Power tool and control method thereof

A control method of a power tool comprising a housing, an electric motor disposed in the housing, a driver circuit comprising a plurality of electronic switches, a current detection module configured to acquire a current value of the electric motor, and a control module electrically connected to the driver circuit, the control method comprising:

• outputting, by the control module, a drive signal to control the driver circuit to cause the electric motor to operate;
• limiting, by the control module, a current of the electric motor within periodic time intervals;
• acquiring, by the control module, a current value of the electric motor in real time through the current detection module within the periodic time intervals;
• turning off, by the control module, an on-state electronic switch among the plurality of electronic switches within a remaining time of a present time interval when the current value exceeds a preset current threshold;
• and
• turning on, by the control module, an electronic switch among the plurality of electronic switches which is controlled by the control module at present to be on when a present period of the drive signal ends;
• wherein a duration of each time interval among the periodic time intervals is the same as a period corresponding to the drive signal at present and a period of the drive signal is determined by the controller by comparing a grid voltage of the electric motor to a present counter-electromotive force of the electric motor.