Hand-guided or stationary power tool having a drive unit
A hand-guided or stationary power tool has a drive unit having a motor that includes a rotor having a permanent magnet and a stator and has a motor control designed to trigger the motor in a first rotational speed range according to a voltage-controlled mode and to trigger the motor in a second rotational speed range following the first rotational speed range in the direction of a higher rotational speed according to a field-weakening operation.
1. A power tool, the power tool being one of hand-guided and stationary, the power tool comprising:
a drive unit including:
a motor including a rotor having a permanent magnet, and a stator; and
a motor control for triggering the motor in a first rotational speed range according to a voltage-controlled mode and for triggering the motor in a second rotational speed range following the first rotational speed range in a direction of a higher rotational speed according to a field-weakening operation;
wherein the motor control has a phase shifter to adjust a phase between a stator magnetomotive force and a rotor magnetomotive force in field-weakening operation.
2. The power tool according to claim 1 , further comprising an operating element for preselecting a rotational speed at no load.
3. The power tool according to claim 1 , wherein the motor control applies a voltage to the motor in the voltage-controlled mode to preselect a rotational speed of the motor, the first rotational speed range being determined by a range between 0 and a medium rotational speed, which is achieved by applying a maximum voltage in the voltage-controlled mode.
4. The power tool according to claim 1 , wherein the phase shifter adjusts the phase between the stator magnetomotive force and the rotor magnetomotive force to be greater than 90° in field-weakening operation.
5. The power tool according to claim 1 , further comprising a power supply in the form of a rechargeable battery.
6. The power tool according to claim 5 , wherein the power tool is a cordless screwdriver.
7. The power tool according to claim 1 , wherein the motor further includes a shaft coupled directly to a machining tool.
8. A method for operating a drive unit for one of a hand-guided and stationary power tool, the drive unit including a motor which includes a rotor having a permanent magnet, and a stator, the method comprising:
triggering the motor according to a voltage-controlled mode in a first rotational speed range and according to a field-weakening operation in a second rotational speed range that follows the first rotational speed range in a direction of a higher rotational speed; and
adjusting a phase, via a phase shifter, between a stator magnetomotive force and a rotor magnetomotive force in field-weakening operation.
9. The method according to claim 8 , further comprising preselecting a rotational speed at no load.
10. The method according to claim 8 , further comprising:
applying a voltage to the motor in the voltage-controlled mode to preselect a rotational speed of the motor, the first rotational speed range being determined by a range between 0 and a medium rotational speed, which is achieved by applying a maximum voltage in the voltage-controlled mode.
11. The method according to claim 8 , wherein the phase shifter adjusts the phase between the stator magnetomotive force and the rotor magnetomotive force to be greater than 90° in field-weakening operation.
12. The method according to claim 8 , wherein the power tool includes a power supply in the form of a rechargeable battery.
13. The method according to claim 12 , wherein the power tool is a cordless screwdriver.
14. The method according to claim 8 , wherein the motor further includes a shaft coupled directly to a machining tool.