Reseach On Control And Fault Diagnosis Method Of DC-DC Converters

The main function of power electronics technology is to convert electric energy into the form required by load.As one of the core of power electronics technology,the application of DC-DC converter is obviously very common.How to control DC-DC converter is a hot topic.At the same time,the occurrence of the fault will bring security problems,once the sensor,components and other faults,the converter will not be able to operate normally,or even cause the breakdown of the power grid.Therefore,it is very important to study the control and fault diagnosis of dc-dc converter.The main work of this paper is as follows:Control strategy design of DC-DC converter.For the circuit model of DC-DC converter,the state space generator is adopted for system modeling.Because the switch of the converter works alternately,the circuit is built into the switching system model.In this process,the final expected value of the system is obtained through derivation and calculation.Then two switching rules are used as control strategies to apply to two types of DC-DC converters.Under the effect of switching rules,the system reaches a stable state and stable output voltage is obtained.Fault detection and fault estimation of DC-DC converter.Firstly,the Buck-boost system is modeled and the fault model is given.Then,based on the technique of switching Lyapunov function,a sliding mode observer for the switching error system is designed,which satisfies an H? perfor:mance index and can guarantee the asymptotic stability of the switching error system.Next,the threshold is compared with the residual generated by the sliding mode observer to obtain the sensor fault detection results.At the same time,the fault estimation is realized based on the fault reconstruction method.Finally,in order to demonstrate the feasibility of the sensor fault detection and estimation,the simulation results are given.Fault detection and fault diagnosis of DC-DC converters.Taking the Single-ended Primary Industry Converter(SEPIC)as an example,the sensor fault isolation problem of DC-DC converters is studied.For the purpose of the study,a set of sliding mode observers for each sensor fault is designed.By comparing the threshold with the residual produced by each SMO,you can determine which sensor failures have occurred.In order to demonstrate the feasibility of fault isolation,simulation analysis is given.Fault identification and adaptive parameter identification of DC-DC converter.First,take the DC-DC buck converter as an example to build the system model and fault model.A fault detection observer and a set of fault recognition observers are designed.Secondly,the fault detection observer detects the fault according to the residual between the observer output and the actual output.The fault is detected and the fault recognition observer is activated.By comparing the residual estimation functions,the fault location is determined.At the same time,adaptive parameter identification is realized by selecting appropriate adaptive rate.Finally,the simulation results are given.