Alternating current power tool and startup method thereof

An alternating current power tool, comprising a brushless motor, a power module, a voltage conversion module, a drive circuit, and a controller, wherein

• the brushless motor comprises a stator winding and a rotor;
• the power module is configured to receive an alternating current to supply power to the stator winding;
• the voltage conversion module is configured to receive the alternating current received by the power module and operatively output a direct current bus voltage;
• the drive circuit is electrically connected to the voltage conversion module and configured to drive the brushless motor,
• wherein when an instantaneous voltage value of the alternating current is greater than or equal to a preset voltage value V0 of the alternating current in each half cycle, the controller is configured to output a first control signal, comprising a single pulse, to the drive circuit to power on the stator winding to start up the motor from a non-moving state where relative movement between the stator winding and the rotor is substantially zero.

A startup method of an alternating current power tool, the alternating current power tool comprising a brushless motor and a power module configured to receive an alternating current, and the method comprising:

• starting timing when the alternating current received by the power module crosses through a point of zero;
• in a preset time interval [T1, T2] of each half cycle, outputting a first control signal, comprising a single pulse, to power on a stator winding of the brushless motor to start up the motor;
• acquiring a rotor position of the brushless motor;
• and
• in the preset time interval [T1, T2] of each half cycle, outputting a second control signal to a drive circuit according to the rotor position to make the brushless motor generate a continuous torque by starting movement of the brushless motor from a non-moving state where movement of the brushless motor is substantially zero, and
• wherein a starting time of the preset time interval is T1 and a cut-off time of the preset time interval is T2.