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thermal_resistance [2020/07/19 01:50]
stan_zurek
thermal_resistance [2020/07/19 01:51]
stan_zurek
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 There are several empirical equations linking the size and shape of a given class of devices. For example for [[EE (ferrite)|EE]], [[EI (ferrite)|EI]], [[ETD (ferrite)|ETD]] and [[EC (ferrite)|EC]] ferrite transformers the following formula could be used:[([[http://google.com/books?isbn=9780123865335|Sanjaya Maniktala, Switching power supplies A-Z, 2nd edition, Newnes, 2012, ISBN 978-0-12-386533-5, p. 155]])] There are several empirical equations linking the size and shape of a given class of devices. For example for [[EE (ferrite)|EE]], [[EI (ferrite)|EI]], [[ETD (ferrite)|ETD]] and [[EC (ferrite)|EC]] ferrite transformers the following formula could be used:[([[http://google.com/books?isbn=9780123865335|Sanjaya Maniktala, Switching power supplies A-Z, 2nd edition, Newnes, 2012, ISBN 978-0-12-386533-5, p. 155]])]
  
-|  <html><div style="font-size: 200%;"> $R_{th} = 53 · (V_{core})^{-0.54}$ </div></html>   (K/W) or (°C/W)  |+|  $$ R_{th} = 53 · (V_{core})^{-0.54} $  (K/W) or (°C/W)  |
  
 where: //V<sub>core</sub>// - core volume in cm<sup>3</sup> (i.e. this the volume of the ferrite core itself as specified by the manufacturer, and not volume of the whole transformer). where: //V<sub>core</sub>// - core volume in cm<sup>3</sup> (i.e. this the volume of the ferrite core itself as specified by the manufacturer, and not volume of the whole transformer).
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 Empirical data given by [[Epcos]] also suggest that the thermal resistance is roughly proportional to the reciprocal of square root (power of -0.5) of the ferrite core volume, which is in agreement with the previous equation:[(Thermal_resistance)] Empirical data given by [[Epcos]] also suggest that the thermal resistance is roughly proportional to the reciprocal of square root (power of -0.5) of the ferrite core volume, which is in agreement with the previous equation:[(Thermal_resistance)]
  
-|  <html><div style="font-size: 200%;"> $R_{th} = \frac{x}{\sqrt{V_{core}}}$ </div></html>   (K/W) or (°C/W)  |+|  $$ R_{th} = \frac{x}{\sqrt{V_{core}}} $  (K/W) or (°C/W)  |
  
-where //x// is the proportionality factor.+where $xis the proportionality factor.
  
 ===== Importance ===== ===== Importance =====
thermal_resistance.txt · Last modified: 2020/07/19 01:51 by stan_zurek

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