Stability and robustness analysis of d/dt-closed-loop IGBT gate drive

Closed-loop IGBT switching trajectory control by means of an active IGBT gate drive (AGD) ensures an operation of the IGBT in the SOA and enables the minimization of switching delays, switching losses and EMI. In this paper the closed-loop control of d_iC/dt and d_vCE/dt by the use of an AGD is investigated on the basis of control-oriented small signal IGBT modeling and the analysis of IGBT module parasitics. Therewith, analytical stability considerations are carried out employing root-locus plots. Furthermore, the transfer functions for different closed-loop controlled IGBT modules are analyzed in dependency of their parameter variations and parasitic inductances. A closed-loop AGD prototype is used to experimentally test, verify and comparatively evaluate the switching behavior of the different considered IGBT modules.