Power tool

A power tool, comprising:

• a motor comprising a rotor and a plurality of phases of stator windings;
• and
• a control circuit configured to control a working state of the motor;
• wherein the control circuit comprises:
• a driver circuit comprising a plurality of switching elements;
• a controller electrically connected to the driver circuit and capable of outputting a control signal to change conducting states of the plurality of switching elements in the driver circuit;
• and
• a parameter detection module configured to detect a working parameter of the motor;
• wherein the control circuit includes:
• a current loop circuit configured to control in, based on a preset current parameter and a current parameter fed back by the motor, the motor to perform current control, wherein the preset current parameter of the current loop circuit comprises a direct axis input parameter and a quadrature axis input parameter;
• wherein the controller is configured to:
• in response to a braking signal, adjust the preset current parameter of the current loop circuit according to a preset parameter and the working parameter to control output power of the motor and/or output torque of the motor, thereby controlling the motor to brake;
• wherein the preset parameter is lower than or equal to a maximum voltage which the control circuit or the motor is configured to withstand so that the bus voltage spike and the reverse bus current spike do not exist during the braking, and a sum of a square of the direct axis input parameter and a square of the quadrature axis input parameter is equal to a square of the maximum current.

A power tool, comprising:

• a motor comprising a rotor and a plurality of phases of stator windings;
• and
• a control circuit configured to control a working state of the motor;
• wherein the control circuit comprises:
• a driver circuit comprising a plurality of switching elements;
• a controller electrically connected to the driver circuit and capable of outputting a control signal to change conducting states of the plurality of switching elements in the driver circuit;
• and
• a parameter detection module configured to detect a working parameter of the motor;
• wherein the control circuit comprises at least:
• a current loop circuit capable of controlling, based on a preset current parameter and a current parameter fed back by the motor, the motor to perform current control;
• and
• a speed loop circuit capable of determining the preset current parameter based on a preset speed parameter and a rotational speed parameter fed back by the motor;
• and
• wherein, in response to a braking signal, the controller is capable of adjusting the preset current parameter according to a preset parameter and the working parameter to control output power of the motor and/or output torque of the motor, thereby controlling the motor to brake;
• wherein the power tool has multiple working conditions, different working conditions correspond to the different maximum currents, and the preset parameter is set as one of the different maximum currents according to the multiple working conditions so that the power tool adaptively changes a braking time according to the multiple working conditions.