A handheld grinder with a brushless electric motor

摘要

A handheld grinder (10) comprising a housing (12); a grinding disk (22); a motor (28); an output shaft connected to the grinding disk (22) and the motor (28) to impart rotary motion thereto; and a circuit board (40) residing in the housing (12) and having thereon a rectifier (44) that receives an alternating current and converts the alternating current to a direct current, a switching arrangement having a plurality of motor switches connected electrically between the rectifier (44) and the motor (28) and operates to deliver the direct current from the rectifier (44) to the motor (28), a capacitor (50) connected electrically between the rectifier (44) and the switching arrangement, wherein the capacitor (50) is coupled in parallel across the rectifier (44), a driver circuit interfaced with the motor switches and operable to control switching operation of the motor switches, and a power switch (32) connected electrically between the rectifier (44) and the driver circuit and operable to selectively energize the driver circuit and power on the grinder disk (22).