how to select motor for any project?

what is the formula to choose a motor to lift load? what parameter should have to consider while selecting a motor?
 how much power it consume? which is the best motor for project(say to drive a vehicle/car) brushless dc motor or any other?

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iceng3 years ago

A single horse power muscle machine.


It's OK but the exhaust emmissions!!!!


Very true .... but it mostly gets walked off ;-D

rickharris3 years ago

All answers totally true, You can also get a long way by looking at similar projects and learning from them. If I tell you I built an electric car with a motor drawing 20 amps at 24 volts and that car could get to 30 MPH on a flat road then you have a pretty good marker that 500 watts will get you 30 MPH if you car performes as well as mine.

iceng3 years ago

  1. First you need need to select the motor with the most desirable speed / torque curve.
  2. Then consider weight and driving electronics.
  3. Efficiency will be a major impact if this is a serious consideration.
  4. One way to reduce motor weight is to run it at higher speed and gear down.
  5. As the motor size goes down the output energy remains the same with less surface to cool the machine leading to novel cooling techniques.
  6. PM motors are the popular machines for vehicles these days.
  7. BUT the Tesla eCar company is using a small high speed induction motor because over the speed range 0.01 to 200 mph that machine is more efficient.
  8. You do have to balance the weight saved by a smaller motor against the added weight of the gear box.
  9. Regeneration.... All motors can do this PM, Induction, Series, Stepper, Torque.
  10. The electronic systems are designed to make breaking between disc and regeneration a seamless deceleration.

Surely you have to know the load, before you can select the motor !

OF Course ... that is how one comes up with a Speed / Torque to match.

Knowing the Load is the Zero "you understood" step !

Given today's induction motors one can reasonably design a speed torque curve by changing deep bar rotor dimensions.

You choose a motor for a job by horsepower, environment, and cost.


Feet pound seconds

How many feet, times how many pounds, times how many seconds equals foot pound seconds.

550 foot pound seconds ft*lb*s = 1 horse power

1 horse power = 746 watts

Watts = amps times volts = P = A*V

Then power supply AC or DC, size, and cost.

Lets face it weight size and added circuitry effects efficacy.

Take the AC DC motor in a power tool it is 1/4 the size and weight of an induction motor the same power, easier to pick up.

So why have Induction motors, they were first called explosion proof motors, without brushes there is no ark to touch off leaking gas. Also brushless motors need fewer repairs making them cheaper to maintain.

Cost is a factor why pay $100 for a motor when a $20 motor will do the same job.

Sorry I did horsepower wrong.

feet times pounds divided by seconds


start by defining the load, what inertia does it possess ? How fast do you want to accelerate it