Temperature Coefficient Characteristics of On-Resistance IGBT Devices
In the Infineon IGBT device datasheet, as presented in the following figure on page no. 8 from the IKW40N120H3 datasheet, the two curves indicate the collector current (Ic) dependency of the gate voltage (Vge) at Tj = 25℃ and Tj = 150℃ respectively.
Gate Voltage Vge and On-Resistance
When the gate voltage (Vge) is higher than 9V, the collector current (Ic) of IGBT device decreases as the temperature increases, i.e., the on-resistance increases, and the on-resistance (Ron) is positive temperature coefficient;
While the gate voltage (Vge) is lower than 9V, the collector current (Ic) of IGBT device increases as the temperature increases, i.e., the on-resistance decreases, and the on-resistance (Ron) is negative temperature coefficient.
When the gate voltage (Vge) is = 9V, that is, the intersection of the two curves, this point is called the zero-temperature coefficient point.
Note: Usually, IGBT devices should be avoided to be working in the on-state resistance negative temperature coefficient region to prevent the local unit inside the IGBT device from overheating and causing it to flow more current, making the local junction temperature of the IGBT device too high and eventually forming a local hot spot leading to the failure of the IGBT device.