Estimating The Power Bjt Excess Charge Recombination Time Constant

Abstract

The paper demonstrates an experimental way of estimating the excess minority carriers charge stored within the the power bipolar transistor in the saturation mode, i.e. with both junctions forward-biased, as a reference to future IGBT switching action analysis. The method is based on analyzing the transient turn-off base current waveforms at different conditions right before this event. The base current is known to supply the minority carriers within the device. Estimating the recombination time constant serves as a basal precondition for further identification of the excess charge storage depending on various operating conditions and retrospectively an accurate identification of power BJT and IGBT various partial stage of switching action.