Insulated Gate Bipolar Transistor Operating Characteristics

3225 50M crystal

1. Static characteristics

The static characteristics of IGBTs mainly include output characteristics and transfer characteristics. The output characteristic expresses the relationship between the collector current IC and the collector-emitter voltage UCE, which is divided into a saturation region, an amplification region, and a breakdown region.

The transfer characteristic of the IGBT indicates the control relationship of the gate voltage UG to the collector current IC. In most cases, IC has a linear relationship with UG.

2. Dynamic characteristics

The dynamic characteristics of the IGBT, ie the switching characteristics, are shown in Figure 2. The turn-on process is primarily determined by its MOSFET structure. When the gate voltage UG reaches the turn-on voltage UG(th), the collector current IC rapidly increases, and the time td(on) required for the gate voltage to increase from the negative bias value to the turn-on voltage is the turn-on delay time; the collector current The time required to increase from 10% to 90% is the current rise time tri, so the total turn-on time is ton=td(on)+tri.

The turn-off process of the IGBT is complicated, and the time required for the UG to fall from the normal 15V to the turn-on voltage UT is the turn-off delay time td(off), and the IC starts to decay. The collector current is reduced from 90% of the rated value to 10% of the rated time is the falling time tfi=tfi1+tfi2, where tfi1 corresponds to the turn-off process of the MOSFET portion of the device, and tfi2 corresponds to the disappearance of the stored charge in the PNP transistor in the device. Since the MOSFET structure is turned off after tfi1 time, the IGBT is not subjected to back pressure, and the stored charge in the device is difficult to be quickly eliminated, so the collector current needs to be reduced for a long time, forming a current tailing phenomenon. Since the collector voltage Uce has been established at this time, the excessive tailing of the current will cause a large power consumption to increase the junction temperature. The total turn-off time is toff=td(off)+tfi.