KR19990047486A - Motor speed control method of drum washing machine - Google Patents

Abstract

A method of controlling the motor speed of a drum washing machine to improve the constant speed control performance, the method comprising: measuring a length of one cycle of a PWM pulse signal supplied to a motor by starting washing; and a pulse length and a reference pulse length of a measurement step. Comparing with the step of performing the speed correction by a constant correction formula according to the comparison result, so that it is possible to improve the constant speed control performance and the washing performance accordingly.

Description

Motor speed control method of drum washing machine

The present invention relates to a washing machine, and more particularly, to a motor speed control method of a drum washing machine.

Generally, a washing machine is a machine for washing laundry by performing washing, rinsing, and dehydrating strokes according to a predetermined algorithm. The washing machine is classified into a pulsator type, a stirring type, a drum type, and the like according to a washing method.

At this time, as shown in FIG. 1, the drum washing machine includes a main body 1, a tub 2 fixed by a damper (not shown) inside the main body 1, and laundry into the tub 2 and a motor ( The driving force of 10) is transmitted through the belt 11 to rotate the drum 3 for washing-related stroke, the thermistor 4 for measuring the temperature of the washing water supplied to the drum 3, and to input detergent. Detergent container (5), the water supply pipe (6) for supplying the washing water or the washing water mixed with the detergent of the detergent container (5) connected to the detergent container (5), drain pipe for discharging the washing water used in the washing stroke to the outside (7) ) Is connected to the end of the drain pipe (7) and comprises a pump (8) and a drain hose (9) for forcibly pumping the washing water.

And when looking at the operation of the drum washing machine configured as described above, first, when the user opens the door (not shown) attached to the front of the main body 1, puts the laundry, and inputs the washing command through the control panel, the washing water is the detergent container (5). Guided by the water supply pipe (6) through the) is filled in the drum (7). Subsequently, when the washing water is filled above a certain level, the motor 10 is driven and the drum 3 rotates to perform washing.

At this time, if the user selects a boiled laundry, washing is performed using high temperature wash water.

On the other hand, when the washing is completed, the pump 8 is operated so that the washing water is drained to the outside via the drain pipe 7 and the drain hose 9, and when the draining is completed, the rinsing and dehydrating stroke are continuously performed, and the washing administration is finished. do.

Hereinafter, a motor speed control method of a drum washing machine according to the related art will be described with reference to the accompanying drawings.

In the conventional method for controlling the motor speed of a drum washing machine, as shown in FIG. 2, first, when a user opens a door of a drum washing machine to input laundry, and then inputs a washing command, the controller of the drum washing machine (not shown) In accordance with the washing instruction and the predetermined algorithm to detect the quantity of water and water supply to drive the motor 10 at a constant speed, that is, 50rpm to proceed with the washing.

At this time, the detailed operation for controlling the constant speed of the motor 10 is as follows.

First, the motor 10 is accelerated by an open loop (S11).

In this case, the open loop means applying a voltage of a predetermined level to the motor 10 without a change in the supply voltage.

In operation S12, the number of pulses applied to the motor 10 is counted corresponding to the predetermined voltage for a predetermined time.

Next, the counted pulse number and the reference pulse number are compared (S13).

The pulse width modulation (PWM) duty control operation, that is, the speed correction operation, is performed according to the comparison result of the comparison step S13 (S14).

That is, if the counted pulse number is not the same as the reference pulse number, the duty ratio of the pulse is appropriately adjusted according to the difference value, and the input voltage level is changed to change the speed of the motor 10 to 50 rpm during the washing operation. Keep it.

Motor speed control method of the drum washing machine according to the prior art has the following problems.

First, since the number of pulses for a certain time is counted to detect the speed of the motor, the sampling time for speed sensing is long, so the control time is long.

Secondly, the use of a high-performance sensor to count the number of pulses increases the cost, and the use of a suitable sensor that does not matter in terms of cost increases the error of the speed detection, thereby degrading the constant speed control performance.

Accordingly, an object of the present invention is to provide a method for controlling a motor speed of a drum washing machine, which is designed to solve the above-mentioned problems.

1 is a cross-sectional view showing the structure of a general drum washing machine

2 is a flowchart illustrating a method of controlling a motor speed of a drum washing machine according to the related art.

3 is a flowchart illustrating a method of controlling a motor speed of a drum washing machine according to the present invention.

Explanation of symbols for main parts of the drawings

1: body 2: tub

3: drum 4: thermistor

5: detergent container 6: water pipe

7: drain pipe 8: pump

9: drain hose 10: motor

11: belt

The present invention provides a method for controlling a motor speed of a drum washing machine, the method comprising: measuring the length of one cycle of a PWM pulse signal supplied to a motor by starting washing, and comparing the pulse length and the reference pulse length of the measuring step to the comparison result. In accordance with the constant correction formula characterized in that it comprises a step of performing a speed correction.

Hereinafter, referring to the accompanying drawings, a motor speed control method of a drum washing machine according to the present invention will be described.

3 is a flowchart illustrating a method of controlling a motor speed of a drum washing machine according to the present invention.

In the method of controlling the motor speed of a drum washing machine according to the present invention, first, a user opens a door of a drum washing machine to input laundry, and then inputs a washing command, and the control unit detects and supplies water according to the washing command and a predetermined algorithm. Washing is performed by driving the motor 10 at a speed, that is, 50 rpm.

At this time, the constant speed control operation for driving the motor 10 at 50 rpm constant speed is as follows.

First, the motor 10 is accelerated by an open loop (S21).

Then, the length of one cycle of the pulse applied to the motor 10 is measured using the counter in the control unit (S22).

PD (n) = PD (n-1) + K _p (R _ref -R _s ) + K _d (R _s -R _s-1 )

PD (n): PWM Duty rate in current constant speed control operation

PD (n-1): PWM duty rate just before PD (n)

K _p : proportional constant

K _d : Differential constant

R _ref : reference motor speed

R _s : Current motor speed

R _s-1 : Motor rotation speed just before R _s

Subsequently, the pulse length measured in step S22 is compared with the reference pulse length, and if the measured pulse length is not equal to the reference pulse length, the speed correction operation is performed according to Equation 1 (S24).

That is, washing the laundry is performed by controlling the motor 10 at constant speed by calculating the PWM duty ratio according to Equation 1 and appropriately changing the input voltage level according to the value (S25).

In this case, in order to maintain constant speed control performance at the highest level even under rapid load fluctuations, it is appropriate to apply 2 for the K _p and K _d values.

As a result, the present invention counts the number of pulses for a predetermined time to determine whether the speed control is correctly performed, whereas by measuring the length of one pulse period, it is determined whether to perform the constant speed control more quickly and accurately. It is to perform constant speed control by formality.

The method of controlling the motor speed of the drum washing machine according to the present invention measures the length of one pulse instead of the number of pulses for a predetermined time and controls the motor speed based on this, thereby greatly reducing the time required for constant speed control and simultaneously detecting the speed. The precision is improved, thereby improving the constant speed control performance and the washing performance thereof.

Claims (4)

In the motor speed control method of the drum washing machine, Starting washing and measuring the length of one cycle of the PWM pulse signal supplied to the motor; Comprising the step of comparing the pulse length and the reference pulse length of the measuring step and performing a speed correction by a constant correction equation in accordance with the comparison result. The method of claim 1, According to the comparison result, the step of performing the speed correction by the constant correction equation If the measured pulse length is not the same as the reference pulse length, the step of performing a speed correction by a constant correction equation, the motor speed control method of the drum washing machine. The method of claim 1, The constant correction formula is PD (n) = PD (n-1) + K _p (R _ref -R _s ) + K _d (R _s -R _s-1 ) ego PD (n) is the PWM duty ratio in the current constant speed control operation, PD (n-1) is the PWM duty ratio in the constant speed control operation immediately before PD (n), and K _p is a proportional constant, K _d is the derivative constant, R _ref is the reference motor speed, R _s is the current motor speed, R _s-1 is the motor speed of the previous stage R _s . The method of claim 3, wherein The motor speed control method of the drum washing machine, characterized in that the K _p and K _d value.