JP3091511B2 - Washing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[Object of the Invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a washing machine, and more particularly to a method for detecting an imbalance caused by a bias of laundry during dehydration.

[0003]

2. Description of the Related Art In a conventional washing machine, as a method for detecting an imbalance caused by an offset of laundry during dehydration, for example, there is a method using a mechanical switch as shown in FIG. Dehydration tub 2 in washing tub 24 suspended by outer case 21 with four rods 22 and suspensions 23
When the motor 5 is rotated via the belt 27 and the clutch 28 by the motor 26 for dehydration while the load distribution is unbalanced due to the laundry load, the eccentricity occurs. Therefore, the washing tub 24 swings greatly. At this time, the washing tub 24 is connected to the switch bar 2 attached to the outer case 21.
When the user touches 9, the mechanical switch 31 is turned on to detect the occurrence of imbalance.
32 is a pulsator.

[0004]

In a conventional washing machine, the detection of the imbalance caused by the deviation of the laundry during spin-drying is performed by detecting the swing of the washing tub caused by the imbalance by attaching a mechanical switch to the outer case. Operation was performed.

[0005] However, the number of switches that can be mounted is limited, and the imbalance cannot be detected unless the washing tub accidentally touches the switch bar. Therefore, there is a problem that the washing tub hits the outer box many times before detecting the imbalance. Further, it is difficult to make the mounting position and the shape of the switch bar constant, and a variation in the mounting position directly results in a variation in the unbalance detection sensitivity. For this reason, depending on the washing machine, it is possible to detect the imbalance and stop dehydration even if it is not so imbalanced, or conversely, the washing tub may hit the outer box many times without detecting the imbalance easily there were. Further, the imbalance cannot be detected unless the washing tub swings and hits the outer box.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a washing machine capable of quickly and accurately detecting an imbalance caused by an offset of laundry during spin-drying and reducing the variation in detection sensitivity among the washing machines. With the goal.

[Structure of the Invention]

[0008]

In order to solve the above-mentioned problems, the present invention firstly provides a brushless DC motor for rotating a dewatering tub and a brushless DC motor which periodically switches a DC voltage with a switching element. An inverter circuit for driving a motor; a duty ratio signal generator for outputting a duty ratio signal for changing an on / off ratio of the switching element in the inverter circuit; an inverter current flowing through the inverter circuit or the brushless D
A current detection circuit for detecting at least one of a motor current flowing through the C motor, a rotation speed detection circuit for detecting a rotation speed of the brushless DC motor, and a duty ratio signal
When the on / off ratio of the switching element is steadily adjusted by a generator , at least any one of a change in the current detection value of the DC detection circuit and a change in the rotation speed detection value of the rotation speed detection circuit. The present invention has an imbalance detecting means for detecting an imbalance of the laundry load at the time of spin-drying.

Second, a brushless D for rotating a dewatering tank
A C motor, an inverter circuit for periodically switching a DC voltage by a switching element to drive the brushless DC motor, and a duty ratio for outputting a duty ratio signal for changing an on / off ratio of the switching element in the inverter circuit A signal generator and an inverter current flowing through the inverter circuit or the brushless DC
A current detection circuit for detecting at least one of the motor currents flowing through the motor, a rotation speed detection circuit for detecting the rotation speed of the brushless DC motor, and a duty ratio signal such that the current detection value of the current detection circuit is constant. Adjusting the duty ratio signal value output from the duty ratio signal generator at that time or the rotation speed detection value of the rotation speed detection circuit based on at least any change in the laundry during dehydration. The gist of the present invention is to have an unbalance detecting means for detecting a load imbalance.

Third, a brushless D for rotating a dewatering tub
A C motor, an inverter circuit for periodically switching a DC voltage by a switching element to drive the brushless DC motor, and a duty ratio for outputting a duty ratio signal for changing an on / off ratio of the switching element in the inverter circuit A signal generator; a current detection circuit for detecting at least one of an inverter current flowing through the inverter circuit and a motor current flowing through the brushless DC motor; a rotation speed detection circuit for detecting a rotation speed of the brushless DC motor; Adjust the duty ratio signal so that the rotation speed of the DC motor is constant, and
Said imbalance detection for detecting the unbalance of the laundry load during dehydration based on at least one of variation in the detected current value of the duty ratio signal value or the current detecting circuit is output from the duty ratio signal generator when the And the means.

[0011]

When the washing tub swings due to the imbalance of the laundry during the dehydration, the torque applied to the brushless DC motor fluctuates. At this time, if an attempt is made to control such that the ON / OFF ratio of the switching element in the inverter circuit is kept constant, the inverter current, the motor current, and the motor speed fluctuate. Therefore, in the first invention, the imbalance of the laundry load during dehydration is determined based on at least one of the inverter current, the motor current, and the motor speed when the on / off ratio of the switching element is constant. It is detected quickly and accurately.

Further, if an attempt is made to control the inverter current or the motor current to be constant, the on / off ratio of the switching element in the inverter circuit and the motor speed change. Therefore, in the second invention, the laundry load at the time of spin-drying is determined based on at least one of the ON / OFF ratio of the switching element in the inverter circuit or the motor speed when the inverter current or the motor current is constant. Imbalance is detected quickly and accurately.

Further, if an attempt is made to perform control to keep the motor speed constant, the on / off ratio of the switching element in the inverter circuit, the inverter current or the motor current will fluctuate. Therefore, in the third invention, the laundry load at the time of spin-drying is determined based on at least one of the ON / OFF ratio of the switching element, the inverter current, and the motor current in the inverter circuit when the motor speed is fixed. Imbalance is detected quickly and accurately.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

First, the circuit configuration of the washing machine will be described with reference to FIG. In the figure, reference numeral 10 denotes an inverter circuit;
Is a brushless DC that rotates a pulsator and a dewatering tank
(DC) motor, 30 is a motor control circuit, 40 is a PWM oscillator as a duty ratio signal generator, 50 is a rotation speed detection circuit for detecting the rotation speed of the brushless DC motor 20, and 60 is a function as unbalance detection means. The microcomputer 70 has a current detection circuit for detecting an inverter current (or a motor current). Brushless DC motor 2
As 0, a general three-phase armature winding u, v, w is used, and a three-phase full-wave bridge type inverter is used as the inverter circuit 10 for driving the brushless DC motor 20. Have been. Reference numeral 2 in the inverter circuit 10 denotes a diode bridge for rectification, and 3 denotes a smoothing capacitor. After the AC voltage from the commercial AC power supply 1 is rectified by the diode bridge 2, the capacitor 3
To obtain a DC voltage. Then, this DC voltage is converted into a three-phase AC at a portion of the transistor module 4 which forms a three-phase full-wave bridge with six transistors as switching elements. That is, the portion of the transistor module 4, three pairs of arms corresponding to the 3-phase, six transistors _{u 1, u 2, v 1} , v 2, w 1, w 2 are connected. Hereinafter, the transistors u ₁ , v ₁ ,
upper arm three arms on the side where w ₁ is connected, the other transistor u _2, v _2, w ₂ is connected to the other three arms of the side of the lower arm. Each of the six transistors u ₁
To w ₂ , the free wheel diodes 5 are respectively connected in parallel, and three connection points of the upper arm and the lower arm are connected to the three-phase armature windings u, in the brushless DC motor 20.
v, w are connected.

The brushless DC motor 20 includes, in addition to the armature windings u, v, and w, a rotor (not shown) formed of a permanent magnet, and three Hall ICs 6a for detecting the rotational position of the rotor. , 6b, 6c. The rotor position detection signals of the Hall ICs 6a, 6b, 6c are given to the motor control circuit 30 and the rotation speed detection circuit 50. The output of the motor control circuit 30 is supplied to the AND gate 7a,
7b, 7c, the upper-arm transistors u ₁ , v
_1, it is given as base drive signals w _1, also given as the transistors u _2, v _2, direct drive signals to the base for w ₂ of the lower arm. Hall IC 6a, 6b, the rotor position detection signal 6c are logically converted by the motor control circuit 30, in response to the rotor position, for example, transistors v ₂ in transistor u ₁ and the lower arm in the upper arm, similarly transistors v
A drive signal for sequentially turning on the transistors of each combination of ₁ and w ₂ and transistors w ₁ and u ₂ is output. The DC voltage is converted into a three-phase AC by the ON switching of the transistor, and the armature winding u− of the brushless DC motor 20 is turned on.
Current flows sequentially through v, vw, and wu, resulting in a brushless DC
The motor 20 rotates in one direction. The forward and reverse rotations of the brushless DC motor 20 are determined by armature windings u and
This is performed by reversing the order of the currents flowing through v and w,
The forward / reverse control is performed via the motor control circuit 30 by the output of the forward / reverse signal from the microcomputer 60.

The PWM oscillator 40 has a brushless D
It is provided to change the rotation speed of the C motor 20.
PWM based on duty ratio instruction signal from microcomputer 60
PW with ON / OFF duty varied from oscillator 40
An M signal is output. The AND signals of the PWM signal and the drive signal from the motor control circuit 30 are ANDed by the AND gates 7a, 7b, 7c and given to the three transistors u ₁ , v ₁ , w ₁ of the upper arm. The rotation speed of the brushless DC motor 20 is varied. That is, the shorter the ON period of the transistors u ₁ , v ₁ , w ₁ is, for example, the shorter the brushless DC motor 2
The number of rotations of 0 becomes low.

When the brushless DC motor 20 is stopped, all the transistors u _{1 to} w ₂ are turned off via the motor control circuit 30 by outputting a stop signal from the microcomputer 60.
This is done by setting F.

The rotation speed of the brushless DC motor 20 is determined by synthesizing the rotor position detection signals of the Hall ICs 6a, 6b and 6c in a rotation speed detection circuit 50. The rotation speed detected by the rotation speed detection circuit 50 is read into the microcomputer 60.

A resistor R is provided between the capacitor 3 and the transistor module 4 in the inverter circuit 10.
Is connected, and the resistance R converts the inverter current into a voltage value, which is amplified by the amplifier 8 to detect the inverter current (motor current). That is, the current detection circuit 70 is configured by the resistor R and the amplifier 8.

Next, the operation of detecting the imbalance during dehydration in the washing machine configured as described above will be described.

First, a first detection example will be described with reference to the flowcharts of FIGS. In this detection example, the microcomputer 60 controls the on / off duty ratios of the three transistors u ₁ , v ₁ , w ₁ of the transistor module 4, and the brushless DC motor 20 based on the rotation speed detection signal of the rotation speed detection circuit 50. Motor rotation speed is constant.
The imbalance of the laundry load is detected based on the fluctuation of the inverter current I at this time.

A duty ratio instruction signal for increasing the on / off duty ratio of the transistors u ₁ , v ₁ , w ₁ is supplied from the microcomputer 60 to the PWM oscillator 40, and a start signal is supplied to the motor control circuit 30.
As a result, the brushless DC motor 20 starts rotating, and accordingly, the dewatering tub also starts rotating. At this time, if there is no imbalance of the laundry in the dewatering tub, the current curve is as shown by the broken line in FIG. That is, the value of the inverter current I increases as the motor speed increases from the initial stage of the startup.
When the motor rotation speed reaches the set fixed rotation speed, the required torque decreases, and the inverter current I monotonously decreases even if the motor rotation speed is constant. When there is an imbalance in the laundry, the current curve is as shown by the solid line in FIG.
That is, since the imbalance has occurred, the inverter current I from the initial stage of the start is unstable, and greatly fluctuates even after the motor rotation speed reaches a certain rotation speed, and the value of the inverter current I becomes monotonous. Does not decrease. This inverter current I
Has an absolute value that varies depending on the amount of laundry load, but has the same property of vibrating.

The microcomputer 60 monitors the inverter current I output from the current detection circuit 50 by sampling it every fixed time ΔT (steps 11 to 15). ΔT is a time sufficiently shorter than the rotation cycle of the dewatering tank. The sampling times are t ₀ , t ₁ , t ₂ ,..., T _n, and the values of the inverter current I at this time are I ₀ , I ₁ , I 2
_2, ..., and I _n.

[0025] In this case, put the _{ΔI n = I n + 1 -I} n. Also, δ is a constant for considering current fluctuation due to noise.

After the value of the inverter current I rises and the motor speed reaches a certain speed, if the inverter current I falls below a certain value, m is added (step 1).
6) If the value of m exceeds a certain set value (that is, if the inverter current value fluctuates more than a set number of times), it is regarded as unbalanced (step 18). In this way, it is possible to quickly and accurately detect the occurrence of the imbalance of the laundry based on whether the inverter current monotonously decreases or vibrates after the motor rotation speed reaches a certain rotation speed. .

FIG. 4 shows a second detection example. In this detection example, the microcomputer 60 controls the on / off duty ratio of the three transistors u ₁ , v ₁ , w _{1 in} the transistor module 4 while reading the rotation speed detection signal of the rotation speed detection circuit 50, thereby controlling the motor. Keep the speed constant. Then, the transistors u ₁ , v ₁ ,
The on / off duty ratio of w ₁ , that is, the PWM oscillator 40
The imbalance of the laundry load is detected based on the fluctuation of the duty ratio signal (PWM signal).

First, the microcomputer 60 gives an instruction to the PWM oscillator 40 to increase the on / off duty ratio of the transistors u ₁ , v ₁ , w ₁ and a start signal to the motor control circuit 30. As a result, the brushless DC motor 20 starts rotating, and accordingly, the dewatering tub also starts rotating. At this time, if there is no imbalance, a duty ratio curve as shown in FIG. That is, the value of the inverter current increases with the increase in the motor rotation speed from the initial stage of the startup. When the set number of revolutions is reached, the required torque decreases, and the required inverter current value decreases monotonously even when the number of revolutions is constant. Therefore, the on / off duty ratio of the transistors u ₁ , v ₁ and w ₁ also monotonically increases. Will be reduced to From this, the duty ratio signal of the PWM oscillator 40 also decreases monotonically. When there is an imbalance, a duty ratio curve as shown in FIG. That is, due to the torque fluctuation due to the unbalance, the on / off duty ratio fluctuates in order to maintain the constant rotation speed even when the rotation speed reaches a certain value, and vibrates without monotonously decreasing. Therefore, the duty ratio signal from the PWM oscillator 40 also oscillates. Although the absolute value of the on / off duty ratio changes depending on the amount of the laundry load, the on / off duty ratio has the same property of vibrating. Microcomputer 60
Is the PWM required to maintain a constant motor speed.
Whether the duty ratio output from the oscillator 40 monotonically decreases,
Alternatively, it is possible to quickly and accurately detect the occurrence of imbalance of the laundry by vibrating.

FIG. 5 shows a third detection example. In this detection example, the microcomputer 60 controls the on / off duty ratio of the three transistors u ₁ , v ₁ , w _{1 in} the transistor module 4 while reading the current value detection signal of the current detection circuit 70, thereby controlling the inverter current. Constant. This means that the torque of the brushless DC motor 20 is kept constant. The imbalance of the laundry load is detected based on the fluctuation of the motor speed at this time.

First, the microcomputer 60 sends the PWM oscillator 40
Is given to increase the on / off duty ratio of the transistors u ₁ , v ₁ , w ₁ , and a start signal is given to the motor control circuit 30. As a result, the brushless DC motor 20 starts rotating, and accordingly, the dewatering tub also starts rotating. At this time, if there is no imbalance, a rotation speed curve as shown in FIG. 5A is obtained, and the motor rotation speed increases with an increase in the inverter current from the initial stage. When the inverter current reaches a set constant current value, that is, a fixed torque, the motor rotation speed becomes constant. When there is an imbalance, a rotation speed curve as shown in FIG. Due to external torque fluctuation due to unbalance, brushless DC is maintained even if constant inverter current is maintained.
The torque applied to the motor 20 fluctuates, which causes the motor speed to fluctuate. Although the absolute value of the motor rotation speed changes according to the amount of the laundry load, it has the same property of vibrating. When maintaining a constant inverter current, the microcomputer 60 quickly and quickly generates the imbalance of the laundry depending on whether the rotation speed detection signal output from the rotation speed detection circuit 50 is a constant value or vibrates. It is possible to detect accurately.

FIG. 6 shows a fourth detection example. In this detection example, the microcomputer 60 controls the oscillation duty ratio of the PWM oscillator 40 so that the inverter current value is constant while reading the current value detection signal of the current detection circuit 70,
The on / off duty ratio of the three transistors u ₁ , v ₁ , w _{1 in} the transistor module 4 is determined.
Then, the imbalance is detected based on the change in the output duty ratio of the PWM oscillator 40 at this time.

First, the microcomputer 60 sends the PWM oscillator 40
Is given to increase the on / off duty ratio of the transistors u ₁ , v ₁ , w ₁ , and a start signal is given to the motor control circuit 30. As a result, the brushless DC motor 20 starts rotating, and accordingly, the dewatering tub also starts rotating. At this time, if there is no imbalance, a duty ratio curve as shown in FIG. 6A is obtained, and the motor speed increases with an increase in the inverter current from the initial stage of startup. Constant current value set by inverter current,
That is, when a certain torque is reached, the transistors u ₁ , v ₁ ,
on-off duty ratio of w ₁ is constant. When there is an imbalance, a duty ratio curve as shown in FIG. Due to external torque fluctuation due to unbalance, brushless D
The torque applied to the C motor 20 fluctuates, so that the on / off duty ratio of the transistors u ₁ , v ₁ , w ₁ oscillates. Although the absolute value of the on / off duty ratio changes depending on the amount of the laundry load, the on / off duty ratio has the same property of vibrating. When maintaining a constant inverter current, the microcomputer 60 can quickly and accurately detect the occurrence of laundry imbalance depending on whether the output duty ratio of the PWM oscillator 40 is constant or vibrates. It becomes possible.

FIG. 7 shows a fifth detection example. In this detection example, the microcomputer 60 controls the on / off duty ratio of the three transistors u ₁ , v ₁ , w ₁ of the transistor module 4 to be constant by making the duty ratio signal of the PWM oscillator 40 constant. Then, the imbalance is detected based on the fluctuation of the motor speed at this time. First, the microcomputer 60 gives an instruction to the PWM oscillator 40 to increase the on / off duty ratio of the transistors u ₁ , v ₁ , w ₁ and a start signal to the motor control circuit 30. This allows brushless DC
The motor 20 starts to rotate, and thus the spin tub also starts to rotate. At this time, if there is no imbalance, FIG.
A rotation speed curve as shown in (a) is obtained, and the motor rotation speed increases as the on / off duty ratio increases from the initial stage of startup. When the set on / off duty ratio is reached, the motor speed becomes constant. When there is an imbalance, a rotation speed curve as shown in FIG. Constant on / off due to external torque fluctuation due to unbalance
Even if the off-duty ratio is maintained, the motor speed oscillates. Although the absolute value of the motor rotation speed changes depending on the amount of the laundry load, the motor has the same property of vibrating. The microcomputer 60 generates the imbalance of the laundry depending on whether the rotation number detection signal output from the rotation number detection circuit 50 when the constant on / off duty ratio is maintained is constant or vibrates. Can be quickly and accurately detected.

FIG. 8 shows a sixth detection example. In this detection example, the microcomputer 60 controls the on / off duty ratio of the three transistors u ₁ , v ₁ , w ₁ of the transistor module 4 to be constant by making the duty ratio signal of the PWM oscillator 40 constant. Then, the imbalance is detected based on the fluctuation of the inverter current at this time.

First, the microcomputer 60 sends the PWM oscillator 40
Is given to increase the on / off duty ratio of the transistors u ₁ , v ₁ , w ₁ , and a start signal is given to the motor control circuit 30. As a result, the brushless DC motor 20 starts rotating, and accordingly, the dewatering tub also starts rotating. At this time, when there is no imbalance, the current value curve is as shown in FIG. 8A, and the value of the inverter current increases with the increase of the on / off duty ratio from the initial stage of the startup. When the set ON / OFF duty ratio is reached, the value of the inverter current becomes constant. When there is an imbalance, a current value curve as shown in FIG. Due to external torque fluctuation due to imbalance, the value of the inverter current oscillates even if a constant on / off duty ratio is maintained. Although the absolute value of the inverter current changes depending on the amount of the laundry load, the inverter current has the same property of oscillating. The microcomputer 60 generates an imbalance in the laundry depending on whether the detection signal of the inverter current output from the current detection circuit 70 when the ON / OFF duty ratio is maintained at a constant value or vibrates. Can be quickly and accurately detected.

[0036]

As described above, according to the first aspect, the ON / OFF state of the switching element in the inverter circuit is reduced.
The imbalance of the laundry load during dehydration is determined based on the inverter current flowing through the inverter circuit when the OFF ratio is constant, the motor current flowing through the brushless DC motor, or at least one of the motor rotation speeds of the brushless DC motor. When the dehydration tub swings due to imbalance due to the bias of the laundry during dehydration, the torque applied to the brushless DC motor fluctuates, and the on / off ratio of the switching element is controlled to be constant. Since a large fluctuation occurs in the inverter current, the motor current, and the motor speed, it is possible to quickly and accurately detect the imbalance caused by the bias of the laundry load during dehydration, and to reduce the variation in the detection sensitivity due to the washing machine. Can be smaller.

According to the second aspect of the present invention, when the inverter current or the motor current is constant, the ON / OFF of the switching element is reduced.
Since the imbalance of the laundry load during spin-drying is detected based on at least one of the variation of the OFF ratio or the motor speed, the spin-drying tub swings due to imbalance due to the bias of the laundry during spin-drying. Then, the torque applied to the brushless DC motor fluctuates, and a large fluctuation occurs in the on / off ratio of the switching element and the motor speed when the inverter current or the motor current is controlled to be constant. The effect of is obtained.

According to the third aspect of the present invention, the on / off ratio of the switching element when the motor speed is kept constant,
In order to detect the imbalance of the laundry load at the time of spin-drying based on at least any fluctuation of the inverter current or the motor current, when the dehydration tub swings due to imbalance due to the bias of the laundry during spin-drying. Since the torque applied to the brushless DC motor fluctuates and the ON / OFF ratio of the switching element, the inverter current, or the motor current when the motor speed is kept constant, a large fluctuation occurs, the first and second aspects of the present invention. The same effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a circuit configuration of an embodiment of a washing machine according to the present invention.

FIG. 2 is a diagram showing a change in inverter current when the motor rotation speed is constant in the embodiment.

FIG. 3 is a flowchart for explaining a method of detecting imbalance from a change in inverter current when the motor rotation speed is constant in FIG. 2;

FIG. 4 is a diagram for explaining a method of detecting imbalance from a change in the on / off duty ratio of the switching element when the motor rotation speed is constant in the embodiment.

FIG. 5 is a diagram for explaining a method for detecting imbalance from a change in motor rotation speed when the inverter current is constant in the embodiment.

FIG. 6 is a diagram for explaining a method of detecting imbalance from a change in the on / off duty ratio of the switching element when the inverter current is constant in the embodiment.

FIG. 7 is a diagram for explaining a method of detecting imbalance from fluctuations in the motor rotation speed when the on / off duty ratio of the switching element is constant in the embodiment.

FIG. 8 is a diagram for explaining a method of detecting imbalance from a change in inverter current when the on / off duty ratio of the switching element is constant in the embodiment.

FIG. 9 is a configuration diagram of a conventional washing machine.

[Explanation of symbols]

10 inverter circuit 20 a brushless DC motor 40 PWM oscillator microcomputer 70 current detecting circuit u ₁ that functions as (a duty ratio signal generator) 50 rotation speed detection circuit 60 imbalance _{detector, u 2, v 1, v} 2, w 1, w ₂ transistor (switching element)

Continuation of the front page (56) References JP-A-2-111220 (JP, A) JP-A-3-215289 (JP, A) JP-A-62-112596 (JP, A) JP-A-2-144096 (JP, A) , A) JP-A-60-132598 (JP, A) JP-A-58-23576 (JP, U) European Patent Application Publication 394177 (EP, A2) (58) Fields investigated (Int. Cl. ⁷ , DB Name) D06F 33/02 D06F 49/04 H02P 6/12

Claims (3)

(57) [Claims] 1. A brushless DC motor for rotating a dewatering tank, an inverter circuit for periodically switching a DC voltage by a switching element to drive the brushless DC motor, and an on / off ratio of the switching element in the inverter circuit. A duty ratio signal generator that outputs a duty ratio signal that changes the current, a current detection circuit that detects at least one of an inverter current flowing through the inverter circuit and a motor current flowing through the brushless DC motor, and a rotation of the brushless DC motor. A rotation number detection circuit for detecting the number of rotations, and the duty ratio signal generator.
Constant adjustment more on-off ratio of the switching element
The imbalance detector for detecting the imbalance of the laundry load during dehydration based on at least one of variation in the rotation speed detection value of the current detection value or the rotation speed detection circuit of the current detection circuit when it is A washing machine comprising: 2. A brushless DC motor for rotating a dewatering tank, an inverter circuit for periodically switching DC current by a switching element to drive the brushless DC motor, and an on / off ratio of the switching element in the inverter circuit. A duty ratio signal generator that outputs a duty ratio signal that changes the current, a current detection circuit that detects at least one of an inverter current flowing through the inverter circuit and a motor current flowing through the brushless DC motor, and a rotation of the brushless DC motor. a rotation speed detection circuit for detecting the number, the current current detection value of the detection circuit adjusts the duty ratio signal so as to be constant, the duty ratio signal value outputted from the duty ratio signal generator when the its or the Change of at least one of the rotation speed detection values of the rotation speed detection circuit A washing machine comprising: an unbalance detecting unit configured to detect an unbalance of a laundry load during dehydration based on movement. 3. A brushless DC motor for rotating a dehydration tank, an inverter circuit for periodically switching a DC voltage by a switching element to drive the brushless DC motor, and an on / off ratio of the switching element in the inverter circuit. A duty ratio signal generator that outputs a duty ratio signal that changes the current, a current detection circuit that detects at least one of an inverter current flowing through the inverter circuit and a motor current flowing through the brushless DC motor, and a rotation speed of the brushless DC motor. And a rotation speed detection circuit for detecting the rotation speed of the brushless DC motor.
The duty ratio signal is adjusted so as to be constant, and the duty ratio signal value output from the duty ratio signal generator at that time or the current detection value of the current detection circuit at the time of dehydration based on at least any fluctuation of the current detection value A washing machine comprising: an unbalance detecting unit configured to detect an unbalance of a laundry load.