Abstract
Nowadays, power electronics can be found in various applications like chargers
and high-power transmission systems. Power MOSFETs which are used in many
power converters should be very efficient as this reduces the electricity costs and
it will absolutely be required to meet future climate targets. Therefore, power
MOSFETs should be designed for low on-resistances to reduce the conduction
losses. The switching frequency of future power applications shows an increasing
trend which requires the usage of wide-bandgap (WBG) semiconductors with
lower switching losses. The higher the power rating, the higher currents will flow
through the devices which requires improved cooling systems. In case of semiconductors, a so-called self-heating effect occurs. They have the property that at
room temperature, the ohmic resistance of these materials decreases with increasing temperatures and which in turn increases the current. Due to the high
internal temperatures of power semiconductors, the packaging and the cooling
system are subject to high thermal requirements. Electrothermal co-simulations
allow to identify the potential weak points of power devices already in the development phase.
This thesis focuses on the thermal investigation of power MOSFETs which are
typically used for different kinds of power converter topologies. Two different electrothermal co-simulation approaches based on two different power electronic circuits are presented. After explaining the purpose and the function of these circuits, the development process of the electrical and thermal models which are
required for creating these simulations are shown. Furthermore, thermal measurements have been performed to verify the simulation results. Based on the simulated device temperatures, a reliability analysis has been executed. The gained
results and the conclusion of this analysis are presented at the end of this thesis.
and high-power transmission systems. Power MOSFETs which are used in many
power converters should be very efficient as this reduces the electricity costs and
it will absolutely be required to meet future climate targets. Therefore, power
MOSFETs should be designed for low on-resistances to reduce the conduction
losses. The switching frequency of future power applications shows an increasing
trend which requires the usage of wide-bandgap (WBG) semiconductors with
lower switching losses. The higher the power rating, the higher currents will flow
through the devices which requires improved cooling systems. In case of semiconductors, a so-called self-heating effect occurs. They have the property that at
room temperature, the ohmic resistance of these materials decreases with increasing temperatures and which in turn increases the current. Due to the high
internal temperatures of power semiconductors, the packaging and the cooling
system are subject to high thermal requirements. Electrothermal co-simulations
allow to identify the potential weak points of power devices already in the development phase.
This thesis focuses on the thermal investigation of power MOSFETs which are
typically used for different kinds of power converter topologies. Two different electrothermal co-simulation approaches based on two different power electronic circuits are presented. After explaining the purpose and the function of these circuits, the development process of the electrical and thermal models which are
required for creating these simulations are shown. Furthermore, thermal measurements have been performed to verify the simulation results. Based on the simulated device temperatures, a reliability analysis has been executed. The gained
results and the conclusion of this analysis are presented at the end of this thesis.
| Original language | English |
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| Supervisors/Advisors |
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| Publication status | Published - 18 Mar 2022 |