Washing machine and control method of the same

Abstract

To acquire a washing machine capable of suppressing heat generation from a motor drive circuit when rotating a pulsator.SOLUTION: A washing machine: a washing tub in which laundry is stored; a pulsator disposed in the washing tub; a motor for rotating the pulsator; a motor drive circuit for driving the motor; and a control device. The control device includes: a cloth amount detection part for detecting the cloth amount which is the amount of the laundry stored in the washing tub; and a setting part for setting a current value of a control current supplied to the motor from the motor drive circuit for rotating the pulsator, based on the cloth amount detected by the cloth amount detection part.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a washing machine and a control method thereof. [Background technology]

[0002] A washing machine according to the background art is disclosed in Patent Document 1. The washing machine includes a pulsator, a motor, a motor drive circuit, a power supply circuit, a control unit, and a laundry amount detection unit. The power supply circuit supplies current to the motor. The control unit executes acceleration control, constant speed control, and pause control of the motor. The laundry amount detection unit detects the amount of laundry based on the average current value during constant speed control or the rotation angle of the motor during pause control. This allows the laundry amount to be detected easily and accurately without using a position sensor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 065539 Summary of the Invention [Problem to be solved by the invention]

[0004] In the washing machine disclosed in Patent Document 1, sufficient measures are not taken against heat generated from the motor drive circuit when the pulsator is rotated.

[0005] An object of the present disclosure is to provide a washing machine and a control method thereof that can suppress heat generation from a motor drive circuit when rotating a pulsator. [Means for solving the problem]

[0006] A washing machine according to one aspect of the present disclosure comprises a washing tub in which laundry is stored, a pulsator disposed in the washing tub, a motor for rotating the pulsator, a motor drive circuit for driving the motor, and a control device, wherein the control device has a laundry amount detection unit for detecting the amount of laundry stored in the washing tub, and a setting unit for setting the current value of a control current supplied from the motor drive circuit to the motor to rotate the pulsator based on the amount of laundry detected by the laundry amount detection unit.

[0007] Another aspect of the present disclosure provides a method for controlling a washing machine that includes a washing machine tub containing laundry, a pulsator disposed in the washing tub, a motor for rotating the pulsator, and a motor drive circuit for driving the motor, wherein a control device detects the amount of laundry contained in the washing tub, and sets the current value of a control current supplied from the motor drive circuit to the motor to rotate the pulsator based on the detected amount of laundry. [Effects of the Invention]

[0008] According to the present disclosure, heat generation from the motor drive circuit when rotating the pulsator can be suppressed. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of a main part showing a simplified configuration of a washing machine according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a simplified block diagram showing the configuration of a motor drive system. [Figure 3] FIG. 2 is a diagram showing some of the functions of a control means. [Figure 4] FIG. 2 is an equivalent circuit diagram of the motor. [Figure 5] FIG. 2 is a simplified block diagram showing the configuration of a control unit when open-loop control is performed. [Figure 6] FIG. 3 is a simplified block diagram showing the configuration of a control unit when feedback control is performed. [Figure 7]FIG. 2 is a block diagram showing a configuration of a speed phase estimation means. [Figure 8] 4 is a timing chart showing a simplified agitation operation by a pulsator. [Figure 9] 10 is a flowchart simply showing a process executed by a control unit in, for example, a washing step including an agitation operation. [Figure 10] 10 is a timing chart showing, in simplified form, the rotation speed of the pulsator and the waveform of the current value of the control current for two successive stirring operations. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Findings that formed the basis of this disclosure) Conventional washing machines use position sensors such as Hall elements or rotary encoders to detect motor rotation (detection of rotation speed and rotation position). However, from the perspective of cost reduction and structural constraints, washing machines that control motors using a so-called sensorless method, which detects rotation without using a position sensor, have been put into practical use.

[0011] One type of sensorless method is a method that uses induced voltage. This method detects the motor current flowing through the motor, calculates the induced voltage based on the voltage applied to the motor and the motor current, and estimates the motor rotation speed based on this induced voltage.

[0012] The induced voltage is proportional to the rotational speed of the motor, so in the low-speed region where the motor rotational speed is low, the induced voltage is small and the motor rotational speed cannot be accurately estimated.

[0013] Therefore, the sensorless method using induced voltage has a motor control period consisting of an open-loop control period in the low-speed range and a feedback control period in the high-speed range. Open-loop control is control that does not estimate the motor rotation speed and does not feed back the estimated rotation speed value to the input side. In open-loop control, the voltage applied to the motor is controlled based on a target value of the control current (magnetic flux current or torque current) supplied to the motor and a target value of the motor rotation speed. Feedback control is control that estimates the motor rotation speed based on the induced voltage and feeds back the estimated rotation speed value to the input side. In feedback control, the control current (magnetic flux current or torque current) and the voltage applied to the motor are controlled based on the deviation between the target value of the motor rotation speed and the fed-back estimated value.

[0014] In vertical washing machines, a pulsator is located at the bottom of the washing tub (washing and spin-drying tub). During the washing or rinsing process, the pulsator is rotated by a motor to generate a water flow in the washing tub, which agitates the laundry.

[0015] In the washing machine according to the background art, in the open-loop control for rotating the pulsator, the target value of the control current is set to a relatively large value (e.g., 5 A) so that the pulsator can rotate reliably even when the maximum load of laundry is placed in the washing tub. Therefore, when the pulsator rotates, an extremely large current (e.g., 10 A) flows instantaneously, causing excessive heat generation in the motor drive circuit, such as an IPM (Intelligent Power Module).

[0016] In order to solve this problem, the inventor discovered that heat generation from the motor drive circuit can be suppressed by detecting the amount of laundry contained in the washing tub and appropriately setting the current value of the control current based on the detected amount of laundry, and this finding formed the subject of the present disclosure.

[0017] Therefore, the present disclosure provides a washing machine and a control method thereof that can suppress heat generation from a motor drive circuit when rotating a pulsator.

[0018] (Embodiments of the present disclosure) Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters or redundant description of substantially the same configuration may be omitted.

[0019] The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the disclosure, and are not intended to limit the subject matter described in the claims.

[0020] FIG. 1 is a cross-sectional view of a main part showing, in a simplified form, the configuration of a washing machine according to an embodiment of the present disclosure.

[0021] A washing and spin-drying tub (washing tub) 2 is disposed inside a water receiving tub 3 so as to be rotatable left and right. A pulsator 1 is disposed on the inner bottom of the washing and spin-drying tub 2 so as to be rotatable left and right. A motor 4 is disposed on the outer bottom of the water receiving tub 3. When the motor 4 rotates, its torque is transmitted to the pulsator 1 via a motor pulley 31, a belt 5, an impeller pulley 32, and a speed reducer / clutch 6. The speed reducer / clutch 6 connects or disconnects the pulsator 1 and the washing and spin-drying tub 2. This allows the motor 4 to rotate the pulsator 1 and the washing and spin-drying tub 2 together, or to rotate only the pulsator 1. Note that, in this embodiment, the rotation of the motor 4 is transmitted to the pulsator 1 and the washing and spin-drying tub 2 via the belt 5, but this is not limiting. A direct drive system may be employed in which the rotation of the motor 4 is transmitted to the pulsator 1 and the washing and spin-drying tub 2 without a belt.

[0022] A panel unit 10 is disposed on top of the washing machine's outer frame 9. A lid 11 that can be opened and closed is disposed on the top surface of the panel unit 10. A control device 13 having a display unit 12 is disposed inside the panel unit 10. The control device 13 controls all of the washing processes performed by the washing machine. The washing processes include a washing process, a rinsing process, and a spin-drying process, and the desired washing process is performed according to the washing course input by the user. The control device 13 performs the washing processes by controlling the operation of the motor 4, the reduction mechanism / clutch 6, the geared motor 7, the water supply valve 14, the drain valve 15, etc. The geared motor 7 has a brake belt 8 that mechanically brakes the rotation of the washing / spin-drying tub 2 by contacting the rotating part.

[0023] FIG. 2 is a block diagram showing a simplified configuration of the motor drive system.

[0024] The motor drive system includes a rectifier circuit 16, an inverter circuit 17, a current detection means 18, a PWM control means 19, and a control means 20. The control means 20 is configured using a microcontroller or the like. The control means 20 may be part of the functions of the control device 13.

[0025] FIG. 3 is a diagram showing some of the functions of the control means 20. As shown in FIG.

[0026] The control means 20 has a control unit 51, a laundry amount detection unit 52, a setting unit 53, an error calculation unit 54, and a correction unit 55 as functions realized by a processor such as a CPU executing a program. The control means 20 may be configured without the error calculation unit 54 and the correction unit 55. The details of the processing executed by each of these units will be described later.

[0027] Referring to Fig. 2, the rectifier circuit 16 is configured as, for example, a voltage doubler rectifier circuit. The rectifier circuit 16 voltage-doubles and rectifies an AC voltage input from an AC power supply, thereby inputting a DC voltage Vdc to the inverter circuit 17. The inverter circuit 17 is a motor drive circuit that drives the motor 4 with applied voltages Vu, Vv, and Vw, and is configured using, for example, an intelligent power module (hereinafter referred to as "IPM"). The IPM incorporates a three-phase full-bridge inverter circuit, a drive circuit, and a protection circuit. The three-phase full-bridge inverter circuit has six power switching elements such as insulated gate bipolar transistors (hereinafter referred to as "IGBTs"), and diodes connected in anti-parallel to each power switching element.

[0028] The current detection means 18 detects the current value of the motor current flowing through the motor 4 by measuring the voltage across the shunt resistor. The shunt resistor is connected to a wiring path between the negative voltage terminal of the inverter circuit 17 and the negative voltage terminal of the motor 4. The motor current includes phase currents Iu, Iv, and Iw of the motor 4. The current detection means 18 inputs the phase currents Iu, Iv, and Iw to the control means 20.

[0029] The control means 20 inputs voltage commands Vus, Vvs, and Vws for driving the three-phase motor to the PWM control means 19.

[0030] The PWM control means 19 generates a PWM signal based on the voltage commands Vus, Vvs, and Vws, and inputs the PWM signal to the inverter circuit 17 to control the switching operation of the IGBTs included in the inverter circuit 17 .

[0031] Figure 4 is an equivalent circuit diagram of motor 4. For simplicity of explanation, Figure 4 shows an example of a two-pole configuration in which one mechanical angle rotation corresponds to one electrical angle rotation. If the number of poles changes to four, eight, etc., the relationship changes to one mechanical angle rotation corresponds to two, four, etc. electrical angle rotations.

[0032] The motor 4 is a three-phase synchronous motor and has three-phase windings 4a, 4b, and 4c (U, V, and W), and a permanent magnet 4d, which is a rotor that rotates around a rotation axis. The axis that passes through the N-pole side of the permanent magnet 4d in the positive direction is defined as the d-axis (direct axis), and the axis perpendicular to this is defined as the q-axis (quadrature axis). With these definitions, the torque of the motor 4 is primarily governed by the magnetic field in the q-axis direction. Furthermore, the phase θ (electrical angle) is the angle formed by the axis α that passes through the U-phase winding 4a and the d-axis. All phases described below are electrical angles. Note that the inductance of the winding when a voltage is applied to generate a magnetic field in the d-axis direction is defined as Ld, and the inductance in the q-axis direction is defined as Lq. In an interior magnet type three-phase synchronous motor, Ld <Lqとなる。

[0033] The washing machine according to this embodiment is a sensorless washing machine using induced voltage. As described above, the sensorless method using induced voltage has a control period for the motor 4, which is an open-loop control period in the low-speed range and a feedback control period in the high-speed range. Open-loop control is control in which the rotational speed of the motor 4 is not estimated and the estimated value of the rotational speed is not fed back to the input side. In open-loop control, the voltage applied to the motor 4 is controlled based on a target value of the control current (magnetic flux current or torque current) supplied to the motor 4 and a target value of the rotational speed of the motor 4. In feedback control, the rotational speed of the motor 4 is estimated based on the induced voltage and the estimated value of the rotational speed is fed back to the input side. In feedback control, the control current (magnetic flux current or torque current) and the voltage applied to the motor 4 are controlled based on the deviation between the target value of the rotational speed of the motor 4 and the fed-back estimated value.

[0034] Because the sensorless system does not use a position sensor, the control unit 20 cannot accurately detect the rotor position. In particular, in open-loop control, the rotational speed of the motor 4 is not estimated, and the estimated rotational speed value is not fed back to the input side. Therefore, the control unit 20 assumes the rotor position to be a phase θc, and an error Δθ occurs between the phase θc and the phase θ. Therefore, the axis controlled by the control unit 20 assuming the phase θc is the γ-axis (estimated d-axis) relative to the d-axis, and the δ-axis (estimated q-axis) relative to the q-axis. Hereinafter, the current component corresponding to the d-axis magnetic flux current is referred to as the γ-axis current Iγ, and the current component corresponding to the q-axis torque current is referred to as the δ-axis current Iδ. Furthermore, the command voltage component corresponding to the d-axis magnetic flux is referred to as the γ-axis voltage command Vγs, and the command voltage component corresponding to the q-axis torque is referred to as the δ-axis voltage command Vδs.

[0035] FIG. 5 is a simplified block diagram showing the configuration of the control unit 51 when open-loop control is performed.

[0036] The phase calculation means 30 receives a speed command ωs corresponding to a target value for the rotational speed of the motor 4 and an initial phase θinit of the motor 4. The phase calculation means 30 calculates the phase θ by integrating the phase per unit time based on the initial phase θinit and the speed command ωs set for each unit time. Since open-loop control does not perform speed estimation, the speed command ωs is treated as the speed ω as is. The phase calculation means 30 inputs the phase θ to the three-phase to two-phase converter 22 and the two-phase to three-phase converter 25.

[0037] The phase θ and the phase currents Iu, Iv, and Iw are input to the three-phase to two-phase converter 22. The three-phase to two-phase converter 22 calculates the δ-axis current Iδ and the γ-axis current Iγ using the following equation (1) based on the phase θ, the phase currents Iu, Iv, and Iw, and sine wave data required for conversion from the stationary coordinate system to the rotating coordinate system.

[0038]

number

[0039] The Iδ error amplifier 23 receives an error ΔIδ between the δ-axis current Iδ and a δ-axis current command Iδs corresponding to the target value of the control current. The Iδ error amplifier 23 calculates a δ-axis voltage command Vδs as the sum of a proportional component and an integral component. The Iδ error amplifier 23 inputs the δ-axis voltage command Vδs to a two-phase to three-phase converter 25.

[0040] An error ΔIγ between a γ-axis current command Iγs corresponding to a target value of the control current and the γ-axis current Iγ is input to the Iγ error amplifier 24. The Iγ error amplifier 24 calculates a γ-axis voltage command Vγs as the sum of a proportional component and an integral component. The Iγ error amplifier 24 inputs the γ-axis voltage command Vγs to a two-phase to three-phase converter 25.

[0041] At least one of the δ-axis current command Iδs and the γ-axis current command Iγs corresponds to the control current supplied from the inverter circuit 17 to the motor 4 during the open-loop control period.

[0042] The phase θ, a δ-axis voltage command Vδs, and a γ-axis voltage command Vγs are input to the two-phase to three-phase converter 25. The two-phase to three-phase converter 25 calculates sinusoidal voltage commands Vus, Vvs, and Vws using the following equation (2) based on the phase θ, the δ-axis voltage command Vδs, the γ-axis voltage command Vγs, and sinusoidal wave data required for inverse transformation from the rotating coordinate system to the stationary coordinate system.

[0043]

number

[0044] The two-phase to three-phase converter 25 inputs voltage commands Vus, Vvs, and Vws to the PWM control means 19 .

[0045] FIG. 6 is a simplified block diagram showing the configuration of the control unit 51 when feedback control is performed.

[0046] The speed phase estimation means 21 receives the initial phase θinit of the motor 4, the δ-axis current Iδ, the γ-axis current Iγ, and the γ-axis voltage command Vγs.

[0047] FIG. 7 is a block diagram showing the configuration of the speed phase estimation means 21. As shown in FIG.

[0048] The speed phase estimation means 21 has a γ-axis induced voltage calculator 28 and a γ-axis induced voltage error amplifier 29. The γ-axis induced voltage calculator 28 calculates the γ-axis induced voltage Veγ by the following equation (3) based on the inductance value L, the resistance value Ra, the δ-axis current Iδ, the γ-axis current Iγ, the γ-axis voltage command Vγs, and the estimated speed ω.

[0049]

number

[0050] With the γ-axis induced voltage command Veγs=0, the error ΔVeγ relative to the γ-axis induced voltage command Veγs is input to the γ-axis induced voltage error amplifier 29 .

[0051] The γ-axis induced voltage error amplifier 29 outputs an estimated speed ω calculated from the integral gain Kω, adds the estimated speed ω to a value calculated from the proportional gain Kθ, and performs time integration in an integrator to output an estimated phase θ.

[0052] Referring to FIG. 6, the speed phase estimation means 21 inputs the estimated phase θ to the three-phase to two-phase converter 22 and the two-phase to three-phase converter 25.

[0053] An error Δω between a speed command ωs corresponding to a target value of the rotation speed and an estimated speed ω is input to the speed error amplifier 26. The speed error amplifier 26 calculates a δ-axis current command Iδs as the sum of a proportional component and an integral component.

[0054] The field-weakening setting means 27 receives the estimated speed ω and the DC voltage Vdc input to the inverter circuit 17. The field-weakening setting means 27 calculates a γ-axis current command Iγs in the negative direction based on the estimated speed ω and the DC voltage Vdc.

[0055] An error ΔIδ between the δ-axis current command Iδs and the δ-axis current Iδ is input to the Iδ error amplifier 23. The Iδ error amplifier 23 calculates a δ-axis voltage command Vδs as the sum of a proportional component and an integral component. The Iδ error amplifier 23 inputs the δ-axis voltage command Vδs to a two-phase to three-phase converter 25.

[0056] An error ΔIγ between the γ-axis current command Iγs and the γ-axis current Iγ is input to the Iγ error amplifier 24. The Iγ error amplifier 24 calculates a γ-axis voltage command Vγs as the sum of a proportional component and an integral component. The Iγ error amplifier 24 inputs the γ-axis voltage command Vγs to a two-phase to three-phase converter 25.

[0057] At least one of the δ-axis current command Iδs and the γ-axis current command Iγs corresponds to the control current supplied from the inverter circuit 17 to the motor 4 during the feedback control period.

[0058] The two-phase to three-phase converter 25 receives the estimated phase θ, a δ-axis voltage command Vδs, and a γ-axis voltage command Vγs. The two-phase to three-phase converter 25 calculates sinusoidal voltage commands Vus, Vvs, and Vws using the above equation (2) based on the estimated phase θ, the δ-axis voltage command Vδs, the γ-axis voltage command Vγs, and sine wave data required for inverse transformation from the rotating coordinate system to the stationary coordinate system. The two-phase to three-phase converter 25 inputs the voltage commands Vus, Vvs, and Vws to the PWM control means 19.

[0059] As described above, in the vertical washing machine, the pulsator 1 is disposed at the bottom of the washing / spinning tub 2. During the agitation operation included in the washing process, rinsing process, etc., the pulsator 1 is rotated by the motor 4 to generate a water current in the washing / spinning tub 2, and the laundry is agitated by this water current.

[0060] 8 is a timing chart showing in simplified form the stirring operation by the pulsator 1. The pulsator 1 is rotated multiple times at a predetermined target value R0 for the number of rotations and at predetermined time intervals, thereby performing multiple stirring operations (four stirring operations S1 to S4 in this example) intermittently. Note that the direction of rotation of the pulsator 1 may include both left and right directions, and at least one of the target value R0 for the number of rotations, the time interval, and the acceleration may be varied.

[0061] FIG. 9 is a flowchart simply showing the process executed by the control means 20 in, for example, a washing step including an agitation operation.

[0062] The control period of the pulsator 1 includes an open-loop control period in which the estimated value of the rotational speed of the motor 4 is not fed back in a speed range in which the rotational speed of the pulsator 1 is below a predetermined value, and a feedback control period in which the estimated value of the rotational speed of the motor 4 is fed back in a speed range in which the rotational speed of the pulsator 1 is above a predetermined value.

[0063] First, in step SP01, setting unit 53 acquires the laundry amount, which is the amount of laundry contained in washing and spin tub 2. Laundry amount detection unit 52 detects the laundry amount at the start of the washing operation and stores data indicating the detected laundry amount in a memory unit included in control device 13. Setting unit 53 acquires the laundry amount by reading out the data from the memory unit.

[0064] The laundry amount detection unit 52 may detect the laundry amount in any manner. For example, similar to the method disclosed in Patent Document 1, the control unit 51 may execute acceleration control, constant speed control, and pause control of the motor 4, and the laundry amount detection unit 52 may detect the laundry amount based on the average current value (average torque current) during the execution of constant speed control or the rotation angle (integrated rotation angle) of the motor 4 during the execution of pause control. Alternatively, similar to the method disclosed in Japanese Patent Application Laid-Open No. 2014-54498, the control unit 51 may execute acceleration control and deceleration control of the motor 4, and the laundry amount detection unit 52 may detect the laundry amount based on the difference between the acceleration current value supplied to the motor 4 during acceleration control and the deceleration current value supplied to the motor 4 during deceleration control. Alternatively, a weight sensor may be provided to detect the laundry amount, and the weight sensor may be used to detect the laundry amount.

[0065] Next, in step SP02, the setting unit 53 sets the current value of the control current in the open loop control based on the laundry amount acquired in step SP01. As described above, the control current is at least one of the δ-axis current command Iδs and the γ-axis current command Iγs.

[0066] The setting unit 53 sets the current value of the control current to be larger as the laundry amount increases, and sets the current value of the control current to be smaller as the laundry amount decreases. For example, when the laundry amount is a first laundry amount, the setting unit 53 sets the current value of the control current to a first current value, and when the laundry amount is a second laundry amount greater than the first laundry amount, the setting unit 53 sets the current value of the control current to a second current value greater than the first current value.

[0067] Next, in step SP03, the control unit 51 executes open-loop control of the pulsator 1 using the control current whose current value was set in step SP02.

[0068] When the rotation speed of the pulsator 1 is increased to or above the predetermined value by the open loop control, the control unit 51 then executes feedback control of the pulsator 1 in step SP04.

[0069] Next, in step SP05, control unit 51 determines whether or not to end the washing process based on the elapsed time since the start of the washing process, etc.

[0070] If the washing step is not to be ended (step SP05: NO), then in step SP06, a correction process for the current value of the control current is executed.

[0071] FIG. 10 is a timing chart showing, in simplified form, the rotation speed of the pulsator 1 and the waveform of the current value of the control current for two consecutive stirring operations.

[0072] Times T0 to T1 correspond to the open-loop control period for the (N-1)th (N is a natural number greater than or equal to 2) stirring operation, and times T1 to T2 correspond to the feedback control period for the (N-1)th stirring operation. Times T3 to T4 correspond to the open-loop control period for the Nth stirring operation, and times T4 to T5 correspond to the feedback control period for the Nth stirring operation.

[0073] The setting unit 53 sets the current value of the control current in the open-loop control of the (N-1)th agitation operation to a current value I1 based on the laundry amount.

[0074] The error calculation unit 54 calculates the error (R1-R0) between the target value R0 and the estimated value R1 of the rotation speed of the pulsator 1 at the transition timing (time T1) from the open loop control period to the feedback control period of the (N-1)th stirring operation.

[0075] The correction unit 55 corrects the current value of the control current for the Nth agitation operation (the current value I1 set by the setting unit 53 based on the laundry amount) based on the error calculated by the error calculation unit 54 for the (N-1)th agitation operation. The correction unit 55 corrects the current value I1, for example, by multiplying the current value I1 by the reciprocal of the ratio of the estimated value R1 to the target value R0. The correction unit 55 may also set the correction amount for the Nth agitation operation based on the level of error between the target value R0 and the estimated value R1 for the (N-1)th agitation operation. For example, the correction unit 55 may set the correction amount to −0.1 A if the level of the error is greater than 0 rpm and equal to or less than +10 rpm, set the correction amount to −0.3 A if the level of the error is greater than +10 rpm and equal to or less than +50 rpm, and set the correction amount to −0.4 A if the level of the error is greater than +50 rpm.

[0076] As a result, in the Nth stirring operation, the control unit 51 uses the control current with the corrected current value I2 to perform open-loop control of the pulsator 1. Thereafter, the same processing as above is repeatedly performed.

[0077] Because the current value I1 of the control current has been corrected to the current value I2, the error (R2-R0) between the target value R0 and the estimated value R2 in the Nth stirring operation is smaller than the error (R1-R0) between the target value R0 and the estimated value R1 in the N-1th stirring operation.

[0078] 10 illustrates an example in which the correction unit 55 corrects the current value I2 to be less than the current value I1 when the estimated value R1 exceeds the target value R0 (i.e., when an overshoot occurs), but the present invention is not limited to this example. The correction unit 55 may correct the current value I2 to be greater than the current value I1 when the estimated value R1 is less than the target value R0 (i.e., when an undershoot occurs).

[0079] Furthermore, when the error between the estimated value R2 and the target value R0 converges within a predetermined allowable range, the control unit 51 may perform open-loop control of the pulsator 1 using a control current of current value I2 for the stirring operation from the (N+1)th onwards.

[0080] 9, if the current value of the control current corrected in step SP06 after the Nth stirring operation is performed is excessively small, there is a risk that motor 4 will lose synchronization when performing open-loop control in step SP03 or feedback control in step SP04 in the (N+1)th stirring operation. In this case, in correcting the current value of the control current in step SP06, which is performed after motor 4 loses synchronization, the current value of the control current used in the Nth stirring operation may be used as the corrected current value for the (N+2)th stirring operation. Also, if control means 20 stores the current values ​​of the control current used in each stirring operation, the smallest current value of the control current used in the stirring operations up to the Nth stirring operation may be used.

[0081] As described above, in this embodiment, the washing machine includes washing and spin-drying tub 2 in which laundry is stored, pulsator 1 disposed in washing and spin-drying tub 2, motor 4 for rotating pulsator 1, inverter circuit 17 for driving motor 4, and control means 20. Control means 20 includes a laundry amount detection unit 52 for detecting the laundry amount, which is the amount of laundry stored in washing and spin-drying tub 2, and a setting unit 53 for setting the current value of the control current supplied from inverter circuit 17 to motor 4 for rotating pulsator 1 based on the laundry amount detected by laundry amount detection unit 52.

[0082] This allows the current value of the control current to be appropriately set based on the laundry amount detected by the laundry amount detection unit 52. As a result, heat generation from the inverter circuit 17, which is a motor drive circuit, can be suppressed.

[0083] Furthermore, as in this embodiment, the control period of the pulsator 1 includes an open-loop control period in which the estimated value of the rotational speed of the motor 4 is not fed back in a speed range in which the rotational speed of the pulsator 1 is below a predetermined value, and a feedback control period in which the estimated value of the rotational speed of the motor 4 is fed back in a speed range in which the rotational speed of the pulsator 1 is equal to or greater than the predetermined value, and the control current is preferably a current supplied from the inverter circuit 17 to the motor 4 in the open-loop control period.

[0084] This allows the control current during the open loop control period in a sensorless washing machine to be appropriately set based on the laundry amount detected by laundry amount detection unit 52. As a result, heat generation from inverter circuit 17 can be suppressed.

[0085] A heat sink for heat dissipation is provided in the inverter circuit 17 configured using an IPM. According to this embodiment, the heat generation is suppressed by optimizing the control current, which allows the heat sink to be made smaller, thereby realizing a smaller and less costly control device 13.

[0086] Furthermore, as in this embodiment, the washing machine performs agitation operations multiple times to agitate the laundry by rotating the pulsator 1, and the control means 20 may further include an error calculation unit 54 that calculates the error between the target value and the estimated value of the rotation speed of the pulsator 1 at the timing of transition from the open-loop control period to the feedback control period, and a correction unit 55 that corrects the current value of the control current set by the setting unit 53 in the Nth agitation operation (N is a natural number greater than or equal to 2) based on the error calculated by the error calculation unit 54 in the N-1th agitation operation.

[0087] This makes it possible to appropriately correct the current value of the control current in the Nth stirring operation based on the error in the (N-1)th stirring operation, thereby further suppressing heat generation from inverter circuit 17.

[0088] Furthermore, as in this embodiment, the setting unit 53 sets the current value of the control current to a first current value when the laundry amount is a first laundry amount, and sets the current value of the control current to a second current value when the laundry amount is a second laundry amount greater than the first laundry amount.

[0089] This allows the current value of the control current to be set small when the amount of laundry is small, and large when the amount of laundry is large, so that the current value of the control current can be set appropriately based on the amount of laundry detected by the laundry amount detection unit 52.

[0090] It should be noted that the above-described embodiments are intended to illustrate the technology of the present disclosure, and various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents. [Industrial Applicability]

[0091] The present disclosure is broadly applicable to washing machines equipped with pulsators. [Explanation of symbols]

[0092] 1 Pulsator 2 Washing and spin tub (washing tub) 4 motors 17 Inverter circuit (motor drive circuit) 20 Control means (control device) 52 Cloth amount detection unit 53 Setting section 54 Error calculation section 55 Correction section

Claims

1. a washing tub in which laundry is stored; a pulsator disposed in the washing tub; a motor that rotates the pulsator; a motor drive circuit that drives the motor; a control device; Equipped with The control device a laundry amount detection unit that detects the amount of laundry contained in the washing tub; a setting unit that sets a current value of a control current supplied from the motor drive circuit to the motor to rotate the pulsator based on the laundry amount detected by the laundry amount detection unit; having washing machine.

2. The control period of the pulsator is an open-loop control period in which the estimated value of the rotational speed of the motor is not fed back in a speed region in which the rotational speed of the pulsator is less than a predetermined value; a feedback control period in which an estimated value of the rotational speed of the motor is fed back when the rotational speed of the pulsator is in a speed range equal to or higher than the predetermined value; and the control current is a current supplied from the motor drive circuit to the motor during the open-loop control period; The washing machine according to claim 1.

3. The washing machine performs an agitation operation agitating the laundry by rotating the pulsator a plurality of times, The control device an error calculation unit that calculates an error between a target value and an estimated value of the rotation speed of the pulsator at a transition timing from the open loop control period to the feedback control period; a correction unit that corrects the current value of the control current set by the setting unit in an N-th stirring operation (N is a natural number equal to or greater than 2) based on the error calculated by the error calculation unit in an N-1-th stirring operation; further comprising The washing machine according to claim 2.

4. The setting unit When the laundry amount is a first laundry amount, the current value of the control current is set to a first current value; When the laundry amount is a second laundry amount that is greater than the first laundry amount, the current value of the control current is set to a second current value that is greater than the first current value. The washing machine according to claim 1.

5. A method for controlling a washing machine comprising: a washing tub for accommodating laundry; a pulsator disposed in the washing tub; a motor for rotating the pulsator; and a motor drive circuit for driving the motor, The control device Detecting the amount of laundry contained in the washing tub; a current value of a control current supplied from the motor drive circuit to the motor for rotating the pulsator is set based on the detected laundry amount; How to control a washing machine.

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