Adaptive, Iterative Closed-Loop Control for the Turn-on of IGBTs with Improved Efficiency

Abstract:
This paper addresses the turn-on switching process of insulated-gate bipolar transistor (IGBT) modules with anti-parallel free-wheeling diodes (FWD) used in inductive load switching power applications. An increase in efficiency, i.e. decrease in switching losses, calls for a fast switching process of the IGBT, but this commonly implies high values of the reverse-recovery current overshoot. To overcome this undesired behaviour, a solution was proposed which achieves an independent control of the collector current slope and peak reverse-recovery current by applying a gate current that is briefly turned negative during the turn-on process. The feasibility of this approach has already been shown, however, a sophisticated control method is required for applying it in applications with varying currents, temperature and device parameters. In this paper a solution based on an adaptive, iterative closed-loop control is proposed. Its effectiveness is demonstrated by experimental results from a 1200 V / 200 A IGBT power module for different load currents and reverse-recovery current overshoots.