Efficient Control of IGBT Transistor as Part of Overvoltage Protection

Abstract

The paper analyzes the phenomena of appearance of overvoltage during the switching-off of the IGBT transistor which are
caused by the presence of parasitic inductance in the switching circuit. This problem can be solved in two ways – by preventing the
cause of the overvoltage, or by limiting the overvoltage level. Therefore, the characteristics of good PCB design have been noted, and
the typical snubber’s circuits have been listed. The paper focuses on solving the problem of IGBT transistor overvoltages on a specific
power electronics converter. A computerized model of power electronics converter has been created in order to analyze the influence
of parasitic inductance on the overvoltage level. A special analysis was performed on the simulation results which indicate that the
control of the IGBT transistor turning-off process can provide a lower overvoltage level. The paper also describes the design and the
implementation of the overvoltage protection elements on a developed power electronics converter prototype. The driver circuit TD350
which performs intelligent control of IGBT transistors in order to control overvoltages has been described in detail. The efficiency of
this driver is based on the idea of two-level turn-off, where the intermediate level and its duration can be set according to the specific
conditions in the IGBT transistor circuit. This way, the speed of current change is reduced, which directly affects the overvoltage level
on the transistor switching. Finally, within experimental results, the waveforms of control signals, as well as the overvoltage waveforms
have been shown at different input voltage levels.