To highly accurately detect an electric leakage between a high-voltage circuit to be mounted on a vehicle and a vehicle body.SOLUTION: An electric leakage detection circuit detects a drop in a resistance value of insulation resistance between a DC power source of a vehicle and a body earth. The electric leakage detection circuit comprises: an oscillation circuit that outputs an oscillation signal; detection resistance that is provided between the oscillation circuit and the DC power source; a determination unit that, when a crest value of the oscillation signal pressure-divided by the detection resistance and insulation resistance is smaller than a threshold, determines that the resistance value of the insulation resistance reduces; a stray capacitance acquisition unit that acquires a capacitance value of a stray capacitance appearing parallel to the insulation resistance; and a frequency setting unit that sets a frequency of the oscillation signal on the basis of the capacitance value of the stray capacitance. The frequency setting unit is configured to, when the capacitance value of the stray capacitance is a first capacitance value, set the frequency of the oscillation signal to be a first frequency, and, when the capacitance value of the stray capacitance is a second capacitance value greater than the first capacitance value, set the frequency of the oscillation signal to be a second capacitance value lower than the first frequency.SELECTED DRAWING: Figure 1
【課題】車両に搭載される高電圧回路とボディとの間の漏電を精度よく検知する。【解決手段】漏電検知回路は、車両の直流電源とボディアースとの間の絶縁抵抗の抵抗値の低下を検知する。漏電検知回路は、発振信号を出力する発振回路と、発振回路と直流電源との間に設けられる検出抵抗と、検出抵抗と絶縁抵抗とで分圧された発振信号の波高値が閾値より小さいときに、絶縁抵抗の抵抗値が低下していると判定する判定部と、絶縁抵抗に並列に現れる浮遊容量の容量値を取得する浮遊容量取得部と、浮遊容量の容量値に基づいて発振信号の周波数を設定する周波数設定部と、を備える。周波数設定部は、浮遊容量の容量値が第1の容量値であるときは発振信号の周波数を第1の周波数に設定し、浮遊容量の容量値が第1の容量値より大きい第2の容量値であるときは発振信号の周波数を第1の周波数より低い第2の周波数に設定する。【選択図】図1
ELECTRIC LEAKAGE DETECTION CIRCUIT
漏電検知回路
2021-07-26
Patent
Electronic Resource
Japanese
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