Insulation monitoring device based on non-balanced bridge for direct current system

Abstract

The invention discloses an insulation monitoring device based on a non-balanced bridge for a direct current system and belongs to the technical field of ground insulation monitoring of buses of directcurrent systems. The device mainly solves the problem that the adaptive capability cannot be achieved in existing measurement and the measurement reliability cannot be ensured. The device is mainly characterized by comprising a first branch circuit, a second branch circuit, a main control single chip microcomputer, a signal conditioning circuit and a switch array, wherein the signal conditioningcircuit and the switch array are connected with the main control single chip microcomputer; the first branch circuit is in parallel connection with the second branch circuit, and the two ends of the first branch circuit are connected with a sixth switch and a seventh switch respectively; the junction point between a first switch and a third sensor and the junction point between a second switch anda fourth sensor are both connected with a fifth switch; a first sensor, a second sensor, the third sensor and the fourth sensor are electrically connected with the signal conditioning circuit; the signal conditioning circuit is also connected with a fifth sensor; the switch array is electrically connected with the first switch, the second switch, a third switch, a fourth switch, the fifth switch,the sixth switch and the seventh switch separately. The device is mainly applied in insulation resistance of positive and negative electrodes of direct current systems on low-voltage ground (case ground) in BMSs or high-low voltage direct current systems with similar demands.

Description

technical field [0001] The invention belongs to the technical field of direct current system busbar-to-earth insulation monitoring. Specifically, it relates to a measuring device for monitoring the insulation state of a DC bus of a new energy power battery system to ground based on an unbalanced bridge. Background technique [0002] When the unbalanced bridge method is used to measure the insulation resistance of the DC busbar to the ground, it is easy to have large measurement errors, slow measurement, easy damage to the system, and easy interference of the measurement results, and the measurement process will reduce the insulation state of the current DC busbar to the ground. The invention greatly improves the above problems through the measurement circuit and measurement algorithm. [0003] The national standard stipulates a test method. For more information, please refer to "GB / T 18384.1 Electric Vehicles-Safety Requirements Part 1". The specific principles are as follo...

AI Technical Summary

Problems solved by technology

[0013] The existing measurement methods have the following deficiencies: 1. No self-adaptive ability, unable to ensure measurement reliability; 2. Unable to quantify the influence of parasitic capacitance on measurement, unable to achieve the best match of measurement speed and measurement accuracy; 3. It can take into account the protection of the measurement system in specific scenarios; 4. The algorithm adopted can reduce the abnormal calculation of system parameters caused by the sudden change of external insulation; 5. It fails to consider the impact of the unbalanced bridge on the insulation resistance of the system during the measurement process ; 6. Basically not self-diagnostic, resulting in false positives

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