The stator is made of three parts: a stator core, conducting wire, and frame. The stator core is a group of steel rings that are insulated from one another and then laminated together. These rings include slots on their inside that the conducting wire will wrap around to form the stator coils.
Simply put, in a three-phase induction motor, there are three different wire types. You can call these wire types Phase 1, Phase 2, and Phase 3. Each wire type is wrapped around the slots on opposite sides of the inside of the stator core. Once the conducting wire is in place within the stator core, the core is placed within the frame. Because of the complexity of the topic, the following is a simplified explanation of how a four-pole, three-phase AC induction motor works in a car.
It starts with the battery in the car that is connected to the motor. The coils within the stator made from the conducting wire are arranged on opposite sides of the stator core and act as magnets, in a way. Therefore, when the electrical energy from the car battery is supplied to the motor, the coils create rotating, magnetic fields that pull the conducting rods on the outside of the rotor along behind it.
The spinning rotor is what creates the mechanical energy needed to turn the gears of the car, which, in turn, rotate the tires. Now in a typical car, i. The battery powers the engine, which powers the gears and wheels. The rotation of the wheels is what then powers the alternator in the car and the alternator recharges the battery. This is why you are told to drive your car around for a period after being jumped: the battery needs to be recharged in order to function appropriately.
There is no alternator in an electric car. So, how does the battery recharge then? While there is no separate alternator, the motor in an electric car acts as both motor and alternator.
This is due to the alternating nature of the AC signal that allows the voltage to be easily stepped up or stepped down to different values. As referenced above, the battery starts the motor, which supplies energy to the gears, which rotates the tires. This process happens when your foot is on the accelerator — the rotor is pulled along by the rotating magnetic field, requiring more torque.
But what happens when you let off of the accelerator? When your foot comes off the accelerator the rotating magnetic field stops and the rotor starts spinning faster as opposed to being pulled along by the magnetic field. When the rotor spins faster than the rotating magnetic field in the stator, this action recharges the battery, acting as an alternator. The conceptual differences behind these two types of currents should be obvious; while one current DC is consistent the other AC is more intermittent.
The continuous current refers to a constant and unidirectional electric flow. Furthermore, the voltage keeps the polarity in time. On batteries, in fact, it is clearly marked which the positive and negative poles is. Around the armature is the stator, which holds insulated coils of wire, usually copper. When a current is applied to the motor, the stator generates the magnetic field that drives the armature.
Depending on the design of the motor, you might also find brushes, or fine metal fibers that keep current running to the opposite side of the motor as it spins. You may have noticed that, when you have two magnets, opposite poles attract and like poles repel. The electric motor uses this principle to create torque, or rotational force. It is not the electric current per se, but the magnetic field it creates that generates force when an electric motor is in motion.
Electricity moving through a wire creates a circular magnetic field with the wire as the source and center of the rotation. When you add current, the stator and armature form a stable magnetic field and an electromagnet that is pushed or rotated within that field, respectively. The basic motor runs on DC, or direct current, but other motors can run on AC, or alternating current.
Batteries produce direct current, while the outlets in your home supply alternating. They move the motor through a phenomenon known as induction.
Some DC motors are also brushless and instead use a switch that changes the polarity of the magnetic field to keep the motor running. Universal motors are induction motors that can use either source of power. Because of the flip, the north pole of the electromagnet is always above the axle so it can repel the stator's north pole and attract the stator's south pole. Usually the rotor will have three poles rather than the two poles as shown in this article.
There are two good reasons for a motor to have three poles:. It is possible to have any number of poles, depending on the size of the motor and what it needs to do. Now, we're going to look at the AC motor. AC motors use alternating current instead of direct current.
It shares many parts with a DC motor, and it still relies on electromagnetism and flipping magnetic fields to generate mechanical power. The winding of the stator in an AC motor kind of does the job of the rotor of a DC motor. In this case, it's a ring of electromagnets that are paired up and energized in sequence, which creates the rotating magnetic field. You'll remember that the rotor in a DC motor is hooked up to the battery.
But the rotor in an AC motor does not have any direct connection to a power source. Nor does it have brushes. Instead, it often uses something called a squirrel cage.
You read that right. The squirrel cage in an AC motor is a set of rotor bars connected to two rings, one at either end. It's kind of like something a caged mouse or squirrel would run inside. The squirrel cage rotor goes inside the stator. When AC power is sent through the stator, it creates an electromagnetic field. The bars in the squirrel cage rotor are conductors, so they respond to the flipping of the stator's poles. That's how the rotor rotates, which creates its own magnetic field.
The key to an AC induction motor, where the field of the rotor is induced by the field of the stator, is that the rotor is always trying to catch up. It's always looking for stasis, so it's rotating to find that steady state. But the electromagnetic field produced by the stator using AC power is always going to be a little faster than the rotor's field.
The spin of the rotor is creating the torque needed to create mechanical power to turn the wheels of a car or the whirr of a fan. Some AC motors use a wound rotor, which is wrapped with wire instead of being a squirrel cage. The squirrel cage kind is more common, though. In either case, there's only one moving part in an AC motor, which means there are fewer things that need replacing or maintenance. Look around your house and you will find that it is filled with electric motors.
Since our homes use AC power, most of these gadgets have AC motors. DC motors are more likely to be found in things that use batteries. Starting in the kitchen, there are motors in:. You might be wondering about electric cars, which use AC motors but run on batteries, which supply DC power.
The answer is easy: Electric vehicles have an extra part, called a converter, that converts the DC power from the batteries to AC power that the motor can use.
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Electric motors are everywhere. Inside an Electric Motor " ". You might be surprised to find out just how much work is done by electric motors.
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