Halbach Array is one of the most famous magnetic assemblies, with big magnetic strength. We have rich experience in Halbach Array production.
What is Halbach Array?
The Halbach array is a magnet arrangement structure. Halbach array is one of the most efficient ways to use permanent magnets. It is made up of multiple high-grade magnets placed on a flat surface in an alternating pattern. The magnetic fields of each magnet point toward the middle of the array where they can combine to create an incredibly powerful magnetic strength.
Before we study this structure, let’s take a look at the distribution of the magnetic field lines of some common permanent magnets.
From these pictures, that is easy to find that the direction and arrangement of the magnet will directly affect the distribution of the magnetic field lines, that is the form of the magnetic field distribution around the magnets.
- The left picture is a single magnet set, all of them are north pole, and the color shows that the strength of the magnetic field is at the bottom and top of the magnet.
- The right picture is a Halbach. The magnetic field on the top of the magnet is high, while the bottom is relatively weak.
In the same volume, the strong side surface magnetic field strength of the Halbach array magnet group is about 1.4 times of the traditional single magnet, especially when the thickness of the magnet is 4-16mm.
The most common example of the Halbach array is probably the flexible refrigerator sticker. These magnets are thin and soft, usually printed on the refrigerator or behind the car. Although their magnetic properties are relatively weak (only 2% -3% strength) compared to NdFeB. The low price and practicality make it widely used.
Halbach Array Structure
There are many different structures (combinations) of Halbach. But no matter how the number changes, whether the structure is square, straight, circular, or arc. In the end, the magnetic strength is brought together on one surface.
The ring-shaped Halbach array can be regarded as a ring shape formed by combining linear Halbach arrays end to end.
In the permanent magnet motor, the permanent magnet motor using the Halbach array structure has a more sinusoidal air gap magnetic field than the traditional permanent magnet motor. With the same amount of permanent magnet material, the air gap magnetic density of the Halbach permanent magnet motor is greater. The iron loss is small.
In addition, Halbach ring arrays are also widely used in permanent magnetic bearings, magnetic refrigeration equipment and magnetic resonance equipment.
The linear type is the most basic form of Halbach array. This array magnet can be regarded as a combination of radial array and tangential array, as shown below.
Linear Halbach arrays are currently mainly used in linear motors. The levitation principle of a maglev train is that the interaction between the moving magnet and the magnetic field generated by the current induced in the conductor generates levitation force, and is accompanied by magnetic resistance.
Improving the buoyancy-to-resistance ratio is the key to improving the performance of the levitation system. This requires the weight of the onboard magnet Light, strong magnetic field, uniform magnetic field and high reliability. The Halbach array is installed horizontally in the center of the car body, and generates a propulsive force with the winding in the center of the track.
The magnetic field is maximized with a smaller amount of magnets, and the other side has less magnetic field, which can avoid passengers being exposed to strong magnetic fields.
This is not only a special structure, but the grade of the magnet is also special. Because in this structure, two-grade magnets are used. N52 and N48SH.
In the permanent magnet motor, the permanent magnet motor using the Halbach array structure has a more sinusoidal air gap magnetic field than the traditional permanent magnet motor. With the same amount of permanent magnet material, the air gap magnetic density of the Halbach permanent magnet motor is greater. The iron loss is small. In addition, Halbach ring arrays are also widely used in permanent magnetic bearings, magnetic refrigeration equipment and magnetic resonance equipment.
- Magnetic Crawler: A famous Halbach robot, which can walk on the cabin and do cleaning work.