Patent ID: 8749247

Claim:
An abnormality detecting apparatus for a high-voltage circuit which includes a direct-current power source and an inverter circuit connected to the direct-current power source via a fastening section, the abnormality detecting apparatus configured to detect a ground fault of the high-voltage circuit and a loosening of the fastening section, the abnormality detecting apparatus comprising: a first capacitor whose one end is connected to a positive terminal of the direct-current power source, and whose other end is designated as a measuring point; a pulse output section configured to output a square wave pulse signal to the measuring point; a series connection circuit of a second capacitor and a switch, provided between a positive terminal of the inverter circuit and the ground; a voltage measuring section configured to measure a first voltage occurring at the measuring point at a time when a phase of the square wave pulse signal outputted from the pulse output section becomes a first phase, and a second voltage occurring at the measuring point at a time when the phase of the square wave pulse signal becomes a second phase different from the first phase, and to obtain a difference voltage between the first voltage and the second voltage; a ground fault detector configured to detect a ground fault of the direct-current power source on the basis of the difference voltage measured by the voltage measuring section with the switch opened; and a loose state detector configured to detect a loose state of the fastening section on the basis of the difference voltage measured by the voltage measuring section with the switch closed when no ground fault is detected by the ground fault detector.