KR100279624B1 - Linear compressor automatic deviation correction device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for automatically compensating deviation of a linear compressor. In the related art, a conventional linear oscillating compressor requires precise control of a clearance volume. Due to the deviation of important machine parts, there is a problem that a serious deviation is caused from the desired cooling power even under the same stroke control. Accordingly, the present invention provides an electric circuit section 20 for controlling electric power applied to the linear oscillating motor 10, and a gate for matching a stroke command value according to temperature information with a stroke following the stroke voltage applied to the motor. In the apparatus consisting of a control unit 30 for providing a drive signal to the electric circuit unit, the control unit receives the stroke voltage (V0-V3) supplied to the linear oscillating motor 10 to receive the stroke value and current information A sensorless stroke estimator 32 for estimating and outputting, an instability monitor 36 for monitoring whether the current state is unstable or stable in response to the information output from the estimator 32, and the instability monitor 36 The tuning point is determined from the information on the instability provided by the ") and the stroke value estimated by the sensorless stroke estimator 32. An output tuning point determiner 37, a stroke command value determiner 31 for determining a stroke command value using the tuning point determined by the tuning point determiner 37 and temperature information from the outside, and the sensorless stroke estimator ( A stroke controller 33 which controls the stroke estimated in 32) to be well estimated to the stroke command value determined by the stroke command value determiner 31 and outputs a timer command value according thereto, and detects a zero-cross point from the input voltage waveform. And a zero-cross detector 34 for outputting a zero-cross signal thereto and a time point at which the zero-cross signal output from the zero cross detector 34 is output, according to the estimated value estimated by the stroke controller 33. It is composed of a timer 35 that provides a gate drive signal to stabilize the system operation and to compress To prevent the failure will have to provide a long service life.

Description

Linear compressor automatic deviation correction device

The present invention relates to an automatic compensator for the deviation of a linear compressor for automatically compensating the characteristic deviation of components and the deviation of important mechanical parts in the compressor. An automatic deviation correction device.

Since the linear compressor is driven by a linear oscillating motor, there is no friction loss because there is no crankshaft that converts rotational movement into linear movement.

Therefore, it is known that the efficiency is better than other compressors.

In addition, when the compressor is used as a refrigerator or an air conditioner, the compression ratio can be varied as the stroke of the motor is varied, so that the compressor can be used for variable cooling power control.

1 is a block diagram of a conventional apparatus for controlling a linear compressor. As shown in FIG. 1, a linear oscillating motor 10 for adjusting a cooling force by varying a stroke by a vertical movement of a piston and an AC according to a gate driving signal The electric circuit unit 20 controls the power applied to the linear oscillating motor 10 by intermittent power, and the stroke command value according to the input temperature information and the stroke voltage applied to the linear oscillating motor 10. The controller 30 is configured to control the following strokes to coincide with each other and provide a timer driving signal accordingly to the electric circuit unit 20.

The controller 30 receives the temperature information, receives a stroke command value determiner 31 that determines and outputs a stroke command value corresponding to the temperature, and receives stroke voltages V0-V3 supplied to the linear oscillating motor. A sensorless stroke estimator 32 for estimating a stroke value and outputting the estimated stroke value, and control so that the stroke estimated by the sensorless stroke estimator 32 is well estimated to the stroke command value determined by the stroke command value determiner 31; And a stroke controller 33 for outputting a timer command value according thereto, a zero-cross detector 34 for detecting a zero-cross point from an input voltage waveform and outputting a zero-cross signal thereto, and the zero cross. The weight estimated by the stroke controller 33 at the time point at which the zero-cross signal output from the detector 34 is output. It consists of a timer 35 to provide a gate driving signal according to the value.

Looking at the prior art configured in this way in detail as follows.

When supplying the 220V power supply voltage as shown in (a) of FIG. 3 from the power supply voltage terminal, the power supply voltage is connected to the current sensing resistor (R), triac (Tr), and capacitor (C) of the electric circuit unit (20). It is supplied to the linear oscillating motor 10 through.

Accordingly, current flows through the linear oscillating motor 10.

Then, the piston 11 of the linear oscillating motor 10 reciprocates, and the reciprocating stroke distance of the piston 11 is a stroke, and this stroke is varied to vary the cooling force.

Accordingly, the cooling power of the refrigerator or air conditioner is adjusted.

At this time, when the user sets the temperature of the refrigerator or the air conditioner, the set temperature information is received by the stroke command value determiner 31 of the controller 30.

The temperature information thus input is input to the cooling mode determiner 31a of the stroke command value determiner 31 shown in FIG.

Then, the cooling mode determiner 31a determines the cooling mode corresponding to the input temperature, and provides the determined cooling mode to the stroke command value generating unit through the switch SW1.

For example, when the cooling mode 1 is selected by the cooling mode determiner 31a, the stroke command value ref_s and ref_s = S1 are controlled by the switch SW2 in the first cooling mode controller of the stroke command value generator 31b. When the cooling mode 2 is selected in the cooling mode determiner 31a, the stroke control value ref_s and ref_s = S2 are provided to the stroke controller 33 through the switch SW2 in the second cooling mode controller. .

As a result, when the temperature information is input, the stroke command value determiner 31 determines the cooling mode corresponding to the temperature, and provides the stroke command value ref_s corresponding to the thus determined cooling mode to the stroke controller 33.

At this time, the sensorless stroke estimator 32 is a voltage (Vo) between the power supply voltage terminal and the current sensing resistor (R) from the electric circuit unit 20 for supplying the current to the linear oscillating motor 10, the current sensing resistance (R) and the triac (Tr), a voltage between the (V _1), the tri-voltage supplied to the Ill (Tr) the linear oscillating motor 10 from (V ₂₎ and the linear via the capacitor (C) The stroke voltage and current information are estimated by receiving the voltage V ₃ supplied to the oscillating motor 10, and the estimated stroke information and current information are transmitted to the stroke controller 33.

The stroke controller 33 then controls the stroke command value determined by the stroke command value determiner 31 to be equal to the estimated stroke value.

The timer command value thus obtained is transferred to the timer 35.

The zero-cross detector 34 is the electric circuit 20 within the power supply voltage end of the previous undergo a voltage (Vo) or a capacitor (C) from the said power supply voltage terminal between for current sensing resistance (R) voltage (V ₄ ), A zero cross point is detected, and the detected zero-cross signal is provided to the timer 35.

The timer 35 then accepts the zero-cross signal as a start terminal.

When the zero-cross signal is input to the start terminal (start), the timer 35 sets the time t1 shown in (c) of FIG. 3 by the timer command value provided by the stroke controller 33.

When the set time t1 is reached, the timer 35 outputs the gate driving signal to the gate G of the triac Tr of the electric circuit unit 20.

For example, when t1 is small as in (c) of FIG. 3, the gate driving signal is shortly set from the zero-cross point of time as in (c) of FIG. 3, and a large amount of current flows as in (d) of FIG. 3. When t1 is large as shown in (e) of FIG. 3, the gate driving signal is far from the zero-cross time point, so that a small current flows as shown in (f) of FIG. 3.

When the gate driving signal is output to the gate G of the triac Tr of the electric circuit unit 20, the triac Tr is turned on so that a current is supplied to the linear oscillating motor 10. The piston of the oscillating motor 10 moves up and down to adjust the cooling power of the refrigerator or air conditioner.

When the input current is applied to the cycle function, the piston movements have the same cycle. The appearance varies depending on the suction and discharge pressures.

One example is shown in FIG.

When the period of the piston is referred to as T, the stroke is defined as follows because the stroke represents the maximum displacement within one period.

here Is an estimate by sensorless, so the actual value and the error May be present.

When modeling the linear oscillating motor 10 with the R-L circuit having the counter electromotive force as shown in FIG. 4, the theoretical basis for the piston's movement can be explained by two nonlinear simultaneous differential equations as follows.

Mechanical equations of motion

Electrical equivalence equation

Where x is the displacement of the piston, i is the current flowing through the motor, m is the mass of the piston, C is the damping coefficient, and k is the equivalent spring constant. F _P : Force on the piston, α: Back EMF constant, L: Equivalent inductance coefficient, R: Equivalent resistance, r: Resistor for detecting current magnitude r <R, V: External voltage

In the above formula F _P Represents the force due to the pressure difference between the suction and the discharge. As shown in FIG. 6, the compressor is non-linearly changed as the compressor goes through the suction-compression-discharge process.

Therefore, when the voltage V increases, the right side of the equation (2) increases, and the current on the left side also increases, and when the current increases, the right side of the equation (1) increases, and the displacement of the piston on the left side also increases.

That is, the stroke distance of the piston is changed by the applied voltage, and using the triac, which is a semiconductor switching element, the applied voltage can be controlled by switching, which can have the same effect.

However, although the conventional linear oscillating compressor as described above requires precise control of the clearance volume, the same stroke control may be due to characteristic deviations of components in complex sensorless circuits or deviations of important mechanical components in the compressor. There is a problem that causes a serious deviation from the desired cooling power even under.

Accordingly, an object of the present invention for solving the conventional problems as described above is to automatically correct the deviations by the optimum compromise between the mechanism and the control unit by itself to finally achieve a uniform cooling capacity automatic deviation deviation correction device In providing.

Another object of the present invention is to detect an unstable section of the current stroke, and to compensate for and control the deviation of the detected section, to stabilize the system operation, prevent the failure of the compressor deviation of the linear compressor to provide a long life An automatic correction device is provided.

1 is a block diagram of a conventional apparatus for controlling a linear compressor.

2 is a detailed view of a stroke command value determiner in FIG. 1;

3 is an input / output signal waveform diagram of each part in FIG. 1;

FIG. 4 is an equivalent circuit diagram when modeling a linear oscillating motor as an R-L circuit with back electromotive force in FIG. 1. FIG.

5 is a waveform diagram showing the period of the movement of the piston in accordance with the suction and discharge pressure in FIG.

FIG. 6 shows the force applied to the piston that is nonlinearly changed during the suction-compression-discharge process in FIG. F _P Waveform diagram for).

FIG. 7 is a waveform diagram showing an unstable and stable case with respect to a period of movement of a piston according to suction and discharge pressures in FIG. 1; FIG.

8 is a block diagram of the automatic deviation correction device of the linear compressor of the present invention.

9 is a detailed configuration diagram of the stroke command value determiner in FIG. 8;

FIG. 10 is a periodic waveform diagram showing, in FIG. 8, a stroke deviation according to the movement state of the discharge valve surface and the movement state of the center of the piston movement in the linear oscillating motor. FIG.

FIG. 11 is an analog circuit diagram for the sensorless stroke estimator in FIG.

FIG. 12 is a block diagram of FIG. 11;

FIG. 13 is a waveform diagram illustrating a period of movement of a piston in the instability monitor of FIG. 11. FIG.

14 is an operation flowchart illustrating a monitoring process of an instability monitor unit in FIG. 11;

FIG. 15 is an explanatory diagram illustrating a process of detecting a section in which instability appears in the tuning point determiner in FIG. 8. FIG.

FIG. 16 is an explanatory diagram illustrating a process of detecting a section in which instability appears in a tuning point determiner using a RAMP function in FIG. 8; FIG.

17 is a table showing absolute coordinates and relative coordinates according to the cooling mode.

*** Explanation of symbols for main parts of drawing ***

10: linear oscillating motor 11: piston

20: electric circuit portion 30: circuit portion

31: Stroke command value determiner 32: Sensorless stroke estimator

33: stroke controller 34: zero cross detector

35: timer 36: unstable monitor

37: tuning point determiner

The present invention for achieving the above object is a device comprising a linear oscillating motor, an electric circuit unit and a control unit, wherein the control unit receives the stroke voltages supplied to the linear oscillating motor to estimate the stroke value and current information and outputs A sensorless stroke estimator, an instability monitor unit for receiving information output from the stroke estimator to monitor whether the current state is unstable or stable, and a stroke value estimated by the sensorless stroke estimator when the instability monitor provides instability information. A tuning point determiner for determining and outputting a tuning point from the controller, a stroke command value determiner for determining a stroke command value using the tuning point determined by the tuning point determiner and temperature information from the outside, and the sensorless stroke estimator A stroke controller for controlling a predetermined stroke to be well estimated at the stroke command value determined by the stroke command value determiner, and outputting a timer command value accordingly, and detecting a zero-cross point from an input voltage waveform and outputting a zero-cross signal thereto. A zero-cross detector and a timer for providing a gate driving signal according to an estimate estimated by the stroke controller at a time point at which the zero-cross signal output from the zero-cross detector is output.

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

8 is a block diagram of the automatic deviation correction device of the linear compressor according to the present invention. Wow; An electric circuit portion 20 including a capacitor C and a triac Tr for controlling electric power applied to the linear oscillating motor 10; A sensorless stroke estimator 32 for receiving stroke voltages V0-V3 supplied to the linear oscillating motor 10 to estimate stroke values and current information, and information output from the estimator 32. From the instability monitor unit 36 for monitoring whether the current state is in an unstable state or a stable state, information on the instability provided by the instability monitor unit 36 and the stroke value estimated by the sensorless stroke estimator 32 A tuning point determiner 37 for determining and outputting a tuning point, a stroke command value determiner 31 for determining a stroke command value using the tuning point determined by the tuning point determiner 37 and temperature information from the outside, and The stroke estimated by the sensorless stroke estimator 32 is well suited to the stroke command value determined by the stroke command value determiner 31. A stroke controller 33 which controls to estimate and outputs a timer command value according thereto, a zero-cross detector 34 which detects a zero-cross point from an input voltage waveform and outputs a zero-cross signal thereto; The controller 30 includes a timer 35 that provides a gate driving signal according to an estimated value estimated by the stroke controller 33 at a time point at which the zero-cross signal output from the zero cross detector 34 is output.

In the configuration of the stroke command value determiner 31, as shown in FIG. 9, the cooling mode determines whether to select a tuning mode or a cooling mode by judging whether the starting state or the cooling state is selected according to the input temperature information. 31A, the first switch SW1 for switching to the corresponding mode in accordance with the output of the cooling mode determiner 31A, and the stroke command value for tuning when the cooling mode determiner 31A determines the starting state. A tuning mode controller 31B for outputting the control mode and a cooling mode control unit 31c for outputting a stroke command value according to the first, second, and n-th cooling modes when the cooling mode determiner 31A determines the cooling state. And a second switch SW2 for providing a stroke command value output from the tuning mode controller 31B and the cooling mode control unit 31C to the stroke controller, respectively.

Referring to the operation and effect of the present invention configured as described in detail as follows.

There are control factors and mechanisms that cause cold power deviation.

First, the control factor is due to a circuit, and when the sensorless stroke estimator 32 is configured as an analog circuit in FIG. C _S , C1, C2 The characteristic deviation of the capacitor causes a recognition error of the stroke.

Referring to FIG. 8 as a block diagram, it is the same as in FIG. 12, where the capacitor value is closely related to the transfer function.

In other words, the transfer function between the current stroke and the voltage stroke when there is no component deviation is assumed to be G1 and G2, respectively.

Then, when defining the input side as a vector of [current, voltage], the transfer function becomes G = [G1, G2].

Therefore, the deviation of the capacitor ΔG _S , ΔC1 , ΔC 2 Is the deviation of the transfer function ΔG = [ΔC 1, ΔC 2] This causes a recognition error on the stroke.

And ΔG〉 0 In the case of, the stroke is recognized as a value larger than the actual stroke value, so that the stroke is smaller than the true value when the closed-loop control is performed so that the stroke control follows the command value well.

With the same logic ΔG <0 In this case, the stroke is larger than the true value due to the feedback control.

This deviation should be reduced.

In addition, the cold power deviation due to mechanical deviation is also very important.

This occurs when the linear oscillating motor 10 is controlled. FIG. 10 (a) shows the case where the discharge valve surface is in a normal state, and FIG. 10 (b) shows the case where the discharge valve surface is raised. 10 (c) is a case where the discharge valve surface is lowered.

In such a case, if the distance to the discharge valve surface is changed, the compression ratio is changed and the cooling force is changed even under the same stroke.

The factors that cause the distance deviation to the discharge valve surface are machining and assembly errors.

10 (d) is a case where the middle line of the piston movement is in the normal position, and FIG. 10 (e) is a case where the middle line of the piston movement is lowered, and FIG. 10 (f). Is when the center of piston movement is raised.

In such a case, the error of the mechanism spring causes the positional deviation of the permanent magnet to cause a deviation of the center of the piston movement. In this case, even under the same stroke, the compression ratio is changed to change the cooling force.

Therefore, even in the above-described deviation, in order for the mechanism and the controller to be well matched, the stroke command value of FIG. 10 (b) (e) needs to be larger. ΔG <0 Condition is preferable, and in the case of FIG. 10 (c) (f), the stroke command value is smaller. ΔG〉 0 Phosphorus conditions are preferred.

If the sensorless stroke estimator 32 circuit ΔG〉 0 When the control unit having the combination with the case where the deviation of the mechanism unit is the case of Fig. 10 (b) (e), when the error is large, the cooling capacity in the refrigerator or air conditioner may hardly come out.

And the sensorless stroke estimator 32 circuit is ΔG <0 When the control unit having the control unit is combined with the case in which the deviation of the mechanism unit is shown in FIG. It may be shortened.

Therefore, when such deviations exist, it is necessary to self-tuning or self-matching to correct these deviations by themselves.

Next, the present invention which performs the self-tuning or self-matching will be described.

When the 220V power voltage is supplied from the power supply voltage terminal, the power supply voltage is supplied to the linear oscillating motor 10 through the current sensing resistor R, the triac Tr, and the capacitor C of the electric circuit unit 20. Supplied.

Accordingly, current flows through the linear oscillating motor 10.

The piston 11 of the linear oscillating motor 10 then performs a reciprocating motion to vary the stroke, thereby varying the cooling force by the variable stroke.

Accordingly, the cooling power of the refrigerator or air conditioner is adjusted.

At this time, the sensorless stroke estimator 32 reads the voltage V0-V3 supplied to the linear oscillating motor 10 from the electric circuit unit 20.

The stroke value and current information are estimated using the voltage read in this way, and the estimated stroke information and current information are transmitted to the instability monitor 36, the tuning point determiner 37, and the stroke controller 33, respectively.

Then, the instability monitor 36 checks whether the current state is in an unstable state or a stable state by using the stroke information estimated by the sensorless stroke estimator 32. Referring to FIG. 13 and FIG. As follows.

First, the instability monitor 36 has a predetermined period from the stroke information provided by the sensorless stroke estimator 32 as shown in FIG. (W) Read the stroke s (k) of (S101).

Maximum value from this read stroke (s (k)) And minimum (S102)

Where max And minimum Is obtained as shown below.

Then the difference between the maximum and minimum values of the stroke ( ) And compares the calculated error with a preset reference value (THD) (S103).

As a result of the comparison, if the error is larger than the reference value THD, it is recognized as unstable (S105), and if it is smaller than the reference value THD, it is recognized as stable (S104).

Then, after recognizing in the unstable or stable state in the step S104 and S105 sets the next predetermined interval (S106), and proceeds to the step S101 to repeat.

In the same manner as described above, the unstable monitor unit 36 determines whether the stroke is in a stable state or in an unstable state, and transmits the determined information to the tuning point determiner 37.

Accordingly, when the information monitored by the instability monitor 36 is in an unstable state, the tuning point determiner 37 scans from the lower limit LB of the stroke estimated by the sensorless stroke estimator 32 as shown in FIG. 15. In the low stroke band, there is no instability even if there is a component deviation, so that the scanning starts from the lower limit LB in order to accelerate the scanning, and accelerates rapidly until then.

And it is important to raise the stroke set point slowly for the certainty of the band test. Therefore, it increases with step STEP.

In addition, it is important to slowly increase the stroke command value for the certainty of the band check, and the RAMP function may be used as shown in FIG.

Scan in the same way as above to detect the stroke value of the section where instability appears, and detect the unstable stroke (S _C ) To the stroke command value determiner 31.

Accordingly, the stroke command value determiner 31 is an unstable stroke transmitted from the tuning point determiner 37. (S _C ) Is added to the relative value determined by the relative coordinates of the cooling mode according to the temperature information input from the outside, and the value thus obtained is output to the stroke controller 33 as the stroke command value.

When the result of monitoring by the instability monitor 36 is stable, the tuning point determiner 37 does not provide the estimated stroke of the sensorless stroke estimator 32 to the stroke command value determiner 31.

Then, the stroke command value determiner 31 outputs the stroke command value according to the stable and unstable state. Referring to FIG. 9, the stroke command value determiner 31 receives the temperature information determined by the external device from the cooling mode determiner 31A for the first time. Determine and output cooling mode.

For example, if the result determined by the cooling mode determiner 31A is the start mode, the first switch SW1 is switched to the tuning mode controller 31B.

Then, the tuning mode controller 31B provides the stroke command value ref_s for driving the linear oscillating motor 10 to the stroke controller 33 through the second switch SW2 with ref_s = f (t). .

If the result determined by the cooling mode determiner 31A is the cooling mode, the cooling mode is determined based on temperature information input from the outside.

Then, the first switch SW1 is connected to the corresponding cooling mode controller C1-CM among the cooling mode determiner 31A and the cooling mode controller 31C.

Accordingly, the cooling mode controller C1-CM outputs a stroke command value by the absolute coordinate method shown in FIG. 18 when the stroke is stable, and outputs a stroke command value obtained by the relative coordinate method when the stroke is unstable.

That is, in the unstable state, the unstable stroke provided by the tuning point determiner 37 (S _C ) The stroke command value obtained by adding the threshold value d according to the cooling mode by the relative coordinate is output to the stroke controller 33 through the second switch SW2.

The stroke command value output from the cooling mode controller C1-CM is determined by the absolute coordinate method and the relative coordinate method as shown in FIG. 18 according to the stable and unstable state, and provides the corresponding command value.

The stroke controller 33 then controls the stroke command value determined by the stroke command value determiner 31 to be equal to the estimated stroke value.

The timer command value thus obtained is transferred to the timer 35.

The zero-cross detector 34 is the electric circuit 20 within the power supply voltage end of the previous undergo a voltage (Vo) or a capacitor (C) from the said power supply voltage terminal between for current sensing resistance (R) voltage (V ₄ ), A zero cross point is detected, and the detected zero-cross signal is provided to the timer 35.

The timer 35 then accepts the zero-cross signal as a start terminal.

When the zero-cross signal is input to the start terminal (start), the timer 35 sets the gate driving signal according to the timer command value provided from the stroke controller 33, and the triac ( It is provided to the gate terminal G of Tr).

Then, the triac Tr is turned on to supply current to the linear oscillating motor 10, and accordingly, the piston of the linear oscillating motor 10 moves up and down to adjust the cooling power of the refrigerator or the air conditioner.

Therefore, the present invention is to minimize the serious imbalance of the cooling capacity due to the component deviation, the characteristic deviation of the compressor mechanical parts and the assembly deviation in the control circuit such as the sensorless stroke estimator when the linear compressor is used in a refrigerator or air conditioner. To check whether the current stroke is stable or unstable, and if it is unstable, the stroke command value in the unstable state is corrected by using the relative coordinate value to stabilize the system operation and prevent the failure of the compressor. It has the effect of providing long life.

Claims (4)

An electric circuit section for controlling the power applied to the linear oscillating motor that regulates the cooling power by regulating the AC power according to the gate drive signal to adjust the stroke, and following the stroke command value according to the temperature information and the stroke voltage applied to the motor. An apparatus comprising a controller for providing a gate driving signal to the electric circuit unit to match the strokes, wherein the controller receives stroke voltages supplied to the linear oscillating motor and estimates and outputs a stroke value and current information. A sensorless stroke estimator, an instability monitor unit for receiving information output from the stroke estimator to monitor whether the current state is unstable or stable, and a stroke estimated by the sensorless stroke estimator when the instability information is provided by the instability monitor unit A tuning point determiner for determining and outputting a tuning point from the controller, a stroke command value determiner for determining a stroke command value using the tuning point determined by the tuning point determiner and temperature information from the outside, and an estimated value at the sensorless stroke estimator. A stroke controller that controls the stroke to be well estimated at the stroke command value determined by the stroke command value determiner, and outputs a timer command value according to the stroke command; A linear compressor comprising a cross detector and a timer for providing a gate driving signal according to an estimate estimated by the stroke controller at a time point at which the zero-cross signal output from the zero cross detector is output; Automatic deviation compensator. The apparatus of claim 1, wherein the stroke command value determiner comprises: a cooling mode determiner configured to determine whether to select a tuning mode or a cooling mode by judging whether the starting state or the cooling state is selected according to the input temperature information, and the output of the cooling mode determiner. A first switch for switching to the corresponding mode, a tuning mode controller for outputting a stroke command value for tuning when the cooling mode determiner determines the start mode, and the cooling mode determiner determines that the cooling mode and the current stroke are unstable. In the state, the cooling mode control unit for correcting the stroke command value according to the first, second, n-th cooling mode by using the relative coordinate value, and outputting the corrected stroke command value in the tuning mode controller and the cooling mode control unit. Consists of a second switch that provides each stroke command value output to the stroke controller Automatic compensation device variation of the linear compressor according to claim. 2. The apparatus of claim 1, wherein the tuning point determiner is configured to scan and determine the tuning point by incrementally increasing the estimated stroke in the sensorless stroke estimator. 2. The apparatus of claim 1, wherein the tuning point determiner is configured to scan the estimated stroke by the sensorless stroke estimator using a gentle RAMP function to determine the tuning point.