Patent ID: 11866867
Assignee: LG ELECTRONICS INC.
Field: Other consumer goods (Other fields)
Classification: CPC D | IPC D

Claim 14:
15. A laundry treatment machine comprising:
a washing tub;
a driver to drive the washing tub;
a drain pump;
a motor to drive the dram pump;
a converter to output a direct current (DC) power;
an inverter to convert the DC, power at a DC terminal into an alternating current (AC) power based on a switching operation and to output the converted AC power to the motor;
an output current detector to detect an output current flowing in the motor; and
a controller configured to increase or decrease stepwise a speed of the motor during dewatering,
wherein the controller is configured to drive the speed of the motor at a first speed, to increase the speed of the motor from the first speed to a second speed, and then to decrease stepwise from the second speed to a third speed,
wherein a width of a speed ripple of the motor sequentially decreases during decreasing stepwise from the second speed to the third speed,
wherein the width of the speed ripple corresponds to a difference between a maximum value of the speed ripple of the motor and a minimum value of the speed ripple of the motor,
wherein the controller calculates, during drainage before the dewatering, a lift based on the speed of the motor, and is configured to increase the speed of the motor, during the dewatering, as a level of the calculated lift increases, and
wherein the lift is a difference between a height of the drain pump and a height of a drain pipe connected to the drain pump.