Hybrid vehicle and control method thereof

A hybrid vehicle, having an internal combustion engine capable of outputting power for driving the hybrid vehicle, a motor constructed to input and output power for driving the hybrid vehicle, and a secondary battery designed to transmit electric power to and from the motor, the hybrid vehicle being capable of motor travel where the hybrid vehicle is driven only with input and output power to and from the motor and hybrid travel where the hybrid vehicle is driven with output power from the internal combustion engine and with the input and output power to and from the motor, the hybrid vehicle comprising:

• a charger connected to an external power supply in a system-off state of the hybrid vehicle to charge the secondary battery with electric power from the external power supply;
• a driving power setting module that sets a driving power required for driving the hybrid vehicle;
• an accumulated charge ratio calculation module that calculates an accumulated charge ratio based on a state of the secondary battery, the accumulated charge ratio being a ratio of an accumulated charge amount in the secondary battery to a whole capacity of the secondary battery;
• an output limit setting module that sets an output limit of the secondary battery as a maximum allowable electric power to be output from the secondary battery based on the state of the secondary battery;
• a mode setting module that, in a case that the calculated accumulated charge ratio is at least more than or equal to a first preset ratio upon system-on of the hybrid vehicle, sets a motor travel priority mode where the motor travel is prioritized for driving the hybrid vehicle until the calculated accumulated charge ratio becomes less than a second preset ratio that is less than the first preset ratio during vehicle traveling, while setting a hybrid travel priority mode where the hybrid travel is prioritized for driving the hybrid vehicle in a case that the motor travel priority mode is not set;
• and
• a control module that, in a case that the motor travel priority mode is set and a preset condition for restricting the motor travel is not satisfied, controls the motor so that the hybrid vehicle is driven with the motor travel on condition that the set driving power is not more than the set output limit of the secondary battery, while controlling the internal combustion engine and the motor so that the hybrid vehicle is driven with the hybrid travel on condition that the set driving power is more than the set output limit of the secondary battery, and
• in a case that the motor travel priority mode is set and the preset condition is satisfied, the control module controlling the motor so that the hybrid vehicle is driven with the motor travel on condition that the set driving power is not more than a threshold power that is a smaller power between the set output limit of the secondary battery and a predetermined power, while controlling the internal combustion engine and the motor so that the hybrid vehicle is driven with the hybrid travel on condition that the set driving power is more than the threshold power.