IGBT module state monitoring method based on cooling curve time constant

The invention provides an IGBT module state monitoring method based on a cooling curve time constant, and the method comprises the steps: S1, controlling a cooling fan of an IGBT module to work at a wind speed FS1, then electrifying the IGBT module, stopping electrifying after the temperature of the IGBT module reaches a steady state, and maintaining the cooling fan to be in a state of the wind speed FS1 until the temperature of the IGBT module is equal to the environment temperature; recording the temperature change value of the IGBT module; s2, fitting based on the temperature change value of the IGBT module to form a temperature change curve of a third-order Cauer thermal network model; determining time constants tau 1, tau 2 and tau 3 based on the temperature change curve; s3, changing the wind speed of a cooling fan of the IGBT module to FS2, keeping the wind speed, repeating the steps S1 to S2, and determining time constants tau '1, tau' 2 and tau '3, S4, constructing a thermal capacity and thermal resi