Method of controlling hybrid construction machine and hybrid construction machine

A method of controlling a hybrid construction machine provided with an engine and a generator motor coupled to each other, a swing motor which electric power is supplied to from the generator motor for swinging a part of a body relative to other parts, a capacitor for storing the electric power generated by each of the generator motor and the swing motor and supplying the electric power to the generator motor and the swing motor, and a booster for boosting voltage of the capacitor to output, the method comprising:

• an assist torque limit value calculating step of calculating an assist torque limit value of the generator motor corresponding to capacitor voltage of the capacitor when the booster performs an output associated with discharge of the capacitor;
• a generator motor torque command value calculating step of calculating a torque command value of the generator motor according to a target speed of the generator motor;
• and
• a generator motor actual torque command value generating step of comparing the assist torque limit value calculated at the assist torque limit value calculating step with the torque command value calculated at the generator motor torque command value calculating step, and generating an actual torque command value of the generator motor by using the smaller of the assist torque limit value and the torque command value.