US 12,334,858 B2
Small electrical appliance with improved motor speed control
Ferdinand Hermann, Koenigstein (DE); Torsten Klemm, Eschborn (DE); and Timo Schmitt, Hintertiefenbach (DE)
Assigned to Braun GMBH, Kronberg (DE)
Filed by Braun GmbH, Kronberg (DE)
Filed on Mar. 9, 2023, as Appl. No. 18/119,386.
Claims priority of application No. 22161473 (EP), filed on Mar. 10, 2022.
Prior Publication US 2023/0291337 A1, Sep. 14, 2023
Int. Cl. H02P 7/29 (2016.01); A61C 17/22 (2006.01); A61C 17/34 (2006.01); B26B 19/28 (2006.01); H02K 7/14 (2006.01)
CPC H02P 7/29 (2013.01) [A61C 17/221 (2013.01); A61C 17/34 (2013.01); B26B 19/28 (2013.01); H02K 7/145 (2013.01); A61C 2204/002 (2013.01)] 15 Claims
OG exemplary drawing
 
1. Small electrical appliance, wherein the small electrical appliance is a hair removal device or an electric toothbrush, comprising
an electric DC motor;
a detector for acquiring a detector signal indicative of a rotational speed of the electric DC motor; and
a controller for controlling the electric DC motor;
characterized in that the controller is configured to:
determine, based on the detector signal, a first parameter indicative of the rotational speed of the DC motor;
determine, based on the detector signal, a second parameter indicative of the rotational speed of the DC motor, wherein the second parameter is different from the first parameter, and wherein the second parameter is determined based on a frequency domain analysis of the detector signal; and
adjust a supply voltage of the electric DC motor based on the first parameter and the second parameter;
wherein the controller is adapted to perform coarse control for adjusting the supply voltage based on the first parameter and to perform fine control for adjusting the supply voltage based on the second parameter.