JP2009005722A - Washing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a washing machine provided with a fabric volume detecting means which can accurately detect the volume of fabrics inside a drum. <P>SOLUTION: The washing machine is provided with a motor 7 which revolves the drum, a rotation speed detector 14 that detects the rotation speed of the motor 7, and a controlling section 31 that controls the rotation of the motor 7 from the detected output of the rotation speed detector 14. The controlling section 31 controls: a first detecting step of accelerating the rotation of the drum by the motor 7 at a specified accelerating torque and measuring time t1 required for increasing the rotating speed by ΔN1; and a second detecting step of decelerating the rotation of the drum by the motor at a specified decelerating torque and measuring the time t2 required for decreasing the rotating speed by ΔN2. The volume of fabrics can be detected accurately with a simple structure by offsetting the variations of frictional torque of a drum rotary shaft and by suppressing its effect, as the fabric volume is detected based on an angular acceleration α1 during the acceleration and an angular acceleration α2 during the deceleration by these processes. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a washing machine having a cloth amount sensor for detecting a cloth amount that is the amount of laundry put in a drum.

  An example of the structure of the drum type washing machine is shown in FIG. In the washing machine main body 1, a water tank 2 is supported in a suspended state by a suspension structure (not shown) having a vibration isolation structure. In the water tank 2, a drum 3 formed in a bottomed cylindrical shape is rotatably supported with its axial direction inclined downward from the front side to the back side. On the front side of the aquarium 2 is formed a clothing doorway 4 leading to the opening end of the drum 3, and by opening and closing the door 5 that closes the opening provided in the upward inclined surface on the front side of the washing machine body 1 so as to be openable and closable. The laundry can be taken in and out of the drum 3 through the clothing entrance 4.

  The drum 3 has a large number of through holes 6 formed in the peripheral surface thereof that communicate with the water tank 2, and is provided with stirring protrusions 15 for stirring clothes at a plurality of positions on the inner peripheral surface. The drum 3 is rotationally driven in the forward and reverse directions by a motor 7 attached to the back side of the water tank 2. In addition, a water injection pipe 8 and a drain pipe 9 are connected to the water tank 2 to perform water injection and drainage into the water tank 2 by controlling a water injection valve and a water discharge valve (not shown).

  When the door 5 is opened, laundry and detergent are put into the drum 3, and the operation is started by an operation on the operation panel 10 provided on the front surface of the washing machine body 1, for example, a water injection conduit is provided in the water tank 2. A predetermined amount of water is injected from 8 and the drum 3 is rotationally driven by the motor 7 to start the washing process. By the rotation of the drum 3, the laundry accommodated in the drum 3 is lifted in the rotation direction by the stirring protrusion 15 provided on the inner peripheral wall of the drum 3, and the stirring operation of dropping from the lifted appropriate height position is repeated. As a result, the laundry has the effect of tapping and washing. After the required washing time, the dirty washing liquid is discharged from the drain pipe 9 and the washing liquid contained in the laundry is dehydrated by a dehydrating operation of rotating the drum 3 at a high speed. The rinsing process is performed by pouring water from 8. Also in this rinsing step, the laundry stored in the drum 3 is rinsed by repeating a stirring operation in which the laundry is lifted and dropped by the stirring protrusion 15 by the rotation of the drum 3.

  In addition, on the back surface of the motor 7, a rotation detection unit 14 including a position detection element that detects the position of the rotor (rotor) of the motor is provided in order to detect the rotation state.

  The drum-type washing machine has a function of drying laundry stored in the drum 3, and the air in the water tank 2 is exhausted and dehumidified by the circulation air passage 11 to be dried by heating. Air is blown again into the water tank 2 by the blower fan 12.

  In the drum-type washing machine having the above-described configuration, a function of detecting the amount of clothes such as clothes put in the drum 3 and automatically determining the washing time according to the amount of cloth is added. Is generally (see, for example, Patent Document 1). An example of a method for detecting the amount of cloth will be described below with reference to FIGS. 7 and 8.

  The cloth amount is detected by a control circuit (not shown) having a function of controlling the motor 7 for driving the drum 3 to rotate.

  When washing is started, first, the control circuit starts the motor 7 and a detection output is input from the rotation detection unit 14. The detection frequency of the rotation detector 14 changes linearly in proportion to the rotation of the motor 7. That is, the control circuit increases the average voltage of the power supply voltage of the motor 7 by means of phase control when the input frequency from the rotation detector 14 is small, and decreases the average voltage when the frequency increases.

  In the cloth amount detection process, while performing rotation control, the average voltage applied to the motor 7 is gradually increased inside the control circuit to shift to high speed rotation so that the clothes are uniformly attached to the inner wall of the drum 3 by centrifugal force. To. In this state, the rotation of the motor 7 is stopped after continuing the rotation for a predetermined time. Thereby, the inertial rotation of the drum 3 is in a state where the motor 7 is rotated. At this time, as shown in FIG. 8, the rotation detection unit 14 converts the inertial rotational force of the drum 3 to gradually decrease due to the friction torque and stops and converts it into a partial rotational speed and outputs it.

  In FIG. 8, the horizontal axis represents time, and the vertical axis represents the rotational speed of the drive motor (motor). The time from the energization stop point E to the stop of the drum 3 is long when the amount of cloth is large, and the amount of cloth is When there are few, it is short. The cloth amount is detected by utilizing the fact that the difference in time required for the stop is proportional to the cloth amount.

  Here, when the weight of the cloth is m, the average radius of the cloth distributed on the inner periphery of the drum 3 is r, and the inertia moment of the drum 3 or the motor 7 is Jd, the inertia moment J of the rotating system including the cloth is expressed by the equation (1 ).

J = Jd + mr ² (1)
Further, assuming that the generated torque of the motor 7 is T, the friction torque of the drum and the rotating shaft is Tb, and the angular acceleration of the drum 3 is α, these relationships are expressed by Expression (2).

T = Jα + Tb (2)
Since the angular acceleration α is expressed by the equation (3) as a function of the angular velocity ω and the time t, as shown in the equation (4), if the average radius r of the cloth is constant, the rotation depends on the weight m of the cloth. The speed, that is, the angular speed ω changes.

α = dω / dt (3)
dω / dt = (T−Tb) / (Jd + mr ² ) (4)
From the above equation (4), it can be seen that dω / dt, that is, the change in the rotational speed, is inversely proportional to the fabric amount m.

That is, the cloth amount can be known by stopping energization of the motor 7 to rotate the drum 3 by inertia and measuring the change in the rotational speed in a certain time interval until the drum 3 stops.
JP-A-5-168786

  When using the above conventional cloth amount detection method, the inertial rotational force of the drum gradually decreases due to the friction torque, and the proportional relationship between the time until the drum stops and the cloth amount is obtained in advance by experiments, The obtained measurement value is applied to all washing machines of the same model.

  However, as can be seen from Equation (4), the proportional relationship between the time until the drum stops and the amount of cloth is not constant due to the variation in the friction torque Tb of the drum rotation shaft, and the numerical value varies depending on each washing machine. Have For this reason, there is a problem that the conventional cloth amount detection method has variations and the detection accuracy is limited.

  Further, in the conventional cloth amount detection method, the rotation of the drum is temporarily raised regardless of the state of the clothes, so that the laundry stored in the drum 3 is affected by the bias (unbalance distribution), and the washing tub. Vibrates greatly, and the washing tub collides with the washing machine main body and makes an abnormal sound.

  Accordingly, the present invention solves the above-described conventional problems, and the amount of cloth fed into the drum can be accurately detected with a simple configuration while suppressing the influence of variation in friction torque of the drum rotation shaft. It is an object of the present invention to provide a washing machine having a detection means and a washing machine having a stable cloth amount detection means that eliminates the influence of clothing bias and the like.

  In order to solve the above-described conventional problems, the washing machine of the present invention includes a motor that rotationally drives a drum, a rotation speed detection device that detects the rotation speed of the motor, and a motor that is based on a detection output of the rotation speed detection device. A controller that controls the rotation of the drum, the controller accelerates the rotation of the drum by generating a predetermined acceleration torque in the motor, and the rotation speed increases from a predetermined rotation speed N1 to N2. After the first detection step of measuring the acceleration angular acceleration α1 between the first detection step and the first detection step, the rotation of the drum is decelerated by generating a predetermined deceleration torque in the motor, and the predetermined rotation speed A second detection step of measuring the deceleration angular acceleration α2 while the rotational speed is decreased from N3 to N4, and detecting the cloth amount based on the acceleration angular acceleration α1 and the deceleration angular acceleration α2. This The one in which the features.

  As a result, since the amount of cloth is measured using both the speed of rising and lowering of the drum rotation, the friction torque variation of the drum rotation shaft is offset, and the influence of the variation can be suppressed. The amount of cloth can be accurately detected with a simple configuration.

  The washing machine of the present invention measures the maximum rotation speed and the minimum rotation speed of the drum in the predetermined rotation angle section in the first detection step, and the difference between the maximum rotation speed and the minimum rotation speed is a predetermined value or more. Is controlled so as to stop the rotational driving of the drum.

  Thereby, even when the distribution of the cloth in the drum becomes non-uniform and the vibration of the drum becomes larger than a predetermined value, the drum can be stopped safely.

  The washing machine of the present invention can obtain the cloth amount detecting means that can accurately detect the friction torque of the drum rotating shaft with a simple configuration while suppressing the influence of variations of individual devices.

  According to a first aspect of the present invention, there is provided a drum having a central axis of rotation in a horizontal direction or an inclination direction, accommodating a laundry and performing a rotational movement, and rotatably enclosing the drum in a washing machine body. A water tank, a motor for rotationally driving the drum, a rotational speed detection device for detecting the rotational speed of the motor, and a control unit for controlling the rotation of the motor based on the detection output of the rotational speed detection device. In the washing machine, the control unit accelerates the rotation of the drum by generating a predetermined acceleration torque in the motor, and the acceleration angular acceleration α1 while the rotation speed increases from a predetermined rotation speed N1 to N2. After the first detection step and the first detection step, the rotation of the drum is decelerated by causing the motor to generate a predetermined deceleration torque, and the rotation speed is increased from a predetermined rotation speed N3 to N4. A second detection step of measuring the deceleration angular acceleration α2 during lowering, and detecting the cloth amount based on the acceleration angular acceleration α1 and the deceleration angular acceleration α2, Since the amount of cloth is measured using both the ascending and descending speeds, variations in the friction torque of the drum rotation shaft can be offset and the influence of these variations can be suppressed. Can be detected.

  In the second aspect of the invention, in particular, at least during the first detection step and the second detection step, the control unit of the first aspect of the invention controls the voltage applied to the motor or the energization current. Since the acceleration torque and the deceleration torque are controlled to be constant at respective predetermined values, the acceleration torque and the deceleration torque are made constant, whereby the left side of equation (2) becomes constant, and the acceleration torque In addition, it is possible to detect the cloth amount with high accuracy without complicatedly considering the influence of the fluctuation of the deceleration torque.

  According to a third aspect of the present invention, in particular, in the control unit of the first or second aspect, during the first detection step and the second detection step, the q-axis current supplied to the motor is the first detection step. And the q-axis current related to the magnet torque that is the main component of the torque in the motor by controlling the acceleration torque and the deceleration torque of the motor by controlling to be a predetermined constant value in each of the second detection steps. Since the acceleration torque and the deceleration torque can be controlled to be substantially constant by making the pressure constant, the cloth amount can be detected with high accuracy.

  According to a fourth aspect of the invention, in particular, the control unit according to the first to third aspects of the invention is configured such that the d-axis current supplied to the motor is substantially zero during the first detection step and the second detection step. As a result, the generated torque in the motor is only the magnet torque, and the acceleration torque and the deceleration torque are controlled only by the q-axis current, making it easy to control. Is possible.

  In the fifth aspect of the invention, in particular, the control unit of the first to fourth aspects of the invention measures the maximum rotation speed and the minimum rotation speed of the drum in the predetermined rotation angle section in the first detection step, and the maximum rotation speed and the minimum rotation speed. If the difference is equal to or larger than a predetermined value, the rotation of the drum is controlled to stop, so that the distribution of the cloth in the drum becomes uneven, and the vibration of the drum is lower than the predetermined value. Even when it becomes larger, the drum can be safely stopped.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows a schematic configuration of a control device for controlling the operation of the drum type washing machine in the first embodiment of the present invention. The schematic structure of the drum type washing machine is the same as that of the conventional example shown in FIG.

  In the control device shown in FIG. 1, AC power from a commercial power source 20 is rectified by a rectifier 21, and DC power smoothed by a smoothing circuit including a choke coil 22 and a smoothing capacitor 23 is used as drive power, and a motor is driven by an inverter circuit 24. 7 is driven to rotate. Further, the rotation of the motor 7 is controlled based on the driving instruction input from the input setting unit 25 and the monitoring information of the driving state detected by each detecting means (not shown), and the water supply valve 27 is controlled by the load driving unit 26. The operation of the drain valve 28, the blower fan 12, and the heater 29 is controlled.

  The motor 7 includes a stator having three-phase windings 7a, 7b, and 7c and a rotor having a two-pole permanent magnet, and is configured as a DC brushless motor provided with three position detection elements 30a, 30b, and 30c. The rotation is controlled by a PWM control inverter circuit 24 configured by the switching elements 24a to 24f. The rotor position detection signals detected by the position detection elements 30a, 30b, and 30c are input to the control unit 31 configured by a microcomputer. Based on this rotor position detection signal, the drive circuit 32 performs PWM control of the on / off states of the switching elements 24a to 24f, thereby controlling the energization of the three-phase windings 7a, 7b, and 7c of the stator, thereby requiring the rotor. Rotate at rotation speed.

  The control unit 31 includes a rotation speed detection unit 33 to which detection outputs of the three position detection elements 30a, 30b, and 30c are input. The rotation speed detection unit 33 detects the period each time the signal state of any of the three position detection elements 30a, 30b, 30c changes, and calculates the rotation speed of the rotor from the period. The detection output of the rotation speed detection unit 33 is supplied to the cloth amount detection unit 34, and the cloth amount is detected based on the detected rotation speed as described below.

  Since the detection output of the rotation speed detector 33 corresponds to the rotation speed of the drum 3, the rotation speed of the drum 3 is obtained from the detection output of the rotation speed detector 33 in the following description.

  The characteristics of the cloth amount detection method in the present embodiment will be described below with reference to FIG.

  FIG. 2 is a diagram showing the operation of detecting the cloth amount, showing the relationship between the time required for increasing the rotational speed of the drum 3 and the time required for lowering the rotational speed. Time and the vertical axis are rotational speeds.

  When the cloth amount detection is started, the acceleration torque T1 is generated by the motor 7 after the elapse of a predetermined time or when the predetermined rotation speed N1 is reached, and the rotation speed is increased by ΔN1 during the time t1 to reach the predetermined rotation speed N2. A first detection process for detecting the arrival time t1 is performed. After the end of the first detection step, the rotational speed of the drum 3 is changed from acceleration to deceleration, and then the deceleration torque T2 is generated by the motor 7 that has rotated by inertia, and the predetermined rotational speed N3 is generated during the time t2. The second detection step is performed in which the rotational speed is decreased by ΔN2 to reach a predetermined rotational speed N4.

  Here, the operation state of the first detection process will be considered.

  From equation (3), the angular acceleration α1 in the first detection step is represented by equation (5).

α1 = ΔN1 / t1 (5)
Moreover, Formula (6) is materialized from Formula (1) and (2).

T1 = α1 (Jd + mr ² ) + Tb (6)
Similarly, considering the second detection step, Equation (7) and Equation (8) are obtained when the angular acceleration in the second detection step is α2.

α2 = ΔN2 / t2 (7)
T2 = α2 (Jd + mr ² ) + Tb (8)
When the component of the friction torque Tb is eliminated from the equations (6) and (8), the equation (9) is obtained.

α1-α2 = (T1-T2) / (Jd + mr ² ) (9)
FIG. 3 is a diagram showing the relationship between the cloth amount and the acceleration difference, the horizontal axis is the cloth amount, and the vertical axis is the acceleration difference, which shows the above equation (9) in an easy-to-understand manner.

  When the average radius r, acceleration torque T1, and deceleration torque T2 in the drum inner periphery of the cloth are constant values, the equation (9) is expressed as (α1−) according to the weight m of the cloth as shown in FIG. It shows that α2) changes.

  Here, α1 and α2 can be easily obtained by measuring the relationship between the rotational speed of the drum 3 and time as shown in the equations (5) and (7). Therefore, if only the relationship between the fabric weight m and the change in the angular acceleration (α1-α2) is grasped and stored as a calculation table in the fabric amount detection unit 34 of the control unit in FIG. It can be seen that the amount of cloth can be detected easily and accurately regardless of the relationship.

  FIG. 4 is a flowchart showing the cloth amount detection method.

  In FIG. 4, when the cloth amount detection starts (step S1), the control unit 31 drives the motor 7 to increase the rotation speed of the drum 3 with a predetermined torque from the predetermined rotation speed N1, thereby rotating the rotation speed. Is controlled to reach a predetermined rotational speed N2 increased by ΔN1 (step S2). When the drum 3 reaches the rotational speed N2 (step S3), a time t1 required for the rotational speed to increase by ΔN1 is calculated (step S4).

  Next, a decrease in the rotational speed of the motor 7 is started (step S5). When the drum 3 reaches a predetermined rotational speed N4 where the rotational speed has decreased by ΔN2 from the predetermined rotational speed N3 (step S6), a time t2 required for the rotational speed to decrease by ΔN2 is calculated (step S6). S7).

  Next, the angular acceleration α1 of the first detection step and the angular acceleration α2 of the second detection step are calculated from ΔN1, t1, ΔN2, and t2 based on the equations (5) and (7), and the difference α1 between the two angular accelerations is calculated. -Α2 is obtained (step S8), and the amount of cloth is obtained based on the formula (9) from the relationship between the determination value S measured in advance and the amount of cloth (step S9).

  In order to accurately detect the amount of cloth using Expression (9), it is desirable to control the acceleration torque T1 and the deceleration torque T2 of the motor 7 to be constant.

  Although the control as described above can be realized by controlling the voltage applied to the motor 7, generally, the constant torque control of the motor can be performed by vector control as described below.

  FIG. 5 is a block diagram showing vector control in the cloth amount detection.

  In the control block diagram of FIG. 5, at least a two-phase current out of the current supplied to the motor 7 and a rotational position signal of the motor obtained by a Hall IC or the like are detected. Using these signals, the current of the motor 7 is converted into two orthogonal currents, Iq which is a torque component and Id which is a magnetic flux component. Thereafter, the converted Iq and Id are compared with the commanded Iq * and Id *, and the appropriate control gains P and I are used to control the Iq and Id of the motor 7 to be constant. Can do.

  Here, since the torque T of the motor 7 is expressed by the following equation (10), the torque T of the motor 7 can be controlled by controlling Iq (q-axis current) and Id (d-axis current).

T = P (ψa · Iq + (Ld−Lq) IqId) (10)
Here, P is the number of pole pairs of the motor 7, ψa is a flux linkage by a magnet, Ld is a d-axis inductance, and Lq is a q-axis inductance.

  In particular, ψa · Iq in equation (10) represents a magnet torque and is the main component of the torque generated by the motor. Therefore, the torque of the motor 7 can be controlled mainly by Iq (q-axis current). In addition, when Id (d-axis current) is not zero, if Ld and Lq change depending on the rotation state, an error is likely to occur when calculating the torque T when calculating the variation of the torque T or the amount of cloth.

  That is, there is a case where the torque T does not become constant even if Iq (q-axis current) and Id (d-axis current) are controlled to be constant. Therefore, Id (d-axis current) is set to zero, and Iq (q-axis current) ) Is controlled to be constant, and the torque of the motor 7 is controlled to be constant, so that the cloth amount detection calculation error can be reduced.

  In the cloth amount detection of the washing machine configured as described above, the cloth amount is measured using the angular accelerations of both the drum rotation rise (first detection) and the descent speed (second detection). Therefore, the variation in the friction torque of the drum rotation shaft is canceled out, and the influence of the variation is suppressed, so that highly accurate detection is possible.

(Embodiment 2)
FIG. 6 is a diagram illustrating a control method of the washing machine according to the second embodiment of this invention.

  The configuration of the washing machine, the configuration of the control device, and the cloth amount detection method in the second embodiment are basically the same as those described in the first embodiment. The difference in the present embodiment is that when the rotational speed of the drum 3 is increased in order to detect the amount of cloth, the driving of the drum 3 is stopped according to the change in the rotational speed accompanying the increase in the rotational speed. This is the point where control is provided.

  FIG. 6A shows how the rotational speed of the drum 3 increases with time. The horizontal axis represents the elapsed time when the motor 7 is driven and the rotational speed of the drum 3 is increased by a predetermined torque, and the vertical axis is the rotational speed of the drum 3. As illustrated, the rotational speed of the drum 3 does not increase uniformly, but increases while repeating vertical movement. This is because the laundry tub vibrates due to the balance of the laundry accommodated in the drum 3. If the vibration becomes too large, the washing tub collides with the washing machine body and generates an abnormal sound.

  In the present embodiment, control for avoiding such a situation is performed. That is, the difference between the maximum rotation speed and the minimum rotation speed is detected for the rotation speed of the drum 3 in the predetermined rotation angle section during the acceleration of the rotation of the drum 3. If the difference is greater than or equal to a predetermined value, the drum 3 is controlled to stop rotating. As the maximum rotation speed and the minimum rotation speed of the drum 3 in the predetermined rotation angle section, for example, the rotation speed is measured four times during one rotation, and the maximum rotation speed and the minimum rotation speed are obtained.

  FIG. 6B is a diagram showing the relationship between the rotation speed of the drum and the upper limit value of the difference between the maximum and minimum of the rotation speed.

  As shown in FIG. 6B, the upper limit value of the difference between the maximum rotation speed and the minimum rotation speed is set based on the experiment so as to correspond to the rotation speed of the drum 3, and is provided in the control unit 31 as a table. The upper limit value of the difference between the maximum rotation speed and the minimum rotation speed as shown in FIG. 6B may be set based on the experimentally determined allowable vibration range at each rotation speed of the drum 3.

  As described above, in the second embodiment, the balance of the laundry is poor by controlling so that the difference between the maximum rotation speed and the minimum rotation speed in the predetermined rotation angle section of the drum 3 does not exceed the upper limit value. As a result, it is possible to avoid a situation where the washing tub vibrates greatly and collides with the washing machine main body, and once it is stopped, it can be started again and detected.

  According to the present invention, it is possible to accurately detect the amount of cloth put into the drum with a simple configuration, and to perform appropriate washing time setting, detergent amount display, and appropriate time setting dehydration process. It is useful for home and commercial washing machines.

The circuit diagram which shows the control apparatus of the drum type washing machine in Embodiment 1 of this invention The figure which shows the operation | movement of the cloth amount detection used for the drum type washing machine The figure which shows the cloth amount and acceleration difference of the cloth amount detection Flow chart showing the cloth amount detection method Block diagram showing vector control in cloth amount detection The figure which shows the control method of the drum type washing machine in Embodiment 2 of this invention. Sectional drawing which shows schematic structure of a drum type washing machine The figure which shows the cloth amount detection method of the drum type washing machine of a prior art example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Washing machine main body 2 Water tank 3 Drum 7 Motor 14 Rotation detection part 20 Commercial power supply 30a, 30b, 30c Position detection element 31 Control part 32 Drive circuit 33 Rotation speed detection part 34 Cloth amount detection part

Claims (5)

A drum having a central axis of rotation in a horizontal direction or an inclined direction and accommodating a laundry to perform a rotational movement; a water tub that rotatably includes the drum and elastically supported in a washing machine body; and the drum A rotation speed detection device that detects the rotation speed of the motor, and a control unit that controls the rotation of the motor based on the detection output of the rotation speed detection device. A first detection step of accelerating the rotation of the drum by generating a predetermined acceleration torque in a motor and measuring an angular acceleration during acceleration α1 while the rotation speed increases from a predetermined rotation speed N1 to N2. After the first detection step, the rotation of the drum is decelerated by generating a predetermined deceleration torque in the motor, and the angular acceleration during deceleration α2 while the rotation speed decreases from a predetermined rotation speed N3 to N4. A washing machine having a second detection step of measuring, wherein the cloth amount is detected based on the acceleration angular acceleration α1 and the deceleration angular acceleration α2. The control unit controls the voltage applied to the motor or the energization current, so that the acceleration torque and the deceleration torque are constant at each predetermined value at least during the first detection step and the second detection step. The washing machine according to claim 1 controlled to become. In the first detection step and the second detection step, the control unit is configured so that the q-axis current supplied to the motor becomes a predetermined constant value in each of the first detection step and the second detection step. The washing machine according to claim 1 or 2, wherein an acceleration torque and a deceleration torque of the motor are controlled by controlling the acceleration torque and the acceleration torque of the motor. The washing unit according to any one of claims 1 to 3, wherein the controller controls the d-axis current to be supplied to the motor to be substantially zero during the first detection step and the second detection step. Machine. The control unit measures the maximum rotation speed and the minimum rotation speed of the drum in a predetermined rotation angle section in the first detection step, and if the difference between the maximum rotation speed and the minimum rotation speed is a predetermined value or more, the drum The washing machine according to any one of claims 1 to 4, wherein the rotational driving of the washing machine is stopped.

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