Insulation resistance degradation detector and failure self-diagnostic method for insulation resistance degradation detector

Abstract

An insulation resistance reduction detector (50), comprising a pulse generator (60), which applies a pulse signal (65) to a series circuit in which a detection resistor (70), a coupling capacitor (80) and an insulation resistance (Ri) are connected in series ). In the state where the pulse signal (65) is applied to the series circuit, the control circuit (110) detects the pulse-shaped divided voltage appearing at the node (N1) through the voltage detection circuit (100) through the band-pass filter (90) , thereby sensing a decrease in insulation resistance (Ri). Further, when the voltage detected by the voltage detection circuit (100) is maintained at least a specified voltage over a number of cycles of the pulse signal (65), the control circuit (110) senses that the insulation resistance decrease detector itself failure. In this way, an insulation resistance drop detector with a fault self-diagnosis function is realized with a simple configuration.

Description

technical field [0001] The present invention relates to an insulation resistance reduction detector and a fault self-diagnosis method thereof, in particular to a fault self-diagnosis function for sensing a fault of the insulation resistance reduction detector itself. Background technique [0002] A power source insulated from a ground, for example, a battery (DC power source) installed in a vehicle such as an automobile (the ground corresponds to the vehicle) must be equipped with a device for detecting a decrease in insulation resistance between the power source and the ground circuit. [0003] As such an insulation resistance drop detector, Japanese Patent Laid-Open No. 10-290529 (hereinafter referred to as Patent Document 1) discloses a configuration of an insulation resistance drop detector applied to an electric vehicle having a high voltage power supply. [0004] Japanese Patent Laid-Open No. 2005-114496 (hereinafter referred to as Patent Document 2) discloses a confi...

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Problems solved by technology

[0005] However, with the configuration of the insulation resistance drop detector disclosed in Patent Document 1, failure of the insulation resistance drop detector itself cannot be sensed

[0006] In addition, with the insulation resistance decrease detector disclosed in Patent Document 2, for the fault self-diagnosis function as a function of detecting its own fault, a low-pass filter is required, which increases the number of components constituting the circuit

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