Sensored field oriented control in a power tool

Patent metadata

Field	Value
Publication number	US-2025132707-A1
Application number	US-202418917935-A
Country	US
Kind code	A1
Filing date	Oct 16, 2024
Priority date	Oct 20, 2023
Publication date	Apr 24, 2025
Grant date	—

Abstract

A power tool including a housing, a brushless motor, one or more position sensors, a power switching circuit, and an electronic controller. The one or more position sensors are configured to generate output signals corresponding to a rotational position of the brushless motor. The power switching circuit is configured to provide a supply of power from a power source to the brushless motor. The electronic controller is configured to implement field-oriented control (“FOC”) of the brushless motor. The electronic controller configured to receive the output signals from the one or more position sensors, determine a parameter of the brushless motor based on the output signals, determine drive parameters for the brushless motor based on the parameter of the brushless motor using FOC, generate drive commands based on the drive parameters, and drive the brushless motor based on the drive commands.

First claim

What is claimed is:

1 . A power tool comprising:
a housing; a brushless motor disposed in the housing, the brushless motor including a rotor and a stator, the rotor is coupled to a motor shaft arranged to rotate about a longitudinal axis, the longitudinal axis extending through the motor shaft, the motor shaft arranged to produce a rotational output to a drive mechanism; one or more position sensors disposed adjacent to the brushless motor, the one or more position sensors configured to generate output signals corresponding to a rotational position of the brushless motor; a power switching circuit configured to provide a supply of power from a battery pack to the brushless motor; and an electronic controller connected to the one or more position sensors and the power switching circuit, the electronic controller configured to implement field-oriented control (“FOC”) of the brushless motor, the electronic controller configured to: receive the output signals from the one or more position sensors, determine a parameter of the brushless motor based on the output signals from the one or more position sensors,
determine drive parameters for the brushless motor based on the parameter of the brushless motor using FOC,
generate drive commands based on the drive parameters, and
drive the brushless motor based on the drive commands.

2 . The power tool of claim 1 , wherein the parameter of the brushless motor includes at least one of a rotational position, a speed, or an acceleration of the brushless motor.

3 . The power tool of claim 1 , wherein the drive parameter of the brushless motor is a plurality of duty cycles for each phase of the motor.

4 . The power tool of claim 1 , wherein the electronic controller is further configured to:
generate, with a speed regulator and the output signals from the one or more position sensors, a current command.

5 . The power tool of claim 1 , wherein the electronic controller is further configured to:
determine a rotor speed based on the output signals from the one or more position sensors; and generate a current command using a speed regulator, the current command based on the rotor speed and a target speed.

6 . The power tool of claim 5 , wherein the electronic controller is further configured to:
determine, based on a mode command received through a mode selecting switch, to operate in a torque mode; receive a torque input command based on a user input; and generate a current command based on the torque input command.

7 . The power tool of claim 1 , further comprising:
a battery pack current sensor electrically connected to the battery pack; a stator current sensor electrically connected to the stator of the motor; and a mixed-signal programmable logic device in communication with the battery pack current sensor and the stator current sensor, the mixed-signal programmable logic device configured to detect a fault condition.

8 . The power tool of claim 7 , wherein the fault condition is a short circuit condition.

9 . The power tool of claim 1 , wherein the electronic controller is further configured to:
determine a first feed forward term and a second feed forward term based on a signal from a stator current sensor and the output signals from the one or more position sensors, wherein the first feed forward term corresponds to a motor speed and the second feed forward term corresponds to a motor torque.

10 . A method of controlling a brushless motor of a handheld power tool, the method comprising:
receiving output signals from one or more position sensors; determining a parameter of the brushless motor based on the output signals from the one or more position sensors; determining drive parameters for the brushless motor based on the parameter of the brushless motor using field oriented control (“FOC”); generating drive commands based on the drive parameters; and driving the brushless motor based on the drive commands.

11 . The method of claim 10 , further comprising:
generating, with a speed regulator and the output signals from the one or more position sensors, a current command.

12 . The method of claim 10 , further comprising:
determining a rotor speed based on the output signals from the one or more position sensors; and generating a current command using a speed regulator, the current command based on the rotor speed and a target speed.

13 . The method of claim 12 , further comprising:
determining, based on a mode command received through a mode selecting switch, to operate in a torque mode; receiving a torque input command based on a user input; and generating a current command based on the torque input command.

14 . The method of claim 10 , further comprising:
determining a first feed forward term and a second feed forward term based on a signal from a stator current sensor and the output signals from the one or more position sensors, wherein the first feed forward term corresponds to a motor speed and the second feed forward term corresponds to a motor torque.

15 . A power tool comprising:
a housing; a brushless motor disposed in the housing, the brushless motor including a rotor and a stator, the rotor is coupled to a motor shaft arranged to rotate about a longitudinal axis, the longitudinal axis extending through the motor shaft, the motor shaft arranged to produce a rotational output to a drive mechanism; one or more position sensors disposed adjacent to the brushless motor, the one or more position sensors configured to generate output signals corresponding to a rotational position of the brushless motor; a stator current sensor electrically connected to the stator of the motor and configured to determine the current within at least one phase of the motor; a power switching circuit configured to provide a supply of power from a battery pack to the brushless motor; and an electronic controller configured to implement field-oriented control (“FOC”) of the brushless motor, the electronic controller configured to: receive the output signals from the one or more position sensors, determine a speed of the brushless motor based on the output signals from the one or more position sensors,
determine a first feed forward term and a second feed forward term based on a signal from the stator current sensor and the speed of the brushless motor, the first feed forward term corresponding to a motor speed and the second feed forward term corresponding to a motor torque,
generate drive commands based on the first feed forward term and the second feed forward term, and
drive the brushless motor based on the drive commands.

16 . The power tool of claim 15 , further comprising:
a battery pack current sensor electrically connected to the battery pack; and a mixed-signal programmable logic device in communication with the battery pack current sensor and the stator current sensor, the mixed-signal programmable logic device configured to detect a fault condition.

17 . The power tool of claim 16 , wherein the fault condition is a short circuit condition.

18 . The power tool of claim 15 , wherein the electronic controller is further configured to:
generate, with a speed regulator and the output signals from the one or more position sensors, a current command.

19 . The power tool of claim 15 , wherein the electronic controller is further configured to:
determine a rotor speed based on the output signals from the one or more position sensors; and generate a current command using a speed regulator, the curr

Assignees

• Milwaukee Electric Tool Corp

Inventors

• Jevremovic Vladan
• Ganesan Nandini
• Gaspar Austin E N
• Gupta Shuvam
• Hu Yangpingqing

Classifications

• H02P21/00

  Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation · CPC title

• H02K29/06

  with position sensing devices (H02K29/03 takes precedence) · CPC title

• H02K11/33

  Drive circuits, e.g. power electronics (H02K11/38 takes precedence) · 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

• B25F5/008

  Cooling means · CPC title