An Analysis of High-Power IGBT Switching Under Cascade Active Voltage Control

Abstract

A new gate-drive solution, cascade active voltage control (Cascade AVC), employs classic feedback-control methods with an inner loop controlling the insulated-gate bipolar-transistor (IGBT) gate voltage and an outer loop controlling the collector voltage, simultaneously. They make the switching performance less dependent on the IGBT itself. Feedback control of IGBTs in the active region does not necessarily slow the switching but introduces stability issues. A detailed stability analysis provides a sensible perspective to judge the system stability and justify the controller design, through considering major operating points and determining corresponding IGBT parameters. Experiments on high-power IGBTs including a 4500-V device show that Cascade AVC offers improved performance and is easier to design than the original AVC.