Cycle-by-cycle current limit for power tools having a brushless motor

A power tool, comprising:

• a housing;
• a brushless electric motor drivably connected to an output shaft to impart rotary motion thereto;
• a rectifier configured to receive power from an alternating current (AC) power source and operable to convert an alternating current to a direct current;
• a switching arrangement having a plurality of motor switches and interposed between the electric motor and the rectifier;
• a capacitor electrically coupled across the rectifier and interposed between the rectifier and the switching arrangement;
• a motor drive circuit interfaced with the motor switches;
• and
• a controller interfaced with the motor driver circuit to control a switching operation of the plurality of motor switches at a given frequency for driving the electric motor and configured to operate over periodic time intervals to enforce a current limit on the current delivered to the electric motor, wherein the controller is configured to enforce the current limit by receiving a measure of instantaneous current passing from the rectifier to the switching arrangement within a present time interval of the periodic time intervals, comparing the measure of instantaneous current to the current limit, and, in response to the measure of instantaneous current exceeding the current limit, turning off the motor switches for a remainder of the present time interval and thereby interrupting current flowing to the electric motor, wherein a duration of each time interval of the periodic time intervals is fixed as a function of the given frequency at which the plurality of motor switches is controlled by the controller.