e p limit u2014 1 p 1 p pi u2014 1 a limit torque value is calculated from the output limit power p limit u2014 1 and an angular velocity of the motor and the flow goes to the step s 27 step s 27 the limit torque value is compared with a requested torque received by a hybrid control unit and the smaller one of them is taken as a torque request value to be sent from the hybrid control unit where the control flow corresponding to a discharging state as illustrated in fig3 includes the following steps p step s 31 a measured voltage value of the battery is multiplied by a discharging current limit value of the battery to derive a discharging limit power p 2 step s 32 it is determined whether the actual current value is below an initial control value of discharging current and if so the flow goes to the step s 33 otherwise the flow goes to the step s 34 step s 33 a output limit power p limit u2014 2 is p 2 a limit torque value is calculated from the output limit power and an angular velocity of a motor and the flow goes to the step s 37 step s 34 pi adjusting is performed with i error i battery u2212 i discharge u2014 limit to derive a torque deviation value p pi u2014 2 where i battery is the actually measured current value of the battery and i discharge u2014 limit is the discharging current limit value of the battery and the flow goes to the step s 35 step s 35 step s 36 a resultant output limit power is derived from p pi u2014 2 and p.