JP5151822B2 - Washing machine - Google Patents

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 the rotation, and outputs the converted value.

  The horizontal axis in FIG. 8 indicates time, and the vertical axis indicates the number of rotations 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 fabric is large, and the amount of fabric 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 + mr2 (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 number or angular velocity ω changes.

α = dω / dt (3)
dω / dt = (T−Tb) / (Jd + mr2) (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 cloth amount m.

That is, the cloth amount can be known by stopping the energization of the motor 7 to inertially rotate the drum 3 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 the motor based on a detection output of the rotation speed detection device. A control unit that controls the rotation of the drum, and the control unit accelerates the motor to a predetermined rotational speed N1, and after the acceleration step, generates a predetermined deceleration torque in the motor to generate the drum. The first detection step of measuring the acceleration during deceleration α1 while the rotation speed decreases from the predetermined rotation speed N2 to N3, and after the first detection process, a predetermined acceleration is applied to the motor. A second detecting step of accelerating the rotation of the drum by generating torque and measuring acceleration acceleration α2 while the rotation speed increases from a predetermined rotation speed N4 to N5; α1 and the Based on the acceleration α2 when fast is characterized in that for detecting the laundry weight.

  As a result, since the amount of cloth is measured using both the rising and lowering speeds of the drum rotation, it is possible to offset the variation in the friction torque of the drum rotation shaft, and to suppress the influence of the variation. By providing an acceleration step, the first detection step is started after the garment is sufficiently evenly attached to the inner wall of the drum, so that it is possible to detect the state in which the cloth is stably attached, 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 a detection output of the rotational speed detection device, The control unit decelerates the rotation of the drum by generating a predetermined deceleration torque in the motor after the acceleration step of accelerating the motor to a predetermined rotation speed N1, and the acceleration step,
The first detection step of measuring the deceleration acceleration α1 while the rotation speed decreases from the predetermined rotation speed N2 to N3, and after the first detection process, by generating a predetermined acceleration torque in the motor A second detection step of accelerating the rotation of the drum and measuring acceleration acceleration α2 while the rotation speed increases from a predetermined rotation speed N4 to N5 includes the deceleration acceleration α1 and the acceleration acceleration α2. Based on the above, since the cloth amount is measured by using both the rising and falling speeds of the rotation of the drum, the variation in the friction torque of the drum rotation shaft is offset and the influence of the variation is affected. In addition, since the first detection process is started after the clothes are adhered to the inner wall of the drum sufficiently uniformly by providing an acceleration process, the cloth is stably adhered. Check by condition It becomes possible to, can be detected accurately Nunoryou with a simple configuration.

  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 controller of the first to fourth aspects of the invention measures the maximum and minimum rotation speeds of the drum in the predetermined rotation angle section in the first detection step, and the maximum and minimum rotation speeds. 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, the AC power of the commercial power supply 20 is rectified by the rectifier 21, and the control inverter circuit 24 uses the DC power smoothed by the smoothing circuit including the choke coil 22 and the smoothing capacitor 23 as the driving power. The motor 7 is rotationally driven. 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 operations of the drain valve 28, the blower fan 12, and the heater 29 are 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 the number of revolutions.

  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 cycle whenever the signal state of any of the three position detection elements 30a, 30b, and 30c changes, and calculates the rotation speed of the rotor from the cycle. The detection output of the rotation speed detector 33 is supplied to the cloth amount detector 34, and the cloth amount is detected as described below based on the detected rotation speed.

  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 amount of cloth, showing the relationship between the time required for increasing the number of revolutions of the drum 3 and the time required for decreasing the number of revolutions. Time and the vertical axis represent the number of rotations.

  When the cloth amount detection is started, an acceleration process of starting the rotation of the drum 3 and accelerating to a predetermined rotation speed N1 is performed. Here, N1 is assumed to be sufficiently larger than the number of rotations Nb at which clothes put in the drum 3 stick to the inner wall of the drum 3, that is, the number of rotations Nb in which the centrifugal force and gravity due to the rotation of the drum 3 are balanced. After the acceleration process is completed, the rotation of the drum 3 is decelerated by causing the motor 7 to generate a predetermined deceleration torque T1, and the time t1 during which the rotation speed decreases by ΔN1 from the predetermined rotation speed N2 to N3 is measured. A first detection step is performed. Here, N2 is smaller than N1, and N3 is larger than Nb. After completion of the first detection step, acceleration is resumed, and after reaching the predetermined rotational speed N4, the acceleration torque T2 is generated by the motor 7, and the rotational speed is increased by ΔN2 to reach the predetermined rotational speed N5 t2. The 1st detection process of detecting is performed. 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 + mr2) + 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 + mr2) + Tb (8)
If the component of the friction torque Tb is eliminated from the equations (6) and (8), the equation (9) is obtained.

α2-α1 = (T2-T1) / (Jd + mr2) (9)
FIG. 3 is a diagram showing the relationship between the amount of cloth and the acceleration difference, the horizontal axis is the cloth amount, and the vertical axis is the acceleration difference. The above equation (9) is easily understood.

Equation (9), when a constant value average radius r, deceleration torque T1, there is acceleration torque T2 in the drum circumference of the fabric, as shown in FIG. 3, according to the weight m of the fabric ( It shows that α2-α1) changes.

  Here, α1 and α2 can be easily obtained by measuring the relationship between the number of rotations of the drum 3 and time as shown in the equations (5) and (7). Therefore, if only the relationship between the weight m of the cloth and the change in the angular acceleration (α2−α1) is grasped and stored as a calculation table in the cloth amount detection section 34 of the control section 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 it to a predetermined rotational speed N1 (step S2). When the rotational speed reaches N1 (step S3), the rotational speed is decreased (step S4). When the drum 3 reaches a predetermined rotational speed N3 that is decreased by ΔN1 from the predetermined rotational speed N2 by a predetermined deceleration torque T1 (step S5), a time t1 required for the rotational speed to decrease by ΔN1. Is calculated (step S6). Thereafter, the rotational speed is increased (step S7), and the rotational speed of the drum 3 is increased from the predetermined rotational speed N4 by the predetermined acceleration torque T2 to reach the predetermined rotational speed N5 where the rotational speed has increased by ΔN1. Control is performed as follows (step S8). When the drum 3 reaches the rotational speed N5 (step S8), a time t2 required for the rotational speed to increase by Δ2 is calculated (step S9).

  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 α2 between the two angular accelerations is calculated. -Α1 is obtained (step S10), and the amount of cloth is obtained based on the equation (9) from the relationship between the determination value S measured in advance and the amount of cloth (step S11).

  In order to accurately detect the amount of cloth using Expression (9), it is desirable to control the deceleration torque T1 and the acceleration 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 descending rotation of the drum (first detection) and the rising 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.

  In addition, by including the acceleration step, the cloth amount is reliably detected in a state where the clothes are securely attached to the inner wall of the drum, 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 number of rotations 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 number of rotations accompanying the increase in the number of rotations. This is the point where control is provided.

  FIG. 6A shows how the rotation 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 shown in the figure, 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 a predetermined rotation angle section while the rotation of the drum 3 is being accelerated. 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 illustrating the relationship between the rotation speed of the drum and the upper limit value of the difference between the maximum and minimum rotation speeds.

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 in correspondence with 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 allowable range of vibration obtained experimentally at each rotation speed of the drum 3.

  As described above, in the second embodiment, the balance of the laundry is poor by controlling the difference between the maximum rotation speed and the minimum rotation speed in the predetermined rotation angle section of the drum 3 not to 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

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 number detection device that detects the rotation number of the motor, and a control unit that controls the rotation of the motor based on the detection output of the rotation number detection device. An acceleration step of accelerating the motor to a predetermined rotation speed N1, and after the acceleration step, the rotation of the drum is decelerated by generating a predetermined deceleration torque in the motor, and the rotation speed from the predetermined rotation speed N2 to N3. After the first detection step of measuring the deceleration acceleration α1 during the decrease of the speed, and after the first detection step, the rotation of the drum is accelerated by generating a predetermined acceleration torque in the motor, Rotational speed N A second detection step of rotating speed to N5 to measure the acceleration acceleration [alpha] 2 between rising from, based the the deceleration acceleration α1 in the acceleration acceleration [alpha] 2, and characterized by sensing the laundry weight Washing machine. 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.