Study On Fault Diagnosis And Tolerance Of Powertrain For Hybrid Electric Bus

Because hybrid electric vehicles (HEV) have both the advantages of traditional cars and electric cars, not only become the current auto industry transformation and-upgrading of the only way which must be passed, but also is a currently a hot research.However, because of the complicated power system and immaturity matching technology of control system in HEV, these drawbacks make HEV’s fault rate higher than traditional vehicles. At the same time, the battery belongs to high-voltage power supply. Its voltage extends far beyond the safe voltage which human body can bear. If a fault occurs, it may endanger the safety of human in vehicles. So, in order to improve the reliability and safety of HEV, it has important theoretical significance and practical value to do research on fault diagnosis and tolerant control. This paper takes the parallel hybrid electric buses which run in a demonstration operation city as the research object, mainly focuses on studying fault diagnosis and fault tolerance of high fault rate powertrains.Firstly, according to the hybrid electric bus fault statistics in the demonstration operation city, and then making classification of high fault rate units. This paper, combining with the powertrain principle and fault characteristic, presents many methods which include analytical redundancy, system action feedback, fault tree analysis and multi sensor information fusion to analyze faults.Secondly, this paper presents a method which based on model design to develop fault diagnosis system. Then, using Stateflow which is the theory of finite state machine for complex control logic control system in the modeling and simulation tool, combining with the fault diagnosis method of powertrain, establishing fault diagnosis model of AMT system, drive motor system and battery system. This method gets rid of the defects of traditional code writing and debugging work.Then, according to each powertrain fault, this paper analyzes and puts forward the corresponding fault handing and fault tolerant strategy, and establishes fault tolerant model under MATLAB/Simulink environment. When fault occurs, it makes that HCU can carry out the corresponding fault tolerant strategy to reduce power operation or claudication.Finally, after debugging and packaging each assembly fault diagnosis and fault tolerant model, these powertrain models can be taken off-line simulation by giving input parameters. These input parameters are actual CAN signals and some corresponding analog signals. The actual CAN signals are from the hybrid electric bus remote monitoring and data acquisition system which is developed by our research team. Through comparing with the result of the simulation, the diagnosis result of fault diagnostic instrument, fault repair records, analog input and simulation output signals of tolerant model, it verifies the accuracy of fault diagnosis and the reliability of fault tolerant strategy.