​The Principle of How Transformer Core Affects Current Attenuation

The impact of a transformer core on current attenuation can be explained through the following principles:

1. Inductance Effect:

  - The core of a transformer increases the inductance of the windings. Inductance is a measure of a circuit's ability to oppose changes in current. When current flows through the windings, the magnetic flux in the core changes accordingly. According to Faraday's law of electromagnetic induction, this induces an electromotive force (EMF) in the windings, which always acts to oppose the change in current.

  - When the current attempts to increase, the induced EMF opposes the increase; when the current decreases, the induced EMF opposes the decrease. This effect causes the current to change more slowly, leading to current attenuation.

2. Magnetic Permeability of the Core:

  - The magnetic permeability (μ) of the core is much higher than that of air, enabling it to more effectively concentrate magnetic flux and reduce flux leakage. This means that the core can store more magnetic energy, which in turn generates a greater counteracting force against changes in current, thereby accelerating current attenuation.

3. Hysteresis and Eddy Current Losses in the Core:

  - When the core is subjected to an alternating magnetic field, hysteresis and eddy current losses occur. These losses convert a portion of the electrical energy into heat, reducing the energy available to sustain the current and thus causing current attenuation.

  - Hysteresis loss is due to the energy dissipated as the magnetic domains in the core material realign during the magnetization process.

  - Eddy current loss arises from the heat generated by the closed-loop currents (eddy currents) induced within the core material, which are resisted by the core's electrical resistance.

4. Skin Effect and Proximity Effect:

  - At high frequencies, the skin effect and proximity effect cause the current to flow predominantly near the surface of the windings, increasing the effective AC resistance of the windings and thereby increasing power losses. This also leads to current attenuation.

5. Energy Conversion:

  - The variation of magnetic flux in the transformer core represents the interconversion of electrical and magnetic energy. When the current changes, the magnetic energy in the core also changes. This energy conversion is not instantaneous but rather a dynamic equilibrium process, which prevents the current from reaching the desired value instantaneously and instead causes it to gradually attenuate to a new steady state.

In summary, the transformer core contributes to current attenuation by increasing inductance, enhancing magnetic energy storage, generating hysteresis and eddy current losses, and affecting current distribution. This effect is crucial in the design and operation of switch-mode power supplies and transformers, as it helps control the current waveform and mitigate the adverse effects of rapid current changes.