Hybrid Construction Machine and Method for Controlling the Same

A method for controlling a hybrid construction machine having:

• a swing structure;
• a work machine attached to the swing structure;
• an operating device for operating the swing structure and the work machine;
• an engine mounted on the swing structure;
• a first electric motor driven by the engine, the motor being capable of generating power;
• a hydraulic pump driven by the engine and by the first electric motor;
• a hydraulic actuator which drives and operates the work machine by use of power generated through the hydraulic pump;
• a second electric motor for driving the swing structure;
• and
• a plurality of electric storage devices for supplying electric power to drive the first electric motor and the second electric motor and for being charged with electric power generated through the first electric motor and the second electric motor, the method including a first control mode for executing:
• a first step of determining whether a combined operation involving the work machine and the swing structure in accordance with operating status of the operating device is present or absent;
• a second step which, if the first step determines that the combined operation involving the work machine and the swing structure is present, drives the second electric motor by use of the electric power supplied from at least one electric storage device selected from the plurality of storage devices and from another electric storage device offering a higher output level and a lower stored energy level per unit weight than the selected at least one electric storage device, and
• a third step of driving and controlling the hydraulic pump by use of the engine.