Hi All,
I'm trying to understand how you would estimate the junction temperature of an IGBT and i am getting myself all confused.
Im trying to use the attached IGBT datasheet tutorial provided by ST.
It is based on the STGFW40V60D datasheet. http://www.st.com/en/powertransistors/stgw40v60df.html
It mentions that PToT (the maximum power dissipation for a given case temperature) is as follows :. PTOT = (TJmax  TC )/ Rth JC
Where TJmax = 175°C, TC = measured case temperature, Rth JC igbt = 0.53°C. Where TC = 25°C .:. PToT = 283W
PToT can also be worked out by PToT = Vce * Ic
Question A) ( I am unsure whether Vce is the average voltage accross the collector and emitter or this is the saturation voltage of the IGBT, if so how do i measure this?)
This further leads on to looking at section "2.4.9 Maximum transient thermal impedance (ZthJC)" where TJstart == Tc
Tj = TJstart + ΔTj = TJstart + ZthJc (tp,δ) * Ptot = TJstart + k(tp,δ) * RthJc * Ptot
Looking at the provided graph assuming
δ = 0.5
tp = 0.000025
fs = 0.00005
TC = 25°C
Rth JC igbt = 0.53°C
i would say k(tp,δ) doesn't show on the graph. So wrongly or rightly i would assume K = 0.5 as the response looks fairly flat for 10^5.
so for Tj = TJstart + k(tp,δ) * RthJc * Ptot = 25°C + 0.5 * 0.53°C * Ptot.
Question B) : For Ptot can i use the 283w i calculated earlier or do i need to measure Vce and Ic?
If Ptot == 283w then Tj == 99.995°C is this correct? and is this telling me the peak junction temperature or the steady state temperature?
Thanks for your help!
I'm trying to understand how you would estimate the junction temperature of an IGBT and i am getting myself all confused.
Im trying to use the attached IGBT datasheet tutorial provided by ST.
It is based on the STGFW40V60D datasheet. http://www.st.com/en/powertransistors/stgw40v60df.html
It mentions that PToT (the maximum power dissipation for a given case temperature) is as follows :. PTOT = (TJmax  TC )/ Rth JC
Where TJmax = 175°C, TC = measured case temperature, Rth JC igbt = 0.53°C. Where TC = 25°C .:. PToT = 283W
PToT can also be worked out by PToT = Vce * Ic
Question A) ( I am unsure whether Vce is the average voltage accross the collector and emitter or this is the saturation voltage of the IGBT, if so how do i measure this?)
This further leads on to looking at section "2.4.9 Maximum transient thermal impedance (ZthJC)" where TJstart == Tc
Tj = TJstart + ΔTj = TJstart + ZthJc (tp,δ) * Ptot = TJstart + k(tp,δ) * RthJc * Ptot
Looking at the provided graph assuming
δ = 0.5
tp = 0.000025
fs = 0.00005
TC = 25°C
Rth JC igbt = 0.53°C
i would say k(tp,δ) doesn't show on the graph. So wrongly or rightly i would assume K = 0.5 as the response looks fairly flat for 10^5.
so for Tj = TJstart + k(tp,δ) * RthJc * Ptot = 25°C + 0.5 * 0.53°C * Ptot.
Question B) : For Ptot can i use the 283w i calculated earlier or do i need to measure Vce and Ic?
If Ptot == 283w then Tj == 99.995°C is this correct? and is this telling me the peak junction temperature or the steady state temperature?
Thanks for your help!
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