What is Electric motor: Definition and 219 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. Y

    Axial flux motor core loss model simulation

    Hello, I'm a student, working on project related to electric motor. Currently I'm trying to simulate a 350W power axial flux motor on Ansys Maxwell 3D. Until now I have been able to get BEMF of motor, further I'm trying to find losses in motor like core losses & copper losses. The core loss data...
  2. Ranveer

    Engineering Homemade DC electric motor not working

    Summary : i have tried changing the batteries and wire,but still nothing. The wire is insulated and the coating is removed at the ends of the battery and the point where the wire touches the commutator. I have not counted the number of coils. This is required for a school project. If someone has...
  3. L

    Determine torque required to move load

    Trying to figure out how much torque an electric motor would need to move a load of 100lbs on a flat surface. The device would use two electric motors attached to a 8 inch diameter wheel (each motor is attached to a 8 inch wheel).
  4. M

    Electric motor torque control based on speed interaction/instability

    Hi everyone I'm trying to exert a controlled load into an electric motor with another motor (having first motor spin at a lower speed than second motor, exerting a torque). Both are connected through a shaft, and we're measuring speed and torque at the shaft. Motor #1 has a torque control based...
  5. C

    Electric motor problem -- Power to accelerate a toy train

    For part (b), The solution is, However, if the acceleration was not constant during the 21 ms, then would the power required be larger? I believe the average power required would be larger because if the train started off at a lower speed and then speed up very rapidly towards the end...
  6. M

    Electromagnet Polarity Switching for Reversed Motion

    I am trying to understand the differences in design between a traditional solenoid with a ferrous plunger vs linear motors that use either induction or permanent magnets. From my understanding, a traditional solenoid, whether DC or AC, cannot fire in both directions with polarity switching since...
  7. Nugatory

    Reversible electric motor - what am I looking at?

    I have a reversible electric motor that operates an automatic skylight, vintage 1985. I'm trying to figure out how it is supposed to work, but I don't recognize the rectangular gray components that are secured to the motor case with a length of plastic zip-tie. What might they be and how would...
  8. 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...
  9. A

    I Electric motor with increased load

    How come when the load is increased in an electric motor, the torque and current increase but the motor slows? Isn't how fast the motor is how much torque it has?
  10. S

    Convert 1 phase to 3 phase by using an old washing machine

    We were in the process of going off grid when a tree fell over our power line. Hence we got off grid before we were ready as we didn't want to repair the power line. Now everything in the house runs on solar power, except for the well pump. The problem with the well pump is that it is a 3 phase...
  11. Billygibson2

    What electric motor do I need to rotate a platter that weighs 6 - 10lbs?

    Would a DC motor that had torque of 0.34 Nm be able to generate enough power to rotate a platter that weighs 6 - 10lbs
  12. Fisherman199

    More Efficient Electric Motor?

    Electric Motor Start-Up I have done little research into this so far but my "Law of Thermodynamics" alarm is blaring loud-and-clear. Has anyone here heard of this "new motor?" Has anyone tested one in the field?
  13. F

    Battery Powered Electric Motor and Charging Requirements

    I need to build a battery system to drive a 10 HP pump motor. The actual BHP varies as the pressure in the system rises, but for the most part we are operating at a 10.1 brake horsepower. Run time requirements will vary from a few hours to many hours. I settled on 8 hrs as a basis. Motor...
  14. greg_rack

    What is the physical significance of torque being a vector in an electric motor?

    Hi guys, In my head, torque has also been associated with a bare SCALAR physical quantity given by the formula ##torque=rFsin\theta## which caused a rigid body to spin around its axis. Now, studying magnetism, I find out that torque is a VECTOR, which magnitude is indeed given by ##rFsin\theta##...
  15. Jon Zimmer

    Relation between electric motor and battery current, peak etc.

    Good afternoon guys, I was making some researches about building my own EV and its' specifications but I have a few no direct answered questions and some of them I humbly ask the help for you guys, based on the configuration example below. Considering that I hypothetically have an electric DC...
  16. K

    What kind of an electric motor with a reducer is needed for this?

    Homework Statement: what kind of electric motor with reducer is needed? Homework Equations: what kind of electric motor with reducer is needed? what kind of electric motor with reducer is needed? speed 55mm/s <moved to EE forum>
  17. weilam06

    Work done by an electric motor to drive elevator

    https://www.physicsforums.com/attachments/250022 For the part (a), set the tension of the string that pulls the elevator be ##T_1## and the tension that pushes the counterweight be ##T_2##. Then we have the following equations: $$T_1−1200g=1200 \cdot 1.5$$ $$1000g−T_2=1000 \cdot (−1.5)$$ where...
  18. N

    What are the advantages of a solenoid motor over an electric motor?

    Can force produced by solenoid be converted to mechanical force and be more efficient than electric motor's force?
  19. A

    How to stop a steering wheel using an electric motor?

    Problem Statement: i have a steering wheel mounted on an electric motor, and i want to stop the driver from going beyond a certain angle. i can read the torque applied by the driver, and the steering wheel angular velocity as well. how can i stop the steering wheel, without sending it harshely...
  20. 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...
  21. K

    B Question about forces in a gearbox

    hi all i have a simple question but answer i don't know how to find :) lets say we have a electric motor with 1kw at 1500 rpm and that is 4.75 N.m when the electric motor is connected to worm gearbox n proportion 10:1 then the speed on output point of the gearbox will be 150 RPM. But this mean...
  22. A

    Efficiency of an Electric motor pulling a truck up an inclined plane

    Homework Statement See picture. Homework EquationsThe Attempt at a Solution I tried at first just doing (1/3)*(48kJ) to get the energy dissipated, but that would i=give me 16kJ
  23. S

    What are the key factors for success in the electrical motors industry?

    I'm working in electrical motors industry from past 10 years.
  24. L

    AC magnetic field and how an electric motor works....

    does the magnetic field created by AC alternate? reverse poles? if so why does a motor rotate the same way every time? does it alternate in three phase as well? thanks, if you want to direct me to literature i would appreciate that, what i have in my motors book talks about the hand rule for...
  25. S

    Force from the legs of an electric motor due to torque

    I need to perform stress analysis for the stand for an industrial sized electric motor like pic related. The motor stands on four legs. I need to know the force that the legs of the motor exert on the stand due to its torque. I have all the dimensions of the motor including weight and torque...
  26. S

    What type of motor would have the highest Stalled Torque?

    I am referring to the output torque of an electric motor when the rotational speed of the rotor is 0 RPM. Some sources say that having a stalled torque damages some motors, and I know that some motors have a constant torque regardless of their speed while others have a max torque at 0 RPM. So If...
  27. T

    How does an electric motor convert electrical energy to mechanical energy?

    how does electric motor convert electrical energy to mechanical energy. Hello I do not understand the following electric power is P = V * I electric motors operate on the principle of repulsion and attraction of magnetism. What confuses me where that power ends because as far as I know, the...
  28. R

    Ansys Maxwell- Transient torque fluctuating problem

    Hii Friends, I was trying to model an Induction motor 5 KW in ANSYS Maxwell. The final output of Transient torque looks like shown below. It fluctuates with average torque almost equal to zero Nm. The input passed is a sine wave current with 120 deg phase shift. Any Suggestion will be highly...
  29. C

    Controlling the speed of an AC motor?

    For my IB Physics Extended Essay, I have just changed my topic from momentum to this and I have really little time of doing it... (Due in Oct) :cry::cry::cry::cry::cry::cry: My research question would be The effect of angular velocity of circular motion of a moving sound source on the sound...
  30. T

    How exactly does an armature spin in an electric motor?

    In an electric motor, there exists two magnetic fields where usually one of them is a permanent magnet whilst the other is an electromagnet. However, how does the magnetic fields enable the armature to rotate / spin? Also, how is the torque from the rotation of the armature transmitted to drive...
  31. T

    Questions about friction losses in an electric motor

    1) What is friction loss / are friction losses? 2) How can it be determined / measured / calculated / figured out? 3) How does it affect the power output (force * speed) of an electric motor when an electric motor is moving / lifting objects? Why does it have such affects?
  32. T

    What determines the maximum weight an electric motor can lift?

    What determines the maximum amount of weight an electric motor can lift / move for its size? So assuming the electric motor weighs a specific amount, what would be the limiting factor to how much weight it can move / lift for the weight it weighs?
  33. bachir1994

    Current and voltage relationship in an electric motor

    Hello, I can not understand that a motor (pumping) requires a current of 63 A under a voltage of 390 vac, and requires a current of 72 A under a voltage of 365 vac. Normally when the voltage increases the current increases with (ohm law). Is that the power delivered by the engine which is 37 kw...
  34. J

    Replacing a diesel engine with an electric motor

    Hi all, I have a little project on my hands and I will go into a little detail to help everyone better understand. I built a mobile boutique out of a shuttle bus for my fiancé to run her business out of. There is a large rooftop air conditioner on top of the roof for cooling and the...
  35. ckcurtis

    500cc 50hp electric motor swap

    Hi, I own a 1993 ex500 with that is having engine problems, I would like to swap the motor for one that is has more or equal power. The best specs I can come up with are these the motor puts on the rear wheel, HP 50, Torque 31 ft-lbs, top speed 130mph, I am looking into getting a DC-liquid...
  36. A

    What HP/torque Electric Motor to lift 1K lbs w/ sprokets

    I am building a lift using 4 threaded spindles and sprockets to travel 12 feet. The motor needs to have 56 mount as it will be mounted vertically (Shaft down) attached to a sprocket that drives a chain to the 4 supporting sprockets. The load (1,000 lbs, 250 lbs at each corner) will be lifted...
  37. S

    Electric motor: power and RPMs

    I am helping a friend with a project, and am wondering if this statement is true. "To double the RPMs of a central drive shaft motor, you must quadruple the input." In other words, if an electric motor being supplied with 1 Watt spins at 500 RPMs, one would need 4 watts to spin at 1,000 RPMs...
  38. S

    Analysis Error in Electric Motor: Need Help To Resolve

    I am carrying out a transient analysis of an electric motor. After running up to 250 ms it is showing an error that core loss values cannot be recovered and I am not able to run it further. Please help me to resolve it so that I can carry on ahead with my simulation. Thank you in advance.
  39. ramzerimar

    Calculations for weight-lifting motor....

    The project I'm building involves a 12 V electric motor connected to a spindle lifting a 20kg weight. The radius of the spindle is 2cm, so the torque applied by the weight is 0,02m*20kg*9,8m/s^2, which gives me 3,92N*m. So, my 12 V motor needs to deliver 3,92N*m just to keep the weight steady...
  40. A

    How could a DC electric motor be used to power a computer?

    Homework Statement A group of students found an old DC electric motor in a box. They were looking for a small generator they could use to power their computer while they were out camping. Explain how they might do this with the motor they found. Homework EquationsThe Attempt at a Solution
  41. Diegus

    Battery pack for an electric motor

    Hi Guys! I'm new in this forum and I'm a greenkeeper, it means that you can ask me everything about grass, flowers and trees but I have ZERO knowledge in electrical systems. This is why I'm asking here if someone with good patience and really helpful can help an ignorant gardener with some...
  42. S

    Motors in series: how do you stop one motor from spinning?

    Hi All, I've been reading up on hybrid vehicles and how the Honda Insight has an electric motor attached directly to the gas engine driveshaft. Their combined output causes the wheels to spin. My question is in regards to when the electric motor is off but the gas engine is on. Why doesn't the...
  43. R

    Automotive Coupling electric motor to gas engine in series

    Would it be possible to couple and electric motor to gas engine in series so both would increase the overall power.I currently building a twin engine car with two gas engines coupled together crank to crank like the old school twin dragsters.I would like to connect a large D.C. Motor in front of...
  44. CasVS

    What is the best battery for a Search & Rescue Robot on a budget?

    Hi All! I am a Dutch university student and I have an assignment to make a Search & Rescue Robot. Because we have to work with a budget, we have decided to make our own batteries (using AA penlights). Now while calculating the required capacity of the battery pack, I encountered some...
  45. D

    Making a shop press using a electric motor

    I'd like to make a small shop press from an electric motor, say 18'' tall max, with 6" of travel. It should be able to press say 10,000 psi and hold for several second or even maybe indefinitely. My question is two fold. First, what type of mechanical action would be best to turn circular...
  46. F

    Formula For Calculating Output Power of a Turbine

    Good evening, This Conversation is in regards to questions i have of a project of mine. I am, in a sense, looking to make a generator of sorts, one that uses a magnetic tesla turbine in order to power an electric motor. Unfortunately, i am at a loss for what formula i would need to figure out...
  47. V

    Automotive Calculating acceleration from electric motor

    I am in the process of designing an electric motorcycle, and would like to approximate the acceleration from various motors to inform my decision. I have written simple software to produce performance graphs, but my results seem a bit off - so i'd like to check my calculations. Here is the...
  48. Fizzics

    How to Harness braking energy from an electric motor

    I have a controller fed 3 phase 1kw servomotor which moves a mass over 1 metre ramping up for 1 second whilst energised, then it ramps down for 1 second. The motor is on (energised) for 1 second then it is off (braking) for 1 second which completes the first cycle, the cycle is then repeated...
  49. 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...