Inductor saturation due to high dv/dt

  • #1
likephysics
636
2
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?
 

Answers and Replies

  • #2
the_emi_guy
766
79
You have confirmed that it is the inductor that is getting hot?
 
  • #3
sophiecentaur
Science Advisor
Gold Member
27,567
6,198
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.
 
  • #4
likephysics
636
2
The Core type is Ferrite.
 
  • #5
likephysics
636
2
You have confirmed that it is the inductor that is getting hot?
Yes.
 
  • #6
Windadct
1,433
400
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.
 
  • #7
likephysics
636
2
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.
 
  • #8
Windadct
1,433
400
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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