Control system for a plug-in hybrid vehicle

A control system for a plug-in hybrid vehicle having a drive system including a starter motor, an engine, and a motor/generator, and a power supply system including a high voltage battery representing power supply of the motor/generator, a capacitor representing power supply of the starter motor, and a capacitor charge and discharge control unit that controls charging and discharging of the capacitor, the control system comprising:

• an engine start control unit configured to crank the engine for starter start-up using the starter motor powered by the capacitor,
• a running mode selection unit configured to select a charge depleting (CD) mode in which an electric vehicle (EV) running is performed by consuming power of the high voltage battery when the charge capacity of the high voltage battery is at or above a threshold value and configured to select a charge sustain (CS) mode in which a hybrid vehicle (HEV) running is performed by maintaining the charge capacity of the high voltage battery when the charge capacity of the high voltage battery is below the threshold value, and
• a reverse transition pre-forecast unit configured to predict in advance a transition from the CS mode to the CD mode, wherein the capacity charge and discharge control unit is configured such that, at the time of ignition on with the CS mode being selected, the capacitor voltage is maintained at or below a deterioration free voltage at which deterioration does not proceed, and, upon the reverse transition pre-forecast from the CS mode to the CD mode being established, the capacitor is recharged to and above the starter start-up permission voltage.