Understanding Hysteresis Loss in Magnetic Materials — Lesson 6

This lesson covers the concept of hysteresis loss in magnetic materials. It explains why hysteresis loss occurs and the factors it depends on, similar to Eddy current loss. The lesson uses a magnetic circuit with an exciting coil to illustrate the BH characteristics of a magnetic material. It further explains how the increase in current leads to an increase in magnetic field strength (B) until saturation is reached. The lesson also discusses the concept of residual field and retentivity. The energy supplied to the coil and the energy returned to the source during the process are also calculated. The lesson concludes by stating that the area enclosed by the BH loop is a measure of hysteresis loss per unit volume.

Video Highlights

02:18 - Discussion on the concept of saturation in a magnetic field
06:14 - Calculation of the energy absorbed by a coil when current is increased
15:34 -Discussion on the effect of hysteresis as current increases and decreases
22:30 - Discussion on the energy supplied and returned during a cycle of current
31:15 - Explanation of the hysteresis loop and its relation to hysteresis loss

Key Takeaways

• Hysteresis loss occurs in magnetic materials due to the alignment and realignment of tiny magnets within the material as the external magnetizing force changes.
• The BH characteristics of a magnetic material illustrate how the magnetic field strength (B) increases with the increase in current until saturation is reached.
• The energy supplied to the coil during the process can be calculated by integrating the product of the magnetic field strength (H) and the change in magnetic flux density (dB) over the volume of the core material.
• The energy returned to the source when the current decreases is less than the energy supplied, resulting in hysteresis loss.
• The area enclosed by the BH loop is a measure of hysteresis loss per unit volume.