Ground fault detection device

Abstract

To enable ground fault to be detected at a portion of a motor side relative to a system main relay.SOLUTION: A ground fault detection device is used in an electric motor vehicle including: a motor; an inverter driving the motor; a first power storage device which is connected through a first power line to the inverter; a relay arranged in the first power line; and a second power storage device whose rated voltage is lower than that of the first power storage device. The ground fault detection device detects ground fault at a motor side portion in the motor side relative to the relay. The ground fault detection device comprises: a switch which is arranged in a second power line connected with the second power storage device and the first power line at an inverter side relative to the relay; and a determination processing part in which the switch is turned on while the relay is in an OFF state, the ground fault is determined to generate at the motor side portion whether a voltage at the inverter side relative to the relay on the first power line is raised to be the threshold value or more within a prescribed time, and when the ground fault is determined to generate at the motor side portion, the relay is prohibited from being turned on.SELECTED DRAWING: Figure 2

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