A critical analysis of IGBT geometries, with the intention of mitigating undesirable destruction caused by fault scenarios of an adverse nature

Abstract

Megawatt class Insulated Gate Bipolar Transistors[IGBTs] find many uses in industrial applications such as traction drives, induction heating and power factor correction. At present, these devices are not optimized for higher speed pulsed-power applications, such as kicker magnets or klystron modulators.This paper identifies fundamental issues that limit the dIidt performance of standard commercial packages, and investigates several IGBT design optimizations that significantly improve high-speed performance at high peak power levels.The paper presents design concepts, results of electromagnetic simulations, and performance data of actual prototypes under high dI/dt conditions.

Analysis of high-power IGBT short circuit failures

“…A simulated rate of rise of current of between 7.5 kA/µs and 9.4 kA/µs was applied to the IGBT module. The simulations showed that the current density was greatest in IGBT B [2].…”

“…The prototype solid-state induction modulator has been designed, built and tested at SLAC [2]. The manufacturer "A" IGBT modules in the modulator worked reliably during normal operation but many failed during an arc on the secondary.…”

“…The manufacturer "A" IGBT modules in the modulator worked reliably during normal operation but many failed during an arc on the secondary. Measurements have shown that peak current through an IGBT module can exceed 15 kA during an arc, with a rate of rise greater than 10 kA/µs [2]. An IGBT test circuit was set up to simulate short-circuit faults on the secondary of the modulator.…”

“…Unpredicted current and gate waveforms, and IGBT failures, occurred when tests were performed into extremely low inductance (<50 nH) short circuits. A number of failed IGBT modules were carefully dissected and analyzed, in order to determine the mechanisms of failure [2].…”

“…The solid-state induction modulator uses high voltage (3.3 kV) high current ( emitter voltage (Vge)) IGBT modules from manufacturer "A" [2]. These IGBTs were developed for traction applications and, although not specifically designed for ultrahigh speed pulsed power use, were used successfully in a prototype induction modulator.…”