Vector Hysteresis in Solenoid

This is Daniel Esmaili, and I'm going to talk about vector hysteresis in a solenoid today, on behalf of Ozen Engineering Incorporation.

At Ozen Engineering Incorporation, we use physics-based simulation to solve multidisciplinary engineering problems using industrial leading CA technologies from ANSYS. We work on mechanical and electrical problems and provide engineering services for different industries.

It's worth mentioning that we are also an elite channel partner of ANSYS. In today's PowerPoint, I'm going to talk about the solenoid that you see in this picture and show how we can use Maxwell, which is an ANSYS product, to produce hysteresis in a solenoid. So let's start with the solenoid first.

This is a solenoid profile for this armature. Today, I'm going to talk about what magnetic hysteresis is and then explain the geometry of the model, how to set it up, how to add hysteresis behavior, and post-processing.

In this section, we'll also show you how to have a behavior that doesn't follow hysteresis. So we'll show you how you have both hysteresis and non-hysteresis behavior options.

I'm not going to go too deep into magnetic hysteresis and what it is and how it works but just want to have a touch base on it. On the left-hand side, you see a BH curve, and on the right-hand side, you see another BH curve.

So, at the beginning, when H is zero and B is zero, and nothing has happened to the circuit or the solenoid, you can see that H is zero, and B is zero.

So, at the beginning, when H is zero and B is zero, and nothing has happened to the circuit or the solenoid, you can see that we have to brake the hysteresis loop. The flux density and magnetic field strength must be the same across the area.

However, we need to understand the mechanism of the hysteresis loop. If we construct an equation in the same region, we have a defense curve.

If we add a BH curve in both ditches and in the center of the hysteresis loop, and because the weight doesn't matter, and we don't know why, then gradually, they become oriented, as you can see here, they're all in the same direction.

That's why, after that, there is no more need to increase the magnetic field strength because this is the most you can get out of your material.

Once the magnetic field strength starts decreasing, the number of lines in the flux line starts getting less and less, but it doesn't go all the way to zero, as you can see. It commonly reaches to this BR point, in order to make B equal to zero, we need to decrease the magnetic field strength.

So, let's move to this chart now. We start from the origin, go all the way to point B, where the magnetic field strength is equal to BR. After that, when we decrease the magnetic field strength, the magnetic flux density decreases all the way to point C.

At point C, if we want to start decreasing the magnetic field strength, we can keep doing that, but again, we'll reach point T, which is another saturation. We're doing the same situation but in a different direction. Then, we can start changing the magnetic field strength again.

It comes and hits the y-axis, which is B, at point E, it goes up all the way to get to the point A, which is the same point that we had at the saturation. And after that, when we decrease the magnetic field strength, it just goes on this path and never goes back to the starting point again.

That's what's happening in the hysteresis loop, just in a nutshell. Then, it's worth noting that we have different types of profiles. Some of them have a big area between them, and some of them have a smaller area, depending on how soft or hard it is.

They have different applications, different pros and cons, and depending on the need, the industry chooses one of the others. A good example is that different metals have different parameters.

Now that we know what the hysteresis loop is, let's take a look at the structure, the material, and the armature that we're going to cover today. The one we're going to show you is very similar to this picture here, but it's not exactly the same.

As you can see, we have different parts of this armature here. You'll see the armature, the coil, and the frame, which is this part in the simulation. As you can see, there's a symmetry in this geometry. So, there are two ways you can use Maxwell to solve the equation for this armature.

One is having the whole model, which takes a lot of time. Another one is making it in a small section. For instance, take a look at this section right here. This is a very small section of the armature, but if you solve this, it's the same for all of them because there is a symmetry here.

So, we'll use that in our simulation to decrease the simulation time. In the simulation, we're going to show you how you assign the material. You choose a material from the list of libraries that you have. And then there are two options there. One is choosing a BH curve as this.

Another one is using the BH curve as described here, which has the hysteresis. There's a key point here. If you want to use this profile, the very end and the very beginning have to be exactly the same number, just multiply by minus one. Otherwise, you'll see an error in your simulation.

Next, you need to create a dataset. This dataset is created, as you can see here. We manually input these numbers. When you have no hysteresis behavior, the profile just follows the current. However, when you have the hysteresis behavior, the force will have a little bit change.

And that's, as you can see, there are little bit changes, differences between these two profiles. That is because of the magnetic behavior of the material.