Washing machine and method for controlling the same

Abstract

A washing machine and a method for controlling the same are disclosed. The washing machine includes a rotating washing tub in which laundry is placed and a motor to rotate the washing tub. The method for controlling the same includes performing primary rotation of the motor, detecting a primary laundry amount on the basis of the primary rotation of the motor, supplying, if the detected laundry amount is equal to or greater than a predetermined laundry amount, a predetermined amount of water or water corresponding to a predetermined water level to the washing tub in such a manner that the laundry becomes wet, performing secondary rotation of the motor, and detecting a secondary laundry amount on the basis of the secondary rotation of the motor. Thus, the washing machine correctly detects the amount of laundry.

1 . A method for controlling a washing machine which includes a rotating washing tub in which laundry is placed and a motor to rotate the washing tub, the method comprising:
 performing primary rotation of the motor;   detecting a primary laundry amount on the basis of the primary rotation of the motor;   supplying, if the detected laundry amount is equal to or greater than a predetermined laundry amount, a predetermined amount of water or water corresponding to a predetermined water level to the washing tub in such a manner that the laundry becomes wet;   performing secondary rotation of the motor; and   detecting a secondary laundry amount on the basis of the secondary rotation of the motor.   
     
     
         2 . The method according to  claim 1 , further comprising:
 after performing the primary rotation of the motor, turning a current flowing in the motor off; and   after performing the secondary rotation of the motor, turning a current flowing in the motor off.   
     
     
         3 . The method according to  claim 1 , wherein the amount of water supplied to the washing tub is higher than a water level of an empty washing tub and is lower than a height of the laundry contained in the washing tub. 
     
     
         4 . The method according to  claim 1 , further comprising:
 after supplying water to the washing tub, performing forward or reverse rotation of the washing tub, or performing repeated forward/reverse rotation   
     
     
         5 . The method according to  claim 2 , wherein the laundry amount detecting operation is performed in a specific section in which rotation speed of the motor is linearly reduced from among the current-OFF time. 
     
     
         6 . The method according to  claim 1 , further comprising:
 after detecting the laundry amount, braking the motor.   
     
     
         7 . The method according to  claim 2 , wherein the primary and secondary laundry amount detection includes:
 detecting the laundry amount on the basis of acceleration speed or time of the motor in a plurality of sections from among the current-OFF time.   
     
     
         8 . The method according to  claim 1 , wherein the primary laundry amount detection and the secondary laundry amount detection are performed in different deceleration speed sections of the motor. 
     
     
         9 . A method for controlling a washing machine which includes a rotating washing tub in which laundry is placed and a motor to rotate the washing tub, the method comprising:
 primarily rotating the motor at a predetermined speed by applying a current to the motor;   turning the current flowing in the motor off;   detecting a primary laundry amount on the basis of a deceleration speed or time of the motor in at least some sections of the current-OFF time;   supplying, if the detected primary laundry amount is equal to or greater than a predetermined laundry amount, a predetermined amount of water or water corresponding to a predetermined water level to the washing tub;   secondarily rotating the motor at a predetermined speed by applying a current to the motor;   turning the current flowing in the motor off; and   detecting a secondary laundry amount on the basis of a deceleration speed or time of the motor in at least some sections of the current-OFF time.   
     
     
         10 . A method for controlling a washing machine which includes a rotating washing tub in which laundry is placed and a motor to rotate the washing tub, the method comprising:
 rotating the motor;   detecting a primary laundry amount or laundry quality on the basis of the rotation of the motor;   supplying a predetermined amount of water or water corresponding to a predetermined water level to the washing tub in such a manner that the laundry becomes wet;   after performing the water supply, rotating the motor;   detecting a secondary laundry amount or laundry quality on the basis of the rotation of the motor; and   displaying a calculated operation time on the basis of the detected secondary laundry amount or laundry quality.   
     
     
         11 . The method according to  claim 10 , wherein the displaying of the calculated operation time is performed when an eco mode is selected. 
     
     
         12 . The method according to  claim 10 , further comprising:
 before supplying water to the washing tub, displaying a calculated operation time on the basis of the detected primary laundry amount or laundry quality.   
     
     
         13 . The method according to  claim 10 , wherein the secondary laundry amount detection and the operation time displaying are performed in a washing cycle. 
     
     
         14 . The method according to  claim 10 , wherein the primary and secondary laundry amount or laundry quality detection detects the laundry amount or laundry quality on the basis of current ripples flowing in the motor during the motor rotation. 
     
     
         15 . The method according to  claim 10 , further comprising:
 turning the current flowing in the rotating motor off, and   wherein the primary and secondary laundry amount or laundry quality detection detects the laundry amount or laundry quality on the basis of a deceleration speed or time of the motor in at least some sections of the current-OFF time.   
     
     
         16 . The method according to  claim 10 , further comprising:
 rotating the motor under a no load state or specific load state in a calibration mode;   storing at least one of a reference laundry-amount value, a reference eccentricity value, a reference acceleration slope value, and a reference deceleration slope value on the basis of a current flowing in the motor and a motor speed;   rotating the motor in an operation mode; and   determining at least one of a laundry amount, eccentricity, acceleration slope, and deceleration slope on the basis of the stored reference values and a current flowing in the motor and a motor speed.   
     
     
         17 . A washing machine comprising:
 a washing tub in which laundry is placed, configured to be rotated;   a motor to rotate the washing tub; and   a control unit to perform primary rotation of the motor, to detect a primary laundry amount on the basis of the primary rotation of the motor, to supply, if the detected laundry amount is equal to or greater than a predetermined laundry amount, a predetermined amount of water or water corresponding to a predetermined water level to the washing tub in such a manner that the laundry becomes wet, to perform secondary rotation of the motor, and to detect a secondary laundry amount on the basis of the secondary rotation of the motor.   
     
     
         18 . The washing machine according to  claim 17 , further comprising:
 a water-level sensing unit to detect a water level of the washing tub.   
     
     
         19 . The washing machine according to  claim 17 , further comprising:
 a water amount sensing unit to detect an amount of water supplied to the washing tub.   
     
     
         20 . The washing machine according to  claim 17 , further comprising.:
 an inverter to convert predetermined DC power into AC power having a predetermined frequency, and to output the AC power to the motor;   an output current detection unit to detect an output current flowing in the motor; and   a position sensing unit to detect a rotor position of the motor,   wherein
 the inverter includes three pairs of switching elements, each pair including an upper-arm switching element and a lower-arm switching element, and 
 the control unit, after the primary or secondary rotation of the motor, turns the three pairs of switching elements contained in the inverter off in such a manner that a current flowing in the motor is turned off. 
   
     
     
         21 . The washing machine according to  claim 17 , further comprising:
 an inverter to convert predetermined DC power to AC power having a predetermined frequency, and to output the AC power to the motor;   an output current detection unit to detect an output current flowing in the motor; and   a position sensing unit to detect a rotor position of the motor,   wherein
 the inverter includes three pairs of switching elements, each pair including an upper-arm switching element and a lower-arm switching element, and 
 the control unit, after detecting the laundry amount, turns only lower-arm or upper-arm switching elements contained in the inverter on. 
   
     
     
         22 . A washing machine comprising:
 a display;   a washing tub in which laundry is placed, configured to be rotated;   a motor to rotate the washing tub; and   a control unit to perform primary rotation of the motor, to detect a primary laundry amount on the basis of the primary rotation of the motor, to supply a predetermined amount of water or water corresponding to a predetermined water level to the washing tub in such a manner that the laundry becomes wet, to perform secondary rotation of the motor, to detect a secondary laundry amount on the basis of the secondary rotation of the motor, and to display a calculated operation time on the display on the basis of the detected secondary laundry amount or laundry quality.   
     
     
         23 . The washing machine according to  claim 22 , further comprising:
 an eco key to establish and entering an eco mode,   wherein the control unit controls the display to display the calculated operation time on the display according to the established eco mode.   
     
     
         24 . The washing machine according to  claim 22 , further comprising:
 a storage unit, in a calibration mode, to store at least one of a reference laundry-amount value, a reference eccentricity value, a reference acceleration slope value, and a reference deceleration slope value on the basis of a current flowing in the motor and a motor speed,   wherein the control unit rotates the motor under a no load state or specific load state in a calibration mode, rotates the motor in an operation mode, and determines at least one of a laundry amount, eccentricity, acceleration slope, and deceleration slope on the basis of the stored reference values and a current flowing in the motor and a motor speed.   
     
     
         25 . The washing machine according to  claim 24 , further comprising:
 a calibration key to enter the calibration mode,   wherein the control unit performs the calibration mode in case of an initial operation, in case of a lapse of a predetermined time after installation of the washing machine, or in case of execution of the calibration key.