Washing machine and control method thereof

Abstract

A washing machine includes a drum accommodating laundry, a motor configured to rotate the drum, a speed sensor configured to detect a rotational speed of the drum, and a processor. The processor configured to: determine a mass of the laundry corresponding to each of a first acceleration section and a second acceleration section based on the rotational speed detected by the speed sensor, and control the motor such that an absolute value of the rotational speed at a start time of the first acceleration section is substantially the same as an absolute value of a rotational speed at a start time of the second acceleration section. A rotational direction of the drum corresponding to the rotational speed at the start time of the first acceleration section is opposite to a rotational direction of the drum corresponding to the rotational speed at the start time of the second acceleration section.

What is claimed is: 
     
         1 . A washing machine comprising
 a drum in which laundry is accommodated;   a motor configured to rotate the drum;   a speed sensor configured to detect a rotational speed of the drum; and   a processor configured to:
 identify a mass of the laundry corresponding to each of a first acceleration section and a second acceleration section based on the rotational speed detected by the speed sensor, and 
 control the motor such that an absolute value of the rotational speed at a start time of the first acceleration section is substantially the same as an absolute value of the rotational speed at a start time of the second acceleration section, 
 wherein a rotational direction of the drum corresponding to the rotational speed at the start time of the first acceleration section is opposite to a rotational direction of the drum corresponding to the rotational speed at the start time of the second acceleration section. 
   
     
     
         2 . The washing machine of  claim 1 , wherein:
 before the start time of the first acceleration section, the processor is further configured to control the motor to drive at substantially the same rotational speed in a first constant speed section, and   before the start time of the second acceleration section, the processor is further configured to control the motor to drive at substantially the same rotational speed in the first constant speed section.   
     
     
         3 . The washing machine of  claim 1 , wherein a position of the laundry at the start time of the first acceleration section is different by 180 degrees with respect to a center of the drum from a position of the laundry at the start time of the second acceleration section. 
     
     
         4 . The washing machine of  claim 3 , wherein the processor is further configured to control the drum to rotate an integer number of times in the first and second acceleration sections. 
     
     
         5 . The washing machine of  claim 4 , wherein the processor is further configured to identify the mass of the laundry based on the mass detected in each of the first acceleration section and the second acceleration section. 
     
     
         6 . The washing machine of  claim 5 , wherein the processor is further configured to identify the mass of the laundry based on an average of the mass detected in the first acceleration section and the second acceleration section. 
     
     
         7 . The washing machine of  claim 1 , wherein the processor is further configured to identify the start time of the first acceleration section and the start time of the second acceleration section based on a rotation angle of the drum. 
     
     
         8 . The washing machine of  claim 7 , wherein, based on a half of a rotation of the motor, the processor is further configured to identify a difference between the rotation angle at the start time of the first acceleration section and the rotation angle at the start time of the second acceleration section. 
     
     
         9 . The washing machine of  claim 1 , wherein the processor is further configured to identify the start time of the first acceleration section and the start time of the second acceleration section based on at least one of the rotational speed, a current flowing in the motor, or a voltage applied to the motor. 
     
     
         10 . The washing machine of  claim 9 , wherein a phase difference of one of the rotational speed of the motor, the current flowing in the motor, or the voltage applied to the motor corresponding to the start time of the first acceleration section and the start time of the second acceleration section is 180 degrees. 
     
     
         11 . The washing machine of  claim 1 , wherein, in a continuous driving of the drum, the processor is further configured to:
 perform the first acceleration section and the second acceleration section; and   control the rotational speed of the motor to be substantially 30 revolutions per minute (rpm) or more in the first acceleration section and the second acceleration section.   
     
     
         12 . The washing machine of  claim 1 , wherein the processor is further configured to control the rotational speed of the motor to be substantially 300 rpm or less at an end time of the first and second acceleration sections. 
     
     
         13 . The washing machine of  claim 1 , wherein an angle of a rotation axis of the drum with respect to a horizontal direction is from 0 (zero) degree to 45 degrees. 
     
     
         14 . A control method of a washing machine comprising:
 detecting a rotational speed of a drum in which laundry is accommodated;   identifying a mass of the laundry corresponding to each of a first acceleration section and a second acceleration section based on the detected rotational speed; and   rotating the drum such that an absolute value of the rotational speed at a start time of the first acceleration section is substantially the same as an absolute value of the rotational speed at a start time of the second acceleration section,   wherein a rotational direction of the drum corresponding to the rotational speed at the start time of the first acceleration section is opposite to a rotational direction of the drum corresponding to the rotational speed at the start time of the second acceleration section.   
     
     
         15 . The control method of  claim 14 , wherein the rotating further comprises:
 rotating the drum at substantially the same rotational speed in a first constant speed section before the start time of the first acceleration section; and   rotating the drum at substantially the same rotational speed in the first constant speed section before the start time of the second acceleration section.   
     
     
         16 . The control method of  claim 14 , wherein the rotating further comprises rotating the drum such that a position of the laundry at the start time of the first acceleration section is different by 180 degrees with respect to a center of the drum from a position of the laundry at the start time of the second acceleration section. 
     
     
         17 . The control method of  claim 16 , wherein the rotating further comprises rotating the drum an integer number of times in the first and second acceleration sections. 
     
     
         18 . The control method of  claim 17 , wherein the identifying of the mass further comprises identifying the mass of the laundry based on the mass detected in each of the first acceleration section and the second acceleration section. 
     
     
         19 . The control method of  claim 18 , wherein the identifying of the mass further comprises identifying the mass of the laundry based on an average of the mass detected in the first acceleration section and the second acceleration section. 
     
     
         20 . The control method of  claim 14 , wherein the rotating further comprises identifying the start time of the first acceleration section and the start time of the second acceleration section based on a rotation angle of the drum.