Abstract: A power supply device includes: a first system; a second system; an inter-system switch configured to be able to connect and disconnect between the first system and the second system; a determining unit configured to keep the inter-system switch in an ON state in a normal time, and turn off the inter-system switch and determine which system a ground fault has occurred in, if detecting a ground fault of the first system or the second system; and a suppression circuit configured to suppress an electric discharge of the second power supply and supply electric power for ground fault detection to the second system, and the determining unit determines whether any ground fault has occurred in the second system or not, based on the electric power which is supplied from the suppression circuit to the second system.

Abstract: A power supply device includes: a first system connected to a first load; a second system connected to a second load; an inter-system switch configured to connect and disconnect the first system and the second system to and from each other; a controller configured to normally supply power of a first power supply to the first system and the second system and, in response to a fault of the first system being detected, turn off the inter-system switch to supply power of a second power supply to the second system; and a backup circuit which includes a discharge regulation unit configured to regulate discharging of the second power supply.

Abstract: An example of a relay circuit includes: a capacitor connecting both ends of a load circuit; first and second main relays disposed in power supply lines between a direct-current power supply and the load circuit; a series circuit configured by a first resistor and a precharge relay disposed in parallel with the first main relay; and a second resistor connecting both ends of the load circuit. A discharge process is performed in which both the first main relay and the precharge relay are turned on, the second main relay is turned off, and a reactive current is caused to flow through the load circuit. In this discharge process, an abnormality of the first resistor is detected based on a both-end voltage of the capacitor detected by a voltage sensor and a resistance value that is an equivalent representation of the discharge process.

Abstract: An operation control unit and a driving control unit mutually monitor an operation state of each other, and when a first control unit detects an error of the other (second) control unit, the first control unit performs a driving control on driving sources, at a speed more limited than that in a normal mode based on an operation signal.