Magnetic Circuit and Hysteresis Loss:
A magnetic circuit is a closed path or loop through which a magnetic flux can flow. It is analogous to an electric circuit in which current flows through conductors. In a magnetic circuit, the magnetic flux is produced by a magnetic field and is guided through a material that has magnetic permeability (a measure of how easily a material can be magnetized). Just as in an electric circuit, the magnetic circuit follows similar principles such as Ohm's law, Kirchhoff's laws, and so on.
Key components of a magnetic circuit include:
Magnetic Source: This is the component that generates the magnetic field, such as a permanent magnet or an electromagnet.
Magnetic Core: It is a material with high magnetic permeability (e.g., iron) that provides a low-reluctance path for the magnetic flux to travel. The core enhances the magnetic field's strength and guides it along the desired path.
Air Gap: A region of low magnetic permeability (like air) where the magnetic flux encounters increased reluctance, causing a concentration of magnetic lines and hence affecting the overall performance of the circuit.
Coil or Windings: A coil of wire wrapped around the core is used to generate an electromagnet when current flows through it. The coil produces a magnetic field that interacts with the core and other components of the circuit.
Hysteresis Loss:
When a magnetic material (like iron) is subjected to cyclic changes in magnetic field strength (magnetization and demagnetization), it undergoes a phenomenon known as hysteresis. This results in energy loss due to the material's internal friction, and it's referred to as hysteresis loss.
Hysteresis loss occurs because the alignment of magnetic domains within the material changes as the external magnetic field strength changes. When the field is increased, the domains align; when it decreases, the domains realign. This constant reorientation requires energy, which is converted into heat. This phenomenon is most prominent in ferromagnetic materials like iron and is a major factor in the inefficiency of certain electromagnetic devices.
Hysteresis loss can be minimized by selecting appropriate materials with lower hysteresis loops (narrow loops) or by using laminated cores to reduce the path of eddy currents. The choice of material and design considerations play a crucial role in managing hysteresis losses in various electrical and electronic devices, such as transformers, electric motors, and generators.
In summary, a magnetic circuit involves the flow of magnetic flux through components with varying magnetic permeability. Hysteresis loss is a type of energy loss that occurs in magnetic materials when they undergo cyclic changes in magnetization. It's an important consideration in designing efficient electromagnetic devices.