Insulation resistance measurement device and fault self-diagnosis method

Abstract

The embodiment of the invention provides an insulation resistance measurement device and a fault self-diagnosis method. The insulation resistance measurement device comprises an insulation resistancemeasurement circuit composed of a plurality of measurement resistors and arranged between the cathode terminal and the anode terminal of a battery pack; a micro-control unit used for sensing a voltageapplied to one part of measurement resistors in the insulation resistance measurement circuit, and calculating the voltage of the battery pack according to the voltage and the resistance values of the plurality of measurement resistors; a battery cell voltage acquisition unit used for collecting the voltage of the battery pack; and a diagnosis unit used for obtaining a difference value between the calculated voltage of the battery pack and the acquired voltage of the battery pack and comparing the absolute value of the difference value with a first threshold value. When the absolute value ofthe difference value is larger than the first threshold value, it is judged that the insulation resistance measurement device has a fault. The first threshold value comprises one error or the sum of multiple errors selected from the voltage error of the battery cell voltage acquisition unit, the voltage error of the insulation resistance measurement circuit and the voltage sampling error of the micro-control unit. The device is simple in circuit, low in cost and high in precision.

Description

technical field [0001] The invention relates to the field of batteries, in particular to an insulation resistance measuring device and a fault self-diagnosis method. Background technique [0002] At present, the application prospect of electric vehicles is broad. When electric vehicles work normally, the voltage is high, the current is large, and the instantaneous short-circuit discharge current is large. When the insulation failure of the high-voltage circuit occurs, the high voltage and high current will endanger the safety of passengers on the vehicle. Therefore, the insulation detection of vehicles has become the focus of car companies. The insulation self-diagnosis function can identify whether there is a fault in the insulation resistance measurement circuit of the battery, thereby ensuring the accuracy of sampling and further improving the reliability and safety of the vehicle. [0003] In the prior art, most insulation sampling schemes do not have a self-diagnosis f...

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Problems solved by technology

[0003] In the prior art, most insulation sampling schemes do not have a self-diagnosis function, and it is impossible to identify in time whether there is a fault in the insulation resistance measurement circuit of the battery, so that the accuracy of sampling cannot be guaranteed, which reduces the reliability and safety of the vehicle, or the existing The few insulation sampling schemes with self-diagnosis function in the technology The self-diagnosis method is cumbersome, with low accuracy and poor reliability

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