KR100547338B1 - Breaking control method in an electric washing machine - Google Patents

Abstract

Braking control method in the washing machine according to the present invention, (a) after the dehydration in the washing machine, performing a normal braking by the normal braking mode; (b) detecting an unbalanced state of the washing tank generated during the normal braking; (c) determining whether the sensed imbalance state exceeds a range of a set allowable imbalance state; And (d) in step (c), if the detected imbalance state does not exceed the range of the set allowable imbalance state, and returns to step (a), and if the detected imbalance state exceeds the set allowable imbalance state, Converting the braking mode from the normal braking mode to the rapid braking mode to perform braking.

According to the present invention, when braking after the end of dehydration, even when an unbalanced condition of the laundry in the washing tank or an unbalanced condition of the washing tank is caused by some external factors, braking by the general braking mode is not continued as in the prior art. The controller detects the imbalance at that time, compares it with the set reference value, and converts from normal braking mode to rapid braking mode according to the comparison result to perform braking, and according to the vibration that may occur during braking by the continuous braking mode. It can prevent or minimize excessive noise and mechanical or circuit damage in the system.

Description

Braking control method in an electric washing machine

1 is a block diagram schematically showing a motor control system of a conventional inverter washing machine.

FIG. 2 is a circuit configuration diagram of a motor driving unit (inverter) of the motor control system of the inverter washing machine of FIG. 1.

3 is a flow chart showing an execution process of a braking control method in a washing machine according to the present invention.

Figure 4 is an ideal waveform diagram of the three-phase AC voltage applied to the motor from the motor drive unit (inverter) of a typical inverter washing machine.

5A is an actual waveform diagram of a three-phase AC voltage applied to a motor from a motor driving unit (inverter) of an inverter washing machine in which a braking control method in the washing machine according to the present invention is employed.

5B is an enlarged fragmentary view of a portion “A” of the voltage waveform graph of FIG. 5A.

FIG. 5C is a time chart showing "ON" and "OFF" sections on the graph of FIG. 5B. FIG.

<Explanation of symbols for the main parts of the drawings>

101 Rectifier 102 Motor drive (inverter)

103 Braking resistor 104 Voltage sensing unit

105 ... Voltage comparison section 106 ... Switching section

107 ... sensor (hall sensor) 108 ... microcomputer

109 ... signal output 110 ... motor

The present invention relates to a braking control method in a washing machine, and more particularly, in a washing machine that can prevent the occurrence of noise and damage to the washing machine by changing the braking mode according to an imbalance state generated during braking after the dehydration of the washing machine. It relates to a braking control method.

In general, a washing machine is largely composed of a washing tank for washing and dehydrating laundry, a motor for providing rotation driving force to the washing tank, and a control unit for controlling the motor. In such a washing machine, an inverter is generally used to more precisely control the motor (rotational speed) and to cope with various operating conditions. Thus, such a washing machine may be referred to as an inverter washing machine.

1 is a block diagram schematically illustrating a motor control system of a conventional inverter washing machine.

Referring to FIG. 1, a conventional motor control system of an inverter washing machine includes a rectifying unit 101 which receives an AC power source from the outside and converts the DC power into a direct current, and converts a DC voltage passed through the rectifying unit 101 into a three-phase alternating current. Motor driving unit (inverter) 102 to supply to the motor 110 and the braking for consuming the voltage (reverse electromotive force) flowing back from the motor 110 to the power supply terminal side when braking the motor 110 as thermal energy by the resistance. A voltage comparator comparing the resistance 103, the voltage sensing unit 104 for sensing the voltage at the link terminal of the rectifier 101, and the voltage sensed by the voltage sensing unit 104 and the reference voltage Vref ( 105, the switching unit 106 for turning on / off the braking resistor 103 circuit stage according to the comparison result by the voltage comparing unit 105, the rotational speed of the motor 110 and A sensor 107 for detecting the position of the rotor and a transmission signal from the sensor 107 And control the operation of the motor based on it, while controlling the logic related to the overvoltage release of the system during braking, and according to the control commands from the microcomputer 108 The signal output unit 109 outputs a corresponding control signal to the motor driving unit (inverter) 102. As shown in FIG. 2, the motor driving unit (inverter) 102 includes six switches each configured by parallel connection of one transistor Q1 to Q6 and a diode D1 to D6. It consists of a series / parallel combination circuit of the elements S1 to S6. In FIG. 1, reference numeral C denotes a capacitor for removing an AC component mixed in a DC voltage output through the rectifying unit 101.

Then, the operation of the control system of the conventional inverter washing machine having the above configuration will be described.

First, when AC power from outside (eg, AC 220V, 60Hz) is supplied to the system, the rectifier 101 converts the input AC voltage into DC voltage and outputs the DC voltage. Then, the motor driving unit (inverter) 102 converts the DC voltage back into a three-phase (U, V, W) AC voltage and supplies it to the motor 110. Here, the operation of the motor driving unit 102 (inverter) is made according to the control command of the microcomputer 108 as well. That is, the microcomputer 108 has previously programmed and stored a predetermined control algorithm related to the on / off control of the six switching elements S1 to S6 of the motor driving unit 102 (inverter). By the control algorithm, the switching elements S1 to S6 operate on / off to supply the three-phase AC voltage to the motor 110.

As described above, when the three-phase AC voltage is supplied from the motor driving unit 110 to the motor 110, the motor 110 rotates, thereby performing washing or dehydration.

On the other hand, if the vibration of the washing machine is opened due to the opening of the lid of the washing machine or unbalanced (unbalanced state) of the washing tank during the normal operation as described above, there is a case where the operating state is to be suddenly stopped. That is, a case in which the motor 110 must be stopped suddenly occurs. Here, the braking mechanism at this time will be described.

In the normal operation of the washing machine, the motor 110 can be seen as a load (power consumption source) from the system point of view, so that current flows from the power supply side to the motor 110 side. As such, when the motor 110 is normally operated and brake is applied to the motor 110 (cutting off the power supplied to the motor 110), the motor 110 is stopped while the rotation speed is decreased. That is, the motor 110 is not immediately stopped when power is cut off, but is rotated for a predetermined time by the rotational inertia force and then stopped. At this time, that is, while the motor 110 is rotated by the rotational inertia force after the power is cut off, the motor 110 acts as a generator, not a load, and thus is caused by the back EMF generated by the motor 110 Current flows from the motor 110 side to the power supply terminal (DC link end) side. As such, when the current generated from the motor 110 flows to the power supply terminal side, the voltage detector 104 senses a voltage between the rectifier 101 and the motor driver 102 and transmits the voltage to the voltage comparator 105. Then, the voltage comparator 105 compares the voltage sensed by the voltage detector 104 with the preset reference voltage Vref, and switches when the detected voltage exceeds the reference voltage (more precisely, the predetermined voltage tolerance range). A control signal for turning on the unit 106 is output. As a result, the switching unit 106 is turned on, i.e., the circuit stage composed of the braking resistor 103 and the switching unit 106 is turned on, and as a result, it flows from the motor 110 side to the power supply terminal side, that is, to the rectifier 101. The electric current no longer flows toward the rectifying part 101, but is consumed as thermal energy (Joule heat) through the braking resistor 103. Therefore, adverse effects that may be caused on the system circuit due to the increase in the voltage level of the DC link stage by the counter electromotive force generated from the motor 110 is prevented. That is, the deterioration or damage of the circuit element in the rectifying part 101 or the capacitor | condenser C located between the rectifying part 101 and the motor drive part 102 is prevented.

On the other hand, as described above, the conventional inverter washing machine, as described above, there is an effect that can prevent the adverse effects that may occur on the system circuit due to the rise in the voltage level of the DC link terminal by the back electromotive force generated from the motor 110 during braking. . However, when braking after the end of dehydration in the normal operation process, even when severe vibration occurs due to the unbalanced arrangement of the laundry in the washing tank (washing to one side), the braking is performed in a general braking mode, that is, about 30 seconds. There is a problem that can not prevent noise due to vibration and mechanical damage in the system or the system.

The present invention has been made in view of the above-mentioned problems, and the braking in the washing machine can minimize the occurrence of noise and damage to the washing machine by executing the corresponding braking mode according to the imbalance state of the washing tank during braking after the dehydration of the washing machine. The purpose is to provide a control method.

Braking control method in the washing machine according to the present invention to achieve the above object,

(a) after completion of dehydration in the washing machine, executing general braking by the general braking mode;

(b) detecting an unbalanced state of the washing tank generated during the normal braking;

(c) determining whether the sensed imbalance state exceeds a range of a set allowable imbalance state; And

(d) in step (c), if the detected imbalance state does not exceed the set allowable imbalance state, return to step (a), and if the sensed imbalance state exceeds the set allowable imbalance state, braking It is characterized in that it comprises the step of performing the braking by converting the mode from the normal braking mode to the rapid braking mode.

Here, in order to detect the imbalance in the step (b), a method of detecting a change in the rotational speed (RPM) of the rotor of the motor using a hall sensor, or a touch sensor for detecting the vibration of the washing tank by a contact type The sensing method used may be employed.

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

3 is a flowchart illustrating an execution process of a braking control method in the washing machine according to the present invention.

설정값)이면 상기 단계 302로 프로그램 진행을 귀환시킨다. 그리고, 상기 단계 304에서 불균형값이 설정값을 초과하면(불균형값＞설정값), 급제동(안전제동)모드(약 10초에 걸쳐 제동이 이루어지도록 하는 모드)에 의한 급제동(안전제동)을 실행한다(단계 305). 이에 따라, 모터(110)는 좀 더 짧은 시간 내에 정지하게 되며, 따라서 일반적인 제동모드에 의한 제동 실행 시 발생될 수 있는 진동에 따른 심한 소음 및 기계적인 혹은 시스템 내의 회로적인 손상을 방지하거나 최소화할 수 있게 된다. Referring to Figure 3, the washing process in the washing machine is typically subjected to the process of washing → rinsing → dehydration. Thereafter, the motor 110 is finally braked. Accordingly, the microcomputer 108 first determines whether the dehydration process is finished after washing the laundry (step 301). If the dehydration is not finished in this step 301, it is continuously checked whether or not the dehydration is finished. If the dehydration is finished, normal braking by the normal braking mode (a mode in which braking is performed over about 30 seconds) is executed (step 302). If an unbalanced condition (severe fluctuation of the washing tank) is generated by the unbalanced arrangement of the laundry in the washing tank or other external factors during the normal braking, the imbalance is detected (step 303). Here, the detection of such an imbalance may be made by detecting a change in the rotational speed (RPM) of the rotor of the motor using the sensor (hall sensor) 107 inside the motor 110, or by contact vibration of the washing tank. It may be made by a contact sensor (not shown) to detect by. For example, when the rotational speed (RPM) variation detection method of the rotor of the motor 110 is adopted, the rotational speed (RPM) of the rotor according to the swing of the washing tub is detected by the sensor (hall sensor) 107. The sensing is transmitted to the microcomputer 108. Then, the microcomputer 108 compares the detected rotation speed variation value (unbalance value) with the set rotation speed value (set value: for example, 700 RPM) (step 304), so that the unbalance value is less than or equal to the set value (unbalance value).

Set value), the program proceeds back to step 302. Then, in step 304, if the unbalance value exceeds the set value (unbalance value> set value), rapid braking (safe braking) is executed by the sudden braking (safe braking) mode (a mode in which braking is performed for about 10 seconds). (Step 305). Accordingly, the motor 110 stops in a shorter time, thereby preventing or minimizing the severe noise and vibration or mechanical damage in the system that may occur when braking is performed by the general braking mode. Will be.

Here, the conversion from the normal braking mode to the rapid braking mode is made possible by, for example, adjusting the switching duty ratio of the voltage pulses applied from the motor driving unit 102 to the motor 110. Let's briefly explain.

The three-phase AC voltages U, V, and W supplied from the motor driving unit (inverter) 102 to the motor 110 may be represented as shown in FIG. 4. However, FIG. 4 shows a voltage waveform under the most ideal state without voltage fluctuation, perfect equilibrium between three phases, and no external factors involved, and in fact, the voltage waveform applied to the motor 110 is not. . That is, as shown in FIG. 5A, the voltage actually applied to the motor 110 (selected as the U phase for convenience) generally has one sinusoidal wave shape, but has a waveform having a very fluctuation in instantaneous value. Have 5B is an enlarged view of a portion “A” of the voltage waveform graph of FIG. 5A. In the method according to the present invention, a section of the voltage value rising portion from the lower left to the upper right of the graph is “ON” and the upper left of the graph. Set the section of the voltage value falling portion to the bottom right to "OFF". Here, the "ON" part means that the voltage is applied to the motor 110, and the "OFF" part means that the voltage application to the motor 110 is cut off. FIG. 5C shows a time chart of such "ON" and "OFF" intervals, where a switching duty ratio is a ratio between a load period (ON period) and {load period (ON period) + idle period (OFF period)}. Say. This can be expressed as an expression:

In Equation 1, D _r represents a switching duty ratio, T _on represents a time of an “ON” section, and T _off represents a time of an “OFF” section, respectively.

With the above concept of switching duty ratio in mind, the switching duty ratio is ultimately the denominator value (T _on + T _off ) in Equation 1 under a given condition (eg, one cycle of the ON + OFF interval is 16 kHz). Since it becomes constant, it can be said that it depends _on T _{on which} is a molecular value. Thus, adjusting the switching duty ratio mentioned above eventually means adjusting the T _on value.

Then, on the basis of the above, when considering the conversion from the normal braking mode to the braking mode again, in order to brake the motor 110 more quickly within a short time, the magnitude of the voltage applied to the motor 110 should be reduced. do. In order to reduce the magnitude of the voltage applied to the motor 110 in this way, the amount of discharge from the DC link terminal to the motor 110 must be reduced, which in turn reduces the switching duty ratio to a small value (T _on value). Means that. By doing so, the voltage applied to the motor 110 is drastically reduced and the motor 110 is stopped in a short time.

 In the above series of procedures, the variable adjustment of the switching duty ratio is of course performed by a control algorithm stored in advance in the microcomputer 108, and the switching element in the motor drive unit (inverter) 102 is actually associated with it. S1 to S6 are selectively turned on / off in accordance with the control algorithm, and the duration of the on / off is controlled so that the variation in the duty ratio is realized.

As described above, the braking control method in the washing machine according to the present invention continues as usual even when an unbalanced state in which the washing tank swings due to an unbalanced arrangement of laundry in the washing tank or an external factor occurs during braking after the completion of dehydration. Instead of braking by the braking mode, it detects the imbalance at that time and compares it with the set reference value and converts the braking mode from the normal braking mode to the braking mode according to the comparison result. There is an advantage in that it can prevent or minimize the occurrence of severe noise due to vibration that can occur during braking and the damage of mechanical or system circuits.

Claims (2)

(a) after completion of dehydration in the washing machine, executing general braking by the general braking mode; (b) detecting an unbalanced state of the washing tank generated during the normal braking; (c) determining whether the sensed imbalance state exceeds a range of a set allowable imbalance state; And (d) in step (c), if the detected imbalance state does not exceed the set allowable imbalance state, return to step (a), and if the sensed imbalance state exceeds the set allowable imbalance state, braking Braking control method in a washing machine comprising the step of performing the braking by switching the mode from the normal braking mode to the rapid braking mode. The method of claim 1, The braking control method of the washing machine, characterized in that braking is performed for about 10 seconds.

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