초록 ▼

A rapid increase in motor current (di/dt above a predetermined threshold) causes the motor control system to enter pulse mode operation in-which the motor current is pulsed on and off rapidly to dislodge the workpiece obstruction or binding condition that would otherwise lead to a motor stall. When

A rapid increase in motor current (di/dt above a predetermined threshold) causes the motor control system to enter pulse mode operation in-which the motor current is pulsed on and off rapidly to dislodge the workpiece obstruction or binding condition that would otherwise lead to a motor stall. When the workpiece obstruction or binding has been cleared, the motor resumes normal operation.

대표청구항 ▼

1. A method of controlling a power tool having a motor that imparts torque to an output spindle when actuated by an operator actuable switch, the power tool having a characteristic natural resonant frequency, comprising:sensing a motor parameter indicative of the onset of an impending stall conditio

1. A method of controlling a power tool having a motor that imparts torque to an output spindle when actuated by an operator actuable switch, the power tool having a characteristic natural resonant frequency, comprising:sensing a motor parameter indicative of the onset of an impending stall condition; and in response to the sensed onset of an impending stall condition and while the switch remains actuated, pulsing the motor a plurality of times at a frequency substantially harmonically related to said natural resonant frequency to deliver a series of torque pulses having peak torque substantially greater than the average torque delivered during the series.