Patent ID: 9381584
Filing Date: 2016-07-05
CPC Classification: B23D,H02H,H02P

Claim Text:
1. A cordless electric power tool comprising: a three-phase brushless motor that drives a tool, the motor including a U-phase terminal, a V-phase terminal, and a W-phase terminal; a battery that supplies electric power to the motor; a motor drive circuit that includes a first switching device, a second switching device, and a third switching device, the U-phase terminal of the motor being electrically connected with the battery via the first switching device, the V-phase terminal of the motor being electrically connected with the battery via the second switching device, the W-phase terminal of the motor being electrically connected with the battery via the third switching device, and the first switching device, the second switching device, and the third switching device being connected in parallel with each other; a cut-off switch that includes a semiconductor switch disposed between the battery and the motor drive circuit, the semiconductor switch being electrically connected in series with each of the first switching device, the second switching device, and the third switching device; and a pull-up resister that is electrically connected to a node between the cut-off switch and the motor drive circuit and is configured to apply a predetermined voltage to the node, wherein the battery has a nominal voltage that is no more than 24 volts, and an overall electric efficiency of the cordless electric power tool becomes at least 70 percent when the cordless electric power tool outputs power of at least 450 watts but no more than 550 watts.