KR20050027121A - Drum washing machine - Google Patents

Abstract

The balance of the laundry sticking to the inner periphery surface of the drum of a drum washing machine having a drum rotating on an almost horizontal axis is adjusted before spin- drying. A brushless DC motor is adopted for a drum drive motor. The motor current is separated into a d-axis current and a q-axis current to carry out speed control by vector control for controlling these currents independently. Before spin-drying, the rotating speed is increased (S1) up to a speed at which the laundry sticks firmly to the inner periphery surface of the drum. Then, the machine enters the rotating speed slow- down operation mode (S2) in which the rotating speed is gradually decreased. The balance of the laundry inside the drum is judged to be proper during the speed slow-down, the rotating speed is increased to enter a spin-drying mode (S8). The balance of the laundry inside the drum is judged on the basis of the fluctuation width of the q-axis current.

Description

Drum-type washing machine {DRUM WASHING MACHINE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drum type washing machine having a drum rotating about an approximately horizontal axis, the drum type washing machine having a means for adjusting a balance of laundry attached to a drum inner circumferential surface necessary for dewatering operation.

Conventionally, in the drum type washing machine, when the centrifugal dehydration operation is performed while the laundry is unevenly attached to the drum inner circumferential surface, abnormal vibrations occur, and various modifications for improving the ubiquity of the laundry before moving to high speed rotation (hereinafter referred to as balance adjustment). Driving is proposed. One of them is a method of adjusting the balance by slowly decreasing the rotational speed of the drum. The balance adjustment operation is performed along the speed curve, for example, as shown in FIG. That is, first, the rotational speed of the drum is raised to a rotational speed (angular speed Na) sufficient for the laundry to adhere to the inner circumferential surface, and then slowly descends to the gradient.

Here, the centrifugal force acting on the laundry in the drum rotating at the angular velocity (ω) is expressed as "Ri.ω ² " when the distance from the center of rotation of the drum to the laundry is "Ri". If the axis of rotation of the drum is substantially horizontal, the centrifugal force "Ri and ω ^2" laundry value is greater than the acceleration of gravity (g) of is the state as attached to the inner peripheral surface of the drum, does not act only small centrifugal forces than the gravitational acceleration (g) washing Falls away from the inner circumference near the peak.

FIG. 10A shows a state in the drum 101 when the angular velocity omega is equal to the angular velocity Na. FIG. The laundry 102 does not fall even at the highest point because the centrifugal force acting on it is equal to or greater than the gravity acceleration g. Consider the case where the value of the angular velocity omega is gradually lowered in the above state. Since the centrifugal force acting on the laundry is proportional to the distance from the rotation center, as shown in FIG. 10B, the laundry C having a short distance from the rotation center of the drum 101 has, for example, an angular velocity? It falls before the laundry 101 adhering to an inner peripheral surface at the time of the fall to. As such, all the laundry which fell first is attached to the inner circumferential surface far from the rotational center, and when the state does not fall even at the highest point, the ubiquity (unbalance) of the laundry is eliminated, and the balance is obtained at the angular velocity Nb. do.

As shown in Fig. 12, when the balance adjustment is obtained at the angular velocity Nb, the angular velocity ω is immediately raised to the angular velocity Na or a slightly higher angular velocity Nc. And it confirms again that the balance adjustment was actually obtained over predetermined time Ta. If it is determined by balance that the balance is appropriate, the angular velocity o is raised to " Nd " to enter the centrifugal dehydration operation. If it is determined that the balance is inappropriate, the angular velocity? Is once returned to zero, and the balance adjustment operation is repeated again.

By the way, the rotation drive of the drum 101 is conventionally employ | adopted the method which employs a brushless DC motor as a motor, and voltage-drives it by an inverter apparatus. Fig. 13 shows an example of the configuration of such a conventional inverter device. The inverter device 200 includes a position detecting unit 201, an adder 202, a PI control unit 203, a UVW converting unit 204, a PWM forming unit 205, and a PWM inverter circuit 206. The position detection unit 201 processes a two-phase signal from the hall sensor 208 attached to the motor 207 to detect the phase θ and the angular velocity ω of the rotor. The detected angular velocity ω is calculated by the adder 202 from the angular velocity command value ω ref, and the calculated deviation is led to the PI controller 203. The PI control unit 203 should zero the input deviation, and perform a PI operation on the deviation to calculate the voltage command value to be applied to the motor 207. The result is given to the UVW converting unit 204 in the form of a duty and phase when the DC voltage is PWM modulated later. The UVW conversion unit 204 decomposes the input voltage command value into three-phase command values of U, V, and W and gives it to the PWM forming unit 205. The PWM forming unit 205 refers to the phase (θ) detected by the position detecting unit 201 and finally switches each switching element in the PWM inverter circuit 206 that voltage-drives each phase coil of the motor 207. Generates a PWM signal to operate. As a result, each switching element is turned on and off to apply a voltage according to the voltage command value to each coil, and the speed of the motor 207 is adjusted to match the angular speed command value ω ref.

However, such a conventional control method has the following problems. As described above, the motor 207 is applied with a voltage proportional to the value obtained by calculating the PI between the detected angular velocity ω and the angular velocity command value ω ref. That is, rotation speed control of the motor 207 is performed by voltage control. The rotational torque generated by the motor is proportional to the amount of current flowing through the coil. The current generated in proportion to the angular velocity deviation does not flow in the motor 207 only by applying a voltage proportional to the PI calculated value of the angular velocity deviation, and thus the torque generated is not proportional to the PI calculated angular velocity deviation. Do not. For this reason, in the case of voltage control, the yield of the angular velocity ω to the angular velocity command value ω ref is bad, and the speed control tends to be unstable. Moreover, since the period of feedback control was also several hundred milliseconds conventionally, the response of speed control was slow.

For this reason, when the angular velocity command value ω ref is gradually lowered to the gradient from the time when the angular velocity ω of the drum becomes "Na" in the balance adjustment operation described above, the angular velocity ω is the angular velocity in FIG. It changes like the curve of (ω). That is, the angular velocity omega decreases with the up and down oscillation around a straight line representing the angular velocity command value oref.

The balance adjustment action of the laundry described above occurs in the vicinity of the angular velocity where the centrifugal force acting on the laundry directly attached to the inner circumferential surface of the drum is equal to the gravity acceleration g (in the range of ω1 to ω2 in FIG. 11). In order to raise the balance adjustment effect, it is preferable that the time in which the value of the angular velocity (ω) is in the range of ω1 to ω2 where the balance adjustment action acts is long. When the angular velocity ω decreases in accordance with the angular velocity command value ω ref, the time becomes longer as time T2 in the figure. However, when the angular velocity omega vibrates up and down as shown in the figure, the time becomes short for "T1" in the figure. Therefore, the time for which the balance adjustment action works is shortened, and it becomes difficult to balance adjustment. In addition, when the angular velocity omega oscillates up and down in this manner, it becomes difficult to determine whether the balance is appropriate and a problem that the time required for the determination becomes long.

1 is a motor drive circuit of a washing machine according to the present invention,

2 is a longitudinal sectional view showing a structure of a washing machine according to the present invention;

3 is a flowchart of balance adjustment according to the first embodiment;

4 is a waveform example of the q-axis current of the motor driving circuit shown in FIG. 1;

5A is a waveform of an AC component in the q-axis current shown in FIG. 4;

5B is a waveform obtained by quadratic the AC component of FIG. 5A,

5C is a waveform in which high frequency components are removed from FIG. 5B;

6 is an example of an angular velocity curve when performing balance adjustment according to the first embodiment,

7 is another example of the angular velocity curve at the time of the balance adjustment according to the first embodiment,

8 is an example of an angular velocity curve when performing balance adjustment according to the second embodiment,

9 is another example of the angular velocity curve at the time of the balance adjustment according to the second embodiment,

10A is a diagram illustrating the centrifugal force and the state of the laundry acting on the laundry in the drum when the angular velocity is large;

10B is a view for explaining the centrifugal force and the state of the laundry acting on the laundry in the drum when the angular velocity is small;

11 is a view for explaining a state of change in drum angular velocity according to the prior art;

12 shows an example of the angular velocity curve when the balance adjustment according to the prior art and

13 is a structural example of a motor drive circuit according to the prior art.

An object of the present invention is to provide a drum type washing machine capable of adjusting the balance of laundry attached to the drum inner circumferential surface before entering a centrifugal dehydration operation in a drum type washing machine having a drum rotating about an approximately horizontal axis.

As a motor for rotating the drum, a brushless DC motor having a permanent magnet installed in the rotor is adopted. Then, the current flowing in the motor is separated into d-axis (magnetic flux axis) current parallel to the magnetic flux generated by the permanent magnet and q-axis (torque axis) current orthogonal to it, and independent of these current components to match each command value. Speed control is performed by vector control.

In order to adjust the balance of the laundry attached to the drum inner circumferential surface, the rotational speed of the drum is raised to a speed at which the laundry can be sufficiently attached to the drum inner circumferential surface before starting the centrifugal dehydration operation. Thereafter, the speed reduction operation of the rotational speed is started. If it is judged that the balance of laundry in the drum is appropriate while the speed is gradually reduced, the rotation speed is immediately increased to the rotation speed for centrifugal dehydration, and the process proceeds to the centrifugal dehydration operation. If the rotational speed of the drum is reduced to a low speed at which the laundry cannot attach to the inner circumferential surface of the drum, the rotation is once stopped if it is determined that the balance is not appropriate. And the same operation is repeated again. Even if such a cycle for balance adjustment is performed a predetermined number of times, if it is still determined that the balance of laundry in the drum is not appropriate, an alarm is issued to stop the washing machine.

In the balance adjustment, the determination that the balance of the laundry in the drum is appropriate determines that the variation of the q-axis current is equal to or less than a predetermined value.

By performing such a balance adjustment operation, laundry can be uniformly attached to the drum inner circumferential surface. As a result, it is possible to smoothly transfer to centrifugal dehydration operation.

Hereinafter, one embodiment of the drum type washing machine of the present invention will be described with reference to FIGS. 1 to 11.

A washing machine, which is the object of the present invention, is a drum type washing machine having a drum that rotates about an almost horizontal axis. An example of the entire configuration will be described with reference to the longitudinal cross-sectional view of FIG. The drum type washing machine is provided with the outer box 1 as an outer shell, and the door 2 is provided in the front center part corresponding to the right side in the figure of the said outer box 1. The door 2 is for opening and closing a laundry entrance formed in the front center of the outer box 1. In the upper part of the front door 2, an operation panel 3 having a plurality of switches and indicators is mounted.

In the inside of the outer box 1, the cylindrical water tank 5 is provided in the inclined shaft state below the back. The water tank 5 is elastically supported by one set of elastic support devices 6 from left and right, for example. Inside the water tank 5, a cylindrical drum 7 is formed coaxially with the water tank 5. The drum 7 includes a plurality of dewatering holes 8 that serve as ventilation holes on the inner circumferential wall of the eastern part, and functions as a washing tank, a dehydrating tank, and a drying tank. In addition, a plurality of baffles 9 are also provided on the inner circumferential wall of the drum 7.

The water tank 5 and the drum 7 are provided with openings 10 and 11 for putting laundry into and out of the front part, respectively. Among these, the opening part 10 provided in the water tank 5 is superimposed on the said laundry entrance 4 by the bellows 12 by watertightness. The opening 11 of the drum 7 faces the opening 10 of the water tank 5. A balance ring 13 is provided at the periphery of the opening 11 of the drum 7.

The rear part of the said water tank 5 is equipped with the motor 14 for rotationally driving the drum 7. The motor 14 is an outer rotor type brushless DC motor, and the stator 15 is attached to the outer circumferential portion of the bearing housing 16 attached to the center of the rear portion of the water tank 5. The rotor 17 is arrange | positioned so that the stator 15 may be covered from the outside, and the rotating shaft 18 mounted in the center part is rotatably carried in the said bearing housing 16 through the bearing 19. The front end of the rotating shaft 18 protruding from the bearing housing 16 is connected to the rear center portion of the drum 7. As a result, when the rotor 17 of the motor 14 rotates, the drum 7 also rotates in one.

The warm air generating device 24 is provided in the upper part of the water tank 5, and the heat exchanger 25 is provided in the distribution of the water tank 5. As shown in FIG. The warm air generating device 24 includes a fan 29 installed in the warm air heater 27 and the casing 28 installed in the case 26, and a fan for rotationally driving the fan 29 through the belt transmission mechanism 30. Since it is comprised by the motor 31, the case 26 and the casing 28 are in communication. In addition, a duct 32 is connected to all of the cases 26. The tip end of the duct 32 protrudes from the inside of the water tank 5 and faces the opening 12 of the drum 7.

Warm air is generated by the warm air heater 27 and the fan 29, and the generated warm air is supplied into the drum 7 through the duct 32. The warm air supplied into the drum 7 heats the laundry in the drum 7, removes its moisture, and discharges it to the heat exchanger 25 side.

The upper part of the heat exchanger 25 communicates with the casing 28, and the lower part communicates with the water tank 5. The heat exchanger 25 is a water-cooled type that dehumidifies by cooling and condensing water vapor in the air passing through the water injected from the upper portion. The air passing through the heat exchanger 25 is returned to the warm air generating device 24 to be warmed and circulated.

Next, the drive circuit of the motor 14 which rotationally drives the drum 7 is demonstrated. 1 shows a block diagram of an example of the driving circuit. The motor drive circuit 40 is a motor drive circuit of a sensorless vector control method. The motor drive circuit 40 includes a current control circuit 50, a rotation position estimation circuit 60 of the motor rotor, a current command determination circuit 70, and a balance determination circuit 80.

The current control circuit 50 includes adders 51a and 51b, proportional integrators 52a and 52b, coordinate converters 53, PWM formers 54, PWM inverter circuits 55 and current detection circuits 56. . The current detection circuit 56 is constituted by the current detectors 56a and 56b, the three-phase / two-phase converter 56c, and the vector rotator 56d.

The rotation position estimation circuit 60 includes an induced voltage estimation circuit 61, a proportional integrator 62, and an integrator 63.

The current command determination circuit 70 includes an adder 71 and a proportional integrator 72.

The three-phase currents Iu, Iv, and Iw (Iw calculated from Iu and Iv) detected by the current detectors 56a and 56b connected between the PWM inverter circuit 55 and the motor 14 are three-phase / By the two-phase converter 56c, it is converted into equivalent two-phase currents Iα and Iβ. The converted two-phase currents Iα and Iβ are further converted by the vector rotator 56d to obtain currents Id and Iq of the d-axis and q-axis components. When performing the above conversion operation, the rotation position estimation value [theta] described later is used. Here, the d-axis and the q-axis are rotational coordinate axes in which the magnetic flux direction made by the permanent magnet of the rotor is the d-axis (magnetic flux axis) and the direction orthogonal thereto is the q-axis (torque axis). As is well known, d-axis current Id is a current component that contributes to magnetic flux generation, and q-axis current Iq is a current component that contributes to rotation torque generation.

The calculated currents Id and Iq are obtained by deviations ΔId and ΔIq from the respective current command values Idr and Iqr in the adders 51a and 52b, and output voltage commands through the proportional integrators 52a and 52b. The values Vd and Vq are calculated. The output voltage command values Vd and Vq are converted into the values of the fixed two-axis coordinate system in the coordinate converter 53, and a three-phase pulse width modulated signal is formed in the PWM generator 54 based on this. The rotation position estimation value [theta] described later is also used in the conversion calculation in the coordinate converter 53. The pulse width modulated signal is applied to the PWM inverter circuit 55 so that a voltage is applied to the armature coil of the motor 14. In this manner, power supply to the motor 14 is performed by the current control circuit 50, and the current value flowing depends on the current command values Idr and Iqr.

The rotational position of the rotor necessary for the calculation in the vector rotor 56d and the coordinate transducer 53 may be detected by attaching a rotation sensor such as an encoder to the motor 14, but the motor current Id in the configuration of FIG. , Position sensorless method estimated from Iq).

In the induced voltage estimating circuit 61 in the rotation position estimating circuit 60, the current Id, Iq, the output voltage command value Vd of the d-axis, and the angular velocity estimation value omega of the rotor are input. In addition, in the induced voltage estimating circuit 61, inductances Ld and Lq and resistance R of the armature coil, which are circuit constants of the motor 14, are stored.

The induced voltage estimation circuit 61 uses these input values and circuit constants, and estimates the d-axis direction of the induced voltage generated in the armature coil by the magnetic flux generated by the permanent magnet (d-axis recognized by the inverter device 40). Direction component) (Eds) is calculated by the following equation.

Eds = Vd-R-Id-Ld-pId + ω-Lq-Iq

Where p is the derivative operator.

The calculated induced voltage estimate Eds is input to the proportional integrator 62, for example, the value calculated in the following equation is output as the angular velocity estimate ω.

ω = -G1Eds-G2

In the above, G1 and G2 are gain constants.

The rotational position estimate value [theta] is obtained by integrating the angular velocity estimate value [omega] in the integrator 63 as follows.

θ = ∫ω

If the adjustment operation calculated by Equation 2 is continued by the proportional integrator 62 in the state where the angular velocity estimate ω and the rotation position estimate θ are determined by the rotation position estimation circuit 60 as described above, The calculated d-axis induced voltage estimate Eds converges to zero in a short time.

When the d-axis induced voltage estimate Eds converges to zero, the d-axis recognized (estimated) by the inverter coincides with the magnetic flux direction made by the permanent magnet, and the rotation position estimate (θ) is equal to the actual rotation position and the angular velocity estimate (ω) becomes equal to the actual angular velocity of the rotor. Thus, according to the circuit structure of FIG. 1, the rotation position (theta) and the angular velocity (omega) of a rotor can be detected without using a position sensor.

The angular velocity estimated value ω is calculated by the adder 71 in the current command determining circuit 70 and the deviation Δω from the angular velocity command value ωref given by the operation command circuit 90 of the drum type washing machine. The output calculated by the proportional integrator 72 is output as the q-axis current command value Iqr. The q-axis current command value Iqr is obtained such that the deviation? Iq from the q-axis current Iq detected by the adder 51b is obtained, and the deviation? Iq converges to zero in the adjusting action of the proportional integrator 52b. Adjusted. In this way, the angular velocity estimated value (ω) is made to match the angular velocity command value (ωref) by the adjusting action of the proportional integrators "72" and "52b", and the motor 14 is the angular velocity command value designated by the operation command circuit 90. rotate to (ωref).

Also, since the d-axis current Id does not contribute to torque generation, the current command value Idr is usually set to zero except in the centrifugal dehydration operation requiring high speed rotation. The d-axis current Id is controlled to be equal to the current command value Idr by the adjusting action of the proportional integrator 52a. The balance determination circuit 80 will be described later.

The arithmetic processing described above is periodically processed by an arithmetic device such as a digital signal processor (DSP). The calculation is, for example, a three-phase / two-phase converter 56c, a vector rotator 56d, a balance determination circuit 80, an induced voltage estimation circuit 61, a proportional integrator 62, an integrator 63, an adder 71 ), Proportional integrator 72, adders 51a and 51b, proportional integrators 52a and 52b, coordinate converter 53, and PWM former 54 in this order. The operation cycle is a very short period of, for example, 128 microseconds.

In the motor drive circuit 1 of the sensorless vector control method, the speed control does not function properly when the value of the angular velocity? Of the motor 14 is too small. Therefore, when starting the motor 14 in the stopped state, another start control is executed in the middle until the angular velocity? Rises to a value that can be controlled by the sensorless vector control. Since various proposals have been made for the start control method, detailed descriptions are not given. For example, the operation command circuit uses two-phase voltages Vα and Vβ instead of the output of the coordinate converter 53 as an input to the PWM generator 54. Directly from 90, the rotational speeds of the two-phase voltages Vα and Vβ are sequentially raised from zero to increase the rotational speed of the motor 14.

Next, the balance adjustment operation performed to improve the ubiquity of the laundry attached to the drum inner circumferential surface necessary for the centrifugal dewatering operation in the configuration of the washing machine and the motor driving circuit will be described.

(First Embodiment of Balance Adjustment Operation)

First, the first embodiment will be described with reference to FIGS. 3 to 7. FIG. 6 shows a state of time change of the rotational speed (angular speed?) Of the drum 7 from the start of the balance adjustment operation to the transition to the dehydration operation. FIG. 3 shows the flow of the balance adjustment operation.

In the present embodiment, for the first time in the balance adjustment operation, the rotational speed of the drum 7 is raised to an angular speed Na sufficient for laundry to adhere to the inner circumferential surface (step S1). The speed increase is performed by outputting the angular speed Na as the angular speed command value ω ref than the operation command circuit 90 of the drum type washing machine. Incidentally, the start control is first performed in the speed increase process in the stop state as described above.

After the angular speed Na is reached, the motor moves to the deceleration operation of the rotational speed. The deceleration of the rotational speed is performed by changing the angular velocity command value? Ref to a value only a small value ?? 1 in step S2, which is repeatedly executed in the subsequent flow (step S2). At the same time, during the deceleration operation of the rotational speed, a balance judgment is made as to whether the laundry in the drum 7 is properly balanced.

The balance determination is determined by the magnitude of variation in the q-axis current Iq. Therefore, the balance determination circuit 80 reads and stores the value of the q-axis current Iq in " step S3 " which is repeatedly executed. At the same time, the amount of variation in the value of the q-axis current Iq after the shift to the deceleration operation of the rotational speed is calculated (step S4) to determine the balance (step S5).

The balance determination can be performed based on the magnitude of variation in the q-axis current Iq for the following reason. 4 is an example of the time change of the q-axis current Iq after the shift to the deceleration operation of the rotational speed. The q-axis current Iq of the vertical axis is represented by a relative value. The figure shows waveforms when the laundry is not balanced at the time when the angular velocity Na is reached, and the value of the q-axis current Iq varies greatly. The reason can be explained as follows.

Since the rotating shaft of the drum 7 is almost horizontal, when the circumference of the laundry is driven with the same rotational torque without adjusting the laundry, the rotational speed of the drum 7 varies with the rotational position of the drum 7. In the motor control circuit 1 of the vector control method of this embodiment, the value of the instantaneous angular velocity omega estimated by the rotational position estimation circuit 60 is compared with the angular velocity command value omega ref in the adder 71, and the deviation ( Δω) is calculated. Therefore, the value of the deviation Δω is changed by the rotation angle of the drum 7 when there is an unbalance in the laundry in the drum. The value of the angular velocity deviation [Delta] [omega] is calculated proportionally by the proportional integrator 72, and the q-axis current command value Iqr that must flow on the q-axis to zero the deviation [Delta] [omega] is calculated. Here, the value which proportionally integrated the deviation (DELTA) omega as the q-axis current command value Iqr is because the rotational torque generated by the motor 14 depends only on the q-axis current Iq. That is, the proportional integrator 72 outputs the torque command value which should be generated in order to zero the angular velocity deviation Δω in the form of the q-axis current command value Iqr. The q-axis current Iq detected by the current detection circuit 56 is input to the adder 51b, and the deviation? Iq from the q-axis current command value Iqr is calculated. The deviation? Iq is proportionally integrated at the proportional integrator 52b to calculate the q-axis voltage command value Vq and is given to the coordinate converter 53. In other words, the proportional integrator 52b calculates the q-axis voltage command value Vq that should be applied to the q-axis to zero the q-axis current deviation ΔIq. In this way, if there is a deviation between the angular velocity ω of the drum 7 and the angular velocity command value ω ref due to the presence of unbalance in the attachment of laundry in the drum, the angular velocity deviation Δω is set to zero. The q-axis current command value Iqr is calculated in an instant, and the q-axis voltage command value Vq for matching the q-axis current Iq with the q-axis current command value Iqr is calculated in an instant. As a result, the value of the q-axis current Iq is adjusted in an instant in the direction in which the angular velocity deviation Δω is zero. The reason why the q-axis current Iq varies greatly as shown in FIG. 4 is that such an adjustment operation is performed in an instant. In addition, the time between adjacent peaks of the curve of the q-axis current Iq shown in the figure corresponds to one rotation time of the drum 7.

As described above, if there is unbalance in the laundry attachment, the q-axis current Iq fluctuates greatly during one rotation of the drum 7, and the fluctuation becomes small when the unbalance is small. On the contrary, it means that the balance of the laundry can be grasped by measuring the magnitude of variation in one revolution of the q-axis current Iq. In this embodiment, the determination of whether the balance is appropriate is performed by the magnitude of the variation in the q-axis current Iq for this reason.

The magnitude calculation of the variation of the q-axis current Iq is performed as follows. First, the direct current component included in the q-axis current Iq in FIG. 4 is removed, and only the alternating current component is selected. The direct current component is a component that changes according to the change in the angular velocity command value ω ref, and the alternating current component is a component that changes due to the angular velocity deviation Δω. The selected alternating current component is shown in FIG. 5A. The large alternating current component means that the variation of the angular velocity deviation Δω in one rotation is large. Next, the instantaneous value of the AC component is squared to obtain a result as shown in FIG. 5B. In the above calculation, when the number of instantaneous values of the q-axis current Iq is too large, the number of data may be appropriately subtracted and calculated. Subsequently, the high frequency component is removed from the result of FIG. 5B to obtain a result as shown in FIG. 5C. The obtained curve of FIG. 5C shows the magnitude of variation in one rotation of the q-axis current Iq shown in FIG. 4. Therefore, it is possible to determine whether or not the adhesion balance of the laundry is appropriate by comparing the height of the curve representing the variation size with the reference value Hb of a predetermined value.

In step S5, a determination is made as to whether or not the variation in the q-axis current Iq is equal to or less than a predetermined reference value Hb, that is, whether the balance is appropriate. If the variation does not fall below the predetermined reference value Hb, the process proceeds to "step S6".

In "step S6", it is determined whether the angular velocity? Is equal to or less than the predetermined value Ne. The predetermined value Ne is a value lower than the angular velocity ω 1 to ω 2 in which only the laundry that causes unbalance falls. At the predetermined angular velocity Ne, most of the laundry of the washing machine falls at the highest point. If the value of the angular velocity ω is larger than the predetermined value Ne, the flow returns to " step S2 " to continue the deceleration operation of the rotational speed, the angular velocity ω is lowered, and the balance determination is performed again.

When it is determined in step "S6" that the value of the angular velocity omega is equal to or less than the predetermined value Ne, once the rotation is stopped (step S7), the process returns to "step S1" again and starts again from the beginning. This is because the angular velocity (ω) is lower than the angular velocity range (ω1 to ω2) where the balance adjustment action works, so that the best balance adjustment cannot be expected even if it continues. The curve of the angular velocity omega when the flow in " step S1 " is repeated is as shown in FIG. Fig. 7 shows a speed curve when it is determined that the balance is appropriate at the time when the angular velocity? Becomes "Nb" in the middle of the deceleration operation of the second rotational speed.

When it is determined in step "S5" that the variation in the q-axis current Iq is equal to or less than the predetermined reference value Hb, the process proceeds to "step S8". If the variation in the q-axis current Iq is equal to or less than the predetermined reference value Hb, it means that the laundry is well balanced, so the speed command value? ref is raised to the angular speed Nd to enter the centrifugal dehydration operation.

As described above, in the first embodiment, the deceleration operation of the rotational speed is executed for the balance adjustment at the angular speed Na, and when it is determined that the balance is appropriate in the above process, the process immediately proceeds to the centrifugal dewatering operation.

In the present embodiment, as described above, when the angular velocity deviation Δω occurs even in one rotation of the drum 7, the generated torque is adjusted to zero immediately. Therefore, even if there is unbalance in the attachment of the laundry, the angular velocity ω does not oscillate up and down, and the angular velocity command value ω ref in FIG. Therefore, the time in which the value of the angular velocity omega falls only in the laundry causing the unbalance and the adjustment operation is performed is within the range of the angular velocity omega 1? Omega 2 approximately equal to the time T2 shown in FIG. It's a long time. Since the said time T2 is longer than the time T1 in the case of a prior art, there exists an effect that a balance becomes easy to adjust compared with the case of a prior art.

(2nd Example of Balance Adjustment Operation)

In the first embodiment, after raising the angular velocity? To " Na " for the first time, the flow shifts to the deceleration operation of the first rotational speed and balance adjustment is performed. In the case of the second embodiment, the balance adjustment is also attempted even in the middle of raising the angular velocity? To " Na ".

Therefore, as shown in Fig. 8, the rate of increase of the angular velocity omega to " Na " is made smaller than in the case of the first embodiment, and the deceleration operation of the rotational speed is executed. While the angular velocity omega reaches "Na", it passes through the range of the angular velocities omega 1 to omega 2 in which the balance adjustment action acts. If it is determined that the balance is appropriate at the angular velocity Nb while raising the angular velocity ω to "Na", the angular velocity ω is immediately raised to "Nd" and the process proceeds to centrifugal dehydration operation.

When it is determined that the balance is appropriate until the angular velocity? Reaches "Na", the flow shifts to the deceleration operation at the same rotational speed as in the first embodiment. If it is determined that the balance is appropriate during the deceleration operation of the rotational speed, the angular velocity? Is immediately raised to " Nd "

When it is determined that the balance is not appropriate even when the angular velocity omega drops to "Ne", the rotation is once stopped as shown in FIG. 9, and the speed increasing operation of the first rotational speed is executed again.

The balance can be finally appropriated by repeating the speed increase operation of the rotation speed and the deceleration operation of the rotation speed. However, it is not preferable to execute such repetitive operation without limitation, and if the balance is not appropriate even after a predetermined number of times, a warning is issued to stop the washing machine.

Claims (6)

In a drum type washing machine for motor-driven a drum rotating about an almost horizontal axis, The motor is controlled so that the speed fluctuation during one rotation of the drum is reduced, and before the start of centrifugal dehydration operation, the drum's rotational speed is once raised to a speed at which the laundry is sufficiently attached to the inner circumferential surface of the drum. And if it is determined that the balance of laundry in the drum is appropriate, the drum type washing machine is immediately shifted to a centrifugal dehydration operation. In a drum type washing machine for motor-driven a drum rotating about an almost horizontal axis, The motor is controlled so that the speed variation during one rotation of the drum is reduced, and the rotational speed of the drum is gradually raised to the speed at which the laundry is sufficiently attached to the inner circumferential surface of the drum before the start of the centrifugal dehydration operation. If it is determined that the balance is appropriate, the rotational speed is immediately increased to shift to centrifugal dehydration operation. If the balance is not determined to be appropriate in the process of gradually increasing the rotational speed of the drum, the rotational speed of the drum is gradually lowered to decrease the speed. If it is determined that the balance of laundry in the drum is appropriate, the rotational speed is immediately increased to transfer to centrifugal dehydration operation. If the balance is not appropriate even though the rotational speed of the drum is sufficiently reduced, rotation is once performed. After stopping, the rotation speed of the drum again The drum type washing machine increases gradually, characterized in that return to the operation of. The method according to claim 1 or 2, As the motor, a brushless DC motor having a permanent magnet installed in the rotor is employed, and the d-axis (magnetic flux axis) current Id parallel to the magnetic flux generated by the permanent magnet and the current flowing through the motor are orthogonal thereto. A drum type washing machine characterized by separating the q-axis (torque shaft) current (Iq) and performing rotational speed control by vector control that independently controls the current component to match each command value. The method according to claim 1 or 2, A brushless DC motor having a permanent magnet installed in the rotor as the motor is employed, and the current flowing through the motor is zero in the d-axis (magnetic flux axis) direction component estimated value Eds of the induced voltage due to the rotation of the permanent magnet. Separated into the q-axis (magnetic flux axis) direction component (Id) estimated by the calculation and the q-axis (torque axis) direction component (Iq) orthogonal thereto, and independently controlled so that the current component corresponds to each command value. A drum type washing machine, characterized in that the rotational speed control is performed by sensorless vector control. The method of claim 3, wherein The judgment that the balance of the laundry in the drum is appropriate is determined to be appropriate when the fluctuation range of the q-axis (torque shaft) current Iq is less than or equal to a predetermined value. The method of claim 4, wherein The determination that the balance of laundry in the drum is appropriate is determined as appropriate when the variation width of the q-axis (torque axis) direction component (Iq) of the current flowing in the motor becomes less than or equal to a predetermined value.