JP2001170391A - Washing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately control the rotating speed of a motor for driving a washing-cum-dehydrating drum. SOLUTION: Voltage applied to a motor 7 is regulated by PWM control, and a duty ratio in the PWM control is determined by speed type IP control. At this time, a storage gain a0 in the speed type IP control is increased in proportion to time ta from the start of current application to the motor 7 and reduced when the motor starts rotating. Consequently, even in the case of rotating the motor 7 at low speed, the motor 7 can be quickly started without being influenced by the load quantity in a washing-cum-dehydrating drum 4, and overshoot or the like from the target rotating speed can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a washing machine.

[0002]

2. Description of the Related Art In recent years, a DC brushless motor has been adopted as a motor for driving a washing and dewatering tub, and a voltage applied to the motor has been adjusted by PWM control to control the rotation speed of the motor. Has been put to practical use. In addition, as a control method for determining the duty ratio in the PWM control as to how much voltage is applied to reach the set rotation speed and maintain the set rotation speed, a given deviation (in the rotation speed control, The difference between the set rotation speed and the actual rotation speed), proportional operation (P operation),
PID control (narrow sense), PI control, which determines the output value by adding the operation of the integration operation (I operation) and the differentiation operation (D operation)
So-called PID control (broad sense) such as IP control is employed.

FIG. 7 is a block diagram of speed-type IP control, which is one of the PID controls (in a broad sense). Then, when this is represented by a calculation formula, the following formula 1 and formula 2 are obtained.

[0004]

(Equation 1)

The above calculation is repeated every sampling time (for example, 8 ms) to increase or decrease the manipulated variable Mn, that is, the duty ratio.

The increase / decrease of the duty ratio per operation mainly depends on the control gain, that is, in the case of the above formula, mainly the integral gain a0 and the proportional gain a1.

[0007]

When the washing and dewatering tub is rotated, the load applied to the motor varies greatly depending on the amount (load) of the laundry put into the washing and dewatering tub. Especially when the motor is started, the difference is large.

In the PID control, as shown in the equation (1), at the time of startup, that is, until the motor rotates, the increase / decrease of the duty ratio depends only on the integral gain.

For this reason, in the PID control of the motor that drives the washing and spin-drying tub, the rotation speed of the motor cannot be properly controlled unless the integral gain is properly adjusted. That is, as shown in FIG. 8B, it is ideal that the motor starts quickly and the target rotation speed can be maintained with little fluctuation. However, if the integral gain is set to be small, when the load amount is large, it becomes ideal in FIG. As shown, it takes a long time for the motor to start rotating. However, when the integral gain is set to a large value, when the load amount is small, an overshoot occurs with respect to the target rotational speed as shown in FIG. 8C, or vibration (as shown in FIG. (A state in which the fluctuation is repeated). Note that the washing and dewatering tub may be rotated at an extremely low speed, such as when supplying water during dehydration rinsing, and in this case, overshoot and vibration are particularly likely to occur.

[0010] The present invention relates to a washing machine and solves such a problem.

[0011]

According to a first aspect of the present invention, there is provided a washing machine comprising: a washing and dewatering tub rotatably disposed in an outer tub; A DC brushless motor, a speed sensor for detecting the rotation speed of the motor, and a voltage applied to the motor by PWM control based on the rotation speed detected by the speed sensor, and a predetermined voltage. The duty ratio in the PWM control is determined by adding at least the integral operation among the proportional operation, integral operation, and differential operation to the deviation between the set rotational speed of the motor and the actual rotational speed detected by the speed sensor. And a control device to
The control device, when starting the motor from a stop state, until the motor starts rotating, increasing the integral gain in the integration operation with the lapse of time from the start of energization to the motor, It is assumed that.

In this configuration, the integral gain increases with the lapse of time from the start of energization of the motor, and the increase in the duty ratio also increases.

Therefore, even when the load in the washing and dewatering tub is large, the time until the motor rotates can be shortened.
In addition, when the load is small, the motor starts to rotate while the integral gain is small.
Overshoot and vibration hardly occur.

Since a large torque is absolutely necessary at the time of starting the motor, the above-described configuration tends to increase the integral gain immediately after the start, and the integral gain as it is causes overshoot or vibration. there is a possibility.

On the other hand, in the configuration of the washing machine according to the second aspect of the present invention, the control device reduces the integral gain when the motor starts rotating.

In this configuration, when the load on the motor is greatly reduced by starting the motor, the integral gain is also reduced accordingly, so that overshoot and vibration can be further prevented.

According to a third aspect of the washing machine of the present invention,
A washing and dewatering tub rotatably arranged in the outer tub, a motor capable of changing the rotation speed for driving the washing and dewatering tub,
A speed sensor for detecting the rotation speed of the motor, and increasing or decreasing the voltage applied to the motor based on a deviation between a preset rotation speed of the motor and an actual rotation speed detected by the speed sensor, A control device for controlling the rotation speed of the motor, wherein the control device, when starting the motor from a stopped state, gradually increases the voltage applied to the motor until the motor starts rotating, and It is characterized in that the increase width per turn increases with the passage of time from the start of energization to the motor.

In this configuration, the rate of increase of the voltage applied to the motor increases with time until the motor starts, so that the motor can be shortened even if the load is large, as in the configuration according to claim 1. It can be started up in a short time, and overshoot and vibration can hardly occur even if the load is small.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A washing machine according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a side longitudinal sectional view showing an outline of the washing machine of the present embodiment.

In FIG. 1, 1 is a machine frame, 2 is this machine frame 1
An outer tank having an open upper surface, which is suspended and supported by four suspension rods 3 therein. Reference numeral 4 denotes a washing and dewatering tub having a plurality of dehydration holes (not shown) around the same and disposed in the outer tub 2 and also having an open upper surface. The washing and dehydrating tub 4 is provided on a bottom wall. Around the rotating shaft 5.

Reference numeral 6 denotes a pulsator rotatably disposed at the bottom of the washing and dewatering tub 4; 7 a motor connected to the washing and dewatering tub 4 and the rotary blade 6 via a power transmission mechanism 8; The motor 7 mainly rotates only the pulsator 6 at low speed during washing and rinsing (for rinsing and rinsing with water), and rotates the washing and dewatering tub 4 at high speed in one direction about the rotating shaft 5 during dehydration of the laundry. At this time, the pulsator 6 also rotates at a high speed at the same time). Here, a DC brushless motor is used as the motor 7.

Reference numeral 9 denotes an upper surface plate mounted on the upper surface of the machine frame 2, and a laundry loading port 10 and a loading port 10
And an upper lid 11 that covers the openable and closable.

Reference numeral 12 denotes an operation box provided at the front of the upper surface plate 9. On the upper surface thereof, an operation panel 13 provided with an operation section comprising a start key and the like and a display section for displaying operating conditions and strokes. Is provided inside, and is constituted mainly by a microcomputer.
A control unit 14 for controlling the driving of various loads such as the above and executing the washing operation is accommodated.

Reference numeral 15 denotes a water inlet disposed at the rear of the upper plate 9 and has a detergent container 16 for charging a detergent or the like therein. Reference numeral 17 is connected to the water inlet 15, from above the outer tub 2 and the washing and dewatering tub 4.
An electromagnetic water supply valve 18 is provided in the middle of the water supply pipe 17. 19
Is a drain pipe provided on the bottom wall of the outer tub 2, and 20 is a drain valve provided in the middle of the drain pipe 19, which is opened and closed by the operation of a torque motor 21.

The motor 7 is controlled by an inverter (PWM control) so that the rotation speed can be varied. FIG. 2 is a block circuit diagram showing a control mechanism for controlling the inverter of the motor 7.

The rotation speed sensor 22 detects a magnetic pole position of the motor 7 by a Hall IC arranged on the motor 7, detects a rotation speed from the magnetic pole position, and obtains a microcomputer for an inverter (hereinafter abbreviated as a microcomputer). 23. In the microcomputer 23, the arithmetic expression (Expression 1, Expression 2) of the speed type IP control shown in Expression 1 (described in the section of the prior art) is provided.
The microcomputer 23 calculates the duty ratio of the PWM signal (the ratio of the ON time in one ON / OFF cycle) based on the rotation speed read from the rotation speed sensor 22 using this arithmetic expression. Drive circuit 24
Is based on the PWM signal output from the microcomputer 23,
The switching element 26a of the three-phase bridge circuit 26 connected to the 280V DC power supply 25 is turned on / off, and the voltage applied to the three phases of the motor 7 is adjusted to control the torque of the motor 7. Thus, the rotation speed of the motor 7 is controlled. The voltage applied to the motor 7 increases as the duty ratio increases, and the torque of the motor 7 increases.

In the washing machine according to the embodiment of the present invention, the washing and dewatering tub 4 may be rotated at an extremely low speed, for example, when water is supplied during dehydration and rinsing. The dehydration rinsing is a water-saving rinsing in which the laundry adhered to the tub wall is supplied with water by the dehydration following the washing and water is soaked, and then the washing and dewatering tub 4 is rotated at a high speed to squeeze the detergent together with the soaked water. . The reason why the washing and dewatering tub 4 is rotated at a low speed at the time of supplying water for the dehydration rinsing is to uniformly apply water to the laundry stuck to the entire circumference of the tub. Specifically, the washing and dewatering tub 4
Is rotated at about 20 rpm, so that the motor 7
Rotate at 0 rpm. (In this embodiment, the speed reduction ratio between the motor and the dewatering tub is set to about 0.6.) In this embodiment, even when the motor is rotated at an extremely low speed, the load amount in the In order to quickly start the motor 7 and to minimize overshoot from the target rotation speed without being affected by the motor speed, for example, when the target rotation speed of the motor 7 is set to 30 rpm, the above-described speed-type IP control is performed. , The proportional gain a1 and the integral gain a0 are set as shown in the table of FIG. That is, until the motor 7 is started, the integral gain a0 is increased with the time ta from the start of energization of the motor 7, and when the motor 7 starts rotating, the integral gain a0 is decreased. ing. It should be noted that the proportional gain a1 does not contribute when the motor 7 is started, and is therefore always a constant value.

Hereinafter, the speed control operation of the motor 7 will be described in detail with reference to the PAD charts shown in FIGS. FIG. 4 is a PAD chart of a main routine in speed control, and FIG. 5 is a PAD chart of an initial setting subroutine in speed control.
FIG. 6 shows an AD chart and FIG. 6 shows an IP control subroutine in the speed control.

When a start command for the motor 7 is output from a main microcomputer (not shown) connected to the microcomputer 23 for the inverter, the microcomputer 23 executes an initialization subroutine and then stops the motor 7. The IP control subroutine is executed until a command is output.

That is, in the initial setting subroutine, the values in the memory area of the operation amount (duty ratio) Mn, the memory area of the currently sampled rotational speed ωn, and the memory area of the previously sampled rotational speed ωn−1 are reset. At the same time, a sampling time counter for counting the sampling time tspl and a start-up time counter for counting the time ta from the start of energization of the motor are reset. The memory area and the counter are prepared in the microcomputer 23.

Next, the operation proceeds to the IP control subroutine, and the following operation is performed every time the sampling time tspl reaches 8 ms.

First, the sampling time counter is reset. Next, an integral gain a0 and a proportional gain a1 are set.

The proportional gain a1 is always a constant value, that is, 8
000. On the other hand, the integral gain a0 is changed to a large value with the start time counter ta until the motor 7 rotates. That is, the integral gain a0
Is set to 90 until 10 seconds elapse from the start of energization to the motor 7, is set to 130 after 10 seconds elapses, and is set to 130 until 15 seconds elapse, and is further set to 700 after 15 seconds elapse. You. Further, the integral gain a0 is reduced when the motor 7 starts rotating, and is set to 80.

When the integral gain a0 and the proportional gain a1 are set, the rotational speed of the motor 7 is measured by the rotational speed sensor 22, and the measured rotational speed is stored as the rotational speed ωn sampled this time. Then, using the rotational speed ωn and the like, the increase / decrease (increase / decrease width) Δmn of the duty ratio is calculated by the above-described equation (1). Further, the duty ratio Mn is calculated by Expression 2 of Expression 1. That is, the PWM that is output this time by adding the increase / decrease Δmn to the previous duty ratio Mn.
The duty ratio Mn of the signal is determined.

Thus, the microcomputer 23 outputs a PWM signal having the determined duty ratio Mn. This allows
A voltage corresponding to the duty ratio Mn is applied to the motor 7.

Finally, the rotation speed ωn sampled this time is replaced with the rotation speed ωn
And is stored in the memory area.

Now, as is apparent from the above equation 1,
The increase / decrease width Δmn of the duty ratio Mn depends only on the integral gain a0 until the motor 7 starts rotating. This means that since ωn and ωn−1 become zero, the expression 1 becomes Δmn
= A0 * ωc.

In the present embodiment, the integral gain a0 increases with time until the motor 7 starts rotating. Therefore, the duty ratio Mn, that is, the voltage applied to the motor 7 is constant. Does not increase at the rate of, but increases almost quadratically.

Therefore, when rotating the washing and dewatering tub 4,
Even if the load in the tank is large and a large torque is required to start the motor 7, the motor 7
Can be started. Further, when the load amount in the tank is small, the motor 7 starts in a short time and starts before the integral gain a0 increases. Therefore, even when the motor 7 is controlled at a low speed, overshoot or vibration occurs. Less likely.

When the motor 7 starts to rotate, the motor 7 does not require a large torque. Therefore,
Thereafter, when the motor 7 is rotated at a low speed, it is necessary to reduce the increase width of the duty ratio or to reduce the duty ratio. In this case, ωn or ω
Since n-1 is not zero, the increase width of the duty ratio is suppressed more than at the time of startup, but the integral gain a0
If the ratio remains large, it is not possible to reduce the increase width of the duty ratio or decrease the duty ratio quickly, which may cause overshoot or vibration.

On the other hand, in the present embodiment, when the motor 7 is started, the integral gain a0 is changed to a small value, so that the duty ratio can be quickly adjusted after the motor 7 is started, and the overshoot and vibration can be reduced. Generation can be further prevented.

The above embodiment is an embodiment, and it is apparent that changes and modifications can be made within the scope of the present invention. For example, although the speed-type IP control is used in the present embodiment, other PID control (in a broad sense) may be used.

[Brief description of the drawings]

FIG. 1 is a side longitudinal sectional view showing an outline of a washing machine according to an embodiment of the present invention.

FIG. 2 is a block circuit diagram showing a control mechanism for inverter control of a motor that drives a washing and spin-drying tub.

FIG. 3 is a table showing set values of an integral gain and a proportional gain in speed type IP control.

FIG. 4 is a flowchart showing a main routine P in motor speed control.
It is an AD chart.

FIG. 5 is a PAD chart of an initialization subroutine in motor speed control.

FIG. 6 is an IP control subroutine in motor speed control.

FIG. 7 is a block diagram of speed type IP control.

FIG. 8 is a diagram showing the influence of the magnitude of the integral gain on the rotation speed control of the motor in the speed type IP control.

[Explanation of symbols]

 2 outer tub 4 washing and dewatering tub 7 motor 22 rotation speed sensor (speed sensor) 23 microcomputer (control device)

Claims (3)

[Claims] 1. A washing and dewatering tub rotatably disposed in an outer tub, a DC brushless motor for driving the washing and dewatering tub, a speed sensor for detecting a rotation speed of the motor, Based on the rotation speed detected by the sensor,
The voltage applied to the motor is adjusted by PWM control, and a proportional operation, an integral operation, and a differential operation are calculated based on a deviation between a predetermined rotational speed of the motor and an actual rotational speed detected by the speed sensor. A control device for determining at least the duty ratio in the PWM control by adding at least the operation of the integral operation, wherein the control device, when starting the motor from a stopped state, until the motor starts rotating, A washing machine characterized in that an integral gain in an integral operation is increased with a lapse of time from the start of energization of the motor. 2. The washing machine according to claim 1, wherein the control device reduces the integral gain when the motor starts rotating. 3. A washing and dewatering tub rotatably disposed in an outer tub, a motor capable of changing a rotation speed for driving the washing and dewatering tub, a speed sensor for detecting a rotation speed of the motor, A control device for increasing or decreasing a voltage applied to the motor based on a deviation between a predetermined rotation speed of the motor and an actual rotation speed detected by the speed sensor, and controlling a rotation speed of the motor. When the motor is started from a stopped state, the control device gradually increases the voltage applied to the motor until the motor starts rotating, and supplies the increasing amount per one time to the motor. A washing machine characterized in that the size of the washing machine increases as time elapses from the start.