Detection of reverse recovery characteristics of power diodes

Abstract

A setup was constituted for measuring reverse recovery (RR) waveforms of current I rr and voltage V rr , RR time t rr , RR charges Q rr , as well as the ratio C of absolute value of RR peak voltage V rm to amplitude of reverse biased pulse voltage V r and so on, for power device under test (DUT). Forward pulse current I f and the V r were generated from a central processing unit (CPU). Amplitude of I f was magnified by a transistor, while the scale was regulated via a Darlington array controlling relays for altering different resistors connected to emitter of the transistor to apply on DUT. Pulse of V r was first shaped by a Schmitt trigger and then was magnified by a metal-oxide-semiconductor field-effect transistor (MOSFET), while the edge commutating rate dI f /dt was adjusted through the Darlington controlling relays for changing different inductors linked to drain of the MOSFET to bias on DUT. The waveforms can be observed with an oscilloscope and sampled for further digitally processing. Inputting test parameters via keyboard, calculating and displaying of test results can be controlled by a host CPU. The parameters and metering results can be monitored by a liquid crystal displayer (LCD).