KR100316832B1 - Operating method in Drum Washing machine - Google Patents

Abstract

Disclosed is a method of operating a drum washing machine in which washing efficiency is improved while cost and vibration / noise are reduced in a drum washing machine employing a brushless direct current (BLDC) motor.

According to the present invention, an AC voltage is applied through a power element of an inverter circuit switched by a pulse width modulation (PWM) signal to energize two of three phases of a BLDC motor at an initial startup of a washing machine to enter a two-phase driving mode. And controlling the three-phase driving mode when the BLDC motor is rotated by a predetermined speed or more, each phase having a phase difference of 120 degrees and energizing 180 degrees at an electric angle, thereby controlling the three-phase driving mode. In this case, the duty and phase of the PWM signal are variably controlled.

Accordingly, the cost of the product is reduced by minimizing the required number of position sensors that detect the relative position of the rotor to the stator in the motor, and alternating the motor in two-phase and three-phase driving modes according to the rotational speed. By controlling the phase in the three-phase driving mode while controlling, the commutation torque ripple is minimized, thereby reducing vibration / noise and improving washing efficiency.

Description

Operating method in drum washing machine

The present invention relates to a driving method of a washing machine, and more particularly, in a drum washing machine employing a brushless direct current (BLDC) motor, while using only a minimum position sensor for detecting a relative position of a rotor in a motor. The motor is alternately controlled according to the rotational speed in the two-phase driving mode and the three-phase driving mode, and in the three-phase mode, the conduction phase is variably controlled, thereby improving washing efficiency while reducing cost and vibration / noise.

As is well known, BLDC motors consume less power than induction motors, but have high characteristics. Therefore, BLDC motors have been mainly used in office automation (FA) and factory automation (FA) equipment. As the withstand voltage device is developed and the controllability and durability are improved, its use area is rapidly spreading to home appliances such as washing machines.

As a washing machine employing such a BLDC motor, as shown in FIG. 1, the rotary shaft of the BLDC motor 1 is directly connected to the washing / dehydrating shaft 2a of the washing tub 2, thereby reducing the rotational force of the BLDC motor 1. There is a drum washing machine in which the washing tank 2 is directly received and rotated.

In the figure, reference numeral 2b is a pulsator, and 3 is an outer tank.

On the other hand, the general BLDC motor includes a stator for generating a spatially rotating rotating magnetic field, a permanent magnet is embedded to form a magnetic field, and a rotor rotating relatively in synchronization with the rotational speed of the rotating magnetic field as an essential component, A separate control device for controlling the rotation of the motor is provided.

As shown in Figure 2, the control device is located between each of the three phases (U, V, W) of the motor position sensor (not shown) for detecting the relative position to the stator of the rotor, AC power (AC ) Is composed of a rectifier circuit 11 for converting the DC power into a DC power supply, a smoothing capacitor 12 for removing the voltage pulsation of the converted DC power supply, and a plurality of power power elements for powering the DC voltage passed through the smoothing capacitor 12. Inverter circuit 13 to be applied to the motor with AC voltage of desired average voltage and frequency according to the switching state of the device, control circuit 14 to control the inverter circuit 13 based on the detected value of the position sensor, this control It consists of a power supply circuit 15 for supplying power to the circuit 14. Here, reference numeral 1 denotes a BLDC motor (hereinafter, abbreviated as "motor") represented by an equivalent circuit.

Hereinafter, an operation method according to the related art of the drum washing machine configured as described above will be described with reference to FIGS. 1 to 5.

In the drum washing machine, since the washing tank 2 is directly rotated according to the rotation of the motor 1, the rotational inertia of the drum washing machine is larger than that of the other washing machines in which only the pulsator 2b is rotated.

Therefore, the control method also requires modes such as acceleration, deceleration, braking, and the like. In the reverse rotation pattern, as shown in the current waveform diagram of FIG. 3, a section A for accelerating the torque applied to the motor 1 by a constant slope A ), And the acceleration / deceleration pattern should be set to maintain the constant speed maintenance section and the section B decelerating with a constant slope.

And, as shown in Table 1 below, the three position sensors (Sa, Sb, Sc) respectively positioned between the three phases (U, V, W) of the motor (1) are at an electric angle according to the rotation of the rotor. The detection value is output every 60 degrees, and the power element of the inverter circuit 13 is switched by the pulse width modulation (PWM) signal of the control circuit 14 according to the detection value so that the motor 1 is three-phase (U, V). , W) is driven in such a manner that only two phases are energized, and as shown in FIG. 4, a method of energizing only an electric angle of 120 degrees at an electric angle to the electromotive force (EMF) induced in each phase is adopted.

Sc Sb Sa U ⁺ U ^- V ⁺ V ^- W ⁺ W ^- Direction of rotation 0 One One 0 One 0 0 One 0 Forward (CW) 0 0 One 0 One One 0 0 0 One 0 One 0 0 One 0 0 One One 0 0 One 0 0 0 0 One Reverse (CCW) One One 0 One 0 0 One 0 0 0 One 0 0 0 0 One One 0

On the other hand, the normal and reverse rotation patterns of the PWM signal output from the control circuit 14, that is, the voltage command, the motor 1 and the washing tank 2 are as follows.

First, when the position of the rotor is sensed by the position sensor and the switch to be energized is selected from the power elements of the inverter circuit 13, the duty value of the PWM signal is pre-selected according to the amount of laundry (capacity and load). It gradually increases until it accelerates the forward rotation speed of the motor 1 (acceleration section).

When the washing tank 2 reaches the target rotation angle, the difference between the current speed and the target speed is calculated, added and subtracted to the target PWM duty of the next rotation, and the reset value is stored. The PWM duty becomes 0. Decrease until to decelerate the rotational speed of the motor 1.

Here, when the PWM duty becomes 0, all the power elements of the inverter circuit 13 are turned off for a predetermined time set in accordance with the amount of laundry detected before washing to switch the mode to generate power braking (deceleration section).

Thereafter, when the set off time elapses, the process is switched to the reverse phase braking mode for stopping the washing tank 2.

In the reverse braking mode, data for switching the rotation direction is selected and the selected data is output to generate a braking force. If the braking force is too large, the washing tank 2 and the laundry may be damaged by the impact.

Therefore, the PWM signal is applied only to the lower phase in order to gradually increase the braking force, and the PWM signal is also applied to the upper phase so that the washing tank 2 is stopped by appropriate deceleration while suppressing the rapid rise of the current. That is, in the above Table 1, when a PWM signal is applied to U ⁺ and W ^- to increase the U phase current, a PWM signal is also applied to V ⁺ to suppress the rapid rise of the current (braking section).

Next, when the washing tank 2 stops, the upper phase PWM signal applied in the braking section is interrupted so that the current can be sufficiently applied to the reverse rotation by sufficient acceleration, and the reverse rotation speed is maintained at the same slope as the forward acceleration. Accelerate

At this time, the acceleration maximum PWM duty is increased to the target PWM duty stored in the deceleration section. If the current speed is smaller than the target speed, the target PWM duty is increased according to the speed difference to increase the acceleration power at the next rotation.If the current speed is greater than the target speed, the acceleration power at the next rotation is reduced by appropriately reducing the target PWM duty. To be.

Subsequently, when the washing tank 2 is decelerated / braked according to the same principle as the forward rotation process, a predetermined initial value of the PWM signal according to the target speed is selected in consideration of the current flow, and the PWM duty is increased by a predetermined slope. Repeat the forward and reverse rotation to proceed with the laundry administration.

In the above-described method of operating a drum washing machine, three position sensors Sa, Sb, and Sc for detecting the position of the rotor in the motor 1 are used, and each phase U of the motor 1 is used. It can be seen that the phase of the voltage applied to, V, W is fixed and only a 120 degree section is energized to the electromotive force EMF.

Therefore, since the 120-degree energization method is used as described above, the commutation torque ripple is caused at the time of commutation of the power device in the inverter circuit, thereby causing vibration / noise.

That is, at time C when the switching state of the power device is changed in each of the phases U, V, and W of FIG. 4, the current waveform is changed as shown in FIG. 6 by the harmonic component of the current flowing in the motor 1. Has unstable properties.

In addition, since the phase of the voltage applied to each phase of the motor is fixed, the phase control is not free and the limit point is encountered in improving the washing efficiency, and the position sensor used to detect the position of the rotor is a product. There was a problem acting as a factor to increase the cost of the.

Accordingly, the present invention has been proposed to solve the above problems of the prior art, and in one aspect of the present invention, the cost of the product by using only a minimum position sensor for detecting the relative position of the rotor to the stator in the motor It is an object of the present invention to provide a method for operating a drum washing machine to be reduced.

In another aspect of the present invention, an object of the present invention is to minimize commutation torque ripple by alternately controlling a motor in a two-phase driving mode and a three-phase driving mode according to a rotation speed.

In addition, as another aspect of the present invention, the object of the present invention is to improve washing efficiency by variably controlling the energization phase when the motor is controlled in the three-phase mode.

1 is a block diagram of a general drum washing machine,

FIG. 2 is a circuit diagram of a controller for a brushless direct current (BLDC) motor shown in FIG. 1;

3 is a waveform diagram of current flowing through a BLDC motor by a forward and reverse washing pattern;

4 is an electromotive force and energization waveform diagram flowing in each phase of a BLDC motor by a driving method of a drum washing machine according to the prior art,

5 is a duty change pattern diagram of a pulse width modulation (PWM) signal applied to a power element in the inverter circuit shown in FIG. 2 by a method of operating a drum washing machine according to the prior art,

6 is a phase current waveform diagram flowing to a BLDC motor at the time of two-phase energization by the driving method of the washing machine according to the prior art,

7 is a change pattern diagram of duty and phase of a PWM signal applied to a power device in an inverter circuit to perform a driving method of a drum washing machine according to the present invention.

8 is a flowchart for explaining an initial starting mode in an operation method of a drum washing machine according to the present invention;

9 is a flowchart illustrating a washing operation in a driving method of a drum washing machine according to the present invention.

10 is a graph of the relationship between the amount of laundry (capacity) and the initial conditions of the three-phase energization data in the operation method of the drum washing machine according to the present invention;

11 is a graph of the relationship between the amount of laundry in the operating method of the drum washing machine according to the present invention and the off time of the power generation braking mode,

12 is a phase current waveform diagram flowing to the BLDC motor at the time of three-phase energization in the driving method of the drum washing machine according to the present invention.

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

1: Blessless DC motor 2: Washing tank

14: control circuit 13: inverter circuit

Operation of the drum washing machine according to an aspect of the present invention for achieving the above object, in the drum washing machine is rotated by receiving the rotational force of the BLDC motor:

The process of detecting the rotational speed of the BLDC motor,

(One). Detecting position of the rotor of the BLDC motor every 90 degrees using two position sensors;

(2). The rotation speed of the BLDC motor is calculated based on the time difference between the detection signals output by the two position sensors.

In addition, the operating method of the drum washing machine according to another aspect of the present invention, in the drum washing machine is rotated by receiving the rotational force of the BLDC motor to which the AC voltage is applied through the power element of the inverter circuit switched by the PWM signal:

(One). Energizing two phases of the three phases of the BLDC motor at the initial startup to control the two-phase driving mode;

(2). When the BLDC motor is rotated by a predetermined speed or more, each phase has a phase difference of 120 degrees, and the three phases are energized so as to be energized by 180 degrees at an electrical angle;

In the three-phase driving mode control step, the duty and phase of the PWM signal are variably controlled.

Preferably, the two-phase drive mode control step,

(One). Determining a direction in which the washing tank is to be rotated and increasing the duty to a predetermined slope starting from 0 with the phase of the PWM signal fixed;

(2). Calculating a rotational speed based on a time difference between detection signals output from two position sensors that detect the rotor position of the BLDC motor at an electrical angle every 90 degrees;

When the rotational speed is calculated, the three-phase driving mode control step is performed.

Preferably, the three-phase drive mode control step,

(One). Setting an initial condition related to the duty and phase of the PWM signal according to the amount of water in the washing tank and then increasing the duty and phase by a predetermined slope from an initial value to a target value;

(2). While maintaining the duty and phase at the target value, when the rotation angle of the washing tank reaches the target rotation angle, the target duty of the next rotation is reset according to the difference between the current speed and the target speed, and then the duty and phase are predetermined. Slowing the rotational speed of the washing tank by decreasing the slope of the washing tank;

(3). After power generation braking for a predetermined time set according to the quantity, increasing the duty to a predetermined slope and decreasing the phase to a predetermined slope from at least a value higher than the target value;

(4). Changing the rotational direction according to the initial condition changed to the reset target duty when the BLDC motor is rotated below a predetermined speed to drive the BLDC motor;

Repeating the steps (1) to (4), characterized in that it comprises the step of performing a washing administration during the washing time determined according to the amount.

In this way, while using only two position sensors that detect the relative position of the rotor to the stator in the BLDC motor, the motor is alternately controlled in two-phase and three-phase driving modes according to the rotational speed. It can be seen that the control phase of the current is variably controlled.

As a result, the cost of the product is reduced, the commutation torque ripple is minimized, and vibration / noise is reduced while washing efficiency is improved.

And, there may be a plurality of embodiments of the present invention, hereinafter with reference to the accompanying drawings will be described in detail the most preferred embodiment of the present invention.

This preferred embodiment allows for a better understanding of the objects, features and advantages of the present invention.

In addition, in the figure used for description of this invention, about the component same as a prior art figure, it may display by the same number, and the overlapping description may be abbreviate | omitted.

FIG. 7 is a diagram illustrating a change pattern of duty and phase of a PWM signal applied to a power device in an inverter circuit to perform a driving method of a drum washing machine according to the present invention. FIG. 8 is an initial view of an operation method of the drum washing machine according to the present invention. 9 is a flowchart for explaining a startup mode, and FIG. 9 is a flowchart for explaining a washing operation in an operation method of a drum washing machine according to the present invention.

As shown, the operation method of the drum washing machine according to the present invention, after determining the direction (CW, CCW) to rotate the washing tank 2, the duty is started from 0 with the phase of the PWM signal fixed to 0, the predetermined slope Step 2 is applied to the power element in the inverter circuit 13 while energizing two phases of the three phases of the BLDC motor 1 (hereinafter abbreviated as "motor") to control the two-phase driving mode (ST101 to 105). ) And the rotation speed is calculated based on the time difference between the detection signals output from the two position sensors that detect the rotor position of the BLDC motor 1 at an electric angle every 90 degrees. It consists of the steps ST106 to 107 to proceed.

The washing process sets the initial conditions related to the duty and phase of the PWM signal according to the amount of water in the washing tank 2, and then sets the duty and phase to a predetermined slope from the initial values D1 and A1 to the target values D2 and A2. Increasing to (S1, S4) (ST201 to 203), while maintaining the duty and phase at the target values (D2, A2), when the rotation angle of the washing tank 2 reaches the target rotation angle, the present speed and the target speed Resetting the target duty of the next rotation according to the difference value with and decreasing the duty D2 and the phase A2 to predetermined inclinations S2 and S5 to decelerate the rotational speed of the washing tub 2 (ST204 to 206 and power generation braking for a predetermined time set according to the amount of capacity, the duty D4 is increased to a predetermined slope S3 and the phase is reduced from a value A4 at least higher than the target value to a predetermined slope S6. Step ST207 to 209, and when the motor 1 is rotated below a predetermined speed, It is composed of a step (ST211) for driving by changing the rotation direction in accordance with the changed initial conditions.

The operation method of the drum washing machine according to the present invention configured as described above first determines the direction in which the control circuit 14 rotates the washing tub 2 at the initial startup, that is, the rotation in the forward direction (CW) or the reverse direction (CCW). Among the stored data, two-phase square wave energization data corresponding to the corresponding direction is output to the inverter circuit 13 (ST101 to 103).

At this time, the duty of the PWM signal starts at 0 and increases with a predetermined acceleration slope, and the phase is fixed (ST104 to 105).

Then, due to the increase in the PWM duty, the motor 1 and the washing tank 2 start to rotate, where two position sensors installed in the motor 1 detect the position of the rotor at an electric angle every 90 degrees to detect a signal. Output

Then, the control circuit 14 measures the time difference between the rotor detection signals output from the two position sensors using a timer, and calculates the rotational speed of the motor 1 based on the time difference of the measured signals.

Here, when the motor 1 is rotated at a low speed and the output interval of the rotor detection signal is too long, a time difference cannot be measured by a timer, and an overflow signal is generated, and the control circuit 14 having received the signal is the same as before. The motor 2 is controlled in the two-phase driving mode while continuously increasing the PWM duty by a predetermined slope.

After that, when the motor 1 rotates beyond the predetermined speed and the overflow state is released, the timer measures and outputs the time difference of the rotor detection signal, and the control circuit 14 returns to the electromotive force when the rotation speed is calculated as described above. The washing process is switched to the three-phase driving mode which is energized 180 degrees at the electric angle (ST106 to 107).

Next, in the washing cycle, the inverter calculates three-phase sine wave 180 degree energization data in which each phase (U, V, W) has a 120 degree phase difference based on the rotation speed of the motor 1 calculated in the initial start mode. Output to the circuit 13.

At this time, the initial condition of the three-phase sine wave 180 degree energization data is set proportionally according to the amount of laundry (capacity) as shown in FIG. 10. When the initial duty is set to D1 and the initial phase is set to A1, the duty is set as a target control value D2. The speed is increased according to the acceleration slope S1 until the phase is reached, and the phase is increased according to the change slope S4 until the target phase A2 is reached (ST201 to 203).

Next, even after the target value is reached, the duty is maintained at D2 and the phase is maintained at A2. When the rotation angle of the washing tub 2 reaches the target rotation angle, the difference between the current speed and the target speed is calculated and the next rotation is performed. After adding or subtracting to the target PWM duty, the reset value is stored.

Then, the slope decreases with the slope of S2 until the PWM duty reaches 0 (D3), and the phase decreases with the slope of S5 to A3 during the reduction time of the duty to slow down the rotational speed of the washing tank 2 (ST204 to 206). .

Accordingly, when the PWM duty reaches 0, the control circuit 14 is converted into the power generation braking mode so that the predetermined off time is set to have a proportional characteristic as shown in FIG. 11 with respect to the amount of laundry detected before washing, that is, at initial startup. All the power elements of the inverter circuit 13 are turned off, and when the set off time elapses, the power is switched to the reverse phase braking mode for stopping the washing tank 2.

In the reversed-phase braking mode, the control circuit 14 controls the PWM duty to be increased to D5 with a slope of 0 (D4) to S3, and the phase is controlled to be reduced to A5 with a slope of A4 to S6, which is at least higher than A2. (ST207-209).

On the other hand, when the motor 1 rotates at a low speed and the output interval of the rotor detection signal output from the position sensor becomes longer, an overflow signal is generated again in the timer, and the control circuit 14 generates an overflow signal in the timer. The motor 1 is driven by changing the rotational direction of the motor 1 at the moment.

That is, the motor 1 is accelerated, decelerated, and braked in the opposite direction according to the same principle as the above-described rotation process, and the washing administration is performed during the washing time determined according to the amount of laundry while repeating such forward and reverse rotation (ST209 to 211).

On the other hand, unlike the conventional technique, that is, to control the motor in a phase-fixed two-phase energization method using a conventional position, that is, three position sensors for detecting the position of the rotor in the motor, the present invention has two position sensors While only the dog is used, the motor is alternately controlled in two-phase and three-phase driving modes according to the rotational speed.

As a result, according to the present invention, the commutation torque ripple is minimized as shown in the phase current waveform diagram flowing in the motor during the three-phase energization shown in FIG. 12 while the cost of the product is reduced, thereby reducing vibration / noise and washing efficiency. It can bring an improvement.

In addition, although specific embodiments of the present invention have been described and illustrated above, it is obvious that various modifications may be made by those skilled in the art.

Such modified embodiments should not be individually understood from the technical spirit or the prospect of the present invention, and such modified embodiments should fall within the appended claims of the present invention.

As described above, the present invention reduces the cost of the product by minimizing the required number of position sensors for detecting the relative position of the rotor in the motor, and according to the rotational speed of the motor in two-phase driving mode and three-phase In the three-phase drive mode while controlling alternately in the drive mode, by varying the phase, the commutation torque ripple is minimized, thereby reducing vibration / noise and improving washing efficiency.

Claims (4)

In the washing operation of the drum washing machine operation method in which the washing tank receives the rotational force of the brushless direct current (BLDC) motor and rotates: Detecting the rotational speed of the BLDC motor to determine a driving mode of the BLDC motor to perform a washing operation; The process of detecting the rotational speed of the BLDC motor, (1) detecting the rotor position of the BLDC motor every 90 degrees using two position sensors; (2) a method of operating a drum washing machine, wherein the rotation speed of the BLDC motor is calculated based on the time difference between the detection signals output by the two position sensors. In a drum washing machine in which a washing tub is rotated by receiving a rotational force of a brushless direct current (BLDC) motor to which an alternating voltage is applied through a power element of an inverter circuit switched by a pulse width modulation (PWM) signal: (1) energizing two of three phases of the BLDC motor at the initial startup and controlling the two-phase driving mode; (2) when the BLDC motor is rotated by a predetermined speed or more, each phase has a phase difference of 120 degrees and energizes three phases so as to be energized by 180 degrees at an electrical angle, thereby switching to a three-phase driving mode to control the phase; The three-phase driving mode control step of the operation of the drum washing machine, characterized in that for controlling the duty and phase of the PWM signal variably. The method of claim 2, The two-phase drive mode control step, (1) determining a direction in which the washing tank is to be rotated and increasing the duty to a predetermined slope starting from 0 with the phase of the PWM signal fixed; (2) calculating a rotational speed based on a time difference between detection signals output from two position sensors that detect the rotor position of the BLDC motor at an electric angle every 90 degrees; When the rotational speed is calculated, switching to the three-phase driving mode to perform the step of controlling the drum washing machine. The method of claim 2, The three-phase drive mode control step, (1) setting an initial condition relating to the duty and phase of the PWM signal according to the quantity of water in the washing tank and then increasing the duty and phase by a predetermined slope from an initial value to a target value; (2) While maintaining the duty and phase at the target value, when the rotation angle of the washing tank reaches the target rotation angle, the duty and the duty are reset after resetting the target duty of the next rotation according to the difference between the current speed and the target speed. Reducing the phase by a predetermined slope to slow down the rotational speed of the washing tub; (3) after generating and braking power for a predetermined time set according to the quantity, increasing the duty to a predetermined slope and decreasing the phase to a predetermined slope from at least a value higher than the target value; (4) changing and rotating the rotation direction according to the initial condition changed to the reset target duty when the BLDC motor is rotated below a predetermined speed; Repeating the steps (1) to (4) while the washing operation during the washing time determined according to the amount of the drum washing machine operating method.