Reliability Analysis Of High-voltage Electrical Systems Of Pure Electric Commercial Vehicles

Under the mutual constraint of resource shortage and environmental protection,pure electric commercial vehicles occupy a large share of the new energy commercial vehicle market.At the same time,in the face of the safety problems of high-voltage electrical systems highlighted by vehicles,it is important to analyze various possible failure modes and complete a comprehensive analysis of reliability for system safety and reliability design.In this paper,the reliability of high-voltage electrical systems of pure electric commercial vehicles is studied on the basis of traditional fault tree analysis methods combined with fuzzy mathematical theory,polymorphism theory and Bayesian networks.The main contents are as follows:(1)In the reliability analysis modelling process,the failure forms of the high-voltage electrical system subsystems are divided into functional failure mode with a two-state bottom event and state deterioration mode with a three-state bottom event.What’s more the fuzzy-polymorphic fault tree reliability analysis model for each high-voltage electrical subsystem of a pure electric commercial vehicle is also presented.(2)The reliability analysis model for high-voltage power battery systems is established.The two typical fuzzy numbers of L-R type are compared and the better triangular type fuzzy number is selected to solve the functional failure mode sub-fault tree;the state deterioration mode sub-fault tree is analyzed using polymorphism theory and Bayesian network theory,and the failure probability of the leaf nodes when the root nodes of the polymorphic Bayesian network are in different states with unknown probability is deduced to solve the system reliability.The fuzzy probability importance of the two-state bottom event and the posterior probability,probability importance and critical importance of the polymorphic root node are analyzed to accurately identify the weaknesses affecting the system in each mode.(3)The reliability analysis model of the high-voltage drive motor and high-voltage wiring harness system is established,and the functional failure mode sub-fault tree is solved using triangular type fuzzy numbers;and the failure probability of the leaf nodes when each root node of the polymorphic Bayesian network is in different states with known probability of occurrence is solved to find the reliability of the two systems.Analysis of the fuzzy probability importance of two-state bottom events and the posterior probability,probability importance and critical importance of polymorphic bottom events for two systems respectively,to accurately identify the weaknesses affecting each system under each mode.(4)Design of a MATLAB/GUI-based reliability assessment software for high-voltage electrical systems of pure electric commercial vehicles.The comprehensive evaluation,fault diagnosis and reliability data analysis of the high-voltage electrical system of pure electric commercial vehicles are realized,and the reliability analysis of the high-voltage electrical system is visualized.