Patent ID: 9482721
Filing Date: 2016-11-01
CPC Classification: G01R,H01H

Claim Text:
1. An abnormality diagnosis method for a system, comprising: controlling by a microcomputer, connected to a power supply relay provided to open and close a current path formed between an electric power source and a power conversion circuit, a capacitor connected between a reference potential and the current path formed between the power conversion circuit and the power supply relay, a resistor connected in parallel to the capacitor to provide a discharging path of the capacitor, and a switch operable manually and provided to open and close a pre-charge path formed between the power source and the capacitor to pre-charge the capacitor by the power source, the pre-charge path bypassing the power supply relay, so that the microcomputer, including a memory which stores a code indicating a diagnosis result of the power supply relay, controls the power supply relay and diagnoses the power supply relay with respect to fixed-closure abnormality of the power supply relay, wherein the microcomputer is configured to: check whether the code stored in the memory is other than a predetermined code, which indicates the fixed-closure abnormality of the power supply relay, when the switch is closed to supply power from the electric power source to the computer and pre-charge the capacitor, control the power supply relay to close the current path, when the code is other than the predetermined code, thereby to supply the current from the electric power source through the current path to the power conversion circuit; control the power supply relay to open the current path, when the switch is opened, thereby to stop power supply through the power supply path and cause the capacitor to discharge through the resistor; write the code stored in the memory to be other than the predetermined code, when the switch is opened; and change the code stored in the memory to the predetermined code, when the capacitor continues to maintain a charge voltage sufficient for an operation of the computer after a predetermined period from when the power supply relay is controlled to open the current path.