Washing machine and control method thereof
Disclosed are a washing machine and a control method thereof to alleviate high-frequency noise generated during rotation of a motor. The washing machine includes a speed sensing unit to sense a speed of the motor, and a control unit to output a speed control signal to adjust the speed of the motor. The control unit confirms whether to enter a constant-speed period upon progress of a dehydration operation, and repeatedly raises or lowers the speed of the universal motor within a predetermined magnitude range if it is confirmed to enter the constant-speed period, thereby alleviating high-frequency noise.
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1. Field
Embodiments of the present invention relate to a washing machine and a control method thereof to alleviate high-frequency noise generated during rotation of a motor.
2. Description of the Related Art
Generally, washing machines may be classified into a drum washing machine, a pulsator washing machine, and an agitator washing machine. The drum washing machine washes clothes using collision force between wash water and the clothes as the clothes drop by rotation of a drum. The pulsator washing machine washes clothes by friction between the clothes and wash water as a pulsator is rotated at a bottom surface of a drum. The agitator washing machine washes clothes by friction between the clothes and wash water as an agitator mounted in a washtub forcibly generates water streams.
The above-described various kinds of washing machines performs a washing operation in such a manner that the drum, the pulsator, or the agitator is rotated forward or reverse at a low speed to rotate the wash water or to agitate the clothes. Also, a dehydration operation is performed in such a manner that the drum, in which all of the clothes are received, is rotated at a high speed to apply centrifugal force to the clothes, causing water remaining on the clothes to be removed by the centrifugal force.
Meanwhile, a motor of these washing machines is generally rotated by a Pulse Width Modulation (PWM) control method. In the PWM control method, a specific form of PWM signal is output by inputting a sinusoidal reference signal and a triangular wave carrier signal into a comparator and comparing them with each other. The PWM signal controls switching of an inductor. A motor drive signal output from the inductor is input to each coil of the motor, inducing rotational force of the motor. The PWM control method serves to change a rotational speed of the motor by, e.g., changing frequencies of triangular and sinusoidal waves.
SUMMARYTherefore, it is an aspect of the present invention to provide a washing machine and a control method thereof to alleviate high-frequency noise generated during a constant-speed period of a dehydration operation.
Additional aspects of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
In accordance with one aspect of the present invention, a control method of a washing machine includes confirming whether to enter a constant-speed period upon progress of a dehydration operation, and repeatedly raising or lowering a speed of a universal motor within a predetermined magnitude range if it is confirmed to enter the constant-speed period, so as to alleviate high-frequency noise.
The repeated raising or lowering of the speed of the universal motor within the predetermined magnitude range may include adjusting a command speed of the universal motor to repeatedly raise or lower the speed of the universal motor within the predetermined magnitude range.
The adjustment of the command speed of the universal motor may include repeatedly raising or lowering the command speed of the universal motor within a predetermined magnitude range.
The repeated raising or lowering of the speed of the universal motor within the predetermined magnitude range may include adjusting a voltage applied to the universal motor to repeatedly raise or lower the speed of the universal motor within the predetermined magnitude range.
The adjustment of the voltage applied to the universal motor may include repeatedly raising or lowering the voltage applied to the universal motor within a predetermined magnitude range.
The repeated raising or lowering of the voltage applied to the universal motor within the predetermined magnitude range may include adjusting a duty ratio of the voltage to repeatedly raise or lower the voltage applied to the universal motor within the predetermined magnitude range.
The repeated raising or lowering of the voltage applied to the universal motor within the predetermined magnitude range may include adjusting a phase of the voltage to repeatedly raise or lower the voltage applied to the universal motor within the predetermined magnitude range.
The repeated raising or lowering of the speed of the universal motor within the predetermined magnitude range may include periodically repeatedly raising or lowering the speed of the universal motor within the predetermined magnitude range.
The repeated raising or lowering of the speed of the universal motor within the predetermined magnitude range may include aperiodically repeatedly raising or lowering the speed of the universal motor within the predetermined magnitude range.
In accordance with another aspect of the present invention, a washing machine includes a universal motor, and a control unit to repeatedly raise or lower a speed of the universal motor within a predetermined magnitude range if it is confirmed to enter a constant-speed period upon progress of a dehydration operation, so as to alleviate high-frequency noise.
The control unit may repeatedly raise or lower the speed of the universal motor within the predetermined magnitude range by adjusting a command speed of the universal motor.
The control unit may repeatedly raise or lower the speed of the universal motor within the predetermined magnitude range by adjusting a voltage applied to the universal motor.
The control unit may repeatedly raise or lower the speed of the universal motor within the predetermined magnitude range by repeatedly raising or lowering the voltage applied to the universal motor within a predetermined magnitude range.
The control unit may repeatedly raise or lower the voltage applied to the universal motor within the predetermined magnitude range by adjusting a duty ratio of the voltage.
The control unit may repeatedly raise or lower the voltage applied to the universal motor within the predetermined magnitude range by adjusting a phase of the voltage.
The control unit may periodically repeatedly raise or lower the speed of the universal motor within the predetermined magnitude range.
The control unit may aperiodically repeatedly raise or lower the speed of the universal motor within the predetermined magnitude range.
These and/or other aspects of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
Reference will now be made in detail to the embodiment of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.
As shown in
The housing 20 defines the outer appearance of the washing machine 10. The housing 20 receives a variety of devices required to operate the washing machine 10. The front surface of the housing 20 has an opening 22, to which a door 25 is hinged to open or close the opening 22. The door 25 is centrally provided with an observation window 27, to allow a user to observe the progress of washing from the outside without opening the door 25.
The control panel 30 includes a variety of operating buttons (not shown) required by the user to operate the washing machine 10 and a display window (not shown) to show the progress of washing. The control panel 30 is coupled to the upper end of the front surface of the housing 20 via hook fastening or screwing. A controller (not shown) is installed at a rear end of the control panel 30 and generates control signals required, e.g., to determine the supply amount of water, to adjust the amounts of wash water and rinse water, to control the progress of washing and rinsing, and to change a rotational speed of the universal motor 29.
The drum 40 mounted in the housing 20 has a cylindrical shape and receives laundry therein to provide a space in which washing of the laundry is actually performed. In consideration of the fact that the drum 40 comes into direct contact with wash water, the drum 40 is made of, e.g., rustproof stainless steel. The drum 40 is rotated clockwise or counterclockwise upon receiving rotational force from the universal motor 29, causing washing of the laundry.
The tub 50 is configured to surround the drum 40 and provides a space to receive wash water therein. An inlet channel 52 is connected at one end thereof to an upper end of the tub 50 to introduce the wash water into the tub 50. The other end of the inlet channel 52 is connected to a water source at the outside of the housing 20. A detergent box 53 is located on a portion of the inlet channel 52. Detergent received in the detergent box 53 is dissolved in the wash water as the wash water passes through the detergent box 53. The resulting detergent dissolved wash water is introduced into the tub 50 through the inlet channel 52. An outlet channel 54 to discharge the wash water is connected to a lower end of the tub 50 out of the tub 50. Specifically, the outlet channel 54 serves to discharge contaminated wash water generated during washing out of the washing machine 10 based on a control signal of the controller. If the drum 40 undergoes eccentricity due to the laundry or the wash water, the tub 50 linked to the drum 40 is vibrated. To alleviate vibration of the tub 50, the tub 50 is connected to the housing 20 by use of a supporting device (not shown). A door packing 58 is fitted between the tub 50 and the opening 22 of the housing 20. The door packing 58 is made of a flexible material and thus, acts to prevent vibration of the tub 50 from being directly transmitted to the housing 20.
The universal motor 29 rotates the drum 40, to perform a washing operation, a rinsing operation, and a dehydration operation. Specifically, if commercial alternating current (AC) power output from a power source unit 60 whose a duty ratio or phase is controlled is transmitted to the universal motor 29, rotational force of the universal motor 29 is changed, causing the drum 40, in which the laundry is received, to be rotated at a predetermined speed.
As shown in
In the above-described universal motor 29, if AC power is applied to a coil of the stator 2, electricity moving through the coil of the stator 2 is supplied to the rectifier 5 through one of the brushes 7. The electricity supplied to the rectifier 5 is rectified into direct current (DC) and is supplied to a coil of the rotor 200. The electricity moving through the coil of the rotor 200 is supplied to the coil of the stator 2 through an opposite one of the brushes 7, escaping out of the motor 29. A magnetic field created in the motor 29 upon the above-described movement of the power causes rotation of the rotor 200.
With the above-described configuration of the universal motor 29, the brushes 7 and the rectifier 5 may cause high-frequency noise due to mechanical friction when the universal motor 29 is rotated at a high speed. In addition, as shown in
As shown in
The operation manipulating unit 80 outputs an electric signal corresponding to a user input command when the user selects a washing course (e.g., a washing operation and a rinsing operation).
The speed sensing unit 90 senses the speed of the universal motor 29 to output and transmit a corresponding sensed signal to the control unit 100. For example, the speed sensing unit 90 may be a hall sensor.
The control unit 100 outputs a speed control signal to adjust the speed of the universal motor 29 (or a speed of the drum 40) and a switching control signal to rotate the universal motor 29 forward or reverse. Specifically, the control unit 100 receives key signals transmitted from the operation manipulating unit 80 and outputs the speed control signal for adjustment of the speed of the universal motor 29 to the triac 72 and the switching control signal for forward or reverse rotation of the universal motor 29 to the first and second relays 74 and 76.
The control unit 100 repeatedly raises or lowers the speed of the universal motor 29 within a predetermined magnitude range by changing a command speed of the universal motor 29 during a high or low constant-speed period of a dehydration operation, to alleviate high-frequency noise.
In addition, the control unit 100 repeatedly raises or lowers the speed of the universal motor 29 within the predetermined magnitude range by changing a voltage applied to the universal motor 29 during the high or low constant-speed period of the dehydration operation, to alleviate high-frequency noise.
The control unit 100 repeatedly raises or lowers the voltage applied to the universal motor 29 within a predetermined magnitude range by adjusting a duty ratio of commercial AC power applied from the power source unit 60.
The control unit 100 controls a phase of commercial AC power applied from the power source unit 60 to a Pulse Width Modulation (PWM) signal as the speed control signal, thereby repeatedly raising or lowering the voltage applied to the universal motor 29 within the predetermined magnitude range. The control unit 100 adjusts an input voltage applied to the universal motor 29 via the phase control, thereby changing the rotational force of the universal motor 29.
The triac 72 performs an On/Off operation by the speed control signal transmitted from the control unit 100. With the On/Off operation of the triac 72, the commercial AC power of the power source unit 60 is supplied to the rectifier 78 or is intercepted. The triac 72 controls the applied commercial AC power to a firing angle based on the PWM signal as the speed control signal, so as to change a magnitude of output voltage and consequently, to change the rotational speed of the universal motor 29. That is, the triac 72 controls phase or duty ratio of commercial AC power so as to supply the controlled power to the universal motor 29.
The first relay 74 and the second relay 76 are switched by the switching control signal of the control unit 100, causing forward or reverse rotation of the universal motor 29. For example, if the switching control signal switches the first relay 74 to an A terminal and the second relay 76 to a D terminal, the voltage is supplied to a rotor 29a and a stator 29b of the universal motor 29 via the A terminal of the first relay 74 and the D terminal of the second relay 76, causing forward rotation of the universal motor 29. With the forward rotation of the universal motor 29, the drum 40 is rotated forward, performing the dehydration operation. On the other hand, if the switching control signal switches the first relay 74 to a B terminal and the second relay 76 to a C terminal, the universal motor 29 is rotated in reverse.
The power source unit 60 supplies the commercial AC power required to drive the washing machine 10, and the rectifying unit 78 rectifies and outputs the commercial AC power supplied from the power source unit 60.
The universal motor 29 is driven upon receiving a predetermined voltage output from the rectifying unit 78 and includes the rotor 29a and the stator 29b.
In
To alleviate the high-frequency noise, the control unit 100 repeatedly raises or lowers the command speed of the universal motor 29 within a predetermined magnitude range (for example, 20 rpms). When the command speed of the universal motor 29 is repeatedly raised or lowered within the predetermined magnitude range, an actual speed of the universal motor 29 is repeatedly raised or lowered within a predetermined magnitude range. It may be seen from
As shown in
Next, if it is confirmed to enter the high or low constant-speed period, the control unit 100 repeatedly raises or lowers the speed of the universal motor 29 within the predetermined magnitude range by adjusting the command speed of the universal motor 29. To alleviate the high-frequency noise, the control unit 100 repeatedly raises or lowers the command speed of the universal motor 29 within the predetermined magnitude range (for example, 20 rpms). When the command speed of the universal motor 29 is repeatedly raised or lowered within the predetermined magnitude range (for example, 20 rpms), the actual speed of the universal motor 29 is repeatedly raised or lowered within the predetermined magnitude range (S30).
Next, the control unit 100 confirms whether the dehydration operation is terminated, e.g., by the lapse of a dehydration operation time. If the termination of the dehydration operation is confirmed, the control unit 100 changes the command speed of the universal motor 29 to a command speed depending on a following operation (S40 and S50).
As shown in
Next, if it is confirmed to enter the high or low constant-speed period, the control unit 100 repeatedly raises or lowers the speed of the universal motor 29 within the predetermined magnitude range by adjusting the voltage applied to the universal motor 29. To alleviate the high-frequency noise, the control unit 100 repeatedly raises or lowers the voltage applied to the universal motor 29 within the predetermined magnitude range (for example, 2V). When the voltage applied to the universal motor 29 is repeatedly raised or lowered within the predetermined magnitude range (for example, 2V), the actual speed of the universal motor 29 is repeatedly raised or lowered within the predetermined magnitude range (for example, 20 rpms). The control unit 100 adjusts the voltage applied to the universal motor 29 by controlling the phase of commercial AC power to the PWM signal as the speed control signal. The control unit 100 also adjusts the voltage applied to the universal motor 29 by controlling the duty ratio of commercial AC power (S120).
Next, the control unit 100 confirms whether the dehydration operation is terminated, e.g., by the lapse of the dehydration operation time. If the termination of the dehydration operation is confirmed, the control unit 100 changes the voltage applied to the universal motor 29 to a voltage depending on a following operation (S130 and S140).
As is apparent from the above description, according to the embodiment of the present invention, a speed of a universal motor is repeatedly raised or lowered within a predetermined magnitude range if the motor enters a high or low constant-speed period of a dehydration operation, resulting in alleviated high-frequency noise.
Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that varies may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.
Claims
1. A control method of a washing machine comprising:
- confirming whether to enter a constant-speed period upon progress of a dehydration operation; and
- repeatedly raising or lowering a speed of a universal motor within a predetermined magnitude range if it is confirmed to enter the constant-speed period, so as to alleviate high-frequency noise.
2. The control method according to claim 1, wherein the repeated raising or lowering of the speed of the universal motor within the predetermined magnitude range includes adjusting a command speed of the universal motor to repeatedly raise or lower the speed of the universal motor within the predetermined magnitude range.
3. The control method according to claim 2, wherein the adjustment of the command speed of the universal motor includes repeatedly raising or lowering the command speed of the universal motor within a predetermined magnitude range.
4. The control method according to claim 1, wherein the repeated raising or lowering of the speed of the universal motor within the predetermined magnitude range includes adjusting a voltage applied to the universal motor to repeatedly raise or lower the speed of the universal motor within the predetermined magnitude range.
5. The control method according to claim 4, wherein the adjustment of the voltage applied to the universal motor includes repeatedly raising or lowering the voltage applied to the universal motor within a predetermined magnitude range.
6. The control method according to claim 5, wherein the repeated raising or lowering of the voltage applied to the universal motor within the predetermined magnitude range includes adjusting a duty ratio of the voltage to repeatedly raise or lower the voltage applied to the universal motor within the predetermined magnitude range.
7. The control method according to claim 5, wherein the repeated raising or lowering of the voltage applied to the universal motor within the predetermined magnitude range includes adjusting a phase of the voltage to repeatedly raise or lower the voltage applied to the universal motor within the predetermined magnitude range.
8. The control method according to claim 1, wherein the repeated raising or lowering of the speed of the universal motor within the predetermined magnitude range includes periodically repeatedly raising or lowering the speed of the universal motor within the predetermined magnitude range.
9. The control method according to claim 1, wherein the repeated raising or lowering of the speed of the universal motor within the predetermined magnitude range includes aperiodically repeatedly raising or lowering the speed of the universal motor within the predetermined magnitude range.
10. A washing machine comprising:
- a universal motor; and
- a control unit to repeatedly raise or lower a speed of the universal motor within a predetermined magnitude range if it is confirmed to enter a constant-speed period upon progress of a dehydration operation, so as to alleviate high-frequency noise.
11. The washing machine according to claim 10, wherein the control unit repeatedly raises or lowers the speed of the universal motor within the predetermined magnitude range by adjusting a command speed of the universal motor.
12. The washing machine according to claim 10, wherein the control unit repeatedly raises or lowers the speed of the universal motor within the predetermined magnitude range by adjusting a voltage applied to the universal motor.
13. The washing machine according to claim 12, wherein the control unit repeatedly raises or lowers the speed of the universal motor within the predetermined magnitude range by repeatedly raising or lowering the voltage applied to the universal motor within a predetermined magnitude range.
14. The washing machine according to claim 12, wherein the control unit repeatedly raises or lowers the voltage applied to the universal motor within the predetermined magnitude range by adjusting a duty ratio of the voltage.
15. The washing machine according to claim 12, wherein the control unit repeatedly raises or lowers the voltage applied to the universal motor within the predetermined magnitude range by adjusting a phase of the voltage.
16. The washing machine according to claim 10, wherein the control unit periodically repeatedly raises or lowers the speed of the universal motor within the predetermined magnitude range.
17. The washing machine according to claim 10, wherein the control unit aperiodically repeatedly raises or lowers the speed of the universal motor within the predetermined magnitude range.
18. The control method according to claim 1, wherein the predetermined magnitude range to raise or lower the speed of the universal motor is 20 rpm.
19. The control method according to claim 4, wherein the predetermined magnitude range to adjust the voltage applied to the universal motor to repeatedly raise or lower the speed of the universal motor is 2V.
20. The control method according to claim 1, wherein an operation frequency band of the universal motor is 2 kHz to 4 kHz when the universal motor is rotated at 970 rpm.
Type: Application
Filed: Jun 2, 2010
Publication Date: Mar 10, 2011
Applicant: SAMSUNG ELECTRONICS CO., LTD. (Suwon-si)
Inventor: Jun Hyun Park (Osan-si)
Application Number: 12/801,310
International Classification: D06L 1/20 (20060101); D06F 37/00 (20060101);