IGBT selection method for the design of resonant inverters for domestic induction heating

The power transistor (IGBT) is one of the most important components of the inverter of domestic induction cookers. For this application the maximum junction temperature (Tjmax) of the IGBT is one of the most critical design parameters because the cooker has to decrease the output power when the junction temperature is near to Tjmax of the device. The junction temperature (Tj) of the IGBT principally depends on the power losses. This paper proposes a method to choose the IGBT based on the calculation of the temperature variation ΔTja from the power losses. Nowadays, IGBT behaviour is a trade-off between conduction and switching performance, so it is necessary to measure the IGBT power losses separately. This paper proposes a method to measure the power losses separately based on electrical measurement and the IGBT conduction characteristics. Moreover it is proposed a criterion to determinate the limits of the power losses based on eliminate the offset of device voltage and the switching area is defined from the voltage is over 2.5 V to the current is zero. Finally, the proposed method has been applied to five different IGBTs for different levels of power and with two standard pans with an electronic board of a commercial cooker Moreover this method has been verified with a thermografic camera obtaining similar results.