working on a project where I have a ball-screw type linear actuator being driven by a 24V variable speed DC motor. There is another 24V DC motor that drivers a pinion and ring-gear. The linear actuator controls the system's elevation and the ring gear controls the traverse. I would...
  20. P

    Power DC Motor: Voltage, Current & PID Control

    I have some confusion on how to power a 1 hp DC winch motor that is intended to run off a 12 V battery. I need to precisely control the velocity of the motor and will need a PID controller to do this. Since speed of the motor is proportional to the supply voltage, is 12 V the maximum voltage and...
  21. C

    Dc motor in a chopper circuit

    Will a generic dc motor interrupt the circuit fast enough to get a ac current on the other side of the transformer. I was assuming that a motor interrupt the flow of current.This is to feed a voltage multiplier.
  22. P

    Engineering DC Motor Specifications and Gear Ratio Calculation for Model Boat Propeller"

    Homework Statement A small dc motor has the following specifications and is being considered for powering the propeller of a model boat. The propeller has the intended capability of supplying 0.1Nm of torque at 200rpm. Operating voltage = 4.5V Stall torque = 6.6*10^-3 Nm Stall current =...
  23. B

    How to build a pancake DC Motor?

    I need to build a micro pancake DC Motor. I actually need 32 of them connected in a line with one power supply. The motors need to be about the size of a dime. Could someone write me a how to guide on how this can be done. It is for a prototype.
  24. Y

    Engineering Increasing shaft speed with DC motor

    Hi all, First timer here I would like to understand how to work out how torque is involved when increasing shaft speed using DC motors. Say if a shaft is rotating at X rpm with an applied torque of T [N.m] and a DC motor is connected through a 1:1 gearing to connect the rotating shaft and...
  25. R

    How Can You Calculate Near-Peak Power Consumption for a DC Motor at High RPMs?

    I'm a mechanical engineer selecting a DC motor. I have the values for rated continuous operation, but I would like to have a ball-park figure for "almost" peak power consumed (which can only be sustained for a few seconds). I realize that absolute Peak Torque is when the motor is stalled. For...
  26. R

    Can I Use a 520A RMS Thyristor for Controlling a 500A DC Motor?

    A while ago I built a pc board that serves as a 3 channel SS relay. The output thyristors are 25A. This circuit uses a zero cross opto coupler to fire the thyristor and turn it off (DigiKey MOC3042). I've used many of these to control aa AC wash machine motor (on/off). The first question is if I...
  27. W

    Building a Wind Generator with a DC Motor

    Hi everyone. This is my first time trying this. So please be gentle. My question is to do with a dc motor. I want to build a wind generator and I am trying to figure out what size motor to start with and try to size the blades to get the best out of it. I know that their is a lot of other...
  28. D

    DC motor - Enough torque to rotate load?

    Hi all, I am new here as i want to ask something about an engineering project i am working on. I need a motor to rotate a 200 grams cylinder which will be hanging from the motor's shaft (vertically). I wanted less than 100 rpm so the motor I chose is a 2.1W 6V DC motor with a 50:1 reductor...
  29. C

    DC Motor Control for Portable Telescope Mounts: Maintaining Constant Speed

    I am in the early stages of the design of a telescope mount and I need a control motor. I am hoping to run it on a battery so I think a DC motor is the way to go, but I need to be able to keep the rotation speed extremely constant for photographic purposes. So, to my question: Does anyone...
  30. A

    Engineering Controlling 2 DC Motors with 12V Battery: Tips for Design Engineering Students

    Hi I am a 4Th year design engineering student and have a final project to complete but my knowledge base is mainly mechanical and materials but I have to complete and electronics part of the project. My problem is I need to control 2 12V DC motors off 1 12V battery and I believe they need...
  31. R

    Brushless DC Motor Investigation

    Hey guys, I'm new to this site, and am a university student studying Electrical and Electronics engineering. I just completed a design project controlling a BLDC motor (pretty low powered at 60V, and giving output rpm of about 6000rpm). Now I had an idea where instead of using a single BLDCM...
  32. B

    Wiring a DC motor to two 9 volt batteries

    Hey everyone. I'm a beginner when it comes to making stuff with motors and batteries. Could anyone give me a link or a very good explanation on how to wire a 9 volt DC motor to 2 9V batteries (that are supposed to be wired in parallel) to power a propeller? I have the motors and the batteries...
  33. B

    DC Motor Wires: Current Flow With/Without Insulation

    http://img23.imageshack.us/img23/6131/17743493.jpg One thing bothers me... If we have a wire with NO insulation, and we make a loop like in these 2 examples. Connect those ends to battery. Current runs from + to -. Now, will the current behave like in A or in B(no insulation). I know...
  34. J

    How to reverse the action of a small 12V DC MOtor

    Hey Guys ! I am working on a personal project, and I was hoping you could give me some help and advices. I am looking for a tool/device that would reverse the action of a small 12V DC motor (make it operate clockwise and then counter-clockwise for example). And I was also wondering what kind...
  35. S

    DC Motor / Current Control and Torque/Speed Relationship

    Hello, First time posting here as I havn't been able to find a suitable answer to my question to help me understand some issues I am having with DC motors. I am trying to calculate the maximum speed and acceleration of a dc motor being driven by a current source with a known inertia. I...
  36. K

    Engineering Braking a Separately Excited DC Motor: Calculation and Analysis

    Homework Statement A separately excited DC motor with 220V, 970rpm, 100A and Ra=0.05ohms. It is braked by plugging from an initial speed of 1000rpm. I need to calculate i)the resistance to be placed in the armature circuit to limit braking current to twice the full load value, ii)the...
  37. D

    Urgent Search for 12V DC 1/3 RPM Motor for Telescope Mount Design

    quick and urgent:I need a DC MOTOR hi I'm designing a telescope mount and I need a motor which has less than 1 rpm I think I'm going to need (( 12 V DC 1/3 rpm )) please if you can help me !
  38. F

    PWM Circuit and DC motor problems (for NYE ball drop project)

    Hi all, This is my first time making a somewhat complicated circuit, with the help of an online schematic. (http://www.dprg.org/tutorials/2005-11a/index.html ) My goal is to make a New Year's Eve ball-drop, which has a motorized controlled-release lit-up ball (on a separate power...
  39. L

    Engineering Understanding DC Motor Operation

    I've been studying the concept of operation of DC motors and there are a couple things which I'm having trouble with. When the rotor is rotating, there will be "cutting" of flux and according to Faraday's law an emf is supposed to be generated such that it opposes the change in flux producing...
  40. S

    How to find out the right DC motor

    Hi guys, I am a bit confuse on how to calculate the power of the motor, the torque and the speed of the motor shaft + how to find out the rpm. Basically, i want to buy a motor which will be able to travel 100miles with a min speed of 55mph and have a total load of the vehicle of 600kg. if...
  41. U

    Low RPM, high torque DC motor help

    Hey folks, I have been thinking about doing a little hobby project for while, but didn't have the right knowledge to do it until now. Basically, I need a relatively small Low RPM, high torque DC motor that can be controlled by a microcontroller. I'm using the arduino duemilanove and have...
  42. I

    Speed/torque curves for brushless DC motor

    Hi everyone. I came across this site yesterday during some targeted Googling and thought I'd give it a shot. I have a basic question about speed/torque curves for brushless DC motors. I would like to compute a speed/torque curve for a small three-phase brushless DC motor that I have. It...
  43. E

    Find the Perfect DC Motor for Your Robot: Tips and Tricks for Calculating Torque

    Hello I need a little help here. I need to pick a DC motor to be used on a robot. I'm trying to calculate a minimum torque the motor should be able to produce, but I'm a little confused. torque = Force * distance = Mass * acceleration * distance (Ignoring moment of inertia created by...
  44. F

    Calculation of torque of a DC motor

    Hi everyone, Im currently doing my final year project and I need to calculate the torque of a DC motor so that I can replace it accordingly by another motor. Here are the motor's specification : 400V, 50Hz, 6poles, 200kW, 1400rpm, 371A Can anyone please help me sort this out. regards...
  45. D

    Can a DC drive provide constant torque at varying motor speeds?

    Torque has an inverse relationship with motor speed and I can understand why it's like that (more speed = more cemf = less current = less torque). On the contrary, my SCR controlled DC drive manual said that a DC drive could control a DC motor in a way that give constant torque from 0 rpm to...
  46. H

    Make a Brushless DC Motor this way?

    I know the magnetic field makes a circle around a wire with current flowing through it. So I wondered if a motor could be made in the following way. Take a round plastic sleeve with an inner diameter slightly more than the wire. Glue 4 magnets on the sleeve, such that they form a circular...
  47. D

    Graph of Magnetic Flux for DC Motor from 0-360

    Hey guys, just a quick question, what would a graph from 0 < x < 360 for magnetic flux look like for a DC motor, where the coils initial position is parallel to the magnetic field.
  48. M

    Optimizing Plate Surface for a Weighted DC Motor

    Hey guys, I have a DC motor and i want to glue to it's rotor a round plate (make a hole through it and stick the rotor in that hole :) )(consider the plate weightless) and on this plate i will glue a weight, doesn't matter what the weight is...just know that it's constant. My question is this...
  49. D

    Field loss in a shunt wound dc motor

    In a field loss event, why does a shunt wound dc motor run away? From my understand of electric motor, the armature spins because it's magnetic field pushes/pulls against the field winding's magnetic field. If I remove power to the field winding, then shouldn't the motor slows down because the...
  50. E

    Dc Motor Position Control

    Hello, I'm doing my thesis on dc motor position control, using the Simulink's Real Time windows target.The dc motor is Faulhaber 2342024CR(DC micromotor). First of all, I need to simulate the motor so as to have a full simulation of the whole system(motor,servoamplifier). The problem is that...
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