To make the efficiency of engine assistance higher without spoiling the sensation of acceleration by decreasing the quantity of decided assistance according to the operating condition of a car, by a ratio corresponding to the difference between a detected value of the charged quantity of a capacitor and a threshold set beforehand.
The relation between a capacitor voltage VCAP and each of threshold VCAPLMTL, set beforehand as a lower limit value for compensating the operation of an electrical equipment system and the upper limit value VCAPLMLH of assistance is determined (S32, S33). If VCAP≤VCAPLMLH, a correction factor α is found (S35) by dividing the difference DVCAPLML between VCAP and VCAPLMTL by (VCAPLMTL-VCAPLMLH). An assistance determining flag F.AST is set to 1 (S36, S37), after multiplying the quantity of assistance determined previously by α, and correcting the quantity of assistance in accordance with VCAP If VCAP>VCAPLMLH, F.AST is set to 1, and the motor is driven with ASTPWR. If VCAP≤VCAPLMTL, F.AST is set to zero after setting ASTPWR to 0, and assistance by motor driving is not performed.
NAKANO KENJI
MATSUBARA ATSUSHI
IZUMIURA ATSUSHI
UCHIDA KEISUKE
KONNO FUMIHIKO
