Study On Performance Degradation Assessmentand On-line Monitoring Of Aluminum Electrolytic Capacitance In AC Power Supply

AC power supply has been widely used in various fields of life and production.In particular,high-power AC power supply is a reliable guarantee for the stable operation of modern military electronic equipment.The reliability of AC power supply is particularly important.As one of the key power components of power electronic systems,aluminum electrolytic capacitors play a role in filtering and storing energy in AC power supplies,balancing the energy difference between multi-level converters,and are an important guarantee for the stability of AC power supplies.However,in all power devices,the failure rate of aluminum electrolytic capacitors is high.The failure of aluminum electrolytic capacitors will inevitably cause safety problems for AC power supplies,and even worse,threaten people’s lives.Therefore,research on the reliability of aluminum electrolytic capacitors in AC power supplies is of great significance for improving the stable operation of AC power supplies.In this paper,the 10 k VA three-phase full-bridge inverter power supply is selected as the research object.Firstly,a simulation model is established to observe the waveform signal of DC-Link aluminum electrolytic capacitor,and the failure reason of the inverter module is analyzed.Combined with the physical structure of aluminum electrolytic capacitor,the operating characteristics of several important parameters with the change of operating frequency and temperature are analyzed.Then,from the inside of the capacitor,the degradation failure modes and reasons of the electrolytic capacitor were studied in essence.The equivalent series resistance ESR and capacitance C were selected as the characterization parameters of the degradation failure,and the influence of the change of ESR and C on the whole power supply system was analyzed.The failure physical model of aluminum electrolytic capacitor is studied to provide a theoretical basis for the subsequent residual life prediction research.The degradation of the aluminum electrolytic capacitor will cause the change of the overall performance of the system,among which the change of the DC-Link capacitor waveform is the most obvious and easy to obtain representation.Then through the analysis of the DC-Link capacitor ripple voltage and current,when other parameters of the system remain unchanged,the changes of the aluminum electrolytic capacitor ESR and C have a great impact on the ripple voltage and current,and when the ripple voltage reaches a certain extent,it indicates the failure of the aluminum electrolytic capacitor,which has been verified by the experimental simulation.Secondly,a quantitative analysis of the degradation state of aluminum electrolytic capacitor is carried out through the research of the residual life technology of aluminum electrolytic capacitor.However,the traditional residual life prediction based on ideal degradation model has a large error due to the noise interference in the actual monitoring process.An empirical degradation model based on capacitance C was proposed by using degradation experimental data of electrolytic capacitor C and ESR at NASA Research Center,and the residual life was predicted by using standard particle filter algorithm.Experimental results show that the prediction error of this method is small,and the results obtained can be given by probability density distribution(PDF),which has a good prediction effect.This method is also suitable for ESR.Finally,the online monitoring method of the degradation characterization parameter C and ESR of DC-Link aluminum electrolytic capacitor was studied.Through the study of the traditional offline monitoring method based on pulsed current ESR,a monitoring scheme of aluminum electrolytic capacitor parameters based on discharge law was improved.The experimental simulation verified that this method achieved good monitoring effect.The relative error of C and ESR monitoring is about 1%.However,the use of this method is limited to the shutdown stage of the power supply system,and it is difficult to realize when the DC-Link capacitor exists in parallel structure,which does not meet the requirements of on-line monitoring and simple operation of the aluminum electrolytic capacitor.Then,through the research on the loss power of aluminum electrolytic capacitor,an ESR online monitoring model is designed,and the effectiveness of the scheme is verified through simulation and online monitoring experiments.The relative error of the experiment is within,and good monitoring effect is achieved.