Power supply apparatus

A power supply apparatus, comprising:

• a plurality of systems of power supply circuits that are provided between one or more power sources and a load and that are capable of cooperatively supplying power to the load using power of the power sources, and in which ground lines connected to a negative pole of the one or more power sources are configured independently for each system;
• a plurality of ground current detectors configured to detect a ground current that is a current flowing through the ground line of each system;
• and
• a control unit configured to control an operation of the power supply circuit of each system,
• wherein
• the control unit has a ground line diagnosis portion configured to diagnose an abnormality in the ground line based on the ground current,
• the ground line diagnosis portion calculates a ground power of each system, which is power consumed by energization of the ground line of each system, based on the ground current and a wiring resistance of the ground line of each system, and diagnoses an abnormality based on a ratio of the ground power of two systems selected from among a plurality of systems, wherein the ratio of the ground power comprises a ground power of one system divided by a ground power of another system, and
• the ground line diagnosis portion diagnoses the abnormality in the ground line based on the ratio of the ground power, and
• when the ground line diagnosis portion determines that the ground line of at least one system is abnormal, the control unit changes an operation of the power supply circuit of the system determined to be abnormal.