US 12,289,072 B2
Motor braking using selectively connectable resistance
Timothy R. Obermann, Waukesha, WI (US); and Alexander Huber, Menomonee Falls, WI (US)
Assigned to Milwaukee Electric Tool Corporation, Brookfield, WI (US)
Filed by MILWAUKEE ELECTRIC TOOL CORPORATION, Brookfield, WI (US)
Filed on Feb. 13, 2024, as Appl. No. 18/440,369.
Application 18/440,369 is a continuation of application No. 17/549,048, filed on Dec. 13, 2021, granted, now 11,909,345.
Application 17/549,048 is a continuation of application No. 17/051,238, granted, now 11,201,572, issued on Dec. 14, 2021, previously published as PCT/US2020/036241, filed on Jun. 5, 2020.
Claims priority of provisional application 62/859,274, filed on Jun. 10, 2019.
Prior Publication US 2024/0186919 A1, Jun. 6, 2024
This patent is subject to a terminal disclaimer.
Int. Cl. H02P 3/12 (2006.01); B25F 5/00 (2006.01); H02P 3/14 (2006.01); H02P 27/08 (2006.01)
CPC H02P 3/12 (2013.01) [B25F 5/00 (2013.01); H02P 3/14 (2013.01); H02P 27/08 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A power tool comprising:
a battery pack;
a three-phase motor including three motor terminals;
a power switching network coupled between the battery pack and the motor, wherein the power switching network includes a first power switching element and a second power switching element;
a user input configured to be actuated to drive the motor;
a braking circuit including a resistor and a braking switching element connected to each motor terminal, wherein each braking switching element is configured to selectively connect a respective resistor to a respective motor terminal, and wherein the braking circuit is configured to selectively couple each motor terminal to one selected from the group consisting of ground and a terminal of the battery pack; and
a motor controller connected to the power switching network and the braking circuit and configured to:
control the power switching network to drive the motor in response to actuation of the user input,
determine a variable tool characteristic,
determine that the user input is de-actuated,
determine whether the variable tool characteristic satisfies a tool characteristic threshold in response to the user input being de-actuated,
in response to the variable tool characteristic satisfying the tool characteristic threshold:
control the power switching network to brake the motor,
enable the first power switching element to induce a freewheeling current to flow through the first power switching element, wherein the freewheeling current flows through a diode of the second power switching element, and
disable the first power switching element to provide the freewheeling current to the battery pack, and
control the braking circuit to brake the motor when the variable tool characteristic does not satisfy the tool characteristic threshold.