Permanent Magnet Materials for Wireless Charger

The main types of the magnetic materials are widely applied in wireless charger at present are NdFeB permanent magnets, NiZn ferrite thin disk, MnZn ferrite thin disk, soft ferrite magnetic stripe.

As the main components of wireless charging technology, a variety of absorbing material disks made of soft magnetic ferrite materials play a role of increasing induced magnetic field and shielding interference of coil. The requirement for performance, size, and reliability of soft magnetic ferrite materials is rather high in wireless charger. Nevertheless, the receiving end has a higher requirement.

Wireless Charger

Multi-coil free position type charger can work with multi-terminal at the same time. There are a number of coils arranged in its internal covered most area of the charging dock. Thus, the terminal can be freely placed in the charging dock; the charger will automatically select several efficient transmission coils to work. The working frequency is 105 kHz to 113 kHz for this type charge according to QI standard regulation. Absorbing material disk uses high Bs and low loss characteristics of MnZn power materials.

According to the way of receiver placement, wireless charging transmitter is divided into fixed position type, single coil free position type and multi-coil free position type. These transmitting terminals have different requirements for ferrite products.

Fixed position type charger applied NdFeB permanent magnet as positioning, terminal equipment must be placed on the fixed position to charge and maximize the charging efficiency. In this charger design, work frequency is 110 kHz to 205 kHz based on QI standards. The resonance frequency of fixed position type charger is high, generally using low loss, high-frequency magnetic shielding NiZn ferrite chip as a separate disk.

For single coil free position type charging equipment, there is a drive device in the internal coil which allows plane mobile. Through setting position from the automatic detection device, moving the coil to this position, making the position of the coil in line with the position of terminal receive, eventually realize charging and increasing the charging efficiency. With this design, the receiver can be placed at any position on the charging panel. Based on the QI standard, the working frequency is 140 kHz for this charger. Due to movement requirement of the coil, absorbing material disk must be high reliability. It needs to use a flexible magnetic disk produced by the taper-casting process.

Permanent magnet materials applied to the wireless charging system, on the one hand, enhance magnetic flux between transmit and receive coil, improve transmission efficiency; on the other hand, as a positioning device between transmitting and receiving, facilitate fast and exact positioning of the terminal. Small wireless charging equipment mainly uses NdFeB permanent magnet materials; large wireless charging equipment can use ferrite magnets instead of neodymium permanent magnet materials to reduce the cost.

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NdfeB Magnets for Electrical Fields

With the increasing performance of permanent magnet materials, rare earth permanent magnet materials are widely used in electrical fields.
Using high-performance rare earth permanent magnet materials to make a motor, the structure does not require special electrical excitation system, which helps to improve motor efficiency and power factor, and save energy, to reduce the size of the motor.

electrical motor
Currently in the design of permanent magnet motor, the general assumption that a uniform distribution of the various parts of the magnetic field of the permanent magnet and the magnetic properties of the same batch of neodymium magnets can be the same, while the need to use a permanent magnet demagnetization curve of permanent magnet at room temperature under suppliers, intrinsic connectivity magnetic parameters, residual magnetism, such as density and maximum energy product.

However, since the manufacturing process and the level of the plant and other reasons, there is a temperature in each portion of a permanent magnet hereinafter actual performance differences and the performance of the same group of permanent magnets is different.

The magnetic properties of the permanent magnet
The permanent magnet motor in normal operation can be closely related to the magnetic permanent magnet.
The strong magnet motor can directly determine whether reliable operation.
When the permanent magnet motor is running, sometimes the rotor temperature is high and NdFeB irreversible demagnetization will happen, causing permanent magnet synchronous motor efficiency and power factor and other performance indicators deteriorated.

How to Separate Strong Magnets

Many people want to find a way to separate the magnets from an old hard disk due to the strong magnetic force among permanent magnets.

Well, how to merge and separate strong magnets?

It is a big and serious problem while people working with them.
The strong magnet is NdFeB magnet. Compared with ferrite magnets, AlNiCo, and SmCo magnets, Nd-Fe-B magnets can absorb 640 times weight of their own, so neodymium magnets are often called powerful magnets by outsiders.

The role of powerful magnets:

1. refers to the north and the South

2. attract small objects

3. electromagnet can be used as an electromagnetic relay.

4. motor

5. generator

6. electroacoustics

7. magnetic therapy

8. magnetic levitation

9. nuclear magnetic resonance

In daily life, strong magnets should be placed away from easily magnetized items, such as floppy disks, credit cards, computer monitors, watches, mobile phones, medical devices, etc. The magnet should be far away from the pacemaker. For larger size magnets, plastic or cardboard gaskets should be added between each piece to ensure that the magnets can be easily separated. Magnets should be stored in a dry and constant temperature environment.

Sintered neodymium magnets, even with small sizes, have the very strong magnetic force that will surprise you definitely. Permanent magnets belong to the dangerous object; when you handle them:
1. You should get some magnet safety-danger tips.
2. Do some clean-ups in the workplace to keep iron items away.
3. Prepare some tools like work glove, safety glasses, and woodblock, the wood block is a good spacer for big strong magnets.
4.Although demagnetizer is a way to separate magnets. But it will lose magnetic force. So it is very important to know the principle of separating magnets as below picture:

separate strong magnets

Due to the long shape of neodymium cylinder magnets to let you have the area to grab, you can separate two small cylinder magnets by hand. But for small thin neodymium disc magnets or other very big strong magnets, the first method is the right way. Here are the reasons:
1. Seek leverage from another object such as desk and/or find a better way to grab the magnets
2. Separate magnets apart parallel, which requires less force.

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What Magnet to Use for The World’s Smallest Phone Charger

Today, I will introduce the world’s smallest phone charger – The Nipper.
Comprised of two tiny 17mm x 17mm x 17mm squares, this super handy charger stay together with the use of three strong neodymium block magnets and a small leather strap, weighing only 10g and is as small as key ring accessories.

The Nipper
This Nipper charger is originally designed for emergency use utilizing magnetic force to hold two AA batteries (one of the most common household items) in place between the squares. Meanwhile, it is equipped with a micro USB connector that makes it compatible with Samsung, HTC, LG, and any other devices with this type of port.

Here is a key component – Sintered Neodymium Magnet
The magnets in the Nipper charge are the strongest magnet king- neodymium magnets. These three magnets have two functions of holding the batteries together while at the same time making an electrical connection to the circuit board. This circuit is called a boost converter, it turns the power from the batteries into a 5v power supply, and then it can charge your phone.

Neodymium Magnet

The use of powerful neodymium magnet also saves the connected components, come to simplify the structure, manufacturing technique and raw material saving. Hope this product can inspire you to consider other applications of super-strong rare earth neodymium magnet.
You probably already know that permanent strong neodymium magnets have a very strong magnetic force.

But do you know other properties of the magnet, like conductivity?

Yes, we all know, the magnet is conductive!
Strong permanent magnet contains many metallic elements, such as nickel, cobalt, and iron. All these are electrically conductive. So all strong magnets are conductive, only the degree of electrical conductivity is different.

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What is Halbach Array Motor

Halbach array is a new type of permanent magnet arrangement combined with the radial and tangential array, which can increase the magnetic field on one side of and weakened the magnetic field on the other side.
Using Halbach array in permanent magnet motor can increase the magnetic flux in the air gap and decrease the magnetic flux in the rotor yoke, and it is most suitable for the inner or outer rotor of the external permanent magnet.
At present, the permanent magnet motor is developing toward high power, high function, and miniaturization. The high power density and high efficiency are the basic requirements for all types of permanent magnet motor design.
According to the principle of magnet motor design, the increase of magnetic loading is to increase the motor gap magnetic flux density, which can reduce motor size and improve the power density.

Halbach array motor

For permanent magnet motor, generally, there are two measures to increase air gap flux density in the motor.
1. Change magnetic material: try to use permanent rare earth magnet with higher residual magnetic flux density. But restricted by magnet material performance and price, the actual alternatives are few.
2. Change magnet structure and arrangement

In brief, its application in the permanent magnet motor has great advantages:
1. The sine wave of air-gap magnetic field
2. Good magnetic shielding effect
3. High power density
4. Lightweight
5. Small in size

Neodymium magnets play a very important role in the renewable energy market. So we believe this magnet motor could find a broad range of industrial and automation applications, from electric vehicles, aerospace, independent power generation to other occasions.

The magnetic rotor assemblies are complex, including a wide variety of permanent magnets:
1. Samarium Cobalt (SmCo)
2. Neodymium Iron Boron
3. Ferrite
4. AlNiCo

What Material to Choose? – Neodymium Magnet, SmCo, AlNiCo, Ferrite

When you choose the permanent magnetic materials, you need to consider the following aspects:

permanent magnetic materials

1. Magnetic Performance
BHmax is the point where a magnet delivers more energy to the minimum volume. If you want to compare the magnetic performance of different types and degrees of permanent magnets, the most convenient method is to consider your BHmax.

magnet BHmax

Another parameter that must be taken into account is the flux density at the pole face of a rare earth magnet. This value is often confused with the Br, but in fact, it is purely the induction in a closed circuit. The following table shows the typical densities of the four pole flow point when working at about its BHmax points.

pole face magnet

2. Maximum working temperature
Effects of temperature can be classified into two categories, reversible and irreversible. Reversible changes with temperature have nothing to do with the shape, size or working point of the demagnetizing curve. They depend on the composition of the material. Irreversible losses will not appear in a certain temperature is not exceeded. In addition, they can also be limited by operating at high as a possible work point. But when the outside temperature exceeds the Curie temperature of a magnet, metallurgical changes occur inside the magnet and there will be irretrievable losses.

Maximum working temperature
The working point in the circuit determines the maximum working temperature of a magnet. The higher the working point is, the higher the magnet temperature can operate.

Working Temperature

3. Effects of exposure on Magnetic Stability
Although the high temperature is the greatest threat to magnetic stability, exposure to high external fields also has an effect on certain types of magnets. The following table shows the effects of different grades:
Magnetic Stability

Shock and vibration effects
The traditional magnets have always been affected by shocks and vibrations, but now it has little effect on modern magnetic materials, except for more closely calibrated devices. However, the mechanical impact will cause the magnetic materials to be brittle and fractured. SmCo is the most fragile magnet.

Effects of Radiation
Magnets are used in particle beam deflection applications and those with an upper HCI are more suitable for use in such environments. According to some tests, SmCo magnet has significant losses when exposed to high levels of radiation (109-1010 rads). Losses at low levels of radiation are basically the same as the loss of temperature. It is notable that some magnetic materials have Cobalt in them, and Cobalt can retain the radiation after exposure.

Effects of Shape
The performance and stability of a magnet are also affected by its shape. The shape of the magnet determines its working point along the degaussing curve. The higher the operating point, the more difficult it is for the magnet to be demagnetized. Magnets that have a longer length or are used in an enclosed magnetic circuit have better performance and magnetic stability.

Some methods may be adopted to improve the stability of magnetic performance, such as demagnetization sites and high-temperature aging treatment. After exposing the magnet in advance for possible negative influences, the unstable texture and magnetic domains disappear and the magnet may be magnetically more stable.

The total collapse of the composition will also cause loss of performance. Corrosion can break the magnet structure down, and from neodymium magnets, exposure to hydrogen will lead to structural breakage as well.

4. Corrosion resistance without coating
The coating can prevent the shape of magnets from being corroded. There are many protective coatings available. NdFeB often has nickel, zinc, varnish, epoxy resin or Parylene as a protective layer. Normally Alnico does not need coating, but the powder coating and galvanizing can be used when needed.
Corrosion Resistance

5. Price Comparison
There are several factors that affect the price of a magnet, such as a shape, tolerances, and quantity. However, the most important effect is the cost of the basic raw material. When there is a need for new sizes and production volume of magnets, tooling should be considered at times. In addition, accessories are sometimes required for near-machining tolerance.
Price Comparison

6. Properties of magnetic force lines
• The magnetic lines of force form closed loop outside the magnet is directed from the north pole to the south pole and inside the magnet from the south pole to the north pole.
• Magnetic force lines always look for the path of least resistance between opposing magnetic poles.
• Magnetic force lines can never cross. They repel each other when they travel in the same direction.
• Normally magnetic force lines always move along curved paths.
• Magnetic force lines will always follow the shortest path through any medium.
• Magnetic force lines always enter or exit a magnetic material at right angles to the surface.
• All ferromagnetic materials have limited capacity for power lines. When they reached their limit, they behave as if they were not there, such as an airspace or similar.

7. Useful Project Suggestion
• Always pay attention to the working temperature of the material you need.
• Temperature has the most significant effect on magnetic stability, so always take this into consideration as part of your design and your choice of material.
• The strongest one may not be the best.
• Beside flow resistance, there are still many other magnetic drawing factors to consider.
• Magnet performance can be improved with a steel pole.

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What are the Different Shapes of Magnets?

There are probably few limits to the shapes that magnets can be formed into. The factor that determines the shape that a magnet is formed into is the desired shape of the magnetic field that comes from the magnetic poles.

Uses of Different Shaped Magnets and Strengths:
Each magnet is designed and manufactured for its use and purpose to fit in for its use and the real strength of the magnet comes from the magnetic material, each shape of the magnet have the effect on the strength of the magnet and shape of the magnet is very important and significant.

magnet shape

The most common shapes you will see are rectangular prisms, cylinders, spheres, and rings, however, there are few limits to what shapes you can have with a magnet. You can buy neodymium arc magnets, neodymium bar magnets, neodymium block magnets, neodymium cylinder magnets, neodymium disc magnets, neodymium ring magnets, square pyramid magnets, conical magnets, triangular prism magnets, heart-shaped magnets, etc.

Now, let’s see what are different shapes of magnets now in detail about shapes of magnets:
Blocks and Bars:
These blocks and bars magnets have fully with the flat surface and in shape of perpendicular to each other.
Threaded Tiny Magnets:
Threaded magnets are partial with the use of their threaded shaped through magnetic rings and wooden plates and these include countersunk holes design and threaded shape which helps in holes to perfectly fit in with the threaded shape.
Rubber Coated:
Rubber coated magnets which are used for magnet keepers and used for protection purposes, these are tiny and generate and contact with large fields and these plastic coated magnets are used against the rust without irritations.
Bar Magnets :
Bar magnets are one of the weakest magnets of all shaped magnets.
Horseshoe Magnets :
Uses of horseshoe magnets and Horseshoe magnets are just barred magnets bent in u shaped and the U shaped magnet makes stronger by bending them in U shape just pointing the poles in the same direction which makes them stronger. As it is named horseshoe it can be used to collect pins, industrial materials etc.
Disc Magnets :
Disc magnets are mainly used for holding applications where the drilled hole plays an important role and it is recessed into the hole. There are lot of things we can do with disc magnets. The use of Disc Magnets is shaped in thin flat circular magnets and its thickness does not exceed the diameter.
Cylinder Magnets:
Cylindrically shaped magnets are used as rods and used in medical treatment as well sometimes for multiple surgeries, using this shape of the magnet in human spine bone and etc. Cylindrically shaped magnets posses the high level of magnetism from relatively small surface pole area rod shape with a ball end shape.
Ring Magnets:
Ring magnets are widely used in science experiments and they are used in various daily use products like the vacuum cleaner, motors, generators etc.
Pyramid Magnets:
Pyramid magnets with its shape in pyramid help to produce and designed in a way to fabricate or generate with huge flux density with it.
Sphere Magnets :
The main use of sphere magnets is for toys, and novelty products as it is shape and structure in the sphere and the magnetic flow in shape of sphere flows from north pole on the sphere to south pole on the sphere.


How to Build a Simple Magnet Motor

Building a basic magnet motor engine is easy. With the principles behind electric current and magnetic fields, we’ve looked for the facts on how to make an electric magnet motor most effectively.

1. Winding the Coil
Tape collectively four pencils. Tape the pencils in a by using the cluster. This will provide you with something stable to wrap your coil round. You could alternate the pencils for a cylinder that’s kind of half of an inch in diameter.

Wrap cord across the pencils. Once you have got the pencils taped or find an appropriate cylinder, begin wrapping your twine around it tightly, begin in the center of the cord and wrap the coil fifteen instances towards one give up and fifteen times toward the other. Once you’ve got finished wrapping the coil, cast off the pencils from the middle. This could go away you with loose leads at both give up of the coil.

wrap wire

Loop the unfastened ends around the coil. Wrap the loose ends round either side of the coil 3 or 4 times. This can assist maintain the coil wound tightly, point the ultimate unfastened ends immediately out away from the coil.

2. Connecting the Battery
Relaxed the battery. Use tape or clay to preserve the battery in the region on a flat surface like a tabletop or table. This could permit you to join it to the coil while not having to preserve it with your fingers. Ensure the battery is laying on its side so you can easily reach each terminal.

Strip the ends of the coil cord. Use cord strippers to dispose of the insulation on either stop of the twine. Those leads will hook up with the battery and permit cutting-edge to flow thru the coil. For the exceptional results, you could sand the ends of the leads as nicely. This can cast off any film or protectant that may be implemented to the twine.

secure the battery

Slide each ceases through the attention of a needle. A needle makes the best holder for the cord leads. Insert each gives up into the attention of a separate needle. you can additionally bend two paper clips (one for every facet) to make a holder.

Tape the needles to the battery terminals. Once you have the wire in both needles, it’s time to hook your wire up to the battery. Tape one needle to the positive side of the battery (marked with a “+”). Tape the other needle to the negative side of the battery (marked with a “-”).

3. Placing the Magnet
Deliver a neodymium ring magnet close to the coil. As soon as a cutting-edge is flowing via the coil, it could have interaction with a magnet. Either keep the magnet close to the coil, or tape it to the battery right under the coil. The nearer the neodymium magnet is to the coil the more potent it’ll interact.

ring magnets

Spin the coil. See what happens whilst you spin the coil. Depending at the course the contemporary is flowing and the facet of the magnet this is interacting with the coil, the coil might also maintain to spin or won’t. If the coil does now not preserve spinning, try spinning the alternative path.

Experiment with special methods. Distinct versions will provide you with special effects. The coil can also spin faster, slower, or under no circumstances, if you alternate something. Attempt shifting the magnet in the direction of or further from the coil, select a more potent or weaker magnet, or use the other aspect of the magnet. These variations are a fun way to understand the forces in a magnet rotor.

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