Insulation fault detection method and control device

Abstract

The embodiment of the invention relates to the technical field of electric vehicles, and discloses an insulation fault detection method and a control device. The method comprises the following steps:setting first detection time and second detection time, wherein the first detection time and the second detection time are duration required by an insulation fault detection circuit to reach a stablestate in a first connection state and a second connection state when the resistance value of an insulation resistor is a preset fault threshold; switching the insulation fault detection circuit to thefirst connection state, and sampling from a detection point to obtain a first voltage value when first detection time is up; switching to the second connection state, and sampling from the detectionpoint to obtain a second voltage value when the second detection time is up; calculating an estimated resistance value of the insulation resistor at least according to the first voltage value and thesecond voltage value; and obtaining a fault detection result according to the estimated resistance value and the fault threshold. The embodiment of the invention further provides a control device. Theembodiment method and device of the invention can shorten the insulation fault confirmation time and quickly report the insulation fault.

Description

technical field [0001] The embodiments of the present invention relate to the technical field of detection, and in particular to an insulation fault detection method and a control device. Background technique [0002] The replacement of fuel vehicles by electric vehicles has become the development trend of the automobile industry. The mileage, service life and safety of battery packs are all very important for the use of electric vehicles. The battery pack is one of the key components of electric vehicles, and its high-voltage safety must be one of the primary considerations for the battery pack system. Therefore, the detection of the insulation performance of electric vehicles is an essential part of the design. [0003] At this stage, the bridge balance method is commonly used. By connecting the positive pole and the ground of the battery pack in parallel, and between the negative pole and the ground, the detection branch (the detection branch contains a megohm resistance)...

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Problems solved by technology

[0004] The inventors found that there are at least the following problems in the prior art: in the bridge balance method, the voltage sampling can only be performed after the voltage of the detection branch is stable; and, in order not to affect the actual insulation of the whole vehicle, the resistance connected to the detection branch Can not be too small, resulting in a large RC time constant, making the voltage stable for a long time

Therefore, the long voltage stabilization time leads to a long sampling cycle, which in turn leads to a long fault reporting cycle for electric vehicles, which is not conducive to timely detection of insulation faults

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