After we received a lot of comments on our video about direct current and alternating current motors, we thought it would be nice to explain some types of motors. So today, I'm going to explain to you how this motor works here, which is a stepper motor. What's up engineering lovers, my name is Igor Felipe, and after having several comments on a video we made about engines, we realized that there is a lot of doubt and even distorted information in what people say.
Sometimes the information passed brings together a correct part and a totally wrong part, and this can generate doubt in some people. If you haven't seen this video, relax, I'll leave a card for him at the end of this one. So nothing better than looking for a little more information about each of the engines and how far they are used.
And for starters, we decided to talk about stepper motors. But what are stepper motors? Well, a lot of times when we use engines, we don't necessarily need them to be extremely fast at high revs.
In some cases, we need to fine-tune the rotation and even the torque of this motor. And that's where stepper motors come in. They are motors that have fine control of their turning position through individual control of their coils.
This means that through individual control of each coil, it has more precision in controlling its rotation. They are very precise motors when you need to control the number of cycles or even the necessary angle of rotation of the motor. Here in my hand, we have a very common stepper motor on the market, and it is used for several functions.
It is found for example inside our printers. There are other equipment that also use this type of engine such as 3D printers, scanners, milling machines, but it doesn't stop there. Depending on the type of car you have, this type of engine can control the electronic injection of vehicles and even the idle control in automatic cars.
The main characteristics of this type of motor is that they do not have brushes. But calm down, it's not this toothbrush, but the brushes and commutators that are used in conventional motors. Brushes are a major reason for failure in some types of motors as they are moving parts that need to touch the commutator and consequently end up wearing out.
As the stepper motor does not have these brushes, we have less friction and wear on the internal parts. Another feature is being able to have a fine adjustment even with a high load. If you let it spin falsely or with some heavy system, it still has its fine spin control.
That is of course if you are not ignorant and put a load higher than the maximum torque of the engine, otherwise it just won't turn. And finally, these motors have a fine control, or as we call it, a step control. Motors on the market can have different amounts of steps, and for example, this motor here has 64 steps.
But what does that mean? Well, for a motor to make a complete revolution around its axis, it needs to rotate 360 degrees. When we say that the motor has 64 steps, it is the same as saying that to complete one revolution around its axis, it will have to rotate 64 steps to complete the complete revolution.
This means that each step he takes is the equivalent of 5. 72 degrees. That is, if I want to turn the motor at a certain angle, what it does is control the number of steps needed to get to that desired position.
Wow, but 5 degrees is a lot, isn't it? It won't be as accurate. In the case of this simple little motor, the motor has 64 steps, but it still has a gearbox that goes from 1 to 64.
This means that for one rotation of the final shaft, the motor has to turn 64 times. With this, this stepper motor and reduction box set gives us a total of 4096 adjustment steps, or the equivalent of 0. 088 degrees of adjustment.
That is, when it travels 1 step in the motor, you barely notice it. To go through each step, the motor makes a control between a magnet and coils, which vary according to their poles. On the screen, we have a better demonstration of this type of engine.
The control is done by changing the performance of each coil, that is, they turn on alternately, and this causes the magnets to be attracted according to their magnetic field. When a coil is activated, it produces a magnetic field and the magnet is attracted with its reverse polarity, and while the coils are alternating, the motor is rotating. But stepper motors still have types, which vary according to 3 basic types, which are permanent magnet, variable reluctance and hybrid.
In the case of stepper motors with permanent magnet, the magnets are fixed on a smooth shaft in the center of the motor. They are engines that have a great power and a greater torque when starting, but they end up losing with less precision. When the stator coil is activated, the shaft aligns with the magnetic field until the stator is turned off and the next stator is turned on.
Variable reluctance motors, also called switched variable reluctance motors, have a slightly different characteristic. Its axis is made of iron and not with magnets as we believe, and it is the magnetic field formed by the coils that makes it possible to control the axis. For it to work you need to have sections with teeth on the shaft such that when they line up with a coil assembly, they are misaligned with each other.
When the next group of coils is turned on, the shaft aligns with the other stator and so on over and over again. The problem with these motors is that they have a lower torque at their output. And finally, we have the hybrid motors, which is basically a mixture of the permanent magnet motor with the variable reluctance motor.
This makes this type of motor have a high torque and a high precision in the steps. The motor shaft is constructed with two groups of teeth, one with the south pole and the other with the north pole, so that they are alternated on their own axis. These are exactly the kind of stepper motors that go in our printers.
Similarly, this type of motor needs to be turned on in sequence for the shaft to rotate. Because it has interpolated magnets on its axis, this makes it very accurate in its rotation axis, which can vary from 3. 6 to 0.
9 degrees, without needing a reduction box. And of course, all these types of stepper motors need to be connected, and then they usually have two phases, which can be unipolar or bipolar. Unipolar motors use two windings per phase and usually have a contact in common, and in the end we will have 5, 6 or 8 connections as shown in the figure.
Bipolar motors, on the other hand, have a very large mood swing. This type of motor uses a connection per pole, and needs the circuit that controls it to be able to reverse the direction of the current to drive the coils correctly. And you've already noticed that to start this type of motor, it's not as simple a task as taking a battery, plugging in two poles and that's it, it will spin.
No, this motor needs a controller, which in this case we call it a drive. Stepper motors are motors that run on direct current, but their controllers or drives can be powered by either direct current or alternating current. This drive is responsible for making and inverting the connections for the motor that I showed, so you can have fine control of it.
And for those who have an Arduino at home and enjoy doing some experiments, you can program the stepper motor according to its number of steps, making it accurate for any task you need to perform. In this case, I made a program where I can control the rotation speed of the motor through a potentiometer, and this is super simple to do. And if you don't want to manually control the motor, you can program it to perform a certain number of steps according to your programming.
And if you want to assemble this circuit in your house, I'll leave the sketch of this circuit in the description of the video for those who already have an Arduino. Now if you don't have an Arduino in your house, I'll leave in the description a link to the Arduino Omega Store where you can buy a simple Arduino kit and start experimenting at home. And I'm not getting paid to make this Merchant, that's because I bought this Arduino mega kit and I really liked the service, speed and even the ebook they send teaching you how to create different types of circuits using Arduino.
Now tell me here, when did you discover that under the plate that turns your microwave has exactly one stepper motor? And even you who ever thought about disassembling that old and ruined printer from your house to get your stepper motors? If you identified yourself with any of these questions, leave it here in the comments and we'll exchange an idea.
I'll leave two videos on the side and as I said, the video about engines that I mentioned is up here, so take the opportunity to check it out. Take the opportunity to like the video, subscribe to the channel and cool, copy the video link and post it on your social networks. And that's it my friends, a big hug and see you in the next video.
