Patent ID: 7688606

Claim:
A power supply control device comprising: a DC power supply; a relay provided between one electrode of said DC power supply and a load device; a semiconductor switching element connected in parallel to said relay; and a control unit performing precharge processing for supplying electric charges from said DC power supply to said load device through said semiconductor switching element before turn-on of said relay; and said control unit being configured to control one of: a gate voltage of said semiconductor switching element to be a first voltage threshold, so that a drain current of said semiconductor switching element at a time of start of said precharge processing is set to a value corresponding to a first drain current threshold such that power loss of said semiconductor switching element does not exceed maximum rated power of said semiconductor switching element, and a base voltage of said semiconductor switching element such that a first collector current value at a time of start of said precharge processing is a value corresponding to a first collector threshold such that rower loss of said semiconductor switching element does not exceed maximum rated power of said semiconductor switching element.