5SHX2645L0004 3BHL000389P0104 ABB Electrical Products

ITGQM – Maximum Turn-Off Anode Current:

• Definition:
  • ITGQM is the maximum anode current that the IGCT can turn off under specified conditions.
• Dependence on Parameters:
  • ITGQM depends on commutation voltage (VD), junction temperature (Tvj), and the on-time (ton).
  • Dependencies are specified in the “Safe Operating Area” diagram in the datasheet (see Fig. 11).
  • Turn-off switching outside the safe operating area must be avoided to prevent immediate failure.
• Snubber Types for Asymmetric and Reverse Conducting IGCTs:
  • Asymmetric and reverse-conducting IGCTs are specified with a “clamp circuit” to limit voltage (not dv/dt). Common in voltage-source inverters (VSI).
  • Reverse blocking IGCTs use an R-C snubber to limit both voltage and dv/dt. Typically used in current source inverters (CSI).
  • Low snubber or clamp inductance is necessary to limit the over-voltage spike (VDSP) and prevent dynamic avalanche breakdown and excessive losses.
• Turn-Off Delay Time and Status-Feedback:
  • tdoff and tdoff SF represent turn-off delay time and turn-off delay time status-feedback, respectively.
  • More information on status-feedback is available in Application Note 5SYA2031 “Applying IGCT Gate Units.”
• Eoff – Turn-Off Energy per Pulse:
  • Eoff is the turn-off energy per pulse, defined as the time integral of the power during turn-off.
  • It is calculated using the formula: Eoff = ∫(IT × VD dt) from the start of commutation until IT reaches the static leakage current value.
  • Turn-off power losses (Pturn-off) are calculated as: Pturn-off = f × Eoff, where f is the switching frequency.
• Variability of Eoff:
  • Eoff can be varied to some extent by electron and/or proton irradiation, similar to VT.
  • Eoff varies linearly with ITGQ and VD and is highly dependent on Tvj.

Understanding ITGQM and related parameters is essential for assessing the IGCT’s capability to turn off current under different conditions. Proper consideration of snubber types, turn-off delay times, and turn-off energy is crucial for reliable and controlled IGCT operation.