Using Load Transient Waveform to Analyze Fault Propagation Mechanism in DC-DC Switching Power Supply

The degradation of certain components within DC-DC power supplies can lead to abnormal performance, resulting in the occurrence of faults. The degradation of components can cause changes in output voltage and current, and the different degradation characteristics of components have different impacts on the characteristics of output parameters. Therefore, it is necessary to master this impact relationship, that is, the fault propagation mechanism can be used to effectively diagnose faults and manage health. Studying the fault propagated mechanism is an important prerequisite for fault diagnosis. Output terminals of DC-DC power supply are usually connected in parallel with electrolytic capacitors. The function of electrolytic capacitors is to filter, filtering out most of the AC part of the output voltage, and reducing the ripple of the output voltage. Electrolytic capacitors are the most vulnerable components to failure in switching power supplies, with approximate 60% of failed components being electrolytic capacitors. Therefore, the fault propagation mechanism of electrolytic capacitors is a key research topic. Most research focuses on the fault propagation mechanism based on steady-state output signals. This article studies the fault propagation mechanism based on transient output signals. Through experimental testing, the impact of parameter degradation of electrolytic capacitors on the transient waveform of output voltage and the mapping relationship between capacitor degraded parameters and transient waveform are studied. The method is to analyze the voltage waveform when the current step changes using equivalent degradated experiments of capacitors. Its advantage lies in the fact that transient waveforms are more sensitive than steady-state waveforms and require lower sampling rates, making it easier to analyze the degradated characteristics of electrolytic capacitors. For power supplies with simple structures, data is collected through simulation. For commercial switching power supplies with complex structures, data is collected through capacitance equivalent degradated experiments. Experimental results show that when the equivalent series capacitance of the electrolytic capacitor or the equivalent series resistance has changed, the ripple of the output voltage transient waveform is very different compared to the original.