Research On Prognostic Cell For Astrionic DC/DC Converter Based On PWM Radiation Damage

DC/DC converters are one of the most vulnerable units in electronic systems of satellites and spacecrafts. The reliability of DC/DC converters is extensively concerned. The prognostics and health management (ePHM) methodology are proposed in the trends of Commercial-Off-The-Shelf (COTS) has been widely used in aerospace and military equipment, which enables monitoring the state of reliability of COTS in real time, and therefore can be used to provide advance warning of a failure, to provide condition-based maintenance, and to help in risk reduction.Pulse-Width Modulator (PWM) is the core unit in feedback loop of DC/DC converter. Radiation-induced degradation of PWM will result in instability of DC/DC converter output, even lead to a failure. This paper focuses on the radiation effect, and emphasized researches in how PWM degradation influences the performance of DC/DC converter , the results can be used in designing and developing of the prognostic cell, which can provide early warning when DC/DC converter is about to expire and PWM has exhibited failure prognostic. Besides, degradation sites can be located accurately, which will be helpful in the design of future products with better safety margins and lower failure rate.The test shows that the output voltage of DC/DC converter increases after irradiation. The transfer models of PWM and flyback converter are proposed, which prove that performance degradation of optocoupler and PWM causes drift-up of DC/DC converter's output voltage.Afterward, prognostic model is proposed for estimating the value of output voltage based on the value of reference voltage of PWM. Based on the model, prognostic cell is researched and developed. Simulation and test results confirm that the prognostic cell can guarantee the reliability of DC/DC converters used in radiation environment, and a new method for maintaining aerospace and military equipment effectively is proposed. Finally, the cost-effectiveness analysis shows that prognostic cell is also beneficial.The basic procedure of designing electric prognostic and health management is first proposed, and it provides a reference for developing a complete system for radiation damages prognostics of DC/DC converters.