Method of controlling motor-driven washing machine and control system for the same

Abstract

A method of controlling a motor-driven washing machine and a control system that controls a motor or any other components of the washing machine are disclosed. The method includes the steps of generating an interruption command for braking a motor in motion during a wash cycle, applying a phase-reversed voltage to a voltage input terminal of the motor in motion, and electrically shorting the input terminal of the motor for a predetermined period of time if a second phase-reversed voltage generated by the motor is higher than or equal to a critical voltage level. Using such method, a motor-clutch mechanism is prevented front generating a noise and from being damaged during a wash cycle.

1 . A method of controlling a motor-driven washing machine, the method comprising the steps of: 
 generating an interruption command for braking a motor in motion during a wash cycle;    applying a first phase-reversed voltage to a voltage input terminal of the motor in motion, the first phase-reversed voltage corresponding to a first current speed of the motor; and    electrically shorting the voltage input terminal of the motor for a predetermined period of time if a second phase-reversed voltage is higher than or equal to a critical voltage level, the second phase-reversed voltage corresponding to a second current speed of the motor.    
   
   
       2 . The method of  claim 1 , wherein the interruption command is generated when a user cuts off a power supply to the washing machine, manually touches a key control panel, or opens a washer door of the washing machine during the wash cycle.  
   
   
       3 . The method of  claim 1 , wherein the critical voltage level is predetermined such that the motor generates a brake noise if the second phase-reversed voltage is higher than or equal to the critical voltage level and is applied to the voltage input terminal of the motor.  
   
   
       4 . The method of  claim 1 , further comprising the step of applying a third phase-reversed voltage to the voltage input terminal of the motor in motion if the second current speed of the motor is lower than the critical voltage value, wherein the third phase-reversed voltage corresponds to a third current speed of the motor in motion.  
   
   
       5 . The method of  claim 1 , further comprising the step of applying a third phase-reversed voltage to the voltage input terminal of the motor in motion if the motor is still in motion after the step of electrically shorting the voltage input terminal, wherein the third phase-reversed voltage corresponds to a third current speed of the motor in motion.  
   
   
       6 . A control system for a washing machine, the system comprising: 
 a motor rotating at least one of a washing tub and an agitator provided in the washing machine in a wash cycle;    a motor brake unit initially applying a first phase-reversed voltage to a voltage input terminal of the motor when an interruption command for braking the motor in motion is generated during the wash cycle, the first phase-reversed voltage corresponding a first current speed of the motor in motion, and    a controller measuring a second current speed of the motor and generating a control signal if a second phase-reversed voltage is higher than or equal to a critical voltage level, the second phase-reversed voltage corresponding to the second current speed of the motor, wherein the motor brake unit electrically shorts the voltage input terminal of the motor upon receiving the control signal from the controller.    
   
   
       7 . The control system of  claim 6 , further comprising: 
 a power supply generating an AC power voltage; and    a transformer converting the AC power voltage into a DC power voltage and supplying the converted DC voltage to the motor brake unit in order to drive the motor.    
   
   
       8 . The control system of  claim 6 , wherein the interruption command is generated when a user cuts off a power supply to the washing machine, manually touches a key control panel, or opens a door of the washing machine during the wash cycle.  
   
   
       9 . The control system of  claim 6 , wherein the critical voltage level is predetermined such that the motor generates a brake noise if the second phase-reversed voltage is higher than or equal to the critical voltage level and is applied to the voltage input terminal of the motor.  
   
   
       10 . The control system of  claim 6 , wherein the motor brake unit further applies a third phase-reversed voltage to the voltage input terminal of the motor if the second current speed is lower than the critical voltage value, the third phase-reversed voltage corresponding to a third current speed of the motor in motion.  
   
   
       11 . A method of controlling a motor-driven washing machine having a load controller, the method comprising the steps of: 
 initiating a wash cycle by operating a plurality of load units including a motor according to a wash option selected by a user;    transmitting a brake control signal to the load controller if an opening of a washer door provided in the washing machine is detected, the load controller executing a load-brake algorithm to brake operations of the plurality of load units in response to the brake control signal;    determining whether the load-brake algorithm is properly executed by the load controller by communicating with the load controller; and    transmitting control signals directly to the plurality of the load units so as to brake the operations of the plurality of the load units if the load-brake algorithm is properly executed by the load controller.    
   
   
       12 . The method of  claim 11 , wherein the plurality of load units comprises at least one of a motor rotating a washing tub or an agitator provided in the washing machine, a water supply unit supplying water to the tub, and a drain unit draining water from the tub.  
   
   
       13 . The method of  claim 11 , wherein the step of determining includes the steps of: 
 receiving operation information of the plurality of load units from the load controller; and    analyzing the received operation information of the plurality of the load units in order to determine whether the load-brake algorithm is properly executed by the load controller.    
   
   
       14 . The method of  claim 13 , wherein the operation information includes speed information of the motor.  
   
   
       15 . The method of  claim 13 , wherein the operation information of the plurality of load units is received from the load controller through a serial data communication line connected to the load controller.  
   
   
       16 . A control system for a washing machine, the system comprising: 
 a door sensor detecting an opening of a washer door provided in the washing machine;    a load controller coupled to the door sensor for executing a load-brake algorithm to brake operations of a plurality of load units of the washing machine when the opening of the washer door is detected by the door sensor;    a main controller transmitting control signals directly to the plurality of load units so as to brake the operations of the plurality of load units if the load-brake algorithm is not properly executed by the load controller.    
   
   
       17 . The controller system of  claim 16 , further comprising a display unit displaying an error message indicating that the execution of the load-brake algorithm by the load controller has failed.  
   
   
       18 . The control system of  claim 16 , wherein the plurality of load units comprises at least one of a motor rotating a washing tub or an agitator provided in the washing machine, a water supply unit supplying water to the tub, and a drain unit draining water from the tub.  
   
   
       19 . The control system of  claim 16 , wherein the main controller receives operation information of the plurality of load units from the load controller and analyzes the received information in order to determine whether the load-brake algorithm is properly executed by the load controller.  
   
   
       20 . The control system of  claim 19 , wherein the main controller receives the operation information of the plurality of load units through a serial data communication line connected between the load controller and the main controller.  
   
   
       21 . A method of controlling a motor-driven washing machine, the method comprising the steps of: 
 initiating a wash cycle by operating a motor provided in the washing machine according to a washing option selected by a user;    generating a motor-brake signal to brake the operation of the motor when a motor-interruption command is generated and measuring a brake period which represents a total length of time it takes to completely stop the operation of the motor;    determining malfunction of the motor based on whether the measured brake period exceeds a predetermined period of time; and    displaying a warming message on a display unit, the message indicating the determined malfunction of the motor.    
   
   
       22 . The method of  claim 21 , wherein the determining step comprises the steps of: 
 storing the measured brake period in a memory if the measured brake period exceeds the predetermined period of time;    determining whether a total number of brake periods stored in the memory until the present time is greater than a threshold frequency value;    determining the malfunction of the motor if the total number of the stored brake periods is greater than the threshold frequency value.    
   
   
       23 . The method of  claim 21 , wherein the motor-interruption command is generated when the user manually touches a key control panel or opens a washer door of the washing machine during the wash cycle.  
   
   
       24 . The method of  claim 21 , further comprising the step of continuing the wash cycle according to the washing option selected by the user if the measured brake period is less than the predetermined period of time.  
   
   
       25 . The method of  claim 21 , wherein the initiating step includes the step of rotating the motor so as to rotate a washing tub or an agitator provided in the washing machine according to the washing option selected by the user.  
   
   
       26 . A control system for a washing machine, the control system comprising: 
 a motor rotating a washing tub or an agitator provided in the washing machine according to a washing option selected by a user;    a microprocessor operatively coupled to the motor for braking operation of the motor when a motor-interruption command is generated and measuring a brake period which represents a total length of time it takes to completely stop the operation of the motor, the microprocessor determining malfunction of the motor based on whether the measured brake period exceeds a predetermined period of time; and    a display unit displaying a warning message indicating the determined malfunction of the motor upon receiving a control signal from the microprocessor.    
   
   
       27 . The control system of  claim 26 , further comprising a memory storing the measured brake period if the measured brake period exceeds the predetermined period of time.  
   
   
       28 . The control system of  claim 27 , wherein the microprocessor determines the malfunction of the motor if a total number of brake periods that are stored in the memory until the present time is greater than a threshold frequency value.  
   
   
       29 . The control system of  claim 27 , wherein the memory is an EEPROM and the display unit is an LCD.  
   
   
       30 . The control system of  claim 26 , further comprising a timer that measures the total length of time it takes to completely stop the operation of the motor.  
   
   
       31 . A method of controlling a motor-driven washing machine, the method comprising the steps of: 
 increasing a speed of a motor from zero to a first predetermined speed W 1  to initiate a spin cycle, during which the motor rotates a washing tub containing a load of clothes to be dehydrated;    reducing the motor speed from WV to a second predetermined speed W 2  and measuring a deceleration period that it takes to reduce the motor speed from W 1  to W 2 ;    increasing the motor speed from W 2  to a third predetermined speed W 3 ;    braking the motor according to a slow brake logic if a first interruption of the motor is ordered during the step of increasing the motor speed from W 2  to W 3 ;    increasing the motor speed from W 3  to a fourth predetermined speed W 4 ; and    selecting one of plurality of rapid-brake logics on the basis of the measured deceleration period and braking the motor according to the selected rapid-brake logic if a second interruption of the motor is ordered during the step of increasing the motor speed from W 3  to W 4 .    
   
   
       32 . The method of  claim 31 , wherein the step of reducing the motor speed from W 1  to W 2  is achieved by cutting off a power supply to the motor in motion.  
   
   
       33 . The method of  claim 31 , further comprising the steps of: 
 maintaining the motor speed of W 4  for a predetermined spin period; and    braking the motor according to the selected rapid-brake logic if a third interruption of the motor is ordered during the step of maintaining the motor speed of W 4 .    
   
   
       34 . The method of  claim 31 , further comprising the steps of: 
 reducing the motor speed from W 4  to zero to terminate the spin cycle; and    braking the motor in motion according to the selected rapid-brake logic if a third interruption of the motor is ordered during the step of reducing the motor speed from W 4  to zero and if the motor speed is greater than W 3 .    
   
   
       35 . The method of  claim 34 , further comprising the step of braking the motor according to the slow brake logic if the third interruption of the motor is ordered during the step of reducing the motor speed from W 4  to zero and if the motor speed is less than or equal to W 3 .  
   
   
       36 . The method of  claim 34 , wherein the step of reducing the motor speed from W 4  to zero is achieved by cutting off a power supply to the motor in motion.  
   
   
       37 . The method of  claim 31 , further comprising the step of braking the motor according to the slow brake logic if a third interruption of the motor is ordered during the step of increasing the motor speed from zero to W 1 .  
   
   
       38 . The method of  claim 31 , further comprising the step of braking the motor according to the slow brake logic if a third interruption of the motor is ordered during the step of reducing the motor speed from W 1  to W 2 .  
   
   
       39 . The method of  claim 31 , wherein the first interruption of the motor is ordered when a user inputs a motor-interrupting command by turning the power of the washing machine, opening of a washer door, or manually touching a key control panel during the step of increasing the motor speed from W 2  to W 3 .  
   
   
       40 . The method of  claim 31 , wherein the second interruption of the motor is ordered when a user inputs a motor-interrupting command by turning the power of the washing machine, opening of a washer door, or manually touching a key control panel during the step of increasing the motor speed from W 3  to W 4 .  
   
   
       41 . A method of controlling a motor-driven washing machine, the method comprising the steps of: 
 applying a phase-reversed voltage to a voltage terminal of a motor in motion to brake the motor when a motor-interruption command is generated during a wash or spin cycle, the motor generating a reverse voltage and a reverse current when being braked;    initially reducing the reverse voltage generated by the motor by allowing the reverse current to flow through a braking resistor connected to the motor if the reverse voltage is higher than a predetermined voltage level;    determining malfunction of the braking resistor on the basis of an actual current-flow period of the braking resistor; and    electrically shorting the voltage terminal of the motor for a predetermined period of time if the malfunction of the braking resistor is determined.    
   
   
       42 . The method of  claim 41 , the step of determining malfunction comprises: 
 determining the malfunction of the braking resistor if the actual current-flow period of the braking resistor is less than a normal current-flow period; and    determining the malfunction of the braking resistor if the actual current-flow period of the braking resistor is greater than the normal current-flow period.    
   
   
       43 . The method of  claim 42 , wherein the normal current-flow period is predetermined to represent a length of time that it takes to flow the reverse current through the braking resistor that operates in a normal condition.  
   
   
       44 . The method of  claim 41 , further comprising the step of further reducing the initially reduced reverse voltage by further allowing the reverse current to flow through the braking resistor if the malfunction of the motor is not deter-mined.  
   
   
       45 . The method of  claim 41 , further comprising the step of repeating the step of applying the phase-reversed voltage if the reverse voltage is less than or equal to the predetermined voltage level.  
   
   
       46 . A control system for a washing machine, the control system comprising: 
 a motor rotating a washing tub or an agitator provided in the washing machine in a wash or spin cycle;    a motor driving unit applying a phase-reversed voltage to a voltage terminal of the motor in motion if a motor-interruption command is generated, the motor generating a reverse voltage and a reverse current when the phase-reversed voltage is applied;    a braking resistor connected to the motor; and    a microprocessor initially reducing the reverse voltage generated by the motor by allowing the reverse current to flow through the braking resistor if the reverse voltage is higher than a predetermined voltage level, the microprocessor electrically shorting the voltage terminal of the motor for a predetermined period of time if it determines malfunction of the braking resistor on the basis of an actual current-flow period of the braking resistor.    
   
   
       47 . The control system of  claim 46 , wherein the microprocessor determines the malfunction of the braking resistor if the actual current-flow period is not equal to a normal current-flow period.  
   
   
       48 . The control system of  claim 47 , wherein the normal current-flow period is predetermined to represent a length of time it takes to flow the reverse current through the braking resistor that operates in a normal condition.  
   
   
       49 . The control system of  claim 46 , wherein the microprocessor further reduces the initially reduced reverse voltage by further allowing the reverse current to flow through the braking resistor if the actual current-flow period is equal to a normal current-flow period.  
   
   
       50 . The control system of  claim 46 , wherein the microprocessor generates a control signal to the motor driving unit to further apply the phase-reversed voltage to voltage terminal of the motor if the reverse voltage is less than or equal to the predetermined voltage level.  
   
   
       51 . A method of controlling a motor-driven washing machine, the method comprising the steps of: 
 (a) determining whether a current DC voltage of a driving unit driving a motor is less than or equal to a predetermined voltage level for each predetermined period;    (b) measuring a current leading phase angle of the current DC voltage if the current voltage is less than or equal to the predetermined voltage level; and    (c) decreasing the current leading phase angle of the current DC voltage by a first predetermined level if the measured leading phase angle is greater than zero.    
   
   
       52 . The method of  claim 51 , further comprising the steps of: 
 (d) measuring a current pulse width modulation (PWM) duty if the measured leading phase angle is equal to zero; and    (e) decreasing the current PWM duty by a second predetermined level if the measured PWM duty if greater than zero.    
   
   
       53 . The method of  claim 52 , wherein the first predetermined level is equal to the second predetermined level.  
   
   
       54 . The method of  claim 52 , further comprising the steps of: 
 (f) determining whether the motor is stopped; and    (g) repeating steps (a) to (e) if it is determined in step (f) that the motor is not stopped.    
   
   
       55 . The method of  claim 51 , further comprising the steps of: 
 (f) determining whether the motor is stopped; and    (g) repeating steps (a) to (c) if it is determined in step (f) that the motor is not stopped.    
   
   
       56 . A control system for a motor-driven washing machine, the control system comprising: 
 an electrical motor;    a driving unit that applies an input voltage to the motor to drive the motor;    a voltmeter that measures a reverse voltage generated by the motor for each predetermined period; and    a microprocessor reducing a speed of the motor if the measured reverse voltage is less than or equal to a predetermined voltage level.    
   
   
       57 . The control system of  claim 56 , further comprising a timer that determines whether the each predetermined period has elapsed.  
   
   
       58 . The control system of  claim 56 , wherein the microprocessor is configured to measure a current leading phase angle if the measured reverse voltage is less than or equal to the predetermined voltage level, and to decrease the current leading phase angel by a first predetermined level if the measured leading phase angel is greater than zero.  
   
   
       59 . The control system of  claim 58 , wherein the microprocessor is further configured to measure a current pulse width modulation (PWM) duty if the measured leading phase angel is equal to zero, and to decrease the current PWM duty by a second predetermined level if the measured PWM duty is greater than zero.  
   
   
       60 . The control system of  claim 59 , wherein the first predetermined level is equal to the second predetermined level.  
   
   
       61 . A method of controlling a motor-driven washing machine, the method comprising the steps of: 
 determining whether a command for a spin cycle is received from a user; and    locking a washer door on the basis of whether a speed of a motor reaches a first predetermined speed if the spin cycle command is received, the motor rotating a washing tub containing a load of clothes to be dehydrated.    
   
   
       62 . The method of  claim 61 , wherein the step of locking the washer door comprises: 
 increasing the motor speed from zero to the first predetermined speed to initiate the spin cycle; and    generating a control signal to a door locking unit if the motor speed is equal to the first predetermined speed, the door locking unit locking the washer door upon receiving the control signal.    
   
   
       63 . The method of  claim 62 , further comprising the steps of: 
 further increasing the motor speed from the first predetermined speed to a second predetermined speed;    maintaining the motor speed of the second predetermined speed for a predetermined period for the spin cycle; and    braking the motor in motion if the predetermined period is elapsed.    
   
   
       64 . The method of  claim 62 , wherein the first predetermined speed is 700 RPM and the second predetermined speed is 1000 RPM.  
   
   
       65 . The method of  claim 61 , wherein the command for the spin cycle is received from the user through a key input unit of the washing machine.  
   
   
       66 . A control system for a washing machine, the control system comprising: 
 a washing tub containing a load of clothes to be dehydrated;    an electrical motor rotating the washing tub if a command for a spin cycle is received from a user; and    a microprocessor locking a washer door on the basis of whether a speed of the motor reaches a first predetermined speed.    
   
   
       67 . The control system of  claim 66 , wherein the microprocessor initially increases the motor speed from zero to the first predetermined speed, the microprocessor further generating a control signal to lock the washer door if the motor speed is equal to the first predetermined speed.  
   
   
       68 . The control system of  claim 67 , further comprising a door locking unit that locks the washer door upon receiving the control signal from the microprocessor.  
   
   
       69 . The control system of  claim 66 , further comprising a key input unit, through which the user inputs the command for the spin cycle.  
   
   
       70 . The control system of  claim 66 , wherein the first predetermined speed is 700 RPM.  
   
   
       71 . A method of controlling a motor-driven washing machine, the method comprising the steps of: 
 determining whether a first current speed of a motor is less than a first predetermined speed if a motor-interruption of the motor is generated during a spin cycle, the motor rotating a washing tub containing a load of clothes to be dehydrated during the spin cycle; and    braking the motor in motion by shorting power terminals of the motor for a first predetermined period if the first current speed is less than the first predetermined speed.    
   
   
       72 . The method of  claim 71 , further comprising the step of applying phase-reversed voltages to the power terminals for a second predetermined period if a second current speed of the motor is less than the first predetermined speed and greater than a second predetermined speed.  
   
   
       73 . The method of  claim 72 , further comprising the step of allowing a braking resistor connected to the motor to flow reverse currents generated by the motor so as to dissipate electrical power into heat if the second current speed of the motor is less than the first predetermined speed and greater than the second predetermined speed.  
   
   
       74 . The method of  claim 72 , further comprising the step of braking the motor by shorting the power terminals of the motor if a third current speed of the motor is less than the second predetermined speed.  
   
   
       75 . The method of  claim 71 , wherein the motor-interruption of the motor is generated when a user directly inputs a command for braking the motor or opens a washer door.  
   
   
       76 . A control system for a washing machine, the control system comprising: 
 a washing tub containing a load of clothes to be dehydrated;    a motor rotating to the washing tub during a spin cycle; and    a microprocessor braking the motor shorting power terminals of the motor if a motor-interruption is generated during the spin cycle and if a first current speed of the motor is less than a first predetermined speed.    
   
   
       77 . The control system of  claim 76 , wherein the microprocessor further brakes the motor by applying phase-reversed voltage to the power terminals for a second predetermined period if a second current speed of the motor is less than the first predetermined speed and greater than a second predetermined speed.  
   
   
       78 . The control system of  claim 77 , wherein the microprocessor allows a braking resistor connected to the motor to flow reverse currents generated by the motor if the second current speed of the motor is less than the first predetermined speed and greater than the second predetermined speed.  
   
   
       79 . The control system of  claim 77 , wherein the microprocessor further brakes the motor by shorting the power terminals of the motor if a third current speed of the motor is less than the second predetermined speed.  
   
   
       80 . The control system of  claim 76 , wherein the motor-interruption of the motor is generated when a user directly inputs a command for braking the motor or opens a washer door.  
   
   
       81 . A circuit for limiting a motor current in an electrical appliance, the circuit comprising: 
 a first resistor and a dip switch connected between a power source and a ground in series, the dip switch comprising a plurality of resistors having different resistances;    a capacitor connected to the dip switch in parallel;    an op amplifier having an inverting input connected to a node between the first resistor and the dip switch; and    a third resistor connected between an noninverting input of the op amplifier and a ground, wherein any one of the plurality of resistors of the dip switch can be conveniently selected for limiting a current that flows through the third resistor.    
   
   
       82 . A method of controlling a motor-driven washing machine having a motor and a pair of a transistor and a braking resistor connected to the motor in parallel for limiting the reverse voltages generated by the motor during a motor brake, the resistor being connected to the transistor in series, the method comprising the steps of: 
 measuring a voltage of a node between the transistor and the braking resistor;    displaying a warning message indicating that the brake resistor is in an inoperative condition if the measured voltage is equal to zero;    repeating the step of determining if a command for a wash cycle is received; and    initiating the wash cycle if the measured voltage of the node is not equal to zero.    
   
   
       83 . The method of  claim 82 , further comprising the step of generating a warning sound if the measured voltage is equal to zero.  
   
   
       84 . A control system for a washing machine, the control system comprising: 
 a motor rotating a wash tub or an agitator of the washing machine;    a driving unit that drives the motor by applying input voltages to the motor;    a pair of a braking resistor and a transistor connected to the driving unit in parallel, the transistor being connected to the braking resistor in series;    a voltmeter measuring a voltage of a node between the transistor and the braking resistor; and    a microprocessor generating a warning signal if the measured voltage of the node is not equal to zero.    
   
   
       85 . The control system of  claim 84 , further comprising a display unit displaying a warning message upon receiving the warning signal, the warning message indicating that the brake resistor is in an inoperative condition.  
   
   
       86 . The control system of  claim 84 , further comprising a sound generating unit generating a warning sound upon receiving the warning signal.