Elektronika 2010-11.pdf - Instytut Systemów Elektronicznych ...
Elektronika 2010-11.pdf - Instytut Systemów Elektronicznych ...
Elektronika 2010-11.pdf - Instytut Systemów Elektronicznych ...
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Using the measurement results for the considered transistor<br />
the following empirical dependence is proposed<br />
⎡<br />
⎛ p<br />
⎞ ⎛ ⎞⎤<br />
= ⋅ ⎢<br />
⋅<br />
⎜ −<br />
th<br />
p<br />
+<br />
⋅<br />
⎥ (6)<br />
⎣<br />
⎜ −<br />
th<br />
R<br />
⎟<br />
⎟<br />
th<br />
Rth<br />
max<br />
a1<br />
exp a2<br />
exp<br />
⎝ b1<br />
⎠ ⎝ b<br />
2<br />
⎠<br />
⎦<br />
where R thmax<br />
, a 1<br />
, a 2<br />
, b 1<br />
and b 2<br />
are the model parameters.<br />
In Table 2 the values of the parameters describing Eq. (6)<br />
for various cooling conditions of the investigated devices are<br />
collected. The investigations were carried out for the diode<br />
SDP10S30 and the transistor CRF24010F operating both<br />
without any heat-sink and situated on the small heat-sink.<br />
Measurements were performed with the electrical methods<br />
described in [14].<br />
The results of the measurements – points and the calculations<br />
according to Eq. (6) – lines of the dependence of the<br />
diode and the transistor thermal resistance on the dissipated<br />
power are presented in Fig. 6.<br />
As seen, the measured and calculated results differ from<br />
each other not more than 5%, which confirms well the proposed<br />
model.<br />
In the presented figures, decreasing of the thermal resistance<br />
of both the investigated devices operating at the various<br />
cooling conditions on increasing of the device dissipated<br />
power is observed. It is also seen, that the dependence<br />
R th<br />
(p th<br />
) is stronger for devices operating without any heat-sink.<br />
Z(t) [K/W]<br />
35<br />
30<br />
25<br />
20<br />
15<br />
10<br />
5<br />
SDP10S30<br />
p th = 3.3 W<br />
p th = 4.7 W<br />
p th = 1 W<br />
p th = 2.1 W<br />
p th = 5.7 W<br />
0<br />
0,0001 0,001 0,01 0,1 1 10 100 1000 10000<br />
t [s]<br />
Fig. 4. Measured (solid lines) and calculated (dotted lines) courses<br />
of Z(t) of the diode SDP10S30<br />
Rys. 4. Zmierzone (linie ciągłe) i obliczone (linie kreskowe) przebiegi<br />
Z(t) diody SDP10S30<br />
Z(t) [K/W]<br />
100<br />
80<br />
60<br />
40<br />
20<br />
CRF24010F<br />
T a = 20 o C<br />
p th = 0.51 W<br />
p th = 1.06 W<br />
p th = 1.5 W<br />
p th = 0.21 W<br />
p th = 2.03 W<br />
p th = 2.72 W<br />
0<br />
0,0001 0,001 0,01 0,1 1 10 100 1000 10000<br />
t [s]<br />
Fig. 5. Measured (solid lines) and calculated (dotted lines) courses<br />
of Z(t) of the transistor CRF24010F<br />
Rys. 5. Zmierzone (linie ciągłe) i obliczone (linie kreskowe) przebiegi<br />
Z(t) tranzystora CRF24010F<br />
Tabl. 2. Values of the parameters in Eq. (6) for the diode SDP10S30<br />
and the transistor CRF24010F<br />
Tab. 2. Wartości parametrów w równaniu (6) dla diody SDP10S30<br />
i tranzystora CRF24010F<br />
a)<br />
Parameters<br />
Rth [K/W]<br />
b)<br />
Rth [K/W]<br />
Diode without<br />
any heat-sink<br />
Diode on<br />
the<br />
heat-sink<br />
Transistor<br />
without any<br />
heat-sink<br />
Transistor<br />
on the<br />
heat-sink<br />
R thmax<br />
78 34 93 22.2<br />
80<br />
70<br />
60<br />
50<br />
40<br />
30<br />
20<br />
10<br />
a 1<br />
0.88 0.9 0.85 0.92<br />
a 2<br />
18 25 18 45<br />
b 1<br />
0.12 0.1 0.15 0.08<br />
b 2<br />
1.5 1.5 0.7 1.5<br />
0<br />
0 1 2 3 4 5 6<br />
p th [W]<br />
Fig. 6. Calculated and measured dependences of the thermal resistance<br />
of the diode SDP10S30 (a) and the transistor CRF24010F<br />
(b) on the dissipated power<br />
Rys. 6. Obliczone i zmierzone zależności rezystancji termicznej<br />
diody SDP10S30 (a) oraz tranzystora CRF24010F (b) od mocy<br />
It probably results from the fact, that the influence of the heat<br />
conduction, radiation and convection is different in the devices<br />
situated on the heat-sink and operating without it.<br />
As it is seen, that in the considered range of device dissipated<br />
power the device thermal resistance can change even<br />
more than 20%.<br />
Conclusions<br />
SDP10S30<br />
device without any heat-sink<br />
device on the heat-sink<br />
100<br />
90<br />
CRF24010F<br />
80<br />
device without any heat-sink<br />
70<br />
60<br />
50<br />
40<br />
30<br />
20<br />
device on the heat-sink<br />
10<br />
0<br />
0 2 4 6 8 10<br />
p th [W]<br />
In the paper the compact nonlinear thermal model of two SiC<br />
semiconductor devices is proposed. The accuracy of this model<br />
is verified on the example of the power MESFET transistor<br />
CRF24010F and the Schottky diode SDP10S30. A good agreement<br />
between the measurements and the calculations with<br />
the use of the new model in the wide range of changes of the<br />
device dissipated power and for various conditions of theirs<br />
cooling is achieved.<br />
<strong>Elektronika</strong> 11/<strong>2010</strong> 11