Inductor saturation due to high dv/dt

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Discussion Overview

The discussion revolves around the heating issue in a buck regulator, particularly focusing on the effects of switching frequency on inductor performance and core losses. Participants explore the relationship between high dv/dt, high dI/dt, and the resulting heat generation in the inductor core material, specifically ferrite.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes that reducing the switching frequency of the buck regulator has led to a decrease in temperature, questioning the role of high dv/dt in heating the inductor core.
  • Another participant confirms that the inductor is indeed the source of heat in the circuit.
  • A participant suggests that magnetic materials can experience high losses when operated above their design frequency and asks about the core material used.
  • It is mentioned that the core material is ferrite.
  • One participant argues that the heating is not due to high dv/dt but rather high dI/dt or higher frequency causing increased losses due to induced currents in the core material.
  • Another participant reiterates the point about high dI/dt and discusses the mechanism of changing flux within the core leading to higher losses and heat generation.
  • A participant inquires about the technical term for the loss mechanism associated with these currents.
  • One response suggests that these losses are referred to as core losses due to eddy currents, explaining the use of laminated steel in transformer cores to reduce these losses.

Areas of Agreement / Disagreement

Participants express differing views on whether high dv/dt or high dI/dt is the primary cause of heating in the inductor. There is no consensus on the exact mechanism behind the heat generation, indicating ongoing debate.

Contextual Notes

The discussion does not resolve the specific contributions of dv/dt versus dI/dt to the heating issue, nor does it clarify the assumptions regarding the inductor's operational limits or the specific characteristics of the ferrite core material.

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I have a buck regulator running hot. I reduced the switching frequency and the temperature is almost normal.
The current rating of the inductor is high(2A) compared to current consumption on the board (300mA).
Why does reducing the switching frequency solve the heat problem?
Does the inductor core get hot due to high dv/dt at the switching node?
 
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You have confirmed that it is the inductor that is getting hot?
 
Magnetic materials can have high losses when operating above their design frequency. What is the core material you are using? You could find out its characteristics from the manufacturers.
 
The Core type is Ferrite.
 
the_emi_guy said:
You have confirmed that it is the inductor that is getting hot?
Yes.
 
It is not hi dV/Dt - but high dI/dt - or higher frequency causing higher losses. When you magnetize a core ( both a magnetic and conductive material) the expansion and contraction of the flux lines (changing flux) within the core - cause currents. The higher the frequency ( as well as harmonics) the more currents are induced and collapsed in the core material itself - yielding higher losses = heat.
 
Windadct said:
It is not hi dV/Dt - but high dI/dt - or higher frequency causing higher losses. When you magnetize a core ( both a magnetic and conductive material) the expansion and contraction of the flux lines (changing flux) within the core - cause currents. The higher the frequency ( as well as harmonics) the more currents are induced and collapsed in the core material itself - yielding higher losses = heat.

Windact, can you tell me the techincal term for this loss mechanism.
 
Ummm.. I think just referred to as core losses due to eddy (circulating) currents. This is the reasoning for laminated steel to be used in the cores for transformers - it forces the currents into the individual laminations - smaller loops... smaller currents... smaller losses

Scroll down on this page... http://www.electronics-tutorials.ws/transformer/transformer-construction.html
 

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