Power tool, arrangement, method, computer program product and computer-readable medium

Patent metadata

Field	Value
Publication number	US-12496698-B2
Application number	US-202418415065-A
Country	US
Kind code	B2
Filing date	Jan 17, 2024
Priority date	Jan 20, 2023
Publication date	Dec 16, 2025
Grant date	Dec 16, 2025

Abstract

A power tool, in particular a hand-held power tool, for example a polishing device, a grinding device, a sawing device and/or a router, with a tool, an electric motor for driving the tool and a control unit for controlling the electric motor, in which the power tool is designed for connection to an AC supply voltage and includes a rectifier arrangement with an intermediate circuit for providing an intermediate circuit voltage on the basis of the AC supply voltage. The intermediate circuit voltage has a plurality of successive voltage half-waves, and in which the control unit is configured to calculate, for each voltage half-wave, a respective torque half-wave for controlling the electric motor, the control unit being configured to sample each voltage half-wave in order to obtain a plurality of voltage half-wave values, and to convert each voltage half-wave value into a respective torque half-wave value in order to calculate the respective torque half-wave.

First claim

The invention claimed is:

1 . A power tool having a tool, an electric motor for driving the tool and a control unit for controlling the electric motor, wherein the power tool is designed for connection to an AC supply voltage and comprises a rectifier arrangement with an intermediate circuit for providing an intermediate circuit voltage on the basis of the AC supply voltage, wherein the intermediate circuit voltage has a plurality of successive voltage half-waves, and wherein the control unit is configured to calculate, for each voltage half-wave, a respective torque half-wave for controlling the electric motor, the control unit being configured to sample each voltage half-wave in order to obtain a plurality of voltage half-wave values, and to convert each voltage half-wave value into a respective torque half-wave value in order to calculate the respective torque half-wave.

2 . The power tool according to claim 1 , wherein the control unit is configured to calculate the respective torque half-wave taking into account a present rotational speed of the electric motor.

3 . The power tool according to claim 2 , wherein the control unit is configured to convert each voltage half-wave value into a respective torque half-wave value, taking into account the present rotational speed.

4 . The power tool according to claim 2 , wherein the control unit is configured to calculate the respective torque half-wave with a narrower curve shape for a higher rotational speed than for a lower rotational speed.

5 . The power tool according to claim 2 , wherein the control unit is configured to calculate the respective torque half-wave with a higher maximum for a higher rotational speed than for a lower rotational speed.

6 . The power tool according to claim 1 , wherein the control unit is configured to calculate a lower limit and/or an upper limit and to calculate the respective torque half-wave on the basis of the lower limit and/or the upper limit.

7 . The power tool according to claim 6 , wherein the control unit is configured to calculate the lower limit and/or the upper limit as a function of a present rotational speed of the electric motor, so that the lower limit and/or the upper limit increases as the rotational speed increases.

8 . The power tool according to claim 6 , wherein the control unit is configured to compare the intermediate circuit voltage with the lower limit and, in response to the intermediate circuit voltage being less than or equal to the lower limit, to set the respective torque half-wave value to zero.

9 . The power tool according to claim 6 , wherein the control unit is configured to compare the intermediate circuit voltage with the upper limit and, in response to the intermediate circuit voltage being greater than or equal to the upper limit, to limit the respective torque half-wave value to a torque half-wave maximum value.

10 . The power tool according to claim 6 , wherein the control unit is configured to calculate a respective present lower limit value and a respective present upper limit value for the calculation of each torque half-wave value.

11 . The power tool according to claim 10 , wherein the control unit is configured to calculate the respective present lower limit value and/or the respective present upper limit value as a function of a present rotational speed of the electric motor.

12 . The power tool according to claim 11 , wherein the dependency between the respective present lower limit value and/or the respective present upper limit value and the present rotational speed is such that a higher lower limit value and/or a higher upper limit value is calculated for a higher present rotational speed.

13 . The power tool according to claim 10 , wherein the control unit is configured to calculate the respective torque half-wave value as a product of a torque setpoint with a respective curve profile value.

14 . The power tool according to claim 13 , wherein the control unit is configured to calculate the respective curve profile value as a quotient of a difference between the respective voltage half-wave value and the lower limit and a difference between the upper limit and the lower limit.

15 . An arrangement comprising a generator and a power tool according to claim 1 , wherein the generator is designed to provide the alternating supply voltage.

16 . The arrangement according 15 , wherein the generator is a combustion generator.

17 . An arrangement comprising a transformer and a power tool according to claim 1 , wherein the transformer is designed to provide the supply AC voltage.

18 . The power tool according to claim 1 , wherein the power tool is a hand-held power tool.

19 . The power tool according to claim 1 , wherein the power tool is a polishing device, grinding device, sawing device and/or a router.

20 . A method for operating a power tool having a tool, an electric motor for driving the tool and a control unit for controlling the electric motor, comprising the steps of:
providing, by means of a rectifier arrangement with an intermediate circuit, an intermediate circuit voltage on the basis of a supply AC voltage to which the power tool is connected, the intermediate circuit voltage having a plurality of successive voltage half-waves, for each voltage half-wave, calculating a respective torque half-wave for driving the electric motor, wherein each voltage half-wave is sampled to obtain a plurality of voltage half-wave values, and each voltage half-wave value is converted into a respective torque half-wave value to calculate the respective torque half-wave.

21 . A computer-readable medium on which a computer program product is stored, the computer program product comprising instructions, which when executed by a processor, cause a power tool to perform the method steps of the method according to claim 20 .

Assignees

• Festool Gmbh

Inventors

• Hofmann Tobias
• Thüringer Michael
• Calta Michal

Classifications

• H02P7/28

  using semiconductor devices · CPC title

• B25F5/00 Primary

  Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for · CPC title

• H02P7/24 Primary

  using discharge tubes or semiconductor devices · CPC title