Power tool with electronic spindle positioning

1 . A method for operating a power tool, comprising:

electronically braking a motor shaft of a brushless electric motor of the power tool, using a controller of the power tool, wherein a spindle unit positioned on the motor shaft has a known rotational position relative to at least one pole of a plurality of poles of a rotor of the motor shaft;

stopping the motor shaft, using the controller, in a predetermined rotational position relative to a stator of the electric motor based on a detected position state of a plurality of position states as detected by a plurality of position sensors of the electric motor,

wherein the plurality of position states identify a rotational position of the rotor relative to the stator,

wherein at the predetermined rotational position a spindle lock of the power tool is configured to engage the spindle unit without additional rotation of the motor shaft, and

wherein when the spindle lock is engaged with the spindle unit, rotation of the motor shaft relative to the stator is prevented.

2 . The method of claim 1 , further comprising:

electronically braking the motor shaft to a standstill during the electronic braking of the motor shaft using the controller.

3 . The method of claim 2 , wherein:

the predetermined rotational position is included in a plurality of predetermined rotational positions,

the rotational position of the motor shaft at the standstill results in the detected position state,

the method further comprises:

determining, using the controller, the predetermined rotational position of the plurality of predetermined rotational positions based on the detected position state; and

rotating the motor shaft, using the controller, to rotate the motor shaft to the determined predetermined rotational position.

4 . The method of claim 1 , further comprising:

electronically braking the motor shaft to a predetermined speed during the electronic braking of the motor shaft using the controller;

calculating, using the controller, a ramp down procedure that causes the motor shaft to slow from the predetermined speed to a standstill, with the motor shaft being in the predetermined rotational position at the standstill; and

implementing the ramp down procedure, using the controller, so that the motor shaft slows from the predetermined speed and stops directly at the predetermined rotational position.

5 . The method of claim 1 , wherein:

during rotation of the motor shaft, the motor shaft advances through the plurality of position states in a sequential order, and

the predetermined rotational position is determined based on an idle phase of a plurality of stator phase connections during the detected position state.

6 . The method of claim 5 , wherein:

a polarity of the idle phase that moves the motor shaft to the predetermined rotational position is a polarity of the idle phase during an immediate previous position state from the detected position state according to the sequential order of the position states.

7 . The method of claim 1 , wherein:

the plurality of position sensors include a plurality of Hall sensors, and

the plurality of position states includes a plurality of Hall states.

8 . The method of claim 1 , further comprising:

detecting that a main switch of the power tool is in a closed state or an open state using the controller;

operating the electric motor to rotate an accessory when the controller detects that the main switch is in the closed state, the accessory operably connected to the motor shaft; and

performing the electronic braking and then the stopping of the motor shaft at the predetermined rotational position when the controller detects that the main switch is in the open state.

9 . The method of claim 8 , further comprising:

detecting that a spindle switch is in a closed state or an open state using the controller;

operating the electric motor to rotate the accessory when the controller detects that the main switch is in the closed state and the spindle switch is in the open state; and

performing the electronic braking and then the stopping of the motor shaft at the predetermined rotational position when the controller detects that the main switch is in the closed state and the spindle switch is in the closed state.

10 . A power tool, comprising:

a brushless electric motor including (i) a stator, (ii) a motor shaft having a rotor mounted on the motor shaft, and (iii) a plurality of position sensors configured to output a plurality of position states corresponding to a rotational position of the rotor relative to the stator;

a spindle unit mounted on the motor shaft in a known rotational position relative to at least one pole of a plurality of poles of the rotor;

a spindle lock movable to (i) a first position at which the spindle lock engages the spindle unit to prevent rotation of the motor shaft relative to the stator, and (ii) a second position at which the spindle lock is disengaged from the spindle unit and the motor shaft is configured for rotation relative to the stator; and

a controller configured to control rotation of the motor shaft, the controller configured to:

electronically brake the motor shaft to slow rotation of the motor shaft, and

stop the motor shaft in a predetermined rotational position relative to the stator based on a detected position state,

wherein at the predetermined rotational position the spindle lock is movable from the second position to the first position without additional rotation of the motor shaft.

11 . The power tool according to claim 10 , wherein the controller is configured to electronically brake the motor shaft to a standstill during the electronic braking of the motor shaft.

12 . The power tool according to claim 11 , wherein:

the predetermined rotational position is included in a plurality of predetermined rotational positions,

the rotational position of the motor shaft at the standstill results in the detected position state, and

the controller is further configured to:

determine the predetermined rotational position of the plurality of predetermined rotational positions based on the detected position state, and

rotate the motor shaft to move the motor shaft to the determined predetermined rotational position.

13 . The power tool according to claim 10 , wherein the controller is further configured to:

electronically brake the motor shaft to a predetermined speed during the electronic braking of the motor shaft,

calculate a ramp down procedure that causes the motor shaft to slow from the predetermined speed to a standstill, with the motor shaft being in the predetermined rotational position at the standstill, and

implement the ramp down procedure so that the motor shaft slows from the predetermined speed and stops directly at the predetermined rotational position.

14 . The power tool according to claim 13 , wherein:

during rotation of the motor shaft, the motor shaft advances through the plurality of position states in a sequential order, and

the predetermined rotational position is determined based on an idle phase of a plurality of stator phase connections during the detected position state.

15 . The power tool according to claim 14 , wherein:

a polarity of the idle phase that moves the motor shaft to the predetermined rotational position is a polarity of the idle phase during an immediate previous position state from the detected position state according to the sequential order of the position states.

16 . The power tool according to claim 10 , wherein:

the plurality of position sensors include a plurality of Hall sensors, and

the plurality of position states includes a plurality of Hall states.

17 . The power tool according to claim 10 , further comprising:

a main switch operably connected to the electric motor and the controller, the main switch configurable in a closed state and an open state,

wherein the controller is further configured to:

detect that the main switch is in the closed state or the open state,

operate the electric motor to rotate an accessory when the main switch is in the closed state, the accessory operably connected to the motor shaft of the electric motor, and

perform the electronic braking and then the stopping of the motor shaft at the predetermined rotational position when the main switch is in the open state.

18 . The power tool according to claim 17 , further comprising:

a spindle switch operably connected to the spindle lock and the controller, the spindle switch configurable in a closed state and an open state,

wherein the controller is further configured to:

detect that the spindle switch is in the closed state or the open state,

operate the electric motor to rotate the accessory when the main switch is in the closed state and the spindle switch is in the open state, and

perform the electronic braking and then the stopping of the motor shaft at the predetermined rotational position when the main switch is in the closed state and the spindle switch is in the closed state.