Power supply control apparatus for electric vehicle

A power supply control apparatus for an electric vehicle, the power supply control apparatus comprising:

• a main circuit including a smoothing capacitor connecting a power supply to an electric load driven by the power supply to smooth a fluctuation in an input voltage to the electric load;
• a main contactor interposed between the power supply of the main circuit and the electric load;
• a precharge circuit connected in parallel with the main contactor and including a precharge contactor and a resistance element;
• a voltage detector that detects, as a capacitor voltage, a voltage of the smoothing capacitor gradually increasing with progression of charging during the precharging;
• a current detector that detects, as a precharge current, a current flowing through the main circuit and gradually decreasing with progression of charging of the smoothing capacitor during the precharging;
• a controller configured to:
• connect the main contactor and the precharge contactor together to precharge the smoothing capacitor;
• determine, during the precharging, completion of the precharging by determining that the detected capacitor voltage increases to a predetermined voltage within a predetermined period of time;
• when the detected capacitor voltage fails to increase to the predetermined voltage within the predetermined period of time, the controller,
• grant a permission to retry the precharging when the detected precharge current enters a permission region predefined based on a predetermined current range including 0 A within the predetermined period of time during the precharging, and
• inhibit permission to retry the precharging when the detected precharge current fails to enter the permission region within the predetermined period of time and store a failure code in a storage unit;
• and
• generate a warning indicating that the precharging has been inhibited when the failure code is stored in the storage unit.