Voltage Sag Immunity Test And Uncertainty Analysis Of Switching Power Suppliers

During recent decades,some new electrical equipment with more and more sophisticated structures and functions require power supply with higher quality,especially for voltage sag.Therefore,voltage sag immunity test and evaluation for equipment and installations are very important.In this thesis,simulation and experiment tests of voltage sag immunity for switching power supply(SPS)were carried out.The uncertainties of immunity of individual SPS and groups of SPSs were analyzed.The main researches were given as follows.Firstly,simulation and experiment tests of voltage sag immunity for SPSs were performed.The simulation model including sag source and flyback SPS was established with Matlab/Simulink.At the same time,a experimental test platform for voltage sag immunity test was established too.Nine different SPSs were selected as equipment under test(EUTs).By simulations and experiments,there were a lot of voltage immunity results to be the basic data for the following uncertainty analysis.Then,the uncertainties of individual SPS immunity were analyzed with the simulatioan and experiment results.Two aspects including the observable conditions and unknown factors were analyzed respectively.The observable factors include voltage levels,load ratios and point-on-wave of voltage sag.The unpredictability of load ratio is the main cause for the uncertainty of immunity.Meanwhile,the small-range randomness of the repeated experiment test data was analyzed,and the voltage toralence curve(VTC)of individual SPS was obtained.Finally,the uncertainties of immunities of group SPSs were with the experiment results.Based on the experimental data,the difference of immunity characteristics among SPSs in the group were discussed.Based on the experiment results,the uncertainty analysis of immunity was carried out by the statistical tools.The malfuction possibility of the equipment at any point on the two-dimension plane with residual voltage and duration(v-t plane)can be given.The uncertainty analysis was also discussed from the theoretical aspect.A practical uncertainty analysis model for immunity of SPS was presented.The malfuction possibility of equipment of points on v-t plane can be calculated by some parameters,thus describing the disturbance rejection and its uncertainty of individual or group of devices.In this thesis,the quantitative analysis conclusion of the SPS immunity and its uncertainty characteristics were given through simulation and experiment results combined with theoretical analysis,which can provide approaches for optimizing voltage sag immunity of specific equipments.An analytical model for fast evaluation of voltage sag immunity of SPS was given,which can be used as an effective reference for estimating the voltage sag severity to groups of SPSs.