公开(公告)号：US10461674B2

公开(公告)日：2019-10-29

申请号：US15670242

申请日：2017-08-07

Applicant: MAKITA CORPORATION

Inventor： Michisada Yabuguchi ,  Kouichi Takeda ,  Masumi Nishimura ,  Hiroshi Nojiri

IPC: H02P6/28 ,  H02P6/24 ,  H02P6/06 ,  H02P29/032 ,  B25F5/00

Abstract: An electric working machine according to one aspect of the present disclosure comprises a motor, a speed setting unit, a load detection unit, a determination unit, and a parameter setting unit. The determination unit calculates an estimated value of a heat generation amount of the motor, and determines that the motor is in an overload operation state when the estimated value reaches a predetermined threshold. The parameter setting unit sets a parameter to be used for calculating the estimated value and/or the threshold in accordance with a rotation speed set by the speed setting unit.

公开(公告)号：US10833612B2

公开(公告)日：2020-11-10

申请号：US16353157

申请日：2019-03-14

Applicant: MAKITA CORPORATION

Inventor： Masumi Nishimura ,  Yoshiteru Ito

IPC: A01D34/90 ,  H02P6/15 ,  H02P6/28 ,  H02P6/18 ,  A01G3/08

Abstract: An electric working machine includes an inverter and a controller. The controller switches a current conduction pattern via the inverter and performs a PWM control of a conduction current to a brushless motor. The controller includes switching patterns as the current conduction pattern switched for every commutation timing. The switching patterns include different on and off states for different switching elements. The controller sequentially switches a switching pattern synchronously with a period of the PWM control, detects a rotational position of a brushless motor from a magnitude relation between inductances of the brushless motor produced by switching the switching pattern, and sets the commutation timing.