Hello!
I need some help with how to calculate, I want to found out the thermal resistance of a transformer, in order to choose a suitable heatsink for natural cooling.
I assume that I need to find out the operating temperature in order to get the thermal resistance from using this equation:
Rth=delta T /(Pcore + P,cu,winding)
*My question is how do I calculate the operating temperature in this transformer?
I have chosen a transformer core ETD49/25/16 (3F3) and have calculated the core and winding losses. Core loss=4 W and the winding loss=7W, so total loss is 11W.
The area of the copper wire are: A,cu=1.7671 mm^2.
Np=15
Ns=14
The thermal resistance of copper are calculated as: Rthcu,wire=(Rth,cu*l)/A=(0.00250626*0.5mm)/211mm^2 = 5.939*10^6 C/W
Where l is the airgap between the copper wire and the core.
Rth,cu=1/(399 W/mC)
Thermal resistance of air:
Rth,air=26.7 mC/W
Thermal resistance of wire isolation:
Rth,isolation=6.5359 mC/W
Thermal resistance of core material ferrite:
Rth=8 C/W
P.S. don't know if it helps, but have drawn a picture of the EIcore and the heatsink placement, the primary winding and the secondary winding are separated by using bobbin/isolation.
Thanks for any help!
//Stenberg
I need some help with how to calculate, I want to found out the thermal resistance of a transformer, in order to choose a suitable heatsink for natural cooling.
I assume that I need to find out the operating temperature in order to get the thermal resistance from using this equation:
Rth=delta T /(Pcore + P,cu,winding)
*My question is how do I calculate the operating temperature in this transformer?
I have chosen a transformer core ETD49/25/16 (3F3) and have calculated the core and winding losses. Core loss=4 W and the winding loss=7W, so total loss is 11W.
The area of the copper wire are: A,cu=1.7671 mm^2.
Np=15
Ns=14
The thermal resistance of copper are calculated as: Rthcu,wire=(Rth,cu*l)/A=(0.00250626*0.5mm)/211mm^2 = 5.939*10^6 C/W
Where l is the airgap between the copper wire and the core.
Rth,cu=1/(399 W/mC)
Thermal resistance of air:
Rth,air=26.7 mC/W
Thermal resistance of wire isolation:
Rth,isolation=6.5359 mC/W
Thermal resistance of core material ferrite:
Rth=8 C/W
P.S. don't know if it helps, but have drawn a picture of the EIcore and the heatsink placement, the primary winding and the secondary winding are separated by using bobbin/isolation.
Thanks for any help!
//Stenberg
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