Construction machine and control method thereof

A construction machine, which comprises a boom, the construction machine comprising:

• a boom cylinder configured to move the boom upward or downward and comprises a head side and a rod side;
• a boom regeneration valve configured to control a flow rate of a working fluid discharged from a head side of the boom cylinder;
• an operating device configured to generate an operating signal for operating the boom;
• an accumulator configured to store the working fluid discharged from the boom cylinder;
• a regeneration motor configured to produce renewable energy by performing a regenerative operation by using the working fluid discharged from the boom cylinder or the working fluid discharged from the accumulator;
• and
• a control device configured to correct an opening area of the boom regeneration valve on the basis of pressure of the accumulator when the boom descends,
• wherein the control device is configured to:
• determine a target speed of the boom corresponding to the operating signal of the operating device;
• calculate a target passage flow rate at which the working fluid needs to pass through the boom regeneration valve to achieve the target speed;
• and
• calculate the opening area of the boom regeneration valve required to pass the calculated target passage flow rate, and, once the opening area is calculated, transmit a control command to the boom regeneration valve.