Electric Motors

Anatomy of a Motor

Your industrial electric motor has several critical components that enable it to efficiently and effectively convert electrical energy into mechanical energy.  Each one helps drive the critical interaction between your motor's magnetic field, and the electric current in its wire winding, to generate force in the form of shaft rotation.

These six components include:

The Rotor

The rotor is the moving part of your electric motor.  It turns the shaft that delivers the mechanical power mentioned above. In a typical configuration, the rotor has conductors laid into it that carry currents which then interact with the magnetic field of the stator to generate the forces that turn the shaft.  Having said that, some rotors carry permanent magnets and it is the stator that holds the conductors.

The Stator (and Stator Core)

The stator is the stationary part of your motor's electromagnetic circuit and usually consists of either windings or permanent magnets. The stator core is made up of many thin metal sheets, called laminations. Laminations are used to reduce energy losses that would result if a solid core were used.

The Bearings

The rotor in your electric motor is supported by bearings, which allow it to turn on its axis. These bearings are in turn supported by the motor housing.  The motor shaft extends through the bearings to the outside of the motor, where the load is applied. 

The Windings

Windings are wires that are laid in coils, usually wrapped around a laminated iron magnetic core so as to form magnetic poles when energized with current.  Electric motors come in two basic magnet field pole configurations: salient- and non-salient-pole. In the salient-pole motor, the pole's magnetic field is produced by a winding wound around the pole below the pole face. In the non-salient-pole motor, the winding is distributed in pole face slots.

The Air Gap

Although not a physical component, the air gap is the distance between the rotor and stator. Your motor’s air gap has important effects, and is generally as small as possible, as a large gap has a strong negative effect on performance. A magnetic field will weaken as the distance increases.  

The Commutator

And finally, the commutator is a mechanism used by your motor to switch the input of most DC motors and certain AC motors.  It is made up of slip-ring segments that are insulated from each other and from the shaft. Your motor's armature current is supplied through stationary brushes in contact with the revolving commutator, which causes required current reversal, and applies power to the machine in an optimal manner as the rotor rotates from pole to pole.  (The absence of such a current reversal would cause your motor to brake to a stop.)

Direct Current Motor

In a direct current electric motor, there are permanent magnets on the outside casing that produce a permanent magnetic field. The stator is the part of the generator that does not move and the rotor is the part of the generator that spins (or rotates.) In the example to the left, the stator are the permanent magnets and the rotor is the spinning inductor. As direct current is applied to the Rotor it creates a matching magnetic field that pushes it away from like same charge permanent magnet. As the rotor rotates the commutator poles physically switches the polarity of the current flow which changes each side of the rotor back to matching magnetic charges to the permanent magnets. 

Alternating Current Motor

In an alternating current electric motor, there are inductors on the outside casing that produce a magnetic field as alternating current is running through them. The stator is the part of the generator that does not move and the rotor is the part of the generator that spins (or rotates.) In the example to the left, the stator are the inductors and the rotor is the spinning magnet. 

When an an Alternating Current is applied, the rotor spins because the inductors switch from positive to negative magnetic fields. Alternating current moves through the inductors and as its motion oscillates back and forth, the polarity of the magnetic field from the inductor is swapped. This pushes the like poles of the rotors magnet away from the inductor when the inductors charge is the same. We can adjust the frequency of the Alternating current to speed up or slow down the motor. 

To get more consistent power output, you can add inductors to the generator to add phases. This keeps the average amplitude high keeping the average voltage higher and increasing power. 




Experiment with Motors - Build your own DC Motor

Embark on an electrifying journey of hands-on exploration by building your own electric motor! With just a coil of wire, a permanent magnet, and a battery, you can unlock the fascinating principles of electromagnetism. Discover the magic as the coil becomes an electromagnet when connected to the battery, interacting with the magnetic field of the permanent magnet to create motion. This DIY project not only offers a glimpse into the inner workings of electric motors but also provides a thrilling experience of constructing a functional device from basic components. Unleash your inner engineer and witness the power of your homemade electric motor in action!

The core principle behind the electric motor involves the interaction of magnetic fields and the flow of electric current. In this setup, a coil of wire is connected to a battery, creating a flow of electric current through the wire. The coil is positioned within the magnetic field of a permanent magnet.

According to the right-hand rule, the electric current in the coil generates its own magnetic field. This magnetic field interacts with the permanent magnet's field, resulting in a force that causes the coil to rotate. As the coil rotates, it completes a half-turn, and the electric current reverses direction due to the coil's movement in the magnetic field.

This continuous process of the coil rotating and the current changing direction leads to a spinning motion, converting electrical energy from the battery into mechanical motion. Thus, the coil, battery, and permanent magnet work in harmony to create a simple yet fascinating electric motor.

Step One

Use a spool of 22-gauge magnetic wire. (It is magnetic wire because it is used for magnetic windings, not because it has an innate magnetic field.) Wrap the wire into a coil with 100 wraps. Be sure to leave about 2 inches of extra wire at each end. 

Step Two

Use a 1/8" dowel or skewer as a shaft for support of the coil (you can also use an insulated piece of 14-2 Solid Core wire.) Thread the dowel through the coil and secure it with tape or hot glue. Sand the enamel off the extra wire on each end so that the copper is exposed and wrap it around the dowel. 

Step Three

Create a base out of foam core or cardboard. Poke holes in the base about an inch away from the edge and centered. These measurements may have to be adjusted depending on your coil size.

Step Four

Take some scrap 14-gauge solid core wire and bend them into hooks. The hooks should be about two inches tall. Make sure these have the insulation strip off leaving only exposed wire. 

Step Three

Place the hooks into the base and secure them in place with hot glue or tape. Use your coil to gauge the final width and height of these hooks.

Step Six

Place the coil on the hooks making sure the exposed copper of the wire wrapped around the dowel is touching the hooks. Glue a disc magnet to the base under the coil- you can bend the hooks to make the air gap about a 1/4". Connect a 9V battery to either hook to apply direct current to the coil.