KR100311651B1 - Method for breaking of Washing Machine - Google Patents

Abstract

The present invention relates to a brake control method of a washing machine for stably controlling the braking speed during braking of the washing machine to protect the system of the washing machine through smooth braking.

Instead of the braking resistor that releases the overvoltage of the system during braking of the washing machine, the system detects the overvoltage of the system in software and periodically charges and discharges the overvoltage through the power supply and the motor, thereby significantly reducing the capacity of the braking resistor with a simple circuit configuration. B brake resistors can be eliminated, simplifying installation, improving the reliability of the system's voltage level during braking, and lowering product costs.

In addition, a braking mode in which braking modes with different braking abilities are different by software is applied, and a braking mode that can reduce the speed quickly up to a predetermined motor speed is applied, and a braking mode in which a braking effect is less than that of the braking mode below a predetermined motor speed. The smooth braking is applied to prevent damage to the internal circuits of the system and reduce noise.

Description

Method for breaking of Washing Machine

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking control method of a washing machine, and more particularly, to a braking control method of a washing machine capable of protecting a system in a washing machine as well as smooth braking by stably controlling a braking speed during braking of a washing machine.

Inverter washing machine according to the prior art is a rectifier (1) for converting a commercial (AC) power supplied to the system from the outside as shown in FIG. A motor driver (2) for generating a voltage to drive control the motor (M) when DC power is supplied through the rectifier (1); A voltage sensing unit 3 for sensing a voltage flowing in the system when braking the washing machine and outputting a sensing voltage Vdc; A voltage comparator (4) for comparing the sensed voltage (Vdc) of the voltage detector (3) with a predetermined reference voltage (Vref) in the system; A switching unit (5) determining on / off of the braking resistor (R) according to the comparison result of the voltage comparing unit (4); A sensor (6) for detecting an operating state such as a rotation position and a speed of the motor (M); The microcomputer 7 is configured to receive a control signal from the sensor 6 and logically control the motor driver 2.

In general, the washing process is performed in the order of washing, rinsing, and dehydration. In particular, during the dehydration, the lid of the washing machine is suddenly opened or the washing tank is unbalanced so that the dehydration process needs to be stopped suddenly. If the system is to stop the motor (M).

At this time, since the motor (M) is a brushless DC motor and becomes a load when viewed from the system side during normal washing operation, the motor (M) flows in the direction (I-) in which current is discharged from the rectifier (1) to the motor (M) side. When the motor M is suddenly stopped during the high-speed rotation, the motor M itself becomes a generator, and the current I is charged in the direction I + due to the counter electromotive force generated from the motor M, that is, the current is rectified in the motor M. ), The voltage level of the rectifier 1 rises rapidly.

If the reverse current charged in the rectifier 1 is not discharged, the DC voltage level rises indefinitely to exceed the internal voltage of the internal circuit of the system, causing damage to the entire system. Therefore, braking means such as a voltage sensing section 3, a voltage comparing section 4, a switching section 5, a braking resistor R are required to release the overvoltage flowing in the system.

The operation of the brake control circuit of the conventional washing machine constructed as described above will be described with reference to FIG. 1 as follows.

First, when AC power is supplied from the outside, the rectifier 1 converts it to a DC voltage, and the motor driver 2 receives the converted DC voltage of the rectifier 1 to drive the motor M.

When the rotating motor M stops suddenly, the voltage sensing unit 3 senses the voltage between the rectifying unit 1 and the motor M and transmits the sensing voltage Vdc to the voltage comparing unit 4. do.

The voltage comparator 4 compares the reference voltage Vref set by the system with the sensed voltage Vdc sensed by the voltage detector 3, and transmits the comparison result to the switching unit 5. .

The switching unit 5 turns on the braking resistor R when the comparison result of the voltage comparing unit 4 determines that the sensing voltage Vdc exceeds the reference voltage Vref. When the braking resistor R is operated, the overvoltage flowing between the rectifying unit 1 and the motor M does not flow to the rectifying unit 1 but passes through the braking resistor R, so that the excess overvoltage flowing in the system is thermal energy. Emissions in form can keep the system at a constant voltage level.

At this time, the voltage sensing unit 3 continuously detects the voltage level of the system. When it is determined that the sensing voltage between the rectifying unit 1 and the motor M is less than or equal to the reference voltage Vref set by the system, the braking resistor By turning off (R), no current flows to the braking resistor R any more, and current flows only to the rectifier 1.

However, as described above, in the conventional case, since the voltage level of the system is controlled by hardware, the circuit design becomes complicated, and the motor M is connected to the rectifier 1 through the braking resistor R of the motor M. Since the use of the principle of releasing the charged energy as thermal energy, the capacity of the washing machine is increased in the end, thereby increasing the capacity of the braking resistor, thereby complicating component installation and increasing the product cost.

The present invention has been made to solve the problems of the prior art as described above, in place of the braking resistor to release the overvoltage of the system during braking of the washing machine to detect the overvoltage of the system by software and at the same time the overvoltage through the power supply and the motor By periodically charging and discharging, a simple circuit configuration can significantly reduce the capacity of the braking resistor or eliminate the braking resistor, simplifying installation, and improving the reliability of the system's voltage level stabilization during braking. The purpose is to lower.

In addition, a braking mode having different braking abilities with different software functions is applied, and a braking mode that can reduce the speed quickly up to a predetermined motor speed is applied, and a braking effect in which the braking effect is lower than that of the braking mode is below a predetermined motor speed. The purpose of this mode is to provide smooth braking to prevent damage to the internal circuits of the system and to reduce noise.

1 is a block diagram schematically showing a brake circuit configuration of a washing machine according to the prior art.

2 is a graph showing a correlation between dehydration time and a motor speed according to the prior art.

Figure 3 is a block diagram schematically showing the configuration of a braking circuit of a washing machine according to the present invention.

4 is a detailed circuit diagram and a current flow diagram of the motor driver of FIG.

5 is a flowchart illustrating a first embodiment of a brake control method of a washing machine according to the present invention;

6 is a flowchart illustrating a second embodiment of a brake control method of a washing machine according to the present invention;

7 is a graph showing a correlation between dehydration time and a motor speed according to FIGS. 4 and 5;

<Explanation of symbols for main parts of the drawings>

1 ....... Rectifier 10 ...... Voltage supply

2,20 ... motor driver 3,30 ... voltage detector

4 ....... Voltage comparison section 5 ....... Switching section

6,40 .... sensor 7,50 .... microcom

M ....... motor R ....... braking resistor

Q1 to Q6 ... transistors D1 to D6 ... diodes

A first aspect of the present invention for achieving the above object, step 501, the first braking mode is set at the start of braking to perform braking; Step 502 of detecting a speed of the motor while step 501 is performed; Step 503, in which the speed of the motor detected in step 502 is compared with a reference speed determined by the system; When the speed of the motor is slower than the reference speed as a result of the comparison in step 503, the second braking mode is set to detect the speed of the motor during steps 504 and 504 to perform braking (step 505). And step 506 to perform step 504 until it is determined.

The second feature includes steps 605 through 604 that detect the speed of the motor while steps 604 and 604 are performed in steps 501 through 504; Comparing the speed of the motor detected in operation 605 with a second reference speed set in the system; As a result of the comparison of step 606, when the speed of the motor is slower than the second reference speed, the third braking mode is set to detect the speed of the motor during steps 607 and 607 to perform braking (step 608). Includes step 609 to perform step 607 until it stops

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a block diagram schematically illustrating a brake circuit configuration of a washing machine implementing the method according to the present invention, and FIG. 4 is a motor driver configured to charge and discharge a voltage between a voltage supply unit and a motor, which is a part of FIG. 3. It is a figure for showing in detail.

First, referring to FIGS. 3 and 4, the present invention may include: a voltage supply unit 10 converting an AC power supplied from the outside into a DC voltage and supplying a voltage to the motor M using a capacitor; A plurality of transistors Q1, Q2, Q3, Q4, connected between the voltage supply unit 10 and the motor M to drive the motor M while controlling the flow of current flowing into and out of the motor M, A motor driver 20 including Q5 and Q6 and a plurality of diodes D1, D2, D3, D4, D5, and D6; A voltage sensing unit 30 configured to sense a voltage between the voltage supply unit 10 and the motor driving unit 20 to generate a sensing voltage Vdc; A sensor 40 for detecting an operation state such as the position and speed of the motor M; Control signal to receive the output of the sensor 40 and the output of the voltage sensing unit 30 to maintain a constant level of voltage through the charging and discharging operation between the voltage supply unit 10 and the motor (M) It is configured to include a microcomputer 50 for outputting to the motor drive unit 20. In particular, the motor driver 20 has transistors Q1, Q2, Q3, Q4, Q5 and Q6 and diodes D1, D2, D3, D4, D5, and D6 connected in parallel in a 1: 1 fashion. The base of the transistors receives a control signal of the microcomputer 50.

Operation by the braking control circuit of the washing machine configured as described above is as follows.

When commercial power (AC) is externally input to the voltage supply unit 10, the voltage supply unit 10 converts AC power input from the outside into DC power and outputs it to the motor driver 20. The motor driving unit 20 receives a DC voltage from the voltage supply unit 10 to generate a three-phase AC voltage by three electromotive force having the same frequency and different phase, and applies the motor M to the motor M. The driving is performed, and the washing machine performs washing, rinsing, and dehydration strokes by the rotational force of the motor M. FIG.

However, when the lid of the washing machine is opened during the dehydration stroke of the washing machine or when the washing process is suddenly stopped due to the imbalance of the washing tank, the system suddenly stops the motor M. At this time, excessive voltage is generated in the system due to the counter electromotive force generated by the motor M due to the sudden stop of the motor M. The transient voltage generated in this way is processed through the voltage charging and discharging operation between the voltage supply unit 10 and the motor M. This will be described with reference to FIG. 4.

Motor drive unit 20 of the present invention is configured as an inverter for controlling the speed of the three-phase induction motor by varying the voltage and frequency of the three-phase alternating current, first, when driving the motor (M) the control signal from the microcomputer 50 The transistor is applied to the bases of the transistors Q1, Q2, Q3, Q4, Q5 and Q6 constituting the motor driver 20 so that current flows from the voltage supply part 10 toward the motor M (I-direction). Selectively turn them on or off to create a current path. In this case, a voltage is supplied from the voltage supply part 10 to the motor M to drive the motor M.

As mentioned above, when the lid of the washing machine is opened during the dehydration stroke or when the washing machine suddenly brakes, such as an unbalance detection of the washing machine, the motor M is suddenly stopped. Accordingly, the counter electromotive force is generated in the motor M, and the transistors that are turned on / off so that a current flows from the voltage supply unit 10 toward the motor M (I-direction) are turned off / on in reverse and parallel to each transistor. Regeneration energy is transferred to the voltage supply unit 10 through the connected diodes D1, D2, D3, D4, D5, and D6 so that the direction of the current is changed from the motor M to the voltage supply unit 10 (I + direction). The voltage generated by the counter electromotive force of the motor M is charged in the voltage supply unit 10.

The microcomputer 50 continuously receives the detection voltage of the voltage detector 30 and the control signal of the sensor 40 that detects the speed and position of the motor M to generate a duty of a PWM (Pulse Width Modulation) method. To be supplied to the motor driver 20. The motor driver 20 selectively turns on / off the transistors Q1, Q2, Q3, Q4, Q5 and Q6 of the motor driver 20 according to the PWM duty applied from the microcomputer 50. By creating a flow path, the current direction is changed from the motor M to the voltage supply unit (I + direction) or from the voltage supply unit 10 to the motor M (I-direction). That is, the voltage of the voltage supply unit 10 can be maintained at a constant level even without a braking resistor by allowing the voltage of the motor M sudden stop to be charged or discharged based on the voltage supply unit 10.

The motor driver 20 determines the amount of charge or discharge according to the duty ratio of the PWM signal applied from the microcomputer 50. Here, the adjustment of the duty ratio and the charge / discharge relationship of the voltage are based on the following equation. do.

In Equation 1, Dratio denotes a duty ratio, Ton denotes a time of an ON interval, and Toff denotes a time of an OFF interval.

As shown in Equation 1, the duty ratio is determined by Ton value, which is a numerator because the denominator is always constant. Therefore, reducing the duty ratio means that the value of Ton is made small, that is, this means that the amount of discharge from the voltage supply unit 10 to the motor M is small, and the amount charged in the voltage supply unit 10 is increased. On the contrary, increasing the duty ratio means increasing the value of Ton, which increases the amount of discharge from the voltage supply unit 10 to the motor M and decreases the amount of charge in the voltage supply unit 10.

In addition to the method of releasing the overvoltage of the system by the method described above, the method of releasing the overvoltage of the system through a program in the microcomputer will be described as follows.

First, the microcomputer 50 outputs a control signal to turn off all of the transistors Q1 to Q6 constituting the motor driver 20. This method simply removes the braking resistor R in the prior art and may damage the system at the initial stop of the motor M. However, the initial speed at which the counter electromotive force at the motor M suddenly stops due to the decrease in the speed of the motor M is reduced. It can be used when it is reduced.

Secondly, the microcomputer 50 outputs a control signal to turn on all the lower transistors Q4, Q5, and Q6 constituting the motor driving unit 20, so that the counter electromotive force generated in the motor M is generated. Q4 ~ Q6) flows toward the motor (M) to release the overvoltage of the system. This method can be used only when the back EMF is reduced more than the first method.

By using the various braking control methods described above, a smooth washing machine braking method was devised to prevent damage to internal circuits and reduce noise caused by sudden braking of the washing machine.

FIG. 5 is a flowchart illustrating a first embodiment thereof, and the braking method of the present invention will be described with reference to the following.

In step 501, the braking is started by setting the first braking mode at the same time as the braking starts. In the initial braking, the speed of the motor M is high, and thus the braking mode having the highest braking ability is used. The transistors Q1 to Q6 of the motor driving unit 20 are turned on or off according to the duty ratio output from the microcomputer. The overvoltage is discharged by the method of causing the overvoltage to be charged or discharged to the voltage supply unit 10 to perform braking. In step 502, the speed of the motor M is sensed, and braking is performed in the first braking mode, and the speed of the motor is continuously sensed and compared with a reference speed already set in the system (step 503). . If it is determined in step 503 that the speed of the motor M being driven is lower than the reference speed, the second braking mode is set to perform braking (step 504). In the second braking mode, the transistor of the motor driving unit 20 is performed. Refers to a method of performing a braking by releasing overvoltage by charging the counter electromotive force generated by the motor M to the voltage supply unit 10 by turning off all of the Q1 to Q6. The second braking mode is a mode in which braking ability is lower than that of the first braking mode, and the braking of the motor M is partially performed by the first braking mode, so that the counter electromotive force generated in the motor M is reduced to a predetermined value or more. can do. Thereafter, the speed of the motor is sensed while step 504 is performed (step 505), and step 505 is performed until the motor stops (step 506).

6 is a flowchart showing a second embodiment of the present invention, and steps 601 to 604 of the second embodiment are the same as steps 501 to 504 of the first embodiment, and thus description thereof is omitted.

In step 605, the motor M speed is detected in step 604. The speed of the motor M detected in step 605 is compared with the second reference speed already set in the system (step 606). If the speed is slower than the second reference speed, the third braking mode is set to perform braking. In step 607, the third braking mode is set by turning on the transistors Q4 to Q6 constituting the motor driving unit 20 to discharge the counter electromotive force generated by the motor M toward the motor M. Say how to brake. The third braking mode is a method of discharging the overvoltage toward the motor M generating the counter electromotive force. Therefore, the third braking mode has a limitation in overvoltage discharge, and therefore, the third braking mode may be performed in a state in which the speed of the motor M is reduced more than in the second braking mode. Thereafter, the speed of the motor is sensed while step 507 is performed (step 508), and step 507 is performed until the motor stops (step 509).

In the present invention, the third braking mode is described as an example, but the braking mode having more and more various braking capabilities may be implemented by the program of the microcomputer 50.

According to the braking control method of the washing machine of the present invention, the circuit design is simpler than the braking method using the conventional braking resistor, and the manufacturing cost can be reduced.

When braking the washing machine, the braking ability is changed according to the operation speed of the motor, thereby reducing the stress caused by the sudden stop of the motor and providing the effect of reducing the noise due to the stable stopping of the washing tank.

Claims (4)

(a) at the start of braking, a first braking mode is set to perform braking; (b) detecting the speed of the motor while step (a) is performed; (c) comparing the speed of the motor detected in step (b) with a reference speed determined by the system; And (d) braking control method of the washing machine comprising the step of performing a braking until the motor stops when the second braking mode is set when the speed of the motor is lower than the reference speed as a result of the comparison of step (b). The method of claim 1, wherein the braking capability of the first braking mode is greater than that of the second braking mode. (a) at the start of braking, a first braking mode is set to perform braking; (b) detecting the speed of the motor while step (a) is performed; (c) comparing the speed of the motor detected in step (b) with a first reference speed set by the system; (d) performing braking by setting to a second braking mode when the speed of the motor is slower than the first reference speed as a result of the comparison in step (b); (e) detecting the speed of the motor while step (d) is performed; (f) comparing the speed of the motor detected in step (e) with a second reference speed set by the system; (g) a braking control method for a washing machine comprising performing braking until a third stop mode is set and the motor stops when the speed of the motor is lower than the second reference speed as a result of the comparison in the step (f). . The method of claim 3, wherein the magnitude of the braking capability of the first, second, and third braking modes is a first braking mode> a second braking mode> a third braking mode.