Investigation of critical parameters in power supplies components failure due to electric pulse

Abstract

This paper presents an investigation aiming to determine the thresholds that lead to the destruction of power supplies components, such as rectifier bridge and rectifier diode, under differential mode electric pulse injection in the case of High Electromagnetic Pulse (HEMP) scenario. The coupling of HEMP field on long power lines generates high level current and voltage pulse disturbances which can propagate on the power network and flow into power supply input stages such as switch-mode power supplies (SMPS) present on main powered equipment. As a consequence of this injected parasitic, different electrical stresses occur inside the SMPS at electronic components level leading to cascaded destruction events. During a previous study, some internal electrical stresses have been measured and identified as the destruction cause of critical components such as rectifier bridge or rectifier diode. An electrical stress generator made of different capacitor cells is built to reproduce the electric pulses which will be present at the SMPS components terminals during their destruction. Oscilloscope associated to current and differential voltage probes are used to determine the failure moment. The performed tests have shown that rectifier bridge destruction follows a Wunsch and Bell law in current and in power according to the injection pulse duration. Concerning the rectifier diode, its destruction is due to its reverse voltage which has been measured around 135 V. This information will be used, in a future work, to better understand the destruction mechanism observed on complete power supplies and build behavioural models able to predict the destruction of power supplies in the case of HEMP scenario.