Power supply control apparatus and method for hybrid vehicle

A power supply control apparatus for a hybrid vehicle, comprising:

• a first power supply providing a first power supply voltage,
• a motor receiving supply of power from said first power supply to start an internal combustion engine,
• a voltage converter connected parallel to said motor with respect to said first power supply to voltage-convert said first power supply voltage according to a voltage control value for output between first and second power supply lines,
• a second power supply connected between said first and second power supply lines, providing a second power supply voltage that is lower than said first power supply voltage,
• an electric load connected between said first and second power supply lines to receive voltage from at least one of said voltage converter and said second power supply,
• a control device receiving voltage from the at least one of said voltage converter and said second power supply to control startup of said internal combustion engine and said voltage converter according to designation of activation of a vehicle system, and
• a defect diagnosis device giving a diagnosis of a defect at said electric load based on a voltage output between said first and second power supply lines becoming lower than a lower limit of an operating voltage at which a proper operation of said electric load is ensured,
• wherein said control device comprises
• a first voltage conversion control unit that controls said voltage converter by setting said voltage control value to a first voltage that is lower than said second power supply voltage and that is at least the lower limit of an operating voltage of said control device,
• a defect diagnosis prohibition unit that prohibits a defect diagnosis operation of said defect diagnosis device in response to said voltage control value set to said first voltage,
• a low temperature startup control unit that drive-controls said motor to start said internal combustion engine in response to a temperature of at least one of said internal combustion engine and said first power supply being not more than a predetermined threshold value,
• a second voltage conversion control unit that controls said voltage converter by setting said voltage control value to a second voltage that is at least said second power supply voltage in response to completion of the startup of said internal combustion engine, and
• a running permission unit that cancels the prohibition of the defect diagnosis operation of said defect diagnosis device and designating a running permission of said hybrid vehicle in response to said voltage control value being set at said second voltage.