Power supply apparatus, power supply unit diagnostic apparatus, and method for controlling power supply apparatus

A power supply unit diagnostic apparatus for performing diagnosis on a plurality of power supply units connected to one another in parallel and included in a power supply part of a power supply apparatus, the power supply unit diagnostic apparatus comprising:

• a first comparison unit which compares a first output voltage of the power supply part with a first reference voltage value;
• a directing unit that issues a voltage fall direction to one of the power supply units so as to lower a setting value of a voltage outputted from the power supply unit when the first output voltage is higher than the first reference voltage value;
• a second comparison unit that compares the second output voltage of the power supply unit obtained after the voltage fall direction is issued with the second reference voltage value;
• and
• a determining unit that determines that the power supply unit to which the voltage fall direction has been supplied corresponds to a failure power supply unit, when the second comparison unit detects that the second output voltage obtained after the voltage fall direction is issued fell in the voltage level lower than the second reference voltage value.

A method of controlling a power supply apparatus including a power supply part having a plurality of power supply units connected to one another in parallel, the method comprising:

• comparing a first output voltage of the power supply unit part with a first reference voltage value;
• issuing a voltage fall direction to one of the power supply units so as to lower a setting value of a voltage outputted from the power supply unit when the first output voltage is higher than the first reference voltage value;
• comparing a second output voltage of the power supply unit obtained after the voltage fall direction is issued with the second reference voltage value;
• and
• determining that the power supply unit to which the voltage fall direction has been supplied corresponds to a failure power supply unit, when it is detected in the comparing the second output voltage that the second output voltage obtained after the voltage fall direction is issued fell in the voltage level lower than the second reference voltage value.