Electric vehicle fault diagnosis method based on dynamic threshold model

The invention provides an electric vehicle fault diagnosis method based on a dynamic threshold model, and the method is used for the fault diagnosis of a battery system in an electric vehicle, and improves the threshold model building and parameter identification algorithms. A circuit basic characteristic test experiment is conducted at different temperatures, and the parameters of an equivalent circuit model are obtained; An OCV-SOC-Q three-dimensional response surface model is established; and model parameter identification is conducted by adopting a recursive least square method with forgetting factors, and a dynamic threshold model about R0 and tau is established. In the actual fault diagnosis process, parameters and states are identified by using a double extended Kalman filtering algorithm to obtain battery R0, tau, capacity and SOC; a parameter reference value is determined by adopting a temperature interpolation method; a parameter threshold is determined; a residual error is generated; and whether th