KR102441949B1 - Apparatus for controlling linear compressor and refrigerator including the same - Google Patents

Abstract

A control apparatus for a linear compressor according to an embodiment of the present invention includes a detection unit for detecting an operation state of the linear compressor, and based on the detected operation state, a compression stroke frequency and a suction stroke frequency of the linear motor included in the linear compressor and a control unit for each setting, and a driving signal generator for generating a driving signal for driving the linear motor according to the compression stroke frequency and the suction stroke frequency set by the control unit and outputting the driving signal to the linear compressor.

Description

A control device for a linear compressor and a refrigerator including the same

The present invention relates to a control device for a linear compressor, and more particularly, to a control device for a linear compressor capable of varying a frequency for each stroke of a linear motor during operation of the linear compressor, and a refrigerator including the same.

In general, a compressor is a device that converts mechanical energy into compressed energy of a compressive fluid, and is used as a part of a refrigeration device, for example, a refrigerator or an air conditioner.

A linear compressor is a device that sucks, compresses, and discharges refrigerant using the linear driving force of a motor. The linear compressor may be largely divided into a compression unit including a cylinder and a piston for compressing gas, and a driving unit including a linear motor for supplying driving force to the compression unit. Since the linear compressor operates in a linear manner, friction is low, and most of the driving force is used for gas compression, and thus energy use efficiency is high.

The linear motor operates at a predetermined operating frequency fc so that the piston reciprocates linearly with a predetermined stroke S. The piston is provided with a spring so that it can be elastically supported in the motion direction even when the piston reciprocates linearly by the linear motor. For example, a coil spring, which is a kind of mechanical spring, is installed so as to be elastically supported by the sealed container and the cylinder in the movement direction of the piston. In addition, the refrigerant sucked into the compression space also acts as a gas spring. The coil spring has a constant mechanical spring constant (Km), and the gas spring has a gas spring constant (Kg) that varies according to a load. Accordingly, the natural frequency fn of the piston (or linear compressor) is calculated in consideration of the mechanical spring constant (Km) and the gas spring constant (Kg). The natural frequency fn of the piston is as shown in Equation 1 below.

Here, fn is the natural frequency of the piston, Km is the mechanical spring constant of the coil spring, Kg is the gas spring constant, and M is the mass of the piston.

The calculated natural frequency fn of the piston acts as a main factor determining the operating frequency fc of the linear motor. Specifically, by making the operating frequency fc of the linear motor coincide with the natural frequency fn of the piston, that is, by operating the linear motor in a resonance state in which both frequencies match, the operating efficiency of the linear motor is maximized. can The advantage of the linear compressor that the energy use efficiency is high is that it can be obtained in a resonance state in which the natural frequency fn of the piston and the operating frequency fc of the linear motor match, and as the resonance state changes, the energy of the linear compressor It acts as the main factor that lowers the usage efficiency.

During operation of the linear compressor, the gas spring constant (Kg) of the gas spring and the natural frequency (fn) of the piston calculated in consideration thereof are changed as the actual load is changed. For example, as the load of the linear compressor increases, the natural frequency fn of the piston increases. Specifically, as the load increases, the pressure and temperature of the refrigerant in a limited space increase, thereby increasing the elastic force of the gas spring itself to increase the gas spring constant (Kg), and the piston calculated in proportion to the gas spring constant (Kg) The natural frequency fn of is also increased.

As described above, it is preferable to increase the operating efficiency and energy use efficiency of the linear compressor so that the operating frequency fc of the linear motor matches the natural frequency fn of the piston as much as possible. However, the linear compressor has a mechanical natural frequency fm such as a piston, a cylinder, and a spring. In some cases, the phenomenon may cause a loud noise and damage the product.

It is not free to vary the operating frequency fc of the linear motor due to the mechanical resonance phenomenon. For example, even if the operating frequency fc of the linear motor is varied, the natural frequency fm of the piston is avoided or the operating frequency that can be set as the operating frequency fc of the linear motor is limited to several cases. I had no choice but to drive.

An object of the present invention is to provide a control device for a linear compressor capable of variably controlling the frequency for each stroke of the linear motor while fixing the total operating frequency of the linear motor of the linear compressor.

The apparatus for controlling a linear compressor according to an embodiment of the present invention detects the operation state of the linear compressor and sets the compression stroke frequency and the suction stroke frequency of the linear motor included in the linear compressor, respectively, to increase the operating efficiency of the linear compressor can be further improved.

In some embodiments, the compression stroke frequency may be set higher than the suction stroke frequency.

According to an embodiment, the total operating frequency corresponding to the average of the compression stroke frequency and the suction stroke frequency is fixed, so that it is possible to prevent a mechanical resonance phenomenon from occurring in the components in the linear compressor.

According to an embodiment, the detector may include a voltage detector configured to detect a motor voltage of the linear compressor, and a current detector configured to detect a motor current of the linear compressor.

The control unit calculates a counter electromotive force based on the detected motor voltage and motor current, detects a phase difference between the motor current and the counter electromotive force, and each of the compression stroke frequency and the suction stroke frequency based on the detected phase difference can be set.

In some embodiments, the detection unit may further include a stroke detection unit configured to detect a stroke of a piston included in the linear compressor based on the detected motor voltage and motor current.

The controller may detect a phase difference between the motor current and the stroke, and set the compression stroke frequency and the suction stroke frequency, respectively, based on the detected phase difference.

According to an embodiment, the control device further comprises a memory for storing information on at least one of a compression stroke frequency and a suction stroke frequency for each phase difference, and the control unit, based on the information stored in the memory and the detected phase difference , each of the compression stroke frequency and the suction stroke frequency may be set.

For example, when the detected phase difference is the first phase difference, the compression stroke frequency may be set as a first compression stroke frequency, and the suction stroke frequency may be set as the first suction stroke frequency. When the detected phase difference is a second phase difference greater than the first phase difference, the compression stroke frequency is set to a second compression stroke frequency higher than the first compression stroke frequency, and the suction stroke frequency is the first suction stroke frequency It may be set to a lower second suction stroke frequency.

The refrigerator according to an embodiment of the present invention may include the above-described control device for the linear compressor and the linear compressor controlled by the control device.

According to an embodiment of the present invention, the control device of the linear compressor can prevent excessive noise due to mechanical resonance or damage and damage to parts in the linear compressor by fixing the total operating frequency of the linear motor.

In addition, in order to follow the natural frequency of the piston that is changed for each of the compression stroke and the suction stroke of the linear motor, the control device of the linear compressor may set the frequencies of the compression stroke and the suction stroke to be different from each other. Accordingly, efficiency when the linear compressor is driven may be further improved.

1 is a view showing a schematic configuration of a control apparatus for a linear compressor according to an embodiment of the present invention.
2 is a block diagram of an apparatus for controlling a linear compressor according to an embodiment of the present invention.
FIG. 3 is a flowchart for explaining a control method of the control apparatus of the linear compressor shown in FIG. 2 .
4 is a block diagram of an apparatus for controlling a linear compressor according to an embodiment of the present invention.
FIG. 5 is a flowchart for explaining a control method of the control device of the linear compressor shown in FIG. 4 .
6 is a table showing an example of a compression stroke frequency and a suction stroke frequency set according to a phase difference between a motor current and a counter electromotive voltage of a linear compressor or a phase difference between a motor current and a stroke.
7 is a graph showing an example of a frequency change according to each stroke during operation of the linear compressor.
8 is a cross-sectional view illustrating an internal configuration of a linear compressor according to an embodiment of the present invention.
9 is a diagram illustrating a refrigerator as an example of a home appliance including a linear compressor and a control device for the linear compressor according to an embodiment of the present invention.

The terms or words used in the present specification and claims are not to be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. Based on the principle that can be, it should be interpreted as meaning and concept consistent with the technical idea of the present invention. In addition, the embodiments described in this specification and the configurations shown in the drawings are only one of the most preferred embodiments of the present invention, and do not represent all of the technical spirit of the present invention, so they can be substituted at the time of the present application. It should be understood that there may be various equivalents and variations that exist.

The invention disclosed herein can be applied to a control apparatus and a control method of a linear compressor.

However, the invention disclosed herein is not limited thereto, and may be applied to all existing compressor control devices, compressor control methods, motor control devices, motor control methods, etc. to which the technical spirit of the present invention can be applied.

In particular, the invention disclosed herein can be applied to a linear compressor control apparatus and a linear compressor control method capable of controlling various types of linear compressors.

1 is a view showing a schematic configuration of a control apparatus for a linear compressor according to an embodiment of the present invention.

Referring to FIG. 1 , the control device 1 of the linear compressor may include a detection unit 10 , a control unit 20 , and a driving signal generation unit 30 .

The detection unit 10 can detect the operating state of the linear compressor 2 .

The detection unit 10 may detect a motor current as the operation state of the linear compressor 2 . Specifically, when a current is applied to the motor of the linear compressor 2 as a driving signal is applied from the driving signal generating unit 30 , the detecting unit 10 may detect the motor current of the linear compressor 2 .

The detection unit 10 may detect a motor voltage as the operating state of the linear compressor 2 . Specifically, when a voltage is applied to the motor of the linear compressor 2 as a driving signal is applied from the driving signal generating unit 30 , the detecting unit 10 may detect the motor voltage of the linear compressor 2 .

According to an embodiment, the detector 10 may detect a stroke based on a motor current and a motor voltage.

The controller 20 may calculate the counter electromotive voltage using the motor current and the motor voltage. The controller 20 detects a phase difference between the motor current and the counter electromotive voltage, and based on the detected phase difference, the operating frequency of the linear motor (refer to the motor assembly 640 of FIG. 8 ) included in the linear compressor 2 ). It is possible to generate a control signal for adjusting the

According to an embodiment, the controller 20 may detect a phase difference between the motor current and the stroke. Here, the phase difference between the motor current and the stroke may be a difference between the phase of the motor current of the motor of the linear compressor and the phase of the stroke of the piston of the linear compressor. The controller 20 may generate a control signal for adjusting the operating frequency of the linear compressor 2 based on the detected current and the phase difference of the stroke.

The controller 20 may output the generated control signal to the driving signal generator 30 . In particular, according to an embodiment of the present invention, the control unit 20 controls the operating frequency (hereinafter, referred to as 'compression stroke frequency') during the compression stroke of the linear compressor 2 and the operating frequency during the suction stroke (hereinafter referred to as 'compression stroke frequency'). It is possible to generate a control signal for respectively adjusting the suction stroke frequency'). At this time, the total operating frequency of the linear compressor 2 may be fixed. The total operating frequency means an operating frequency of one cycle including a compression stroke and a suction stroke, and may correspond to an average of the compression stroke frequency and the suction stroke frequency.

Meanwhile, the phase difference between the motor current and the counter electromotive voltage may increase as the load of the linear compressor 2 increases.

On the other hand, the piston makes a reciprocating linear motion with a predetermined stroke (stroke distance).

As the stroke (stroke distance) of the piston is changed, the phase difference between the motor current and the stroke may change.

Specifically, when the stroke (stroke distance) of the piston increases, the phase difference between the motor current and the stroke may decrease.

In addition, when the stroke (stroke distance) of the piston decreases, the phase difference between the motor current and the stroke may increase.

The driving signal generator 30 may drive the linear compressor 2 by applying the driving signal to the linear compressor 2 based on the control signal output from the controller 20 .

Specifically, the driving signal generator 30 may generate a driving signal based on the control signal output from the controller 20 . Also, the driving signal generator 30 may apply the generated driving signal to the linear compressor 2 to drive the linear compressor 2 .

Here, the driving signal may be in the form of an AC voltage or an AC current.

Meanwhile, the driving signal generator 30 may include an inverter or a triac.

Hereinafter, the configuration and control operation of the control device 1 of a linear compressor according to embodiments of the present invention will be described in more detail with reference to FIGS. 2 to 5 .

2 is a block diagram of an apparatus for controlling a linear compressor according to an embodiment of the present invention.

Referring to FIG. 2 , the detection unit 10 of the control device 1 of the linear compressor (hereinafter referred to as a 'control device') may include a voltage detection unit 110 and a current detection unit 120 . The control unit 20 may include a counter electromotive force calculator 210 , a frequency setting unit 230 , and a comparison unit 250 . In addition, the driving signal generator 30 may include a PWM controller 310 and an inverter 320 . Meanwhile, the control device 1 may further include a memory 240 .

As described above in FIG. 1 , the voltage detection unit 110 may detect a motor voltage of the linear compressor 2 , and the current detection unit 120 may detect a motor current of the linear compressor 2 . The motor voltage may correspond to an AC voltage, and the motor current may correspond to an AC current.

The back electromotive force calculating unit 210 may calculate the back electromotive force of the linear compressor 2 by using the motor voltage and the motor current detected by the voltage detecting unit 110 and the current detecting unit 120 . For example, the counter electromotive force calculator 210 may calculate the counter electromotive force E according to Equation 2 below.

Here, R corresponds to the equivalent resistance of a conductor such as a coil in the motor of the linear compressor 2 , L is the equivalent inductance of the coil, v is the motor voltage detected by the voltage detection unit 110 , and i is the current detection unit It is the motor current detected by 120, and C corresponds to the capacitance of the capacitor when the capacitor 1 is provided in the control device 1 .

The frequency setting unit 230 may detect a phase difference between the detected motor current and the counter electromotive voltage, and set a frequency for operating the linear compressor 2 based on the detected phase difference. In particular, the frequency setting unit 230 is based on the detected phase difference, while the total operating frequency of the linear compressor 2 is fixed, the frequency during the compression stroke (compression stroke frequency) and the frequency during the suction stroke (suction stroke frequency) Each can be set. For example, the frequency setting unit 230 may set any one of the compression stroke frequency and the suction stroke frequency based on the detected phase difference, and set the other one based on the total operating frequency.

This is because, in Equation 1, the gas spring constant (Kg) that determines the natural frequency fn of the piston of the linear compressor 2 is different from each other during the compression stroke and the suction stroke. The gas spring constant (Kg) may be changed according to the load of the refrigerant, and the load of the gas such as the refrigerant increases as the pressure increases. Comparing the compression stroke and the suction stroke based on this, the pressure increases while the size of the space accommodating the refrigerant decreases during the compression stroke, and as a result, the load of the refrigerant increases, and as the size of the space increases during the suction stroke, the pressure is reduced, and as a result, the load of the refrigerant is lowered. That is, the gas spring constant (Kg) may have a higher value in the compression stroke than in the suction stroke.

Accordingly, the frequency setting unit 320 may set the compression stroke frequency and the suction stroke frequency differently, and the compression stroke frequency may have a higher value than the suction stroke frequency.

Also, as the load of the refrigerant increases, the phase difference between the motor current and the counter electromotive voltage may increase. When the phase difference increases, a difference between the gas spring constant (Kg) during the suction stroke and the compression stroke may increase. Accordingly, as the phase difference increases, the difference between the compression stroke frequency and the suction stroke frequency set by the frequency setting unit 320 may also increase.

According to an embodiment, the frequency setting unit 230 may also change the total operating frequency based on the phase difference and set the compression stroke frequency and the suction stroke frequency to have the changed operating frequency, respectively.

For example, the frequency setting unit 230 may set the compression stroke frequency and the suction stroke frequency based on the phase difference compression stroke frequency and suction stroke frequency information stored in the memory 240 , but this is not necessarily the case.

The comparison unit 250 compares each of the set compression stroke frequency and suction stroke frequency with the current compression stroke frequency and suction stroke frequency, and generates a frequency correction signal for correcting each of the compression stroke frequency and the suction stroke frequency based on the comparison result. It can be output as the control signal described above in FIG. 1 .

The PWM control unit 310 may output a PWM control signal for varying the compression stroke frequency and the suction stroke frequency, respectively, based on the frequency correction signal. For example, the PWM control signal may include a PWM cycle variable signal, and the compression stroke frequency and the suction stroke frequency may be varied by the PWM cycle variable signal.

The inverter 320 may vary the frequency of the voltage applied to the linear compressor 2 , specifically, the linear motor in the linear compressor 2 , based on the PWM control signal. In detail, the inverter 320 may control the on/off time of the internal switching element according to the PWM control signal to vary the frequency of the DC voltage output from the power source and apply it to the linear motor.

FIG. 3 is a flowchart for explaining a control method of the control apparatus of the linear compressor shown in FIG. 2 .

Referring to FIG. 3 , as the electronic device or home appliance including the linear compressor 2 is driven, the control device 1 may operate the linear compressor 2 at the initial operating frequency ( S100 ).

The initial operating frequency corresponds to the frequency of the voltage and current supplied when starting the operation of the linear compressor 2 , and may be preset at the time of shipment of the product. The initial operating frequency may mean an average operating frequency during a compression stroke and a suction stroke of the linear compressor 2 .

The control device 1 may detect the voltage and current of the linear compressor 2 (S110). Specifically, the voltage detection unit 110 of the detection unit 10 may detect the voltage of the linear motor included in the linear compressor 2 , and the current detection unit 120 may detect the current of the linear motor.

The back EMF calculator 210 of the control device 1 may calculate the back EMF based on the detected voltage and current ( S120 ). The frequency setting unit 230 may detect a phase difference between the detected current and the calculated counter electromotive force (S130), and set each of the compression stroke frequency and the suction stroke frequency based on the detected phase difference (S140).

The comparison unit 250 of the control device 1 may compare the set compression stroke frequency and the suction stroke frequency with the current compression stroke frequency and the suction stroke frequency, and generate a frequency correction signal based on the comparison result (S150). . For example, the frequency correction signal may include a compression stroke frequency correction signal and a suction stroke frequency correction signal. The PWM control unit 310 generates a PWM control signal based on the generated frequency correction signal (S160), and the inverter 320 varies the compression stroke frequency and the suction stroke frequency by performing a switching operation based on the PWM control signal. You can (S170).

4 is a block diagram of an apparatus for controlling a linear compressor according to an embodiment of the present invention.

Referring to FIG. 4 , the detection unit 10 of the control device 1 may further include a stroke detection unit 130 . The stroke detection unit 130 may detect the stroke of the piston based on the voltage detected by the voltage detection unit 110 and the current detected by the current detection unit 120 .

The frequency setting unit 220 may detect a phase difference between the detected current and the stroke, and set a frequency for operating the linear compressor 2 based on the detected phase difference. Similar to the embodiment of FIG. 2 , the frequency setting unit 220 may set each of the compression stroke frequency and the suction stroke frequency according to the detected phase difference while the total operating frequency of the linear compressor 2 is fixed. For example, the frequency setting unit 220 may set any one of the compression stroke frequency and the suction stroke frequency based on the detected phase difference, and set the other one based on the total operating frequency. The compression stroke frequency may be higher than the suction stroke frequency.

In addition, the greater the phase difference between the current and the stroke, the higher the load of the refrigerant. When the phase difference increases, the difference between the compression stroke frequency and the suction stroke frequency may also increase.

According to an embodiment, the frequency setting unit 220 may also change the total operating frequency based on the phase difference and set each of the compression stroke frequency and the suction stroke frequency to have the changed operating frequency.

For example, the frequency setting unit 220 may set the compression stroke frequency and the suction stroke frequency based on the compression stroke frequency and suction stroke frequency information for each phase difference between the current and the stroke stored in the memory 240 , but this is not necessarily the case.

Since the comparison unit 250 , the PWM control unit 310 , and the inverter 320 have been described above with reference to FIG. 2 , a description thereof will be omitted.

FIG. 5 is a flowchart for explaining a control method of the control device of the linear compressor shown in FIG. 4 .

Referring to FIG. 5 , as the electronic device or home appliance including the linear compressor 2 is driven, the control device 1 may operate the linear compressor 2 at the initial operating frequency ( S200 ). Step S200 is substantially the same as step S100 described above with reference to FIG. 3 .

The control device 1 may detect the voltage and current of the linear compressor 2 ( S210 ). Specifically, the voltage detection unit 110 of the detection unit 10 may detect the voltage of the linear motor included in the linear compressor 2 , and the current detection unit 120 may detect the current of the linear motor.

The stroke detection unit 130 of the control device 1 may detect the stroke of the piston based on the detected voltage and current (S220). The frequency setting unit 220 may detect a phase difference between the detected current and the stroke (S230), and set each of the compression stroke frequency and the suction stroke frequency based on the detected phase difference (S240).

The comparison unit 250 of the control device 1 compares the set compression stroke frequency and the suction stroke frequency with the current compression stroke frequency and the suction stroke frequency, and based on the comparison result, the compression stroke frequency correction signal and the suction stroke frequency correction signal It is possible to generate a frequency correction signal including (S250). The PWM control unit 310 generates a PWM control signal based on the frequency correction signal (S260), and the inverter 320 performs a switching operation based on the PWM control signal to vary the compression stroke frequency and the suction stroke frequency. can be (S270).

That is, the control device 1 of the linear compressor shown in FIGS. 2 to 5 is a compression stroke and suction in order to follow the natural frequency fn of the piston, which varies according to a change in the gas spring constant (Kg) during each stroke. By setting the frequency at the time of the stroke to be different from each other, the efficiency during operation of the linear compressor 2 may be further improved.

6 is a table showing an example of a compression stroke frequency and a suction stroke frequency set according to a phase difference between a motor current and a counter electromotive voltage of a linear compressor or a phase difference between a motor current and a stroke.

The table of FIG. 6 is merely an example for convenience of explanation, and the values of the compression stroke frequency and the suction stroke frequency set by the control device 1 according to the embodiment of the present invention for each phase difference are limited thereto. not.

Referring to FIG. 6 , when the phase difference between the current and the counter electromotive voltage or the phase difference between the current and the stroke is 0, it is assumed that there is no load, and as the phase difference increases, the load of the refrigerant may increase.

As described above, as the phase difference increases, the difference between the gas spring constant (Kg) during the compression stroke and the suction stroke may increase. When the difference between the gas spring constant (Kg) during the compression stroke and the suction stroke increases, the difference between the natural frequency fn of the piston during the compression stroke and the suction stroke may also increase.

Accordingly, the control device 1 according to the embodiment of the present invention may store information on each of the compression stroke frequency and the suction stroke frequency for each phase difference in the memory 240 . According to an embodiment, the control device 1 may store information on at least one of the compression stroke frequency and the suction stroke frequency in the memory 240 . For example, when only information on the compression stroke frequency is stored, the controller 1 may set the suction stroke frequency based on the detected phase difference, the compression stroke frequency, and the total operating frequency.

The table of FIG. 6 is a visual representation of the information stored in the memory 240 . 6, it is assumed that the total operating frequency of the linear compressor 2 is 60 Hz.

For example, when the phase difference is 0, that is, when there is no load, the gas spring constant (Kg) may be the same during the compression stroke and the suction stroke. In this case, the compression stroke frequency and the suction stroke frequency may be the same. That is, each of the compression stroke frequency and the suction stroke frequency may be set to 60 Hz, and the total operating frequency corresponding to the average of the compression stroke frequency and the suction stroke frequency may be fixed to 60 Hz.

When the phase difference is a first phase difference (eg 45°), the compression stroke frequency is set to the first compression stroke frequency (eg 61 Hz), the suction stroke frequency is set to the first suction stroke frequency (eg 59 Hz), The total operating frequency can be fixed at 60Hz.

When the phase difference is a second phase difference (eg 90°) greater than the first phase difference, the compression stroke frequency is set to the second compression stroke frequency (eg 62 Hz), and the suction stroke frequency is the second suction stroke frequency (eg 58 Hz) ) can be set. That is, the second compression stroke frequency may be higher than the first compression stroke frequency, and the second suction stroke frequency may be lower than the first suction stroke frequency.

Similarly, when the phase difference is a third phase difference (eg 135°) greater than the second phase difference, the compression stroke frequency is set to a third compression stroke frequency (eg 63 Hz) higher than the second compression stroke frequency, and the suction stroke frequency may be set to a third suction stroke frequency (eg, 57 Hz) lower than the second suction stroke frequency.

7 is a graph showing an example of a frequency change according to each stroke during operation of the linear compressor.

Referring to FIG. 7 , in the conventional case, the period of the compression stroke (T (compression)) and the period of the suction stroke (T (suction)) of the linear compressor 2 are set to be the same. Accordingly, even if the total operating frequency is set to follow the natural frequency fn of the piston, the actual frequency in each stroke is different from the natural frequency fn, so the operating efficiency of the linear compressor 2 was not high. . In addition, the method of controlling the natural frequency fn by changing the total operating frequency to follow the natural frequency of the piston, cylinder, spring, etc. in the linear compressor 2 and the total operating frequency coincide with the mechanical resonance phenomenon There was a problem that it was difficult to apply because there was a possibility that noise and damage could occur.

On the other hand, as in the present invention, when the total operating frequency is fixed and the compression stroke frequency and the suction stroke frequency are set differently from each other, it is possible to prevent the occurrence of mechanical resonance as well as to have a relationship with the natural frequency fn in each stroke. difference can be reduced. As described above, the compression stroke frequency may be higher than the suction stroke frequency, and as a result, the period of the compression stroke (T (compression)) may be shorter than the period of the suction stroke (T (suction)) as shown in FIG. 7 . . That is, by setting each of the compression stroke frequency and the suction stroke frequency to reduce the difference from the natural frequency fn of the piston in each stroke, the efficiency when the linear compressor 2 is driven can be further improved.

8 is a cross-sectional view illustrating an internal configuration of a linear compressor according to an embodiment of the present invention.

Referring to FIG. 8 , in the linear compressor 600 according to the embodiment of the present invention, a cylinder 620 provided inside the shell 610 , a piston 630 reciprocating linearly within the cylinder 620 . , and a motor assembly 640 that applies a driving force to the piston 630 .

The shell 610 may be configured by combining an upper shell and a lower shell.

The shell 610 includes a suction unit 611 through which the refrigerant is introduced and a discharge unit 612 through which the refrigerant compressed in the cylinder 620 is discharged.

The refrigerant sucked through the suction unit 611 flows into the piston 630 through the suction muffler 613 . In the process in which the refrigerant passes through the suction muffler 613 , noise may be reduced.

A compression space P in which the refrigerant is compressed by the piston 630 is formed in the cylinder 620 .

In addition, a suction hole for introducing a refrigerant into the compression space (P) is formed in the piston (630). Meanwhile, a suction valve 632 for selectively opening the suction hole is provided at one side of the suction hole.

At one side of the compression space (P), a discharge valve assembly for discharging the refrigerant compressed in the compression space (P) is provided. That is, the compression space P is understood as a space formed between one end of the piston 630 and the discharge valve assembly.

The discharge valve assembly includes a discharge cover 650 forming a discharge space of the refrigerant, a discharge valve 651 that is opened when the pressure of the compression space P is equal to or greater than the discharge pressure, and introduces the refrigerant into the discharge space; A valve spring 652 is provided between the discharge valve 651 and the discharge cover 650 to apply elastic force in the axial direction.

Here, the “axial direction” may be understood as a direction in which the piston 630 reciprocates, that is, a transverse direction.

The suction valve 632 may be formed on one side of the compression space P, and the discharge valve 651 may be provided on the other side of the compression space P, ie, on an opposite side of the suction valve 632 .

In the process of the piston 630 reciprocating and linear motion inside the cylinder 620, when the pressure in the compression space P is lower than the discharge pressure and less than the suction pressure, the suction valve 632 is opened and the refrigerant is sucked into the compression space (P). On the other hand, when the pressure in the compression space (P) is equal to or greater than the suction pressure, the refrigerant in the compression space (P) is compressed while the suction valve 632 is closed.

On the other hand, when the pressure in the compression space (P) is equal to or greater than the discharge pressure, the valve spring 652 is deformed to open the discharge valve 651, and the refrigerant is discharged from the compression space (P) and discharged It is discharged to the discharge space of the cover (650).

In addition, the discharge cover 650 may have a resonance chamber for reducing pulsation of the refrigerant discharged through the discharge valve 651 , and a cooling discharge discharge hole (not shown) for discharging the refrigerant may be formed.

Then, the refrigerant in the discharge space flows to the discharge muffler 614 through the refrigerant discharge hole, and flows into the roof pipe 615 .

The discharge muffler 614 may reduce a flow noise of the compressed refrigerant, and the loop pipe 615 guides the compressed refrigerant to the discharge unit 612 .

The roof pipe 615 is coupled to the discharge muffler 614 to extend into the inner space of the shell 610 , and is coupled to the discharge unit 612 .

The linear compressor 600 further includes a frame 660 .

The frame 660 is a component for fixing the cylinder 620 , and may be configured integrally with the cylinder 620 or may be fastened by a separate fastening member.

In addition, the discharge cover 650 and the discharge muffler 614 may be coupled to the frame 660 .

The motor assembly 640 includes outer stators 641 , 642 , 643 fixed to the frame 660 and disposed to surround the cylinder 620 , and the outer stators 641 , 642 , and 643 . An inner stator 645 that is spaced apart from each other and a permanent magnet 647 positioned in a space between the outer stators 641 , 642 , and 643 and the inner stator 645 are included. The motor assembly 640 may correspond to a linear motor.

The permanent magnet 647 may reciprocate linearly by mutual electromagnetic force between the outer stators 641 , 642 , 643 and the inner stator 645 . In addition, the permanent magnet 647 may be configured as a single magnet having one pole or by combining a plurality of magnets having three poles.

The permanent magnet 647 may be coupled to the piston 630 by a connection member 670 .

The connecting member 670 may extend from one end of the piston 630 to the permanent magnet 647 .

As the permanent magnet 647 moves linearly, the piston 630 may linearly reciprocate along with the permanent magnet 647 in an axial direction.

The outer stators 641 , 642 , and 643 include coil winding bodies 642 , 643 and a stator core 641 .

The coil winding bodies 642 and 643 include a bobbin 642 and a coil 643 wound in a circumferential direction of the bobbin 642 . A cross-section of the coil 643 may have a polygonal shape, for example, a hexagonal shape.

The stator core 641 may be configured by stacking a plurality of laminations in a circumferential direction, and may be disposed to surround the coil winding bodies 642 and 643 .

When a current is applied to the motor assembly 640 , a current flows in the coil 643 , and a magnetic flux may be formed around the coil 643 by the current flowing through the coil 643 . The magnetic flux flows while forming a closed circuit along the outer stators 641 , 642 , and 643 and the inner stator 645 .

The magnetic flux flowing along the outer stator 641 , 642 , 643 and the inner stator 645 and the magnetic flux of the permanent magnet 647 interact to generate a force to move the permanent magnet 647 . .

A stator cover 644 is provided on one side of the outer stators 641 , 642 , and 643 . One end of the outer stators 641 , 642 , and 643 may be supported by the frame 660 , and the other end may be supported by the stator cover 644 .

The inner stator 645 is fixed to the outer periphery of the cylinder 620 . In addition, the inner stator 645 is configured by stacking a plurality of laminations in a circumferential direction from the outside of the cylinder 620 .

The linear compressor 600 further includes a supporter 680 supporting the piston 630 and a back cover 682 extending from the piston 630 toward the suction unit 611 . The back cover 682 may be disposed to cover at least a portion of the suction muffler 613 .

The linear compressor 600 includes a plurality of springs 631 and 633 whose respective natural frequencies are adjusted so that the piston 630 can resonate.

The plurality of springs 631 and 633 includes a first spring 631 supported between the supporter 680 and the stator cover 644 and supported between the supporter 680 and the back cover 682 . A second spring 633 is included.

A plurality of first springs 631 may be provided on both sides of the cylinder 620 or piston 630 , and a plurality of second springs 633 may be provided to the rear of the cylinder 620 or piston 630 . Dogs may be provided.

Here, the term “front” may be understood as a direction from the suction part 611 toward the discharge valve assembly. And, the direction from the piston 630 toward the suction unit 611 may be understood as "rear".

And, the axial direction may mean a direction in which the piston 630 reciprocates, and the radial direction may mean a direction perpendicular to the axial direction. Definitions for these directions may be equally used in the following description.

A predetermined oil may be stored on the inner bottom surface of the shell 610 . In addition, an oil supply device 690 for pumping oil may be provided at a lower portion of the shell 610 .

The oil supply device 690 may be operated by vibration generated as the piston 630 reciprocates and linearly moves to pump oil upward.

The linear compressor 600 further includes an oil supply pipe 691 for guiding the flow of oil from the oil supply device 690 .

The oil supply pipe 691 may extend from the oil supply device 690 to a space between the cylinder 620 and the piston 630 .

The oil pumped from the oil supply device 690 is supplied to the space between the cylinder 620 and the piston 630 through the oil supply pipe 691 to perform cooling and lubrication.

9 is a diagram illustrating a refrigerator as an example of a home appliance including a linear compressor and a control device for the linear compressor according to an embodiment of the present invention.

Hereinafter, an example of a refrigerator to which the control device of the linear compressor according to the above-described embodiment can be applied or used will be described with reference to FIG. 9 . However, it is clear that the apparatus for controlling a linear compressor according to an embodiment of the present invention may not be used only for a refrigerator, but may be used for various electronic or home appliances equipped with a linear compressor.

Referring to FIG. 9 , a refrigerator 700 according to an embodiment of the present invention may include a cabinet 710 in which a storage compartment is formed, and a storage compartment door coupled to the cabinet 710 to open and close the storage compartment. .

The storage compartment door may include a refrigerating compartment door 711 for opening and closing the refrigerating compartment and a freezing compartment door 712 for opening and closing the freezing compartment. Although not limited, the refrigerating compartment door 711 may further include a sub-door 713 for withdrawing an object stored in the refrigerating compartment door 711 without opening the refrigerating compartment door 711 .

The refrigerator 700 has a main board 720 that controls overall operation of the refrigerator 700 therein, and a linear compressor 730 may be connected thereto. The control device 1 of the linear compressor according to an embodiment of the present invention may be provided on the main board 720 .

The refrigerator 700 may operate by driving the linear compressor 730 . The cold air supplied to the inside of the refrigerator 700 is generated by the heat exchange action of the refrigerant, and may be continuously supplied to the inside of the refrigerator 700 while repeatedly performing a cycle of compression-condensation-expansion-evaporation. . The supplied refrigerant is uniformly transferred into the refrigerator by convection, so that food in the freezing and/or refrigerating chamber of the refrigerator 700 can be stored at a desired temperature.

It is to be understood that the above-described embodiments are illustrative in all respects and not restrictive, and the scope of the present invention will be indicated by the following claims rather than the foregoing detailed description. And it should be construed as being included in the scope of the present invention, as well as the meaning and scope of the claims to be described later, as well as all changes and modifications derived from the equivalent concept.

Claims (11)

a detection unit for detecting an operating state of the linear compressor;
a control unit configured to set a compression stroke frequency and a suction stroke frequency of the linear motor included in the linear compressor, respectively, based on the detected operation state; and
and a driving signal generating unit for generating a driving signal for driving the linear motor according to the compression stroke frequency and the suction stroke frequency set by the control unit and outputting the driving signal to the linear compressor,
The detection unit,
A voltage detector for detecting a motor voltage of the linear compressor and a current detector for detecting a motor current of the linear compressor,
Further comprising a memory for storing information about at least one of the compression stroke frequency and the suction stroke frequency for each phase difference,
the control unit
The phase difference between the motor current and the back electromotive force or the phase difference between the motor current and the stroke is detected based on the detected motor voltage and motor current, and based on the information stored in the memory and the detected phase difference, the compression stroke frequency and to set each of the suction stroke frequencies
A control device for a linear compressor. According to claim 1,
the compression stroke frequency is higher than the suction stroke frequency
A control device for a linear compressor. According to claim 1,
The total operating frequency of one cycle including the compression stroke and the suction stroke of the linear motor is fixed,
The total operating frequency is an average of the compression stroke frequency and the suction stroke frequency.
A control device for a linear compressor. delete According to claim 1,
The control unit is
a counter electromotive force calculator configured to calculate a counter electromotive force based on the detected motor voltage and motor current;
a frequency setting unit detecting a phase difference between the motor current and the counter electromotive force and setting each of the compression stroke frequency and the suction stroke frequency based on the detected phase difference; and
Comparing each of the set compression stroke frequency and the suction stroke frequency with the current compression stroke frequency and the current suction stroke frequency, and outputting a frequency correction signal for correcting each of the compression stroke frequency and the suction stroke frequency based on the comparison result including a comparator
A control device for a linear compressor. According to claim 1,
The detection unit,
Further comprising a stroke detection unit for detecting the stroke of the piston included in the linear compressor based on the detected motor voltage and motor current
A control device for a linear compressor. 7. The method of claim 6,
The control unit is
a frequency setting unit detecting a phase difference between the motor current and the stroke, and setting each of the compression stroke frequency and the suction stroke frequency based on the detected phase difference; and
Comparing each of the set compression stroke frequency and the suction stroke frequency with the current compression stroke frequency and the current suction stroke frequency, and outputting a frequency correction signal for correcting each of the compression stroke frequency and the suction stroke frequency based on the comparison result including a comparator
A control device for a linear compressor. delete 8. The method of any one of claims 5 and 7,
The driving signal generator,
a PWM control unit for outputting a PWM control signal for varying each of the compression stroke frequency and the suction stroke frequency, based on the frequency correction signal output from the control unit; and
Based on the PWM control signal, comprising an inverter for varying the frequency of the voltage applied to the linear motor
A control device for a linear compressor. According to claim 1,
when the detected phase difference is the first phase difference, the compression stroke frequency is set to a first compression stroke frequency, the suction stroke frequency is set to the first suction stroke frequency,
When the detected phase difference is a second phase difference greater than the first phase difference, the compression stroke frequency is set to a second compression stroke frequency higher than the first compression stroke frequency, and the suction stroke frequency is the first suction stroke frequency set to a lower second suction stroke frequency
A control device for a linear compressor. A control device for the linear compressor according to claim 1; and
A refrigerator including a linear compressor controlled by the control device.

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