Analysis of characteristics of ten major types of inductors

Today's circuits are inseparable from inductors, so what are its characteristics? In the case of inductors, the structure of an inductor is similar to that of a transformer, but with only one winding. An inductor has a certain inductance, which only blocks changes in current. Let’s take a look at the characteristics and basic common sense of the ten common types of inductors!

1. I-shaped inductor

Its predecessor is the flexible wire chip inductor, and the I-shaped inductor is an improvement of them. The baffle effectively enhances the energy storage capacity, changes the direction and size of EMI, and can also reduce RDC. It can also be said to be a compromise between signal communication inductors and POWER inductors.

SMD I-shaped inductors are mainly used for smaller power switching from a few hundred kHz to one or two MHz, such as LED boosting of digital cameras, ADSL... etc. for lower frequency signal processing or POWER purposes. The Q value is 20, 30, which is quite suitable for signal processing; RDC has a lower inductance than the flexible wire chip inductor, and it is also very useful as a POWER. Of course, a large I-shaped inductor must be used for POWER. .

The biggest disadvantage of the I-shaped inductor is that it still has an open magnetic circuit and has EMI problems. In addition, the noise problem is greater than that of the flexible wire chip inductor. I personally think that the I-shaped inductor is definitely not the optimal structure, and there is still a lot of room for improvement!

2. Color ring inductor

Color ring inductors are the simplest rod-shaped inductors to process and are mainly used for signal processing. The characteristics of the inductor itself are not very different from that of the rod inductor. It just has some more solid objects and some colors to make it easier to distinguish the inductance value. Because the unit price is very cheap, there is less emphasis on size nowadays, and plug-in electronic products can still be used. , there are still many color ring inductors used. Because it is a plug-in type and too traditional, it will only be a matter of time before it is eliminated by the times.

3. Air core inductor

Air-core inductors are mainly used for signal processing, used for resonance, reception, transmission, etc. Air can be used in very high frequency products, so many products with low variation requirements are still in use. Because air is not the best material for fixing coils, there is limited development in the trend of products with increasingly stringent requirements!

4. Toroidal coil inductor

The toroidal coil inductor is an ideal shape in inductance theory. It has a closed magnetic circuit and has few EMI problems. It makes full use of the magnetic circuit and is easy to calculate. Almost all theoretical benefits are attributed to the toroidal coil inductor. However, it has one biggest disadvantage. , it’s just that it’s not easy to bend the thread, and the manufacturing process is mostly done manually. Nowadays, there are many people in China, and girls are very discerning and clever. However, who wants to let young and lively girls waste their youth! Sooner or later, they will not be able to hire anyone! But when it comes to using machines, the competitiveness of the ring flexure line still needs to be mechanically and electronically controlled. engineers to improve. Although toroidal coil inductors are an ideal shape among inductors, they are less commonly used because they are mainly artificially twisted wires. Due to the high requirements for signal processing, very small toroidal coil inductors are still used in large quantities. , mainly used in high-frequency, high-sensitivity communication products.

The largest amount of toroidal coil inductors are made of iron powder cores, mixed with resin, etc., so that the air gaps are evenly distributed inside the iron powder cores. The inductors have a certain sensitivity. When we see the word "air gap" , you know it is used in power, so the iron powder core toroidal coil inductor is the most commonly used type of power inductor, and the IDC can reach more than 20 amps.

I think there is a lot of room for improvement in toroidal coil inductors, so we might as well develop and think in this direction.

The advantage of the iron powder core toroidal coil inductor is the toroidal shape, but the disadvantage is also the toroidal shape. I have said before that the user's favorite shape is square. Therefore, under compromise, the toroidal coil inductor is not the most advantageous.

5. Chip laminated high frequency inductor

Chip laminated high-frequency inductors are actually air-core inductors. They have the same characteristics, but they can be miniaturized because they are easy to fix.

Comparing chip laminated high-frequency inductors with air-core inductors, air is not a good fixator, but the relative magnetic permeability of air is 1, which is very useful at high frequencies. Therefore, it is better to find some with a relative magnetic permeability of 1. of fixtures, that's not very good. In fact, most materials in the world have the same magnetic permeability. The cheapest one is stone. The material of chip laminated high-frequency inductors is stone, and stone is silicon! Materials such as aluminum oxide and so on are also Same intention.

In short, the purpose of the chip laminated high-frequency inductor material is to make it into a laminated chip to facilitate printed circuits. Not only do we not want the material of the chip laminated high-frequency inductor to have characteristics, we hope it has no characteristics at all. , making the chip laminated high-frequency inductor characteristics exactly like an air-core coil, and because it can be fixed, the variation is very small. In terms of manufacturing process, because of the laminated process, it can be miniaturized as much as possible. Z=2*pi*frequency*inductance value, 2 and pi are constants. Regardless of them, the higher the frequency of the same impedance, the smaller the inductance value can be. The frequency of current communication products is getting higher and higher, which means that the inductance Value requirements are getting smaller and smaller.

The smaller the inductance value, it means that we can make smaller ones, and we don’t need high-permeability magnetic materials. We can just use air or stones. Therefore, the use of chip laminated high-frequency inductors will definitely increase. , This is an inevitable trend of human development.

Comparing the chip laminated high-frequency inductor with the chip flexible high-frequency inductor, the Q value of the chip laminated high-frequency inductor is not high enough, which is the biggest shortcoming, but I can confirm that the chip laminated high-frequency inductor on the market now The Q value of high-frequency inductors is definitely not the limit of this product, so there is still a lot of room for improvement. In addition, because the variation requirements for high-frequency products are very strict, the change of materials to temperature is also an important reason why Taiwan and China's patch-laminated high-frequency inductors are not able to compete strongly with the Japanese!

Chip laminated high-frequency inductors will replace chip flex wire high-frequency inductors. Nanhai Shiyilang predicts that in 5 to 10 years, chip film high-frequency inductors will also replace chip laminated high-frequency inductors. Research and market direction must be done correctly!

6. Magnetic rod inductor

The magnetic rod inductor is an enhancement of the air-core inductor. The inductance value is proportional to the magnetic permeability. When magnetic materials are inserted into the air-core coil, the inductance value, Q value...etc. will be greatly increased. You can just imagine the benefits. If you can't figure it out, or don't want to think about it, you should change your career as soon as possible! Magnetic bar inductors are the simplest and most basic inductors. From 30 to 100 years ago, they had whatever applications inductors had. The same is true for characteristics.

7. SMD chip power inductor

SMD chip power inductors mainly emphasize energy storage capabilities and less LOSS.

8. Through-core magnetic beads

The feedthrough magnetic bead is a resistor, and the inductor is a low-pass component that allows low frequencies to pass through and blocks high frequencies.

9. SMD magnetic beads

SMD magnetic beads are the next generation of through-core magnetic beads.

10. SMD high-frequency transformers, plug-in high-frequency transformers, and high-frequency transformers are generally used for switching power supplies. The above is an analysis of some characteristics of inductors. I hope it will be helpful to everyone.