Junction temperature is the key point in power semiconductors and it should be maintained under standard limits. During the operations, the temperature of the junction is either estimated or unknown, that is why designers have to keep huge safety margins. Now, to measure the temperature of power devices, different techniques have been developed. One method includes the use of thermistors which are directly in contact with the die but this method is also critical due to insulation problems and the delay in measurement.

The only method used now is the one involving electrothermal models joint with a temperature checker of the DBC (Direct Bonded Copper) substrate or of heat sink through thermistor. These models are slightly rough, and can lead to estimation errors. Earlier TSEPs (Thermo Sensitive Electrical Parameters) based techniques are now considered as an important method and are used in junction temperature indicator. Most of TSEP based methods are currently limited to laboratories under controlled conditions. They are used for datasheet compilation, providing a creative solution for real cases without dedicated equipment. When good results were obtained from the first POC converter, the need for new three phase invertor was analyzed. This article will discuss a method capable of estimating a precise value of the MOSFETs junction temperature in a 3-phase voltage source inverter…

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