How do Electric Motors Work?
by：SUMWIC Machinery 2020-05-03
Do you know that there are electric motors everywhere? They are in the house, in the car, in the garden mower, in the washing machine, in the cake mixer, food processor, microwave; the list just goes on and on. But have you ever wondered how it works or have you just taken its presence for granted knowing it is there and yet dismissing it as part of everyday life? The fact is, you don't know how it works because you have taken its presence for granted so if your child of 5 asks you how it works, you wouldn't know what to answer. Here are a few basics so at least you won't get embarrassed in front of your five year old kid. The Basics An electric motor is simply about magnets and magnetism. The motor utilizes the magnets for the purpose of creating motion. Take for example a simple toy magnet. There are two opposites which can attract and repel. So if there is one end which is labelled 'north' and the other 'south,' then the north will attract the south. The north end will repel another north end, and the south end will also repel the other south end. This is exactly the same principle inside the motor. There are continuous attraction and repelling forces which will create a rotation motion. The rotor of an electric motor is an electromagnet. It is made of copper wound in a circle around a soft iron core. The magnetic field is a permanent magnet but there are two semi-circular magnets that are fitted inside the casing of steel. Larger motors and generators' electromagnets are also the field magnets which are today being used in cars. Small electric motors Inside a small electric motor are two small permanent magnets inside of a casing, two brushes which are housed and a winding wire around metal laminations or shafts with winding wire wound on them, this is known as the armature or the rotor. There are three poles to the rotor which causes it to move better. If there are two poles the electromagnet is the balancing point and between the two poles is a field magnet. For three poles the motor can start turning from any point. Now, each time the commutator (a switch that will reverse the direction of the current between the rotor and the external circuit) changes the direction of the field in a two-pole type motor, it will short out the battery for a little bit. This will waste the battery and drain it of its power. The three poles will fix this problem for it will only shift the direction when the repulsion is at its strongest point. Now, there are motors with varying number of poles but this really depends on the size of the motor and how it is being used. There are some which use very rare but powerful magnets which can boost the power a lot; however, this makes the motor very expensive. Today, the commutator is not as well utilized as electronics are now commonly used which will rid the motor from sparking and constant servicing. In short, an electric motor utilizes electrical energy to produce a mechanical energy with the use of magnets and magnetic fields.