Insulation resistance value detection method during disconnection of power battery of electric vehicle

The invention discloses an insulation resistance value detection method during disconnection of a power battery of an electric vehicle. According to the method, the influence of a Y capacitor in a high-voltage system of the electric vehicle on a measurement process is actually considered, and function models of sampling voltage and bus voltage are established. The two function models are simplified, the calculation amount is greatly reduced, and the algorithm is more suitable for being used in a vehicle-mounted embedded system; and the simplified models are identified by using a variable forgetting factor recursive least square algorithm, and the insulation resistance values of a positive electrode and a negative electrode are calculated through an identification result. On the basis of a low-frequency signal injection method, the function models of the sampling voltage and bus voltage are established and simplified, the variable forgetting factor recursive least square algorithm is applied to insulation dete