Power tool

A power tool, comprising:

• an AC power module for connecting to a source of AC power;
• a brushless motor coupled to an output shaft for applying a rotational force, the brushless motor comprising a motor and a stator;
• a rectifier module for receiving an alternating current from the AC power module and converting the alternating current into a direct current;
• a drive circuit connected to the brushless motor for driving the brushless motor;
• a controller connecting to the drive circuit for outputting a control signal to the drive circuit to cause the drive circuit to drive the brushless motor;
• a capacitor connected between the rectifier module and the driving circuit;
• an EMI module electrically connected between the AC power module and the rectifier module;
• and
• a circuit board comprising the capacitor, the rectifier module, and the EMI module arranged on the circuit board,
• wherein the EMI module is electrically connected with the AC power module to filter interference signals in an AC current wherein the stator includes a stator metal region housing and windings, the EMI module includes a first EMI capacitor, a second EMI capacitor and a third EMI capacitor, one end of the first EMI capacitor is connected to a high voltage end of the AC power module, another end of the first EMI capacitor is connected to one end of the second EMI capacitor, the another end of the second EMI capacitor is connected with a low-voltage terminal of the AC power module, one end of the third EMI capacitor is connected with a connection of the first EMI capacitor and the second EMI capacitor, another end of the third EMI capacitor is grounded, and the stator metal region housing is directly connected to a node between the first EMI capacitor and the second EMI capacitor, and
• wherein a ratio of a capacitance value of the capacitor to a rated power of the brushless motor ranges from 20 uF/kw to 80 uF/kw.