Electric motor: everything you need to know

electric motor

As you know, there are a large number of models of electric motor on the market, with various types. In this blog we have already analyzed some very specific types of electric motors to use with DIY projects, such as controlling them with Arduino boards using PWM, but they also have many other applications such as robotics, etc.

In this article you will learn a little more about these types of engines that are now becoming quite relevant in various sectors ...

What is an electric motor?

indoor electric motor: stator-rotor

Un electric motor it is nothing more than a device that converts the electrical energy supplied to it into a rotating mechanical energy. That is, a rotor will make a shaft rotate when a current is supplied to it, since it generates magnetic fields inside it capable of operating through coils and magnets to produce the rotation.

Inside there will be a stator and a rotor. The first is in the outermost area and fixed to the electric motor housing, in addition to being generally composed of fixed magnets (represented in the previous image by the red and blue magnetic shields). Instead, the rotor is a moving part that will rotate due to the magnetic action of the stator thanks to its coils that make up an electromagnet (represented in the previous image by the red and blue coils).

That is, the magnetism it will generate an attractive and repulsive force on the rotor windings, depending on the sign, and thus makes it rotate inside the stator.

In addition, some of the electric motors are reversibleThis does not mean that they can reverse the direction of rotation, since that can be done by everyone, but that they can be both a motor and a generator. That is, when you apply energy they rotate and when you rotate their axis they generate an electric current at their terminals.

This is the beginning of generators that are used in the energy industry, such as the generators that exist in wind mills, or those that exist in thermal, hydroelectric plants, etc. In fact, in some applications they can work in both modes, such as the engines of certain vehicles such as the KERS or the regenerative braking of some trains ...


The engine has a series of characteristics which will identify the qualities of an engine. You should know the most important ones to know how to choose the right unit. For example, it highlights:

  • Power: they can be from a few mW in the case of the smallest and lightest, up to thousands of watts in the case of the most powerful and heaviest. And that widens the range of use, from small electronic devices to industrial applications. Depending on its power, you will have more or less turning force.
  • Voltage and current type: there are more and less voltage, from small motors of 5v, 12v, to others that work at 220v or more. Of course, the supplied current can be direct (DC) or alternating (AC).
  • Motor torque: is the force with which the motor shaft will rotate. It is usually practically constant unlike other engines, but you can find less powerful engines and others much more powerful. Some will even be able to generate a lot of torque to move heavy vehicles.
  • Performance: It is not about strength, but about energy efficiency. Typically it is around 75%, with some models being less efficient and others more efficient.
  • Emissions 0: this type of engine does not emit polluting gases into the atmosphere like other internal combustion or reaction gases. In this case, the only pollutant may be the way in which the electricity that powers them is generated. Whether it comes from renewable sources or not.
  • Refrigeration: they generally do not need cooling like other combustion engines. They are self-ventilated, although some of higher performance are likely to need some cooling.
  • Gearbox: they do not need complex gearboxes, the speed and direction of rotation can be controlled electronically. However, there may be reducer or multiplier gears to extract more force or speed as desired ...


There is not only one type of electric motor, as I have already mentioned, but there are several types. You should know the most outstanding, although in this article we focus on the CC for obvious reasons of the theme of this blog.

The types of electric motor are:

  • Universal motor: It is a type of motor that can work with both DC and AC, although it is not very frequent. It is a single phase motor with similarities to a series DC motor, although with some modifications. They are used in various applications, as they have a higher starting torque than induction and a high rotation speed despite being compact and cheap. They are common in portable tools of all kinds and small appliances.
  • Direct Current (DC) Motors- These motors are the ones that run on direct current, like most small motors you use with Arduino and other maker projects. Within this family there are subgroups such as:
    • Independent excitation
    • Serial excitation
    • Shunt or shunt excitation
    • Compound excitation or compund
    • Others: stepper or servo motor, coreless motor, brushless (brushless).
  • Alternating Current (AC) Motors: they are those that work with alternating current, being larger and for use in large electrical appliances, industry, machinery, etc. Inside you can find subtypes like:
    • Synchronous: In this type of motor, the axis of rotation rotates at the frequency of the supply current. Its speed of rotation is therefore constant, always depending on the frequency of the voltage of the electrical network to which it is connected. For example, on a home network it would be 220v 50 / 60Hz.
    • Asynchronous: is one whose rotor rotates at a different speed than the magnetic field. Inside there are also divisions such as:
      • Single phase: they are those that use a single phase power supply, such as that of a house. Inside are:
        • Auxiliary winding
        • Loop shorted
        • Universal (see first point)
      • Triphasic: its stator inductor winding is designed to have three different coils displaced 120º electrically, so that when it is supplied with a three-phase AC, the rotation of the rotor can be generated by the action of each of the phases. Inside you find:
        • Wound rotor (conventional).
        • Shorted rotor (squirrel cage).


An electric motor can be used to large number of applications. From electric vehicles, through certain mechanical actuation mechanisms, to drones, robots, mixers, 3D printers, hard drives, water pumps, household appliances such as washing machines and dishwashers, conventional printers, fans, electricity generators, and much more. .

Generally, single phase They are the most basic used in small applications and they are easy to reverse the rotation simply by changing the polarity of the applied current. They are typical in small electronic devices. Three-phase are used for more powerful applications, such as industrial ones.

That as for the alternating current. But in the maker and DIY world, it is normal for you to use dc motors. These small DC motors are typical for robots, drones, 3D printers, small electric vehicles, etc.

Where to buy

You can buy various types of this device, such as the electric motor models that you find in Amazon and other specialized stores:

More information on engines

I recommend you also read others Related Posts with engines like these:

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