Hysteresis loss is a type of energy loss that occurs in magnetic materials when they are subjected to a cyclic process of magnetization and demagnetization, such as in transformers, motors, and generators. This loss is due to the internal friction of the magnetic domains in the material as they realign with the changing magnetic field. Hysteresis loss occurs primarily in ferromagnetic materials, which are commonly used in electrical devices.
### Hysteresis Loss Formula:
The hysteresis loss (\(P_h\)) in a magnetic material is given by Steinmetz's equation:
\[
P_h = \eta B_{\text{max}}^{n} f V
\]
Where:
- \(P_h\) = Hysteresis loss
- \(\eta\) = Steinmetz coefficient, a constant that depends on the material properties
- \(B_{\text{max}}\) = Maximum magnetic flux density (in Tesla)
- \(n\) = Steinmetz exponent (typically around 1.6 to 2.5 for different materials)
- \(f\) = Frequency of the magnetization cycle (in Hz)
- \(V\) = Volume of the magnetic material (in m³)
### Hysteresis Loss is Directly Proportional to:
1. **Frequency of Magnetic Field (\(f\))**: Hysteresis loss increases with the frequency of the applied magnetic field. This is because the magnetic domains have to realign more often as the frequency increases, leading to greater energy loss due to internal friction. If the frequency doubles, the hysteresis loss also doubles.
2. **Volume of the Material (\(V\))**: Hysteresis loss is directly proportional to the volume of the magnetic material. The larger the volume, the more magnetic domains exist that need to realign with the changing magnetic field, which increases the energy lost.
3. **Maximum Flux Density (\(B_{\text{max}}\))**: The maximum flux density refers to the peak value of the magnetic field applied to the material. Hysteresis loss increases with the maximum flux density raised to a power \(n\), which is typically between 1.6 and 2.5 for different materials. This means that if \(B_{\text{max}}\) increases, the hysteresis loss grows significantly.
4. **Material Properties (Steinmetz coefficient \(\eta\))**: The hysteresis loss depends on the material's internal structure. Soft magnetic materials, like silicon steel, have lower hysteresis losses, while hard magnetic materials exhibit higher losses due to more resistance in realigning magnetic domains.
### Summary of Direct Proportionality:
- **Directly proportional to**:
- Frequency (\(f\))
- Volume of material (\(V\))
- Maximum flux density raised to power \(n\) (\(B_{\text{max}}^{n}\))
- The material's hysteresis constant (\(\eta\))
Thus, hysteresis loss increases with higher frequency, greater material volume, higher magnetic flux density, and for materials with larger hysteresis loops.