WASHING MACHINE AND CONTROLLING METHOD FOR THE SAME

A washing machine for controlling optimal operating revolutions per minute (rpm) of a drain pump in a draining course and a dehydrating course includes a washing tub; a drain pump configured to drain water in the washing tub; a pump motor configured to operate the drain pump; an inverter circuit configured to supply a driving current to the pump motor to operate the drain pump; and a controller configured to control the inverter circuit to supply reference power to the pump motor in response to starting a draining course, determine reference revolutions per minute (rpm) based on average rpm of the pump motor during a preset period of time, and control the inverter circuit to operate the pump motor at the reference rpm in response to the determining of the reference rpm.

BACKGROUND

The disclosure relates to a washing machine and method for controlling the same, and more particularly, to a washing machine and method for controlling the same capable of increasing drain efficiency and minimizing noise and vibration caused by a drain pump during a draining course.

2. Description of Related Art

In general, the washing machine may include a tub for storing water for laundry and a drum rotationally installed in the tub. The washing machine may do laundry by rotating the drum that contains clothes.

The washing machine may perform a washing process for washing the clothes, a rinsing process for rinsing the washed clothes, and a dehydrating process for dehydrating the clothes. The washing machine supplies water into the tub in the washing process and the rinsing process to perform washing and rinsing of the clothes, and performs a draining course to drain the water used for washing and rinsing.

The draining course may refer to a course in which a drain pump in the washing machine operates to drain the water in the tub outside through a drain tube.

The traditional washing machine controls operating revolutions per minute (rpm) of the drain pump without considering environmental conditions of the washing machine, so drain efficiency may be lowered and vibration and noise may occur. In addition, the operating rpm of the drain pump is controlled without considering vibration of the tub in the dehydrating course after completion of the draining course, so the drain efficiency may be reduced.

SUMMARY

According to an aspect of the disclosure, a washing machine includes a washing tub; a drain pump configured to drain water in the washing tub; a pump motor configured to operate the drain pump; an inverter circuit configured to supply a driving current to the pump motor to operate the drain pump; and a controller configured to control the inverter circuit to supply reference power to the pump motor in response to starting of a draining course, determine reference revolutions per minute (rpm) based on average rpm of the pump motor during a preset period of time, and control the inverter circuit to operate the pump motor at the reference rpm in response to the determining of the reference rpm.

The controller may determine the reference rpm based on the average rpm of the pump motor during the preset period of time when a reference time passes after the draining course is started.

The washing machine may further include a display, and the draining course includes a first draining course and a second draining course which starts after the first draining course, and the controller may further control the display to output a visual indication to indicate that the drain pump has a problem based on a difference between first reference rpm determined in the first draining course and second reference rpm determined in the second draining course being equal to or greater than a preset value.

The washing machine may further include a water level sensor for detecting a water level of the water in the washing tub, and the controller may further configured to control the inverter circuit to operate the pump motor at the reference rpm from a time at which the reference rpm is determined to a time at which a reference time passes after the water level in the washing tub reaches a preset water level.

The preset water level may be a reset water level.

The washing machine may further include a driving motor configured to rotate the drum, and the controller may control target rpm of the pump motor based on the reference rpm and an operating rpm of the driving motor at a start of a dehydrating course after the draining course is completed

The controller may further configured to control the inverter circuit to stop driving the pump motor based on determining of the operating rpm of the driving motor being lower than first preset rpm.

The controller may further configured to control the inverter circuit to operate the pump motor at the reference rpm based on determining of the operating rpm of the driving motor being higher than the first preset rpm and lower than second preset rpm.

The controller may further configured to control the inverter circuit to operate the pump motor at first rpm higher than the reference rpm based on determining of the operating rpm of the driving motor being higher than the second preset rpm and lower than third preset rpm.

The controller may further configured to control the inverter circuit to operate the pump motor at second rpm higher than the first rpm based on determining of the operating rpm of the driving motor being higher than the third preset rpm.

According to an aspect of the disclosure, a method of controlling a washing machine includes controlling an inverter circuit to supply reference power to a pump motor which operates a drain pump in response to starting a draining course; determining reference revolutions per minute (rpm) based on average rpm of the pump motor during a preset period of time; and controlling the inverter circuit to operate the pump motor at the reference rpm in response to the determining of the reference rpm.

The determining of the reference rpm may include determining the reference rpm based on the average rpm of the pump motor during the preset period of time when a reference time passes after the draining course is started.

The draining course may include a first draining course and a second draining course which starts after the first draining course. The method of controlling the washing machine may further include providing feedback indicating that the drain pump has a problem based on a difference between first reference rpm determined in the first draining course and second reference rpm determined in the second draining course starting after the first draining course being equal to or greater than a preset value.

The method of controlling the washing machine may further include detecting a water level of the water in a washing tub, and the controlling of the inverter circuit to operate the pump motor at the reference rpm may further include controlling the inverter circuit to operate the pump motor at the reference rpm from a time at which the reference rpm is determined to a time at which a reference time passes after a water level in the washing tub reaches a preset water level.

The preset water level may be a reset water level.

The method of controlling the washing machine may further include controlling target rpm of the pump motor based on the reference rpm and operating rpm of a driving motor which rotates a drum at a start of a dehydrating course after the draining course is completed.

The controlling of the target rpm of the pump motor may include controlling the inverter circuit to stop driving the pump motor based on determining of the operating rpm of the driving motor being lower than first preset rpm.

The controlling of the target rpm of the pump motor may include controlling the inverter circuit to operate the pump motor at the reference rpm based on determining of the operating rpm of the driving motor being higher than the first preset rpm and lower than second preset rpm.

The controlling of the target rpm of the pump motor may include controlling the inverter circuit to operate the pump motor at first rpm higher than the reference rpm based on determining of the operating rpm of the driving motor being higher than the second preset rpm and lower than third preset rpm.

The controlling of the target rpm of the pump motor may include controlling the inverter circuit to operate the pump motor at second rpm higher than the first rpm based on determining of the operating rpm of the driving motor being higher than the third preset rpm.

DETAILED DESCRIPTION

Embodiments and features as described and illustrated in the disclosure are merely examples, and there may be various modifications replacing the embodiments and drawings at the time of filing this application.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present disclosure.

For example, the singular forms “a”, “an” and “the” as herein used are intended to include the plural forms as well, unless the context clearly indicates otherwise.

The terms “comprises” and/or “comprising,” when used in this specification, represent the presence of stated features, integers, steps, operations, elements, components or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

The term including an ordinal number such as “first”, “second”, or the like is used to distinguish one component from another and does not restrict the former component.

Furthermore, the terms, such as “˜ part”, “˜ block”, “˜ member”, “˜ module”, etc., may refer to a unit of handling at least one function or operation. For example, the terms may refer to at least one process handled by hardware such as a field-programmable gate array (FPGA)/application specific integrated circuit (ASIC), etc., software stored in a memory, or at least one processor.

The disclosure provides a washing machine and method for controlling the same for optimally controlling an operating revolutions per minute (rpm) of a drain pump in a draining course and/or a dehydrating course.

According to the disclosure, optimal operating revolutions per minute (rpm) of a drain pump may be determined only by updating simple software without a need for additional hardware.

According to the disclosure, optimal operating rpm of a drain pump may be determined without a requirement for a complex algorithm.

According to the disclosure, vibration and noise that may occur in a draining course and/or a dehydrating course may be reduced.

According to the disclosure, drainage may be efficiently performed in a draining course and/or a dehydrating course.

An embodiment of the disclosure will now be described in detail with reference to accompanying drawings. Throughout the drawings, like reference numerals or symbols refer to like parts or components.

The principle and embodiments of the disclosure will now be described with reference to accompanying drawings.

FIG.1illustrates an example of a washing machine, according to an embodiment.FIG.2illustrates another embodiment of a washing machine, according to an embodiment.FIG.3is a block diagram illustrating a configuration of a washing machine, according to an embodiment.

Referring toFIGS.1,2and3, a washing machine100may include a control panel110, a washing tub120, a drum130, a driving motor140, a water supplier150, a detergent supplier155, a drain160, drivers200and300, a water level sensor (170or175), a vibration sensor180and a controller190.

The washing machine100may include a cabinet101to accommodate the components included in the washing machine100. The cabinet101may accommodate the control panel110, the water level sensor170or175, the drivers200and300, the driving motor140, the water supplier150, the drain160, the detergent supplier155, the washing tub120and the drum130.

An opening101ais formed on one side of the cabinet101for drawing in or out the laundry.

For example, the washing machine100may include a top-loading washing machine with the inlet101a, through which to draw in or out the laundry, formed on the top side of the cabinet101as shown inFIG.1, or a front-loading washing machine with the inlet101a, through which to draw in or out the laundry, formed on the front side of the cabinet101as shown inFIG.2. In the embodiment, the washing machine100is not limited to the top-loading washing machine or the front-loading washing machine, but may correspond to any of the top-loading washing machine and the front-loading washing machine. Of course, the washing machine100may include any loading type of washing machine other than the top-loading washing machine and the front-loading washing machine.

A door102is arranged on one side of the cabinet101to open or close the inlet101a. The door101may be arranged on the same surface as the inlet101aand installed on the cabinet101to pivot on a hinge.

The control panel110may be arranged on one surface of the cabinet101to provide a user interface for interacting with the user.

The control panel110may include, for example, an input button111for obtaining a user input, and a display112for displaying a laundry setting or laundry operation information in response to the user input.

The input button111may include, for example, a power button, an operation button, a course selection dial (or course selection buttons) and washing/rinsing/dehydrating setting buttons. The input button may include, for example, a tact switch, a push switch, a slide switch, a toggle switch, a micro switch, or a touch switch.

The input button111may provide an electric output signal corresponding to the user input to the controller190.

The display112may include a screen for displaying a laundry course selected by turning the course selection dial (or by pressing the course selection button) and an operation time of the washing machine100, and an indicator for indicating a washing setting/rinsing setting/dehydration setting selected by the setting button. The display112may include, for example, a liquid crystal display (LCD) panel112, a light emitting diode (LED) panel, or the like.

The display112may receive information to be displayed from the controller190and display information corresponding to the received information.

The washing tub120and the drum130may be arranged in the cabinet101.

The washing tub120receives water for washing and rinsing, and the drum130is rotationally equipped in the tub120to accommodate clothes.

The tub120may have the shape of e.g., a cylinder with a bottom surface open. The tub120may include a tub bottom surface122shaped almost like a circle and a tub side wall121provided along the circumference of the tub bottom surface122. Another bottom surface of the tub120may be opened to draw in or draw out clothes or may have an opening formed thereon.

In the case of the top-loading washing machine, as shown inFIG.1, the tub120may be arranged with the tub bottom surface122facing the bottom of the washing machine100and a center axis R of the tub side wall121being substantially perpendicular to the floor. In the case of the front-loading washing machine, as shown inFIG.2, the tub120may be arranged with the tub bottom surface122facing the back of the washing machine100and the center axis R of the tub side wall121being substantially parallel to the floor.

A bearing122amay be arranged on the tub bottom surface122to rotationally fix the driving motor140.

The drum130may be rotationally arranged in the tub120. The drum130may accommodate clothes, i.e., loads.

The drum130may have the shape of e.g., a cylinder with a bottom surface open. The drum130may include a drum bottom surface132shaped almost like a circle and a drum side wall131provided along the circumference of the drum bottom surface132. Another bottom surface of the drum130may be opened to draw clothes into or out of the drum130or may have an opening formed thereon.

In the case of the top-loading washing machine, as shown inFIG.1, the drum130may be arranged with the drum bottom surface132facing the bottom of the washing machine100and the center axis R of the drum side wall131being substantially perpendicular to the floor. In the case of the front-loading washing machine, as shown inFIG.2, the drum130may be arranged with the drum bottom surface132facing the back of the washing machine100and the center axis R of the drum side wall131being substantially parallel to the floor.

On the drum side wall131, through holes131amay be formed to connect the inside and outside of the drum130for water supplied to the tub120to flow into the drum130.

In the case of the top-loading washing machine as shown inFIG.1, a pulsator133may be rotationally provided on the inner side of the drum bottom surface132. The pulsator133may be rotated separately from the drum130. In other words, the pulsator133may be rotated in the same direction as or different direction from the drum130. The pulsator133may be rotated at the same rotation speed as or a different rotation speed from the drum130.

In the case of the front-loading washing machine as shown inFIG.2, a lifter131bis provided on the drum side wall131to lift clothes up the drum130while the drum130is being rotated. Furthermore, in various embodiments, even for the front-loading washing machine, the pulsator133may be rotationally arranged on the inner side of the drum bottom surface132. The pulsator133may be rotated separately from the drum130. In other words, the pulsator133may be rotated in the same direction as or different direction from the drum130. The pulsator133may be rotated at the same rotation speed as or a different rotation speed from the drum130.

The drum bottom surface132may be connected to a rotation shaft141of the driving motor140that rotates the drum130.

The driving motor140may rotate the drum130included in the washing tub120based on a driving current applied from the first driver200.

In an embodiment, the driving motor140may produce torque to rotate the drum130.

The driving motor140may be arranged on the outer side of the tub bottom surface122of the tub120, and connected to the drum bottom surface132of the drum130through the rotation shaft141. The rotation shaft141may penetrate the tub bottom surface122, and may be rotationally supported by the bearing122aarranged on the tub bottom surface122.

The driving motor140may include a stator142fixed onto the outer side of the tub bottom surface122, and a rotor143arranged to be rotatable against the tub120and the stator142. The rotor143may be connected to the rotation shaft141.

The rotor143may be rotated by magnetic interaction with the stator142, and the rotation of the rotor143may be delivered to the drum130through the rotation shaft141.

The driving motor140may include e.g., a brush-less direct current (BLDC) motor or a permanent synchronous motor (PMSM) capable of easily controlling the rotation speed.

In the case of the top-loading washing machine as shown inFIG.1, there may be a clutch145for delivering the torque of the driving motor140to both the pulsator133and the drum130or the pulsator133. The clutch145may be connected to the rotation shaft141. The clutch145may distribute the rotation of the rotation shaft141to an inner shaft145aand an outer shaft145b. The inner shaft145amay be connected to the pulsator133. The outer shaft145amay be connected to the drum bottom surface132. The clutch145may deliver the rotation of the rotation shaft141to both the pulsator133and the drum130through the inner shaft145aand the outer shaft145b, or deliver the rotation of the rotation shaft141only to the pulsator133through the inner shaft145a.

In the case of the front-loading washing machine as shown inFIG.2, the driving motor140may rotate both the pulsator133and the drum130, or the pulsator133or the drum130.

In various embodiments, the driving motor140may be a dual-rotor motor equipped with an outer rotor and an inner rotor on the outer side and the inner side in a radial direction of one stator.

The inner rotor and the outer rotor of the driving motor140may be connected to the pulsator133and the drum130through the inner shaft145aand the outer shaft145b, respectively, and may drive the pulsator133and the drum130directly.

However, a method of driving the drum130and the pulsator133is not limited according to the type of the washing machine100(front-loading washing machine or top-loading washing machine), and even for the top-loading washing machine, the dual-rotor motor may be used for the driving motor140to rotate the pulsator133and the drum130separately, and even for the front-loading washing machine, the one stator142, the one rotor143, and the clutch145may be used to rotate the pulsator133and the drum130separately.

The water supplier150may supply water to the tub120and the drum130. The water supplier150includes a water supply conduit151connected to an external water source to supply water to the tub120, and a water supply valve152arranged in the water supply conduit151. The water supply conduit151may be arranged above the tub120and may extend to a detergent container156from the external water source. The water is guided to the tub120via the detergent container156. The water supply valve152may allow or block the supply of water to the tub120from the external water source in response to an electric signal. The water supply valve152may include, for example, a solenoid valve that is opened or closed in response to an electric signal.

The detergent supplier155may supply a detergent to the tub120and the drum130. The detergent supplier155is arranged above the tub120and includes the detergent container156and a mixing conduit157that connects the detergent container156to the tub120. The detergent container156may be connected to the water supply conduit151, and the water supplied through the water supply conduit151may be mixed with the detergent in the detergent container156. The mixture of the detergent and the water may be supplied to the tub120through the mixing conduit157.

The drain160may drain out the water stored in the tub120or the drum130. The drain160may include a drain conduit161arranged below the tub120and extending to the outside of the cabinet101from the tub120. The drain160may further include a drain valve162arranged in the drain conduit161. The drain160may further include a drain pump163arranged in the drain conduit161and a pump motor164for operating the drain pump163. The pump motor164may generate rotational force to create a difference in pressure between both sides of the drain pump163, and the difference in pressure may make the water stored in the tub120discharged outside through the drain conduit161.

The pump motor164may produce the rotational force based on a driving current applied from the second driver300.

The pump motor164may include, for example, a BLDC motor or a PMSM capable of easily controlling the rotation speed.

In the case of the top-loading washing machine as shown inFIG.1, the water level sensor170may be installed at an end of a connecting hose171connected to the bottom of the tub120. In this case, a water level in the connecting hose171may be equivalent to a water level in the tub120. As the water level in the tub120increases, the water level in the connecting hose171increases, and due to the increase of the water level in the connecting hose171, internal pressure of the connecting hose171may increase.

The water level sensor170may measure pressure in the connecting hose171and output an electric signal corresponding to the measured pressure to the controller190. The controller190may identify a water level in the connecting hose171, i.e., a water level in the tub120, based on the pressure in the connecting hose171measured by the water level sensor170or175.

In an embodiment, the controller190may identify the water level in the tub120by analyzing a frequency (water level frequency) of the electric signal corresponding to the pressure measured by the water level sensor170.

In the case of the front-loading washing machine as shown inFIG.2, the water level sensor175may be installed on the inner side of the bottom of the tub120. As the water level in the tub120increases, the pressure applied to the water level sensor175increases, and accordingly, the water level sensor175may detect a frequency changing by the water level when the drum130rotates.

In an embodiment, the controller190may identify the water level in the tub120by analyzing a frequency (water level frequency) of the electric signal corresponding to the pressure measured by the water level sensor175.

In various embodiments, the washing machine100may include the vibration sensor180for detecting vibration of the tub120. The vibration sensor180may be installed in various positions (e.g., in the tub120or the cabinet101) at which to detect vibration of the tub120.

The vibration sensor180may include an acceleration sensor for measuring 3-axis (X, Y and Z) acceleration of the tub120. For example, the vibration sensor180may be provided as a piezoelectric type, strain gauge type, piezoresistive type, capacitive type, servo type, or optical type acceleration sensor. In addition, the vibration sensor180may be provided as various sensors (e.g., gyroscope) capable of measuring vibration of the tub120.

The vibration sensor180may output a sensing value of the vibration of the tub120. For example, the vibration sensor180may output a constant value corresponding to the vibration of the tub120. The vibration sensor180may output a voltage value corresponding to the 3-axis acceleration of the tub120.

In various embodiments, the vibration sensor180may be provided as a micro electro mechanical system (MEMS) sensor. An MEMS is a scheme developed with the advancement of semiconductor technologies, and the MEMS sensor may be made by deposition, photolithographic patterning and etching processes. The vibration sensor180may be formed of various materials such as silicon, polymer, metal or ceramic. The vibration sensor manufactured in the MEMS scheme may have a size in micrometers.

The controller190may determine an amount of vibration of the tub120based on a vibration signal received from the vibration sensor180, and control rotation speed of the driving motor140and/or rotation speed of the pump motor164based on the amount of vibration of the tub120.

For example, the controller190may be mounted on a printed circuit board provided on the rear surface of the control panel110.

The controller190may be electrically connected to the control panel110, the water level sensor170or175, the vibration sensor180, the drivers200and300, the water supply valve152and the drain valve162.

The controller190may be comprised of hardware such as a control processing unit (CPU), a memory, etc., and software such as a control program. The controller190may be implemented to include at least one memory192that stores an algorithm for controlling operations of the components in the washing machine100, and at least one processor191for performing the aforementioned operations using the data stored in the at least one memory192. In this case, the memory192and the processor191may be implemented in separate chips. Alternatively, the memory192and the processor191may be implemented in a single chip.

The processor191may process output signals from the control panel110, the water level sensor170or175, the vibration sensor180and/or the drivers200and300, and include an operation circuit, a memory circuit, and a control circuit, which output control signals to the drivers200and300, the water supply valve152and the drain valve162based on the processing results.

The memory192may include a volatile memory, such as a static random access memory (S-RAM), a dynamic RAM (D-RAM), or the like, and a non-volatile memory, such as a read only memory (ROM), an erasable programmable ROM (EPROM) or the like.

The controller190may control the various components (e.g., the driving motor140and the pump motor164) of the washing machine100, and automatically drive the respective courses such as water supply, washing, rinsing, dehydrating, etc., according to an indication input to the control panel110.

For example, the controller190may control the first driver200to control the rotation speed (hereinafter, operating revolutions per minute (rpm)) of the driving motor140, and control the second driver300to control the operating rpm of the pump motor164.

In various embodiments, the controller190may control the operating rpm of the driving motor140and/or the operating rpm of the pump motor164based on information about a water level in the tub120received from the water level sensor170or175, information about an amount of vibration of the tub120obtained by the vibration sensor180, information about the operating rpm of the driving motor140received from the first driver200, and/or information about the operating rpm of the pump motor164received from the second driver300.

FIG.4illustrates an example of a driver for driving a pump motor and/or a driving motor of a washing machine, according to an embodiment.FIG.5illustrates another example of a driver for driving a pump motor and/or a driving motor of a washing machine, according to an embodiment.

For convenience of explanation, the first driver200and the second driver300may be collectively defined as the driver200or300, and configurations that the first driver200and the second driver300have in common will now be described. InFIGS.4and5, it is assumed that components of the first driver200have reference numerals starting with number2, and components of the second driver300have reference numerals starting with number3.

Referring toFIGS.4and5, the driver200or300may include a rectifying circuit210or310, a direct current (DC) link circuit220or320, an inverter circuit230or330, a current sensor240or340, and/or an inverter controller250or350. A position sensor270or370may be arranged on the motor140or164for measuring rotational displacement of the rotor (electrical angle of the rotor).

The rectifying circuit210or310may include a diode bridge including a plurality of diodes D1, D2, D3and D4to rectify alternate current (AC) power from an external power source (ES).

The DC link circuit220or320may include a DC link capacitor C for storing electrical energy to get rid of ripples of the rectified power and output DC power.

The inverter circuit230or330may include three pairs of switching devices Q1and Q2, Q3and Q4, and Q5and Q6to convert the DC power from the DC link circuit220or320to DC or AC driving power. The inverter circuit230or330may apply a driving current to the motor140or164.

The current sensor240or340may measure a total current output from the inverter circuit230or330or measure each of three-phase driving currents, a-phase current, b-phase current and c-phase current output from the inverter circuit230or330.

The position sensor270or370may be arranged on the motor140or164for measuring rotational displacement of the rotor of the motor140or164(e.g., electric angle of the rotor) and output position data Θ that represents the electric angle of the rotor. The position sensor270or370may be implemented by a hall sensor, an encoder, a resolver, or the like.

The inverter controller250or350may be integrated into the controller190or separated from the controller190.

The inverter controller250or350may include an application specific integrated circuit (ASIC) for outputting a driving signal to the inverter circuit230or330based on e.g., a target speed command ω*, a driving current value, and the rotational displacement Θ of the rotor143. Alternatively, the inverter controller250or350may include a memory for storing a series of instructions for outputting a driving signal based on a target speed command ω*, a driving current value, and rotational displacement Θ of the rotor, and a processor for processing the series of instructions stored in the memory.

The structure of the inverter controller250or350may depend on the type of the motor140or164. In other words, the inverter controller250or350having a different structure may control the motor140or164of a different type.

For example, when the motor140or160is a BLDC motor, the inverter controller250or350may include a speed operator251or351, a speed controller253or353, a current controller254or354, and a pulse width modulator256or356, as shown inFIG.5.

The inverter controller250or350may use pulse width modulation (PWM) to control a DC voltage applied to the BLDC motor. Accordingly, the driving current applied to the BLDC motor may be controlled.

The speed operator251or351may calculate a rotation speed value ω of the motor140or164based on the electric angle θ of the rotor of the motor140or164. For example, the speed operator251or351may calculate the rotation speed value ω of the motor140or164based on a change in electric angle θ of the rotor received from the position sensor270or370. In another example, the speed operator251or351may calculate the rotation speed value ω of the motor140or164based on a change in driving current value measured by the current sensor240or340.

The speed controller253or353may output a current command I* based on a difference between the target speed command ω* of the controller190and the rotation speed value ω of the motor140or164. For example, the speed controller253or353may include a proportional integral controller (PI controller).

The current controller254or354may output a voltage command V* based on a difference between the current command I* output from the speed controller253or353and the current value I measured by the current sensor240or340. For example, the current controller254or354may include PI control.

The pulse width modulator256or356may output a PWM control signal Vpwm to control the magnitude of the driving current applied to the motor140or164by the inverter circuit230or330based on the voltage command V*.

As such, the inverter controller250or350may control the magnitude of the driving current applied to the motor140or164by the inverter circuit230or330based on the target speed command ω* received from the controller190.

In another example, when the motor140or160is a PMSM, the inverter controller250or350may include the speed operator251or351, an input coordinate converter252or352, the speed controller253or353, the current controller254or354, an output coordinate converter255or355and the pulse width modulator256or356, as shown inFIG.5.

The inverter controller250or350may use vector control to control the AC voltage applied to the PMSM. Accordingly, the driving current applied to the PMSM may be controlled.

The speed operator251or351may be equivalent to the speed operator251or351shown inFIG.4.

The input coordinate converter252or352may convert a 3-phase driving current value Iabc into a d-axis current value Id and q-axis current value Iq (hereinafter, a d-axis current and a q-axis current) based on the electric angle θ of the rotor. In this case, the d-axis may refer to an axis in a direction corresponding to a direction of a magnetic field produced by the rotor of the motor140or164. The q-axis may refer to an axis in a direction ahead by 90 degrees of a direction of the magnetic field produced by the rotor of the motor140or164.

The speed controller253or353may calculate a q-axis current command Iq* to be applied to the motor140or164based on a difference between the target speed command ω* and the rotation speed value ω of the motor140or164. The speed controller253or353may determine a d-axis current command Id*.

The current controller254or354may determine a q-axis voltage command Vq* based on a difference between the q-axis current command Iq* output from the speed controller253or353and the q-axis current value Iq output from the input coordinate converter252or352. The current controller254or354may determine a d-axis voltage command Vd* based on a difference between the d-axis current command Id* and the d-axis current value Id.

The output coordinate converter255and355may convert a dq axis voltage command Vdq* into 3-phase voltage commands (an a-phase voltage command, a b-phase voltage command, and a c-phase voltage command) Vabc* based on the electric angle Θ of the rotor of the motor140or164.

The pulse width modulator256or356may output a PWM control signal Vpwm to control the magnitude of the driving current applied to the motor140or164by the inverter circuit230or330based on the 3-phase voltage command Vabc*.

As such, the inverter controller250or350may control the magnitude of the driving current applied to the motor140or164by the inverter circuit230or330based on the target speed command ω* received from the controller190.

In various embodiments, the driver200or300may include a voltage sensor (not shown) for measuring a driving voltage applied to the motor140or164. The driver200or300may further include a power operator (not shown) for computing power to be applied to the motor140or164based on a voltage value output from a voltage sensor and a current value output from the current sensor240or340, and a power controller (not shown) for outputting a target speed command ω* according to power computed by the power operator and a target power command output from the controller190.

The power controller may include a PI controller.

In various embodiments, the controller190may output a target power command to the inverter controller250or350, which may in turn control the inverter circuit230or330to supply target power to the motor140or164based on the target power command. Accordingly, the controller190may perform power control and speed control on the motor140or164.

The controller190may receive information about the operating rpm of the motor140or164from the inverter controller250or350.

FIG.6illustrates an example of a laundry cycle of a washing machine, according to an embodiment.

Referring toFIG.6, in an embodiment, a laundry cycle1000of the washing machine100may be comprised of a washing process1010, a rinsing process1020and a dehydrating process1030.

The washing machine100may perform the washing process1010, the rinsing process1020and the dehydrating process1030sequentially according to a user input through the control panel110.

Clothes may be washed by the washing process1010. Specifically, dirt on the clothes may be separated by chemical actions of a detergent and/or mechanical actions such as falling.

The washing process1010may include laundry measurement1011for measuring an amount of clothes, a water supply course1012for supplying water to the tub120, a washing course1013for washing the clothes by rotating the drum130at low speed, a draining course1014for draining water contained in the tub120, and a dehydrating course1015for separating water from the clothes by rotating the drum130at high speed.

In the water supply course1012, a detergent contained in the detergent container156may be supplied to the tub120by the detergent supplier155.

For the washing course1013, the controller190may control the first driver200to rotate the driving motor140in forward direction or reverse direction. In the case of the front-loading washing machine, the clothes may fall from the upper side to the lower side of the drum130due to rotation of the drum130and may be washed by the falling, and in the case of the top-loading washing machine, clothes may be washed by centrifugal force produced by rotation of the drum130.

For the draining course1014, the controller190may control the second driver300to rotate the pump motor164. The rotation of the pump motor164may cause a difference in pressure between both sides of the drain pump163, allowing the water in the tub120to be drained to the outside.

For the dehydrating course1015, the controller190may control the first driver200to rotate the driving motor140at high speed. Due to the high-speed rotation of the drum130, water may be separated from the clothes contained in the drum130. Furthermore, to discharge the remaining water in the tub120to the outside during the dehydrating course1015, the controller190may control the second driver300to rotate the pump motor164.

The rotation speed of the drum130may gradually increase during the dehydrating course1015. For example, the controller190may control the first driver200to rotate the driving motor140at a first rotation speed, and the driving motor140may be controlled so that the rotation speed of the driving motor140increases to a second rotation speed based on a change in driving current of the driving motor140while the driving motor140is rotated at the first rotation speed. The controller190may control the driving motor140so that the rotation speed of the driving motor140increases to a third rotation speed or the rotation speed of the driving motor140decreases to the first rotation speed based on a change in driving current of the driving motor140while the driving motor140is rotated at the second rotation speed.

In various embodiments, during the dehydrating course1015, the rotation speed of the pump motor164may be changed based on the rotation speed of the driving motor140.

The clothes may be rinsed by the rinsing process1020. Specifically, the remnants of the detergent or dirt on the clothes may be washed by water.

The rinsing process1020may include a water supply course1021for supplying water to the tub120, a rinsing course1022for rinsing the clothes by driving the drum130, a draining course1023for draining water contained in the tub120, and a dehydrating course1024for separating water from the clothes by driving the drum130.

The water supply course1021, draining course1023and dehydrating course1024of the rinsing process1020may correspond to the water supply course1012, draining course1014and dehydrating course1015of the washing process1010. During the rinsing process1020, the water supply course1021, the rinsing course1022, the draining course1023and the dehydrating course1024may be performed one or multiple times.

The clothes may be dehydrated by the dehydrating process1030. Specifically, water may be separated from the clothes by high-speed rotation of the drum130, and the separated water may be discharged out of the washing machine100.

The dehydrating process1030may include a final dehydrating course1031to separate water from the clothes by rotating the drum130at high speed. With the final dehydrating course1031, the last dehydrating course1024of the rinsing process1020may be skipped.

For the final dehydrating course1031, the controller190may control the first driver200to rotate the driving motor140at high speed. Due to the high-speed rotation of the drum130, moisture may be separated from the clothes contained in the drum130. Furthermore, to discharge the remaining water in the tub120to the outside during the final dehydrating course1031, the controller190may control the second driver300to rotate the pump motor164.

The rotation speed of the driving motor140may gradually increase during the final dehydrating course1031.

In various embodiments, during the final dehydrating course1031, the rotation speed of the pump motor164may be changed based on the rotation speed of the driving motor140.

As the operation of the washing machine100is finished with the final dehydrating course1031, a performance time of the final dehydration1031may be longer than a performance time of the dehydration course1015of the washing process1010and the dehydration course1024of the rinsing process1020.

FIG.7is a flowchart illustrating an example of a method of controlling a washing machine during a draining course, according to an embodiment.FIG.8illustrates a water level in a tub after completion of a water supply course of a washing machine, according to an embodiment.FIG.9illustrates a water level in a tub during a draining course of a washing machine, according to an embodiment.FIG.10illustrates a water level in a tub reaching a reset water level during a draining course of a washing machine, according to an embodiment.

Referring toFIG.7, the controller190may control the inverter circuit230or330to supply reference power to the pump motor164at the start of the draining course1014or1023, in1050.

For example, the controller190may control the inverter circuit230or330to supply reference power to the pump motor164by delivering a target power command corresponding to the reference power to the second driver300.

In this case, the reference power value may be stored in the memory192, and may imply a maximum power value for rotating the pump motor164at the highest speed.

In an embodiment, the controller190may control the inverter circuit230or330to supply reference power to the pump motor164in operation1050by delivering a target speed command corresponding to the reference power to the second driver300.

In this case, the target speed value corresponding to the reference power may be stored in the memory192.

After the passage of a reference time from a time when the draining course1014or1023begins, i.e., a time when the inverter circuit230or330is controlled to supply the reference power to the pump motor164, in operation1100, the controller190may determine reference rpm based on average rpm of the pump motor164during a preset period of time, in operation1200.

In this case, the reference time may be a time determined in advance based on a gap between when the inverter circuit230or330is controlled to supply the reference power to the pump motor164and when the reference power is supplied to the pump motor164, and may be stored in the memory192. For example, the controller190may determine the reference time based on a difference between when the inverter circuit230or330is controlled to supply the reference power to the pump motor164and when the reference power is supplied to the pump motor164. For example, the reference time may be determined to be about 10 seconds.

Furthermore, the preset period of time may be set as a period of time to ensure reliability of the operating rpm of the pump motor164, and stored in the memory192. For example, the preset period of time may be determined to be about 5 seconds.

Specifically, the controller190may control the inverter circuit230or330to supply the reference power to the pump motor164at the start of a draining course, receive information about the operating rpm of the pump motor164for the preset period of time from after the passage of the reference time, and determine an average value of the operating rpm of the pump motor164for the preset period of time as the reference rpm.

In this case, the reference rpm may refer to rpm that is a reference for later operation of the pump motor164, and refer to operating rpm of the pump motor164at which minimal vibration and noise is created with optimal efficiency. The reference rpm will be described in detail with reference toFIGS.11to14.

The controller190may control the inverter circuit230or330to operate the pump motor164at the reference rpm in response to the determining of the reference rpm, in operation1300. For example, the controller190may output a target speed command ω* corresponding to the reference rpm.

In various embodiments, the controller190may control the inverter circuit230or330to operate the pump motor164at the reference rpm as soon as the reference rpm is determined.

Referring toFIG.8, when a draining course begins, a water level in the tub120may be almost equal to a target water level determined based on the weight of clothes determined in the laundry measurement course1011.

In the embodiment, the controller190may control the operating rpm of the pump motor164to the reference rpm while the water level in the tub120is not much lowered, e.g., in the state as shown inFIG.9, because the controller190may determine the reference rpm when a certain time (reference time+a preset period of time) passes after the start of a draining course.

Referring toFIG.9, it may be seen that the water level in the tub120is not much lowered as compared to the water level in the tub120as shown inFIG.8. As such, in the embodiment, after the passage of a minimum time after a draining course begins, the operating rpm of the pump motor164may be controlled to the reference rpm, which is optimal rpm, thereby preventing occurrence of noise and vibration due to operation of the pump motor164.

The controller190may control the inverter circuit230or330to operate the pump motor164at the reference rpm before the reference time passes in operation1500after the water level in the washing tub120reaches the reset water level in operation1400. In this case, the reference time may be set to a time to discharge as much water as the reset water level to the outside, and stored in the memory192. For example, the reference time may be set to about 2 minutes. After the reference time passes the draining course is completed in operation1600.

Referring toFIG.10, the water level in the tub120may be identified as corresponding to the reset water level. The reset water level is a threshold water level with low reliability of a measurement value obtained by the water level sensor, and the value of the reset water level may be stored in the memory192in advance. For example, the reset water level may be set to about 10 mm to about 30 mm.

When the reference time passes in operation1500after the water level in the tub120reaches the reset water level, the controller190may determine that the draining course is completed in operation1600and start the dehydrating course1015or1024.

In various embodiments, it may be determined based on the water level in the tub120reaching the reset water level that the draining course is completed, and even when a dehydrating course begins accordingly, the controller190may control the inverter circuit230or330to operate the pump motor164at the reference rpm before the reference time passes.

According to the disclosure, without addition of hardware or a requirement for a complicated algorithm, optimal operating rpm of the pump motor164may be determined by simply using average rpm of the pump motor164during the preset period of time, thereby reducing vibration and noise that may occur in the draining course.

FIG.11illustrates operating rpm of a pump motor depending on different conditions of a washing machine, according to an embodiment.FIG.12illustrates an occasion when a water drainage height of a washing machine has a first value, according to an embodiment.FIG.13illustrates an occasion when a water drainage height of a washing machine has a second value, according to an embodiment.FIG.14illustrates a situation when a drain conduit of a washing machine is blocked by dirt, according to an embodiment.

Referring toFIG.11, it may be seen that operating rpm of the pump motor164may vary depending on different conditions of the washing machine100. The different conditions of the washing machine100may include installation conditions (e.g., drainage heights) of the washing machine100or conditions of the drain pump163(e.g., blockage of the drain conduit161).

The controller may control the inverter circuit230or330to supply the reference power to the pump motor164at the start of the draining course1014or1023, in which case the average rpm of the pump motor164during a preset period of time d1from a time t1after the passage of a reference time may be changed depending on the condition of the washing machine100.

For example, a head of fluid (hereinafter, drainage height) which refers to a vertical height of the drain conduit161may be different depending on the installation condition of the washing machine100.

Referring toFIG.12, the drainage height may be shown as being first height h1, and referring toFIG.13, the drainage height may be shown as being second height h2, which is higher than the first height h1.

In this case, depending on the installation condition of the washing machine100, the first height h1may be about 3 feet and the second height h2may be about 9 feet, without being limited thereto.

When the controller190performs power control to supply the reference power to the pump motor164, actual operating rpm of the pump motor164may be different in the conditions as shown inFIGS.12and13.

For example, when the drainage height corresponds to the first height h1, average rpm of the pump motor164during the preset period of time d1may be about 2,900 rpm, and when the drainage height corresponds to the second height h2, average rpm of the pump motor164during the preset period of time d1may be about 3,100 rpm.

As such, the average rpm of the pump motor164during the preset period of time d1is changed depending on the different condition, and this average rpm may be optimal operating rpm for each condition.

For example, as the drainage height becomes higher, the operating rpm of the pump motor164needs to be increased to drain the water in the tub120with a larger pressure difference, and as the drainage height becomes lower, the operating rpm of the pump motor164needs to be decreased to reduce vibration and noise because the water in the tub120may be drained with a smaller pressure difference,

According to the disclosure, based on the fact that the average rpm of the pump motor164during the preset period of time d1is changed depending on the different condition when the pump motor164is controlled with the reference power, optimal rpm may be calculated simply.

In another example, as shown inFIG.14, when the drain conduit161is blocked by dirt ob, the average rpm of the pump motor164during the preset period of time d1may be increased even when the drainage height is the first height h1.

When the installation condition is not changed, the reference rpm determined in a plurality of draining courses may not be significantly changed. Accordingly, in various embodiments, when a difference in reference rpm between the respective draining courses is equal to or greater than a preset value, the controller190may determine that there is a problem in the drain pump163and notify this to the user.

The controller190may control the inverter circuit230or330to operate the pump motor164at the reference rpm from a time t2at which the reference rpm is determined to a time t3at which the water level in the tub120reaches the reset water level. Similarly, the controller190may control the inverter circuit230or330to operate the pump motor164at the reference rpm even in a reference period of time d2from the time t3at which the water level in the tub120reaches the reset water level.

At a time t4after the reference period of time d2passes from the time t3at which the water level in the tub120reaches the reset water level, the controller190may determine that the draining course is completed and control the inverter circuit230or330to stop operating the pump motor164.

In various embodiments, the controller190may determine the time t3at which the water level of the tub120reaches the reset water level as an ending time of the draining course, and may control the inverter circuit230or330to operate the pump motor164at the reference rpm until the time t4at which the reference period of time d2passes from the ending time t3of the draining course even after completion of the draining course. In this case, even in the early stage of the dehydrating course, the operating rpm of the pump motor164may be kept at the reference rpm.

According to the disclosure, noise and vibration caused by the drain pump163may be minimized and the efficiency of the drain pump163may be maximized by determining the optimal reference rpm in the early stage of the draining course.

Furthermore, according to the disclosure, environmental changes of the washing machine100may be dynamically handled by determining the optimal rpm in all draining courses of the laundry cycle.

As the tub120is vibrated when the drum130is rotated at high speed in a dehydrating course, efficiency of draining is lowered when the pump motor164is maintained at a constant operating rpm.

An embodiment for maximizing efficiency of the drain pump163and minimizing noise and vibration in the draining course will now be described.

FIG.15is a flowchart illustrating an example of a method of controlling a washing machine during a dehydrating process, according to an embodiment.FIG.16illustrates operating rpm of a pump motor and a driving motor during a dehydrating process of a washing machine, according to an embodiment.

In various embodiments, the dehydrating course may include a first dehydrating course to rotate the drum130at relatively low speed and a second dehydrating course to rotate the drum130at relatively high speed, and may stop rotating the drum130in an interval between the first dehydrating course and the second dehydrating course to measure the weight of clothes for washing.

Referring toFIGS.15and16, the controller190may control target rpm of the pump motor164based on the reference rpm determined in the draining course1014or1023and the operating rpm of the driving motor140when the dehydrating course1015,1024or1031begins after completion of the draining course1014or1023.

Specifically, the controller190may determine the target rpm of the pump motor164to be proportional to the operating rpm of the driving motor140.

For example, referring to section a1ofFIG.16, the controller190may control the inverter circuit230or330to stop operating the pump motor164in operation2050, when the operating rpm of the driving motor140is lower than first preset rpm in operation2000.

In this case, the first preset rpm may be set to rpm corresponding to low-speed rotation of the drum130and stored in the memory192. For example, the first preset rpm may be set to about 110 rpm.

In the dehydrating course, water kept in the clothes is separated from the clothes by high-speed rotation of the drum130. The drain pump163may be operated in the dehydrating course not to get rid of the water remaining in the tub120but to drain the water separated from the clothes.

Hence, when the pump motor164is operated even though the driving motor140is being rotated at low speed in the dehydrating course, drain efficiency is lowered and vibration and noise occurs.

According to the disclosure, when it is determined that the drum130is rotated at low speed based on the speed of the driving motor140, the pump motor164may be stopped to reduce the vibration and noise.

The time t4ofFIG.16refers to a point in time at which a draining course is completed and a dehydrating course begins. Even when the water level in the tub120reaches the reset water level, the controller190controls the inverter circuit230or330to operate the pump motor164at the reference rpm in the reference period of time d2. Hence, the controller190may control the inverter circuit230or330to operate the pump motor164at the reference rpm even when the operating rpm of the driving motor140is lower than the first preset rpm in the first dehydrating course.

The purpose of operating the pump motor164at the reference rpm even when the operating rpm of the driving motor140is lower than the first preset rpm is to get rid of the water remaining in the tub120rather than to drain the water separated from the clothes because the first dehydrating course is an early stage of a dehydrating course.

Referring to section a2ofFIG.16, the controller190may control the inverter circuit230or330to operate the pump motor164at the reference rpm in operation2150, when the operating rpm of the driving motor140is higher than the first preset rpm in2000and lower than second preset rpm in operation2100.

In this case, the second preset rpm may be set to rpm at which the drum130is rotated at relatively high speed to separate much of water from the clothes, and stored in the memory192. For example, the second preset rpm may be set to about 130 rpm.

When the operating rpm of the driving motor140is equal to or higher than the first preset rpm, vibration may occur in the tub120, which may prevent the water separated from the clothes from being discharged outside unless the pump motor164is operated. Accordingly, drain efficiency is lowered unless the pump motor164is operated.

According to the disclosure, when the tub120is vibrated to a certain extent and water is separated from the clothes due to the speed of the driving motor140, the pump motor164may be operated at the reference rpm, thereby increasing drain efficiency.

Referring to section a3ofFIG.16, the controller190may control the inverter circuit230or330to operate the pump motor164at first rpm (reference rpm+a) higher than the reference rpm in operation2250, when the operating rpm of the driving motor140is higher than the second preset rpm in operation2100and lower than third preset rpm in operation2200.

In this case, the third preset rpm may be set to rpm at which the drum130is rotated at high speed to separate much of water from the clothes, and stored in the memory192. For example, the third preset rpm may be set to about 300 rpm.

Furthermore, the first rpm may be dynamically determined by adding a first preset value α to the reference rpm, and the first preset value α may be set to as high rpm as to increase efficiency of the drain pump163to a small extent and stored in the memory192. For example, the first preset value α may be set to about 200 rpm.

When the operating rpm of the driving motor140is equal to or higher than the second preset rpm, significant vibration may occur in the tub120, which may prevent the water separated from the clothes from being discharged outside unless the pump motor164is operated at higher rpm. Hence, the drain efficiency is lowered when the operating rpm of the pump motor164is maintained at the reference rpm.

Furthermore, as noise occurs due to vibration of the tub120when the drum130is rotated at high speed, noise occurring from the drain pump163may be canceled out by the noise from the vibration of the tub120even when the operating rpm of the drain pump163is increased.

According to the disclosure, when the tub120is vibrated due to the speed of the driving motor140and the efficiency of the drain pump163is lowered, the pump motor164may be operated at the first rpm higher than the reference rpm, thereby increasing drain efficiency.

Referring to section a4ofFIG.16, the controller190may control the inverter circuit230or330to operate the pump motor164at second rpm (reference rpm+β) higher than the reference rpm in operation2300, when the operating rpm of the driving motor140is higher than the third preset rpm in operation2200.

In this case, the second rpm may be dynamically determined by adding a second preset value β to the reference rpm, and the second preset value β may be a value greater than the first preset value α, may be set to as high rpm as to increase efficiency of the drain pump163to a small extent and stored in the memory192. For example, the second preset value β may be set to about 300 rpm.

When the operating rpm of the driving motor140is equal to or higher than the third preset rpm, significant vibration may occur in the tub120, which may prevent the water separated from the clothes from being discharged outside unless the pump motor164is operated at higher rpm. Hence, the drain efficiency is lowered when the operating rpm of the pump motor164is maintained at the reference rpm.

Furthermore, as noise occurs due to vibration of the tub120when the drum130is rotated at high speed, noise occurring from the drain pump163may be canceled out by the noise from the vibration of the tub120even when the operating rpm of the drain pump163is increased.

According to the disclosure, when the tub120is vibrated due to the speed of the driving motor140and the efficiency of the drain pump163is lowered, the pump motor164may be operated at the second rpm higher than the reference rpm, thereby increasing drain efficiency.

Referring to section a5ofFIG.16, in various embodiments, the controller190may subdivide the operating rpm section of the driving motor140to increase the rpm of the pump motor164.

Specifically, the controller190may control the inverter circuit230or330to rotate the pump motor164at higher speed than the second rpm (reference rpm+β) when the operating rpm of the driving motor140is higher than fourth preset rpm that is higher than the third preset rpm.

In other words, the disclosure may employ any algorithm to increase the operating rpm of the pump motor164with an increase in operating rpm of the driving motor140in the dehydrating course.

According to the disclosure, vibration and noise may be minimized and drain efficiency may be maximized by dynamically controlling the operating rpm of the pump motor164in the dehydrating course.

Furthermore, according to the disclosure, the drain efficiency may be maximized by increasing the operating rpm of the pump motor164when the efficiency of the pump motor164is lowered due to vibration occurring at the tub120when the drum130is rotated at high speed.

Moreover, according to the disclosure, the drain efficiency may be maximized without an increase in noise felt by the user because the operating rpm of the pump motor164increases only when the tub120is vibrated significantly.

FIG.17is a flowchart illustrating an example of a method of controlling a washing machine, according to an embodiment.

Referring toFIG.17, the controller190in an embodiment may store reference rpm determined in the draining course1014or1023in the memory192and use the reference rpm.

In an embodiment, the controller190may determine the reference rpm in the draining course1014of the washing process1010, in operation3000, and control pump rpm for the draining course1023of the rinsing process1020based on the reference rpm determined in the draining course1014of the washing process1010, in operation3100.

For example, the controller190may control the inverter circuit230or330to operate the pump motor164at the reference rpm determined in the draining course1014of the washing process1010at the start of the draining course1023of the rinsing process1020.

In another embodiment, the controller190may determine that there is a problem with the drain pump163when a difference between first reference rpm determined in a first draining course (e.g., a draining course in the previous laundry cycle/a draining course in the washing process) and second reference rpm determined in a second draining course (e.g., a draining course in the next laundry cycle/a draining course in the rinsing process) starting after the first draining course, and control the display112to output a visual indication to indicate that there is a problem with the drain pump163.

For example, the controller190may control the display112to output text that queries as to whether an installation condition of the washing machine100has been changed, and control the display112to output a visual indication to indicate that there is a problem with the drain pump163based on reception of a user input indicating that the installation condition of the washing machine100has not been changed.

For example, the controller190may control the display112to output such a text as “there is a problem with the drain pump” or various visual indications such as icons, figures and/or colors of the drain pump163.

In another example, the controller190may notify the user that there is a problem with the drain pump163by controlling the display112to output text such as “the installation condition of the washing machine has been changed or problem occurs in the drain pump”.

In various embodiments, the controller100may use various kinds of components to provide many different feedback indicating that there is a problem with the drain pump163.

For example, the controller190may use a speaker and/or a buzzer to output a sound indicating that there is a problem with the drain pump163.

According to the disclosure, a change in installation condition of the washing machine100or an error of the discharge pump163may be detected by storing and comparing reference rpm values determined in the respective draining courses.

Furthermore, according to the disclosure, the pump motor164may be operated at optimal rpm in the early stage of the draining course by using the reference rpm determined in each draining course.

FIG.18is a flowchart illustrating another example of a method of controlling a washing machine during a dehydrating process, according to an embodiment.

Referring toFIG.18, as described inFIG.16, the controller190may control target rpm of the pump motor164based on an amount of vibration of the tub120obtained from the vibration sensor180and the reference rpm determined in the draining course1014or1023when the dehydrating course1015,1024or1031begins after completion of the dehydrating course1014or1023.

Specifically, the controller190may determine the target rpm of the pump motor164to be proportional to the amount of vibration of the tub120.

As the rotation speed of the driving motor140and the amount of vibration of the tub120are proportional to each other, overlapping description withFIG.16will not be repeated.

The controller190may control the inverter circuit230or330to stop operating the pump motor164in operation5050, when the amount of vibration of the tub120is smaller than a first preset amount of vibration in operation5000.

In this case, the first preset amount of vibration may be set to a value corresponding to an amount of vibration occurring at the tub120when the driving motor140is rotated at the first preset rpm, and stored in the memory192.

The controller190may control the inverter circuit230or330to operate the pump motor164at the reference rpm even when the amount of vibration of the tub120is smaller than the first preset amount of vibration in the first dehydrating course.

The controller190may control the inverter circuit230or330to operate the pump motor164at the reference rpm in operation5150, when the amount of vibration of the tub120is larger than the first preset amount of vibration in operation5000and smaller than a second preset amount of vibration in operation5100.

In this case, the second preset amount of vibration may be set to a value corresponding to an amount of vibration occurring at the tub120when the driving motor140is rotated at the second preset rpm, and stored in the memory192.

The controller190may control the inverter circuit230or330to operate the pump motor164at the first rpm (reference rpm+α) higher than the reference rpm in operation5250, when the amount of vibration of the tub120is larger than the second preset amount of vibration in operation5100and smaller than a third preset amount of vibration in operation5200.

In this case, the third preset amount of vibration may be set to a value corresponding to an amount of vibration occurring at the tub120when the driving motor140is rotated at the third preset rpm, and stored in the memory192.

The controller190may control the inverter circuit230or330to operate the pump motor164at the second rpm (reference rpm+β) higher than the reference rpm in operation5300, when the amount of vibration of the tub120is larger than the third preset amount of vibration in operation5200.

According to the disclosure, the drain efficiency may be improved by increasing the operating rpm of the pump motor164when the efficiency of the drain pump163is lowered due to a large amount of vibration of the tub120. Moreover, according to the disclosure, the drain efficiency may be maximized without an increase in noise felt by the user because the operating rpm of the pump motor164increases only when the tub120is vibrated significantly.

Meanwhile, the embodiments of the disclosure may be implemented in the form of a recording medium for storing instructions to be carried out by a computer. The instructions may be stored in the form of program codes, and when executed by a processor, may generate program modules to perform operation in the embodiments of the disclosure. The recording media may correspond to computer-readable recording media.

The computer-readable recording medium includes any type of recording medium having data stored thereon that may be thereafter read by a computer. For example, it may be a ROM, a RAM, a magnetic tape, a magnetic disk, a flash memory, an optical data storage device, etc.

The computer-readable storage medium may be provided in the form of a non-transitory storage medium. The term ‘non-transitory storage medium’ may mean a tangible device without including a signal, e.g., electromagnetic waves, and may not distinguish between storing data in the storage medium semi-permanently and temporarily. For example, the non-transitory storage medium may include a buffer that temporarily stores data.

In an embodiment of the disclosure, the aforementioned method according to the various embodiments of the disclosure may be provided in a computer program product. The computer program product may be a commercial product that may be traded between a seller and a buyer. The computer program product may be distributed in the form of a recording medium (e.g., a compact disc read only memory (CD-ROM)), through an application store (e.g., Play Store™), directly between two user devices (e.g., smart phones), or online (e.g., downloaded or uploaded). In the case of online distribution, at least part of the computer program product (e.g., a downloadable app) may be at least temporarily stored or arbitrarily created in a recording medium that may be readable to a device such as a server of the manufacturer, a server of the application store, or a relay server.

The embodiments of the disclosure have thus far been described with reference to accompanying drawings. It will be obvious to those of ordinary skill in the art that the disclosure may be practiced in other forms than the embodiments as described above without changing the technical idea or essential features of the disclosure. The above embodiments are only by way of example, and should not be construed in a limited sense.