Electric vehicle insulation state online detection method

Abstract

The invention discloses an electric vehicle insulation state online detection method which comprises the following steps of: 1, establishing a system dynamic model, performing model parameter identification by utilizing a nonlinear least square method according to the step response of the system dynamic model, and calculating an insulation resistance value Rf1 and a system response period; 2, measuring insulation resistance according to a bridge method, performing parameter identification on the model by adopting a neural network, and calculating an insulation resistance value Rf2; and 3, when the difference value between the Rf1 and the Rf2 is smaller than a preset threshold value, taking a smaller insulation resistance value as a measured value Rf. The detection circuit comprises a dynamic model circuit and a bridge circuit. Compared with a traditional method, the detection time is shortened, and the real-time performance of insulation resistance detection is improved.

Description

technical field [0001] The invention relates to the technical field of insulation state detection, in particular to an online detection method for the insulation state of an electric vehicle. Background technique [0002] In recent years, in order to overcome energy and environmental problems, the automobile industry, especially hybrid and electric vehicles, has developed rapidly. Many components of electric vehicles, including power batteries, motors, chargers, energy recovery devices, auxiliary battery charging devices, etc., will involve high-voltage electrical insulation problems. [0003] The voltage of batteries, fuel cells and supercapacitors of electric vehicles far exceeds the safe limit of the human body, and the working conditions of these components are relatively harsh: vibration, acid and alkali gas corrosion, and changes in temperature and humidity may all cause the insulating materials of these components to rapid aging and even insulation damage. If the in...

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Problems solved by technology

[0004] At present, the traditional detection schemes for electric vehicle power battery insulation resistance include balanced bridge measurement method, external injection low-frequency signal measurement scheme and unbalanced bridge measurement method. The commonly used measurement methods are difficult to accurately measure the insulation state, and when the DC Power V DC The insulation circuit between the positive electrode and the car shell and the DC power supply V DC When the insulation circuit between the negative pole and the car shell fails at the same time, it cannot be detected and is easily affected by external factors.

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