Please Do subscribe this blog by clicking "Joint this Site" Button.
Soft Magnetic Materials:
Ferromagnetic materials are often used to enhance the magnetic flux density (B) produced when an electric current is passed through the material. The magnetic field is then expected to do work. Applications include cores for electromagnets, electric motors, transformers, generators, and other electrical equipment. Because these devices utilize an alternating field, the core material is continually cycled through the hysteresis loop.Note that in these materials the value of relative magnetic permeability depends strongly on the strength of the applied field.
These materials often have the following characteristics:
1. High-saturation magnetization.
2. High permeability.
3. Small coercive field.
4. Small remanance.
5. Small hysteresis loop.
6. Rapid response to high-frequency magnetic fields.
7. High electrical resistivity.
High saturation magnetization permits a material to do work, while high permeability
permits saturation magnetization to be obtained with small imposed magnetic
fields. A small coercive field also indicates that domains can be reoriented with small magnetic fields. A small remanance is desired so that almost no magnetization remains when the external field is removed. These characteristics also lead to a small hysteresis loop, therefore minimizing energy losses during operation.
Eddy current losses are particularly severe when the material operates at high frequencies. If the electrical resistivity is high, eddy current losses can be held to a minimum. Soft magnets produced from ferrimagnetic ceramic materials have a high resistivity and therefore are less likely to heat than metallic ferromagnetic materials.
Permanent Magnets:
Finally, magnetic materials are used to make strong permanent magnets.Strong permanent magnets, often called hard magnets, require the following:
1. High remanance (stable domains).
2. High permeability.
3. High coercive field.
4. Large hysteresis loop.
5. High power (or BH product).
In many applications, we need to calculate the lifting power of a permanent magnet.
The magnetic force obtainable using a permanent magnet is given by:
In this equation A is the cross-sectional area of the magnet, M is the magnetization, and
u0 is the magnetic permeability of free space.
Soft Magnetic Materials:
Ferromagnetic materials are often used to enhance the magnetic flux density (B) produced when an electric current is passed through the material. The magnetic field is then expected to do work. Applications include cores for electromagnets, electric motors, transformers, generators, and other electrical equipment. Because these devices utilize an alternating field, the core material is continually cycled through the hysteresis loop.Note that in these materials the value of relative magnetic permeability depends strongly on the strength of the applied field.
These materials often have the following characteristics:
1. High-saturation magnetization.
2. High permeability.
3. Small coercive field.
4. Small remanance.
5. Small hysteresis loop.
6. Rapid response to high-frequency magnetic fields.
7. High electrical resistivity.
High saturation magnetization permits a material to do work, while high permeability
permits saturation magnetization to be obtained with small imposed magnetic
fields. A small coercive field also indicates that domains can be reoriented with small magnetic fields. A small remanance is desired so that almost no magnetization remains when the external field is removed. These characteristics also lead to a small hysteresis loop, therefore minimizing energy losses during operation.
Eddy current losses are particularly severe when the material operates at high frequencies. If the electrical resistivity is high, eddy current losses can be held to a minimum. Soft magnets produced from ferrimagnetic ceramic materials have a high resistivity and therefore are less likely to heat than metallic ferromagnetic materials.
Permanent Magnets:
Finally, magnetic materials are used to make strong permanent magnets.Strong permanent magnets, often called hard magnets, require the following:
1. High remanance (stable domains).
2. High permeability.
3. High coercive field.
4. Large hysteresis loop.
5. High power (or BH product).
In many applications, we need to calculate the lifting power of a permanent magnet.
The magnetic force obtainable using a permanent magnet is given by:
In this equation A is the cross-sectional area of the magnet, M is the magnetization, and
u0 is the magnetic permeability of free space.
No comments:
Post a Comment