What is Electric motors: Definition and 53 Discussions

An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate force in the form of torque applied on the motor's shaft. Electric motors can be powered by direct current (DC) sources, such as from batteries, or rectifiers, or by alternating current (AC) sources, such as a power grid, inverters or electrical generators. An electric generator is mechanically identical to an electric motor, but operates with a reversed flow of power, converting mechanical energy into electrical energy.
Electric motors may be classified by considerations such as power source type, internal construction, application and type of motion output. In addition to AC versus DC types, motors may be brushed or brushless, may be of various phase (see single-phase, two-phase, or three-phase), and may be either air-cooled or liquid-cooled. General-purpose motors with standard dimensions and characteristics provide convenient mechanical power for industrial use. The largest electric motors are used for ship propulsion, pipeline compression and pumped-storage applications with ratings reaching 100 megawatts. Electric motors are found in industrial fans, blowers and pumps, machine tools, household appliances, power tools and disk drives. Small motors may be found in electric watches. In certain applications, such as in regenerative braking with traction motors, electric motors can be used in reverse as generators to recover energy that might otherwise be lost as heat and friction.
Electric motors produce linear or rotary force (torque) intended to propel some external mechanism, such as a fan or an elevator. An electric motor is generally designed for continuous rotation, or for linear movement over a significant distance compared to its size. Magnetic solenoids are also transducers that convert electrical power to mechanical motion, but can produce motion over only a limited distance.
Electric motors are much more efficient than the other prime mover used in industry and transportation, the internal combustion engine (ICE); electric motors are typically over 95% efficient while ICEs are well below 50%. They are also lightweight, physically smaller, are mechanically simpler and cheaper to build, can provide instant and consistent torque at any speed, can run on electricity generated by renewable sources and do not exhaust carbon into the atmosphere. For these reasons electric motors are replacing internal combustion in transportation and industry, although their use in vehicles is currently limited by the high cost and weight of batteries that can give sufficient range between charges.

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  1. Ahmedbadr132

    Power Efficiency of Linear Piezo Electric Motors

    Hi I want to know the power efficiency of linear piezo electric motors in percentile.
  2. AmericaPacific42

    Are there cheap smartcar EVs with electric motors attached to wheels?

    There are small 15kw electric motors <$500*. LiFePO4 batteries that offer 60kwh** weigh <50kilograms, cost <$500, take as much space as the gas used to take. The hood could be removed or replaced with extra seats or used for cargo. Ultra-lightweight 3D printed magnesium bodies*** should be...
  3. A

    Understanding Back EMF in Electric Motors

    Current drawn by motor = ##\frac{120-75}{90}## = 0.5 Amps The answer says the power output of the motor is 37.5 Watts. The only way I can get that answer is if P = IV = 0.5(75) = 37.5. This implies that in an electric motor, the back emf is the voltage of the motor. This confuses me because...
  4. A

    Sliding doors operated by a remote control device

    Attached are some Sliding doors images. Can they be operated with a remote control device? The remote control device will have buttons for opening & closing the left and right door. What will be the design & construction changes in the sliding doors so that they can be operated using a remote...
  5. C

    Different types of electric motors

    I have to write a report about one of three motors AC type Motors, DC type Motors, Stepper Motors. I am wanting to now if anyone has any insight into which one I should talk about, which one has the most information and would be easiest to write a report on. Thanks
  6. H

    Boosting a petrol generator with a car battery?

    Hi All, So i am looking to buy a petrol generator to run a 2.2KW electric motor. I was thinking of getting a 3KW model which under normal conditions this should be ok - but on start up I've been told an electrical motor draws 6 to 10 times the normal load, which is way too high for the...
  7. J

    Why don't electric motors use exciter coils like generators do?

    I remember (long ago, in college physics) learning about electric motors and generators, specifically about the "exciter" coils in generators which did a better job than permanent magnets, because of a sort of "turbo" or force-multiplier effect. I notice, however, that while basically ALL...
  8. D

    Can low Resistance affect the torque output of an electrical motor

    I've had a side project in mind for a while involving motorized Rollerblade wheels, however I need to figure out a motor size that would give me the needed torque to actually accelerate 250lbs up to 25mph. I realize even a 5hp electric motor is large but I was wondering if ohms have any affect...
  9. T

    Electric motors vs internal combustion engines

    On average, which has higher power to weight ratio between the two? So on average, if both weighed the same, which one is going to have more power?
  10. T

    Can electric motors possibly apply continuous upward force?

    Is it possible for an electric motor to exist (based on our current understanding) which is capable of applying continuous upward force upon an object, enabling that object to fly or lift above the air?
  11. Delta2

    Do Moving Charges Create Magnetic Fields, or is it Something Else?

    Ok so when we have a current carrying conductor inside a magnetic field there would be Laplace force ##L\times Bi## which is the macroscopic form of the microscopic Lorentz force ##v\times Bq## in a large number of electrons ( or it is not ?) But also there will be hall voltage which will...
  12. J

    Using instantaneous torque to determine energy

    Hi all - This may seem like a very simple exercise, but for some reason it's giving me trouble... I am trying to determine the difference in energy (ultimately looking for kWh) used between two different electric motors by utilizing instantaneous torque measurements I have. I would like to do...
  13. L

    Calculating Torque Needed for a DIY Computer Desk

    Hello everyone, I want to build my own computer desk for past few years and soon I will have enough money to do so. What I am trying to do is make it look like normal desk and by pressing "THE"button all monitors will raise up from inside of it. I quickly sketched some mechanism so you can...
  14. A

    Best design for a 300 watt permanent magnet brushed DC motor

    I have noticed there are a few designs for permanent magnet brushed DC motor, but I can't seem to find the benefits and downsides of either one. The first one (first attachment) uses three electromagnets placed on a triangular rotor. There are two arc permanent magnets on the outside. In this...
  15. A

    Electric Bike Motors: Size, Wire Gauge & More

    I have been reading up on electric bike motors, there are a few things regarding size and wire gauge that have me confused. I have seen disassembly videos of around 300 watt electric bike motors with planetary gears, and I can't see how anyone can push through 300 watts through the wires without...
  16. D

    Automotive Selecting electric motors once power requirements are calculated

    So for a school project I got to design an electric car that can meet minimum range and top speed requirements for how heavy it is. I have calculated the amount of power needed(kW) for its heaviest load situation to reach the min speed and range, along with the necessary energy(kWh) required...
  17. D

    Electric machines (looking for books)

    Please help me, this is my last hope. I am an el. engineer student and i need GOOD books on electrical machinery. My proffesor is more a good repairman than a great scientist who could teach me about all the theoretical (matematical and physical) concepts which have led to modern design process...
  18. D

    Do all electric motors follow these two laws?

    Do all electric motor's follow Faraday's law and Lorentz? Is it safe to say generalize that statement?
  19. B

    Can Electric Motors Revolutionize Aircraft Propulsion?

    Greetings, everyone! A couple of my friends and i started work on a project regarding VTOL aircraft design. We are interested in the concept of propelling the air vehicle via propellers rotated by electric motors. As all of us, have relatively limited knowledge on electrical...
  20. S

    Electric Motors: Beginner's Guide for Engineering

    hello I am really new to engineering. i know the rock bottom basics of these stuff but really rock bottom. i have a couple of questions regarding electric motors: 1)torque- what makes a motor have more torque? 2)rpm- what does that effect? and if I am not mistaken higher...
  21. S

    What is torque in electric motors?

    What is torque in electric motors? And why is it largest when a single armature is horizontal to the field?
  22. G

    Questions about batteries and electric motors

    a concept i can't grasp is the meaning of voltage for an electric motor. it seems all the motor needs to operate is a magnetic field which is generated by current. why does the electric motor "care" whether the current is fed to it from a 100V or a 200V battery? Isn't the concept of voltage...
  23. R

    Power-to-weight ratio of electric motors

    I wasn't sure whether to put this in the mechanical engineering board or not but since electrical engineers typically design electric motors, I'll put it here. From what I hear, all types of electric motors have terrible power-to-weight ratios. So if we were to hypothetically one day have a...
  24. C

    Electric motors and gears: torque, rpm questions

    Hi guys, new here to the forum. I was an electrical engineering student but am now working on more of a mechanical issue so I'm a bit out of my element. I am working with a small electric motor attached to a gearbox. The final gear opens and closes a metal valve. I am having trouble finding...
  25. R

    What can be done to make electric motors louder?

    I like pure electric cars but one thing that sometimes annoys me is how quiet they are. Many car enthusiasts will never buy electric cars solely because they don't sound as "cool" as a roaring internal combustion engine. Also, it is dangerous for cars to be so quiet. Many pedestrians and drivers...
  26. Crazymechanic

    Is There Truly a DC Electric Motor or Generator?

    Hi , maybe a pretty simple question and about things that we have long used and know well but is there a electric motor or generator that is truly DC? As much as I think there isn't because either to create , induce electricity in windings (generator) u got to have a changing magnetic field...
  27. R

    Boeing Will electric motors ever propel a 747?

    I've been told that a 747 will never be able to be propelled by electric motors even with room temperature superconductivity because batteries have too low of energy density. So if hypothetically we were able to develop a battery with energy density as high as jet fuel, would electric motors...
  28. I

    Circuit Frequency's effect on electric motors

    What is the effect of the Circuit Frequency on the Electrical Motors which runs the production line! For example if we had like 3 - 4 Motors! Effect on: Efficiency of the motors! Speed of the motors! What about if we had a " Servo Motor " which runs one of the machine!
  29. C

    How electric motors consume energy?

    What exactly makes the motor consume the electrical energy? I s heat dissipation higher that in a normal coil? Is it counter-electromotive force? What makes the voltage drop? Thank you regards
  30. D

    Permanent Magnet Motors vs. Non-Magnetic Motors: Which is the Superior Choice?

    Choose between two: A. Permanent magnet motors( Being the shaft/rotor) B. Non-magnetic material( Same being the shaft/rotor) Give me you're answer and a detailed explanation why please!
  31. A

    Detailed Windage losses calculations, rotating electric motors.

    Hi everyone, Long time reader first time poster. A little background on myself, 4th year in the field of ME mostly in simulation and analysis (FEA). I am currently working on a project of a high speed electric motor. I am putting together all the losses from the rotating motor (Copper...
  32. D

    Electric motors momentum and load

    hi, this is not a question from Hw its pure interest. 1.lets say i have an electric motor with a shaft radius r lengh L, and at its end there is a metal disk with radius R and thickness b. if the motor supplies torque τ what would be the momentum on the disk? i was thinking that i the motor...
  33. X

    Why aren't the coils in electric motors insulated?

    In all the electric motors I have taken apart, the coils on the armature have never been insulated. This has always confused me because, how could the coil make a sufficient magnetic field if it shorts out to the adjacent wires from lack of insulation?
  34. E

    High speed electric motors specifications

    Hello, I'd like to ask if anyone could give me information or a link to web page where I can find some for the most advanced high speed electric motors used today in cutting machines - speed range, torque and etc. I tried to find searching in Google but I haven't found anything. If someone...
  35. P

    Direct current in electric motors?

    1. Small electric motors with only one armature loop sometimes get stuck. They can be started again by giving the armature a small twist. Looking at the diagram below, what might be the explanation for the motor not being able to start on its own? When the brush(es) reaches the split within...
  36. A

    Creating more Power from electric Motors

    I was wondering if there is anyway to get more wattage out of a 1000 watt motor?
  37. L

    Just curious how electric motors work, specifically DC motors.

    Just curious how electric motors work, specifically DC motors. I have some questions i would like to understand better. do the windings of a motor determine the required voltage to power it? Can a 110 volt ac motor be powered by a 12 volt dc battery without an inverter? Can a 110 volt...
  38. F

    Calculating Speed for a Mechanical Dolly Driven by Electric Motors

    Hi there, I have recently been working on a project that involves building a mechanical dolly that is driven by 2 electrical motors. I have decided to use 2 electrical winch motors which each have a rating of 5700kg and a drum size of diameter 64mm My question is, how do I calculate...
  39. A

    Photovoltaics, Electric motors ,Solar energy. Should i go for EE?

    Hello. I want to work with Photovoltaics and with the renewable industry. Electric motors, boats, cars. Is EE a good choice? I was thinking first in ME but looks like you see more of solar energy in EE. Please i need urgent advice i only left like 2 moths to make a choice.
  40. F

    Why do Electric Motors have High Torque?

    Simple question. I've been reading qualitatively about the torque and power curve of electric engines versus internal combustion engines. I'm led to understand that electric engines get much higher torques even at lower speed. One argument for why electric cars are inherently more efficient than...
  41. J

    Ferromagnetic Windings in Electric Motors: Can They Operate?

    Can the wire windings in an electric motor be ferromagnetic and still operate? Why?
  42. N

    Electric Motors and/or Maglev Texts

    I'm trying to learn about electric motors, and I would eventually like to learn about how the maglev trains work beyond the general descriptions. I have found these two books so far: https://www.amazon.com/dp/0750647183/?tag=pfamazon01-20 by Austin Hughes...
  43. S

    Linear Electric Motors: Pros & Cons

    we were learning about electrical motors in class the other day and my teacher mentioned linear electric motors, which from what he said are basically standard motors 'unravelled'. i was wondering why, if this is the case, you would ever use a standard motor when linear motion was required? why...
  44. R

    Power generation using electric motors

    Hi, I am a novice. I have very sensitive high end audio equipment. I want to power them up from an independent source. I was contemplating using a electric motor driven generator. I want to do this to supply cleanest power to the equipment/electronics. My power requirement is about 5 KVA. I am...
  45. J

    Electric motors & faraday's law

    Homework Statement Eliza connects a power supply, switch, and a multimeter (in ammeter mode) in series with a wire coil. The wire coil is held into place by 2 connecting wire leads. One of the wire leads has been stripped off of the insulating enamel coating so that half the wire is bare; the...
  46. M

    Capacitors in Electric Motors: Usage & Benefits

    What is the use of having capacitors in fans, cooler motors or other electric motors ?
  47. K

    Do Displacement Currents Exist In Electric Motors

    I am not asking if they are considered as input into the armature's magnetic field. I strongly believe they are NOT even considered when designing motors. The question is, "DO THEY EXIST IN MOTORS?" Based on evidence from conventional theory, it appears they do infact affect the output of...
  48. J

    Can Electric Motors Match the Power-to-Weight Ratio of Human Muscles?

    Is it possible for electric motors to compare to the strength of human muscles, in terms of power-to-weight ratios? That is, with the proper engineering, is it theoretically possible? I don't see why not, simply increasing voltage increases power, if the heat generated is a problem, can't the...
  49. J

    Best practice for large electric motors

    This may not be the place to ask this question, but I can't seem to get a good answer anywhere else...I have a manufacturing company. I am on a 3-phase demand meter. I'm trying to figure out if it is more cost effective to shut all the electric motors down during breaks and lunch and restart...
  50. S

    Electric motors and motorcycles battry

    can u modify an electric motor so that it uses a motorcycle battery as a power supply?how? and used for a grass trimmer...