Patent ID: 9048687
Filing Date: 2015-06-02
Classification: H02J

Abstract:
1. A power supply device comprising: a main power supply configured to feed power to a load with a constant-voltage output using an external power supply as an electric power supply source; an auxiliary power supply capable of switching between a constant-current output and a constant-voltage output, and configured to feed power to the load using an internal power storage unit as an electric power supply source; a load current detector configured to detect a value of current flowing through the load; a current upper-limit value instruction unit configured to output an upper-limit value of output current of the main power supply; a constant-current/constant-voltage switching power supply configured to feed, based on the value of current flowing through the load detected by the load current detector and the upper-limit value of output current of the main power supply given from the current upper-limit instruction unit, a part of the current flowing through the load by which part the current flowing through the load exceeds the upper-limit value, with the constant-current output from the auxiliary power supply; a power cut detection unit configured to detect a stop of a supply of electric power from the external power supply; a power cut monitoring unit configured to monitor an occurrence of a power cut in accordance with a power cut detection signal resulting from detection by the power cut detection unit; and an output switching unit switching the constant-current/constant-voltage switching power supply from the constant-current output to the constant-voltage output when the power cut monitoring unit determines the stop of the supply of electric power from the external power supply.