Battery charge control system for a hybrid vehicle driven by an electric motor and an internal combustion engine

A battery charge apparatus for a hybrid vehicle, said apparatus comprising:

• electric drive means for rotating wheels of the hybrid vehicle;
• a plurality of batteries serially connected to one another to supply electric power to said electric drive means;
• a generator means driven by an internal combustion engine for generating electric power to charge said serially-connected batteries;
• state-of-charge detecting means for detecting a state-of-charge of each of said serially-connected batteries,
• charge control means for independently charging each of said serially-connected batteries when a dispersion of the state-of-charge detected by said state-of charge detecting means is larger than a predetermined value and for uniformly charging all of said serially-connected batteries when said dispersion of the state-of-charge of each battery is smaller than said predetermined value;
• and
• distribution ratio change means for changing a distribution ratio according to which electric power is supplied by said charge control means from said generator means to respective batteries to eliminate the dispersion of the states-of-charge of said serially-connected batteries.

A battery charge method for a hybrid vehicle having a plurality of serially-connected batteries, said method comprising the steps of:

• detecting a state-of-charge value of each of said serially-connected batteries;
• judging whether a dispersion of a state-of-charge value of each of said serially-connected batteries is within a predetermined allowable zone;
• and
• determining a distribution ratio, according to which electric power is supplied from a generator to respective serially-connected batteries for charging said serially-connected batteries, said distribution ratio being set in such a manner that all of said serially-connected batteries are uniformly charged when said dispersion of the state-of-charge value is within said predetermined allowable zone, while some of batteries having low states of charge are independently charged when said dispersion of the state-of-charge value is out of said predetermined allowable zone, thereby eliminating the dispersion of state-of-charge value.