Apparatus for diagnosing electric power source while power is supplied to load device from the power source

A power source control apparatus provided in an electric system including (a) at least one subject power source, (b) at least one non-subject power source, (c) a load device connected to said at least one subject power source and said at least one non-subject power source and having at least one electrically operated load, and (d) a voltage regulating portion which is provided between said load device and at least one of said at least one non-subject power source and which regulates a voltage of said at least one of said at least one non-subject power source so that the regulated voltage is applied to said load device, said power source control apparatus comprising:

• a power source monitoring device which diagnoses each of said at least one subject power source;
• and
• a supply voltage reducing device for controlling said voltage regulating portion such that a voltage to be applied to said load device is lower when said power source monitoring device has determined that any one of said at least one subject power source is abnormal, than when said power source monitoring device has determined that said at least one subject power source is normal.

A power source monitoring apparatus for monitoring a state of a low-voltage power source in an electric system wherein a load device having at least one electrically operated load is connected to said low-voltage power source and a high-voltage power source, said power source monitoring apparatus comprising:

• a detecting portion which detects at least one of a voltage and an electric current of at least one of said load device, said high-voltage power source and said low-voltage power source;
• and
• a diagnosing device which diagnoses said low-voltage power source for an abnormality on the basis of at least one of an output of said detecting portion and a rate of change of said output, while an electric power is supplied to said load device from both of said high-voltage power source and said low-voltage power source, without temporary disconnection of said high-voltage power source from said load device or temporary limitation of the electric power supplied from said high-voltage power source to said load device.

A method of monitoring a state of each of at least one subject power source which consists of at least one of a plurality of electric power sources in an electric system wherein a load device is electrically connected to the plurality of electric power sources, the method comprising the steps of:

• detecting at least one of a voltage and a current of at least one of said load device, said at least one subject power source and at least one non-subject power source which consists of said plurality of electric power sources except said at least one subject power source;
• and
• diagnosing said each subject power source for an abnormality on the basis of at least one of said at least one of said voltage and said current and a rate of change of said at least one of said at least one of said voltage and said current, while said electric system is placed in a power supply state wherein an electric power is permitted to be supplied from only said subject power source to said load device.

A method of monitoring a state of a low-voltage power source in an electric system wherein a load device having at least one electrically operated load is electrically connected to said low-voltage power source and a high-voltage power source, said method comprising the steps of:

• detecting at least one of a voltage and a current of at least one of said high-voltage and low-voltage power sources;
• and
• diagnosing said low-voltage power source for an abnormality on the basis of at least one of said at least one of said voltage and said current and a rate of change of said at least one of said at least one of said voltage and said current, while said electric system is placed in a power supply state wherein an electric power is permitted to be supplied from at least said low-voltage power source.