Patent ID: 8058748

Claim:
A power supply unit having a pair of input/output terminals to/from which power is to be input/output, and a power supply module to/from which power can be input/output, the power supply unit being connected to an external unit comprising at least one other power supply unit, the power supply unit comprising: a current detection circuit for detecting current flowing in the power supply module; a voltage adjustment circuit for increasing the voltage across the power supply module and outputting the increased voltage to the pair of input/output terminals or for decreasing the voltage between the pair of input/output terminals and outputting the decreased voltage across the power supply module; and a control circuit for controlling operation of the voltage adjustment circuit, wherein the control circuit includes: an output portion for outputting a current detection result of the current detection circuit as a first current detection result to the external unit; and a control portion for generating a control signal on the basis of a target output voltage of the voltage adjustment circuit, the first current detection result, and a second current detection result obtained from the external unit, and for outputting the control signal to the voltage adjustment circuit.