Nonlinear Compact Thermal Model of SiC Power Semiconductor Devices

1. Nonlinear Compact Thermal Model of SiC Power Semiconductor Devices Krzysztof Górecki, Janusz Zarębski, Damian Bisewski and Jacek Dąbrowski Department of Marine Electronics Gdynia Maritime University, POLAND

2. Outline • Introduction • The form of the nonlinear thermal model • Estimation of the model parameters • Verification of the model accuracy • Conclusions

3. Introduction (1) • The thermal models are indispensable for calculating the device internal temperature. • There are the microscopic and the compact thermal models used for this purpose. • In the thermal analysis of electronic networks the compact thermal models are typically used. • The network representation of the compact thermal model is frequently used. • This representation consists of the current source representing the dissipated power and the Cauer or the Foster network representing the transient thermal impedance Z(t)

4. Introduction (2) • Both the networks are fully equivalent from the point of view the terminal Tj, representing the device internal temperature. • The efficiency of abstraction of the heat dissipated in semiconductor devices depends on many factors, e.g. on the dissipated power. • The thermal models presented in literature are the linear models, which do not take into account the dependence of the Z(t) on the dissipated power.

5. In the paper • In the paper the compact nonlinear thermal model of SiC devices is proposed. • This model was experimentally verified for SiC-MESFET and SiC-SBR

6. The form of the nonlinear thermalmodel • Formulating of the nonlinear thermal model • The device transient thermal impedance in the wide range of the dissipated power should be measured. • The values of the elements Ri,Ci (Cauer network) are estimated at various values of the power. • The dependence Ri(pth) and Ci(pth) are drafted. Then, on the basis of these dependences, the proper approximation function is fitted. • The values of the parameters existing in the dependences Ri(pth) and Ci(pth) are estimated. • The proper model of the network form is formulated and implemented to SPICE.

7. The form of the nonlinear thermalmodel Ci0, ai1, ai2, bi1, bi2, di1, di2, ei1, ei2, Ri0, pi1, pi2, pi3, pi4 are the model parameters.

8. Estimation of the model parameters • The estimation was performed for the diode SDP10S10 and MESFET CRF24010F

9. Verification of the model accuracy

10. Verification of the model accuracy

11. Conclusions • In the paper the compact nonlinear thermal model of SiC semiconductor devices is proposed. • The accuracy of this model is verified on the example of the power MESFET transistor CRF24010F and the Schottky diode SDP10S30. • A good agreement between the measurements and the calculations with the use of the new model in the wide range of changes of the device dissipated power and for various conditions of theirs cooling is achieved. • The examples show a strong influence of the power dissipated in the device on the values of its thermal parameters – the thermal resistance and the transient thermal impedance. • For the device operating without a heat-sink, the changes of thermal resistance corresponding to the considered changes of the power equal to even 25% are observed. • The proposed nonlinear thermal model can be used in the construction of the electrothermal models of the considered power semiconductor devices, dedicated to the analyze and design electronic circuits.