KR101718020B1 - Apparatus for controlling linear compressor, method thereof, and refrigerator with the same - Google Patents

Abstract

A control device for a linear compressor, a control method, and a refrigerator having the same are disclosed. The present invention simplifies the control of the refrigerator by performing the cooling power variable control corresponding to the load without receiving the cooling power variable amount from the refrigerator control unit and reduces the power consumption by performing the cooling power variable control that follows the heat load, Improve efficiency.

Description

TECHNICAL FIELD [0001] The present invention relates to a control device for a linear compressor, a control method for the linear compressor, and a refrigerator having the same. [0002] Apparatus for controlling linear compressor,

The present invention relates to a compressor control device, and more particularly, to a control device and a control method of a linear compressor that reduce power consumption by reducing a deviation from a thermal load during variable control of a cooling power according to a load of a refrigerator, and a refrigerator having the same.

BACKGROUND ART Generally, a refrigerator is a device used to store freshly stored foods such as foods, drinks, etc. for a long period of time. The refrigerator is stored by being frozen or refrigerated according to the type of the storage object to be stored.

The refrigerator operates by driving a compressor provided therein. The cold air supplied to the inside of the refrigerator is generated by the heat exchange action of the refrigerant and is continuously supplied to the inside of the refrigerator while repeatedly performing a cycle of compression-condensation-expansion-evaporation. It can be uniformly transferred to the inside of the refrigerator and the food inside the refrigerator can be stored at a desired temperature.

Meanwhile, the refrigerator or the air conditioner is provided with a compressor. In general, a BLDC (Brushless Direct Current) compressor or a reciprocating compressor is used.

In particular, a reciprocating compressor is a compressor that sucks, compresses, and discharges refrigerant gas while linearly reciprocating the piston inside the cylinder. The reciprocating compressor is a reciprocating compressor and a linear compressor Linear method.

In the non-linear type, a crankshaft is coupled to a rotary motor, and a piston is coupled to the crankshaft to convert the rotary force of the rotary motor into a linear reciprocating motion. On the other hand, in the linear type, a piston is directly connected to a mover of a linear motor, And the piston is reciprocated by the linear motion of the piston.

Such a linear reciprocating compressor has less crankshaft for converting rotational motion into linear motion, and therefore has a higher compression efficiency than a general compressor in terms of compression efficiency.

The refrigerator provided with the compressor generally includes a compressor control unit for controlling the operation of the compressor and a refrigerator control unit for controlling the operation of the refrigerator. At this time, the compressor control unit detects the current and voltage flowing through the compressor and controls the stroke or the speed using the detected current and voltage, and the refrigerator control unit controls the compressor control unit to be turned on or off according to the refrigerator load, So as to control the compressor power, thereby driving the refrigerator.

In a refrigerator equipped with a linear compressor or a BLDC reciprocating compressor, a compressor receives a commercial power source and operates through a driving unit composed of power devices such as a triac, an inverter, and the like. The compressor performs operations such as opening / closing (ON / OFF), cooling power variable, speed control, frequency control, and stroke control in response to a command from the refrigerator depending on the load of the refrigerator. By doing so, the temperature of the refrigerator compartment is maintained at an appropriate level through operation of the compressor.

On the other hand, the phase difference (180 ° -? _{I, x} ) between the current and the stroke or the value of the gas spring constant (Kgas) varies depending on the load of the refrigerator. As shown in Fig. 1 or Fig. 2, the phase difference between the current and the stroke, or the value of the gas spring constant increases when the load is large, and decreases when the load is small. Using this characteristic, a general compressor control device generates a load curve in which a phase difference between a current and a stroke, or a gas spring constant and an input power coincide with each other, and sets a power command to control the compressor. At this time, the voltage command is generated by multiplying the load curve by the variable beta depending on the capacity of the refrigerator, and the load curve is generated from the following Equation 1 and can be shown in FIG.

? KGas = power

Here,? And? Are scale factors.

However, according to the control apparatus of the linear compressor according to the related art, there is a problem that the power consumption is increased by having the deviation from the thermal load when performing the cooling power variable control in response to the heat load according to the load curve.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a control device and a control method of a linear compressor for performing a cold-power variable control following a heat load, and a refrigerator having the same.

It is another object of the present invention to provide a control device, a control method, and a refrigerator having a linear compressor that performs variable control of cooling power in response to a load without receiving a variable amount of cooling power from the refrigerator.

According to another aspect of the present invention, there is provided a control apparatus for a linear compressor including: a phase difference detecting unit for detecting a phase difference between a motor current and a stroke applied to a compressor motor; A power calculating unit for calculating load power based on the motor current and a control unit for generating a power command based on the phase differences and the load powers at the time of maximum load and at the time of the load requiring minimum power consumption .

In the control apparatus for a linear compressor according to the present invention, the control unit may include: a first load curve generation module that generates at least one first load curve based on the phase difference and the load power; And a second load curve generation module for generating a second load curve by connecting the characteristic points according to the load powers and the phase differences at the time of the maximum load and at the time of the load requiring the minimum power consumption, do.

The control device for a linear compressor according to the present invention further comprises a gas spring constant calculation unit for calculating a gas spring constant based on the motor current, the stroke and the phase difference. Here, the control unit generates a power command on the basis of the gas spring constants and the load powers at the time of the maximum load and at the time of the load requiring the minimum power consumption.

According to another aspect of the present invention, there is provided a method of controlling a linear compressor, including: detecting a characteristic point at which a phase difference between a current and a stroke applied to a compressor motor coincides with a load power corresponding to a compressor load; The power command is generated based on the phase differences and the load powers during the load requiring minimum power consumption.

A control method of a linear compressor according to the present invention includes a phase difference detection step of detecting a phase difference between a motor current applied to the compressor motor and the stroke and a phase difference detection step of detecting a motor voltage applied to the motor and a motor current applied to the motor A first load curve generation step of generating at least one first load curve based on the phase difference and the load power, and a second load curve generation step of generating, at the first load curves, A second load curve generation step of generating a second load curve by connecting the phase differences at the time of the load requiring the minimum power consumption and the characteristic points according to the load powers, And a motor driving step of driving the motor.

A control method of a linear compressor according to the present invention includes a voltage detecting step of detecting a motor voltage applied to the motor, a current detecting step of detecting a motor current applied to the motor, And a stroke calculating step of calculating the stroke by the stroke calculating step.

The control method of a linear compressor according to the present invention further comprises a gas spring constant calculating step of calculating a gas spring constant based on the motor current, the stroke, and the phase difference.

In order to achieve the above object, the refrigerator according to the present invention includes the linear compressor and the control device of the linear compressor, and the cooling power is changed according to the driving of the motor.

The control device and control method of the linear compressor according to the present invention and the refrigerator having the same are simplified in that the refrigerator control program is simplified by performing the cooling power variable control corresponding to the load without receiving the variable amount of cooling power from the refrigerator control part, Stability and user convenience.

The present invention has an effect of reducing the power consumption and improving the system efficiency by performing the cold-power variable control that follows the thermal load.

1 is a graph showing the relationship between the motor current and the phase difference of the stroke and the load electric power at the time of low load;
FIG. 2 is a graph showing the relationship between the motor current and the phase difference of the stroke and the load power at the time of high load;
3 is a graph for explaining a change of a power command according to a load in a general linear compressor control apparatus;
FIGS. 4 and 5 are block diagrams schematically showing a configuration of a control apparatus for a linear compressor according to embodiments of the present invention; FIG.
FIG. 6 is a graph for explaining the operation of the variable power control according to the present invention; FIG.
7 and 8 are flowcharts schematically illustrating a method of controlling a linear compressor according to embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a control device and a control method of a linear compressor according to the present invention, and a refrigerator having the same will be described in detail with reference to the accompanying drawings.

First, a configuration of a linear compressor to which a control device and a control method according to the present invention are applied will be briefly described. However, the configuration of the following linear compressor may be modified or deleted, or other components may be added, as necessary.

In the linear compressor, an inlet pipe and an outlet pipe through which the refrigerant flows in and out are installed at one side of the closed container, and the cylinder is fixed inside the closed container. In order to compress the refrigerant sucked into the compression space inside the cylinder, a piston is installed so as to reciprocate linear motion within the cylinder. Also, springs are provided in the direction of motion of the piston and are supported by elastic force. The piston is also connected to a linear motor which generates a linear reciprocating driving force, and the linear motor controls the stroke of the piston so that the compression capacity is changed. A suction valve is provided at one end of the piston contacting the compression space, and a discharge valve assembly is installed at one end of the cylinder in contact with the compression space. Here, the suction valve and the discharge valve assembly are automatically adjusted and opened and closed in accordance with the pressure inside the compression space, respectively. The sealed container has an upper and a lower shell joined to each other to seal the inside thereof, and an inlet pipe through which the refrigerant flows and a discharge pipe through which the refrigerant flows out are provided at one side thereof. A piston is elastically supported inside the cylinder in a moving direction so as to be reciprocatingly linear, and the linear motor is assembled to the outside of the cylinder by a frame to constitute an assembly. Such an assembly is elastically supported on the inner bottom surface of the hermetically sealed container by a support spring. Prescribed oil exists on the inner bottom surface of the sealed container. An oil supply device for pumping oil is provided at the lower end of the assembly, and an oil supply pipe for supplying oil between the piston and the cylinder is formed in the lower frame of the assembly. The oil supply device is operated by the vibration generated in accordance with the reciprocating linear motion of the piston to pump the oil. Such oil is supplied to the gap between the piston and the cylinder along the oil supply pipe to cool and lubricate.

The cylinder is formed by a hollow phenomenon so that the piston reciprocates linearly. A compression space is formed on one side of the cylinder. One end of the cylinder is located close to the inlet tube and is installed on the same straight line as the inlet tube. Of course, in the cylinder, the piston is installed so as to reciprocate linearly within one end close to the inflow pipe, and the discharge valve assembly is installed at one end on the opposite side of the inflow pipe. The discharge valve assembly includes a discharge cover that forms a predetermined discharge space of the cylinder, a discharge valve that opens and closes one end of the cylinder on the compression space side, and a coil spring that is a kind of coil spring that gives an elastic force in the axial direction between the discharge cover and the discharge valve And a valve spring. At this time, an O-ring is provided around one end of the cylinder so that the discharge valve closely contacts one end of the cylinder. A loop pipe formed to be bent is connected between one side of the discharge cover and the outflow pipe. The loop pipe guides the compressed refrigerant to be discharged to the outside, thereby buffering vibrations due to the interaction of the cylinder, the piston, and the linear motor from being transmitted to the entire airtight container. A refrigerant passage is formed in the piston to allow the refrigerant flowing from the inlet tube to flow. A suction valve is provided at one end of the inlet pipe opposite to the inlet pipe and is elastically supported by various springs in the direction of movement of the piston. At this time, the suction valve is formed in a thin plate shape, and a central portion thereof is partially cut so that a center portion thereof opens and closes the refrigerant passage of the piston, and one side is fixed to one end of the piston by screws.

When the pressure of the compression space becomes equal to or lower than a predetermined suction pressure lower than the discharge pressure as the piston reciprocates linearly in the cylinder, the suction valve opens and the refrigerant is sucked into the compression space, When the suction pressure becomes equal to or higher than the suction pressure, the refrigerant in the compression space is compressed while the suction valve is closed.

The linear motor includes an inner stator configured to laminate a plurality of laminations in a circumferential direction and fixed to the outside of the cylinder by a frame, a plurality of laminations around the coil winding body configured to wind the coil, An outer stator disposed outside the cylinder by a frame and having a predetermined clearance from the inner stator, and an outer stator disposed at a gap between the inner stator and the outer stator so as to be connected by the piston and the connecting member. And a permanent magnet to be installed. Here, the coil winding body may be fixed to the outside of the inner stator. An electromagnetic force is generated as a current is applied to the coil winding body of the linear motor, and the permanent magnet reciprocates linearly by the interaction between the generated electromagnetic force and the permanent magnet. The piston connected to the permanent magnet reciprocates in the reciprocating linear motion .

4, the control apparatus for a linear compressor according to the present invention includes a phase difference detection unit 300 for detecting a phase difference between a motor current and a stroke applied to a compressor motor, A power calculation unit 400 for calculating a load power based on a motor current applied to the load, and a control unit for generating a power command based on phase differences and load powers at the time of full load and during load requiring minimum power consumption Unit 500 as shown in FIG.

The control device of the linear compressor further includes a voltage detection unit (120) for detecting a motor voltage applied to the motor, a current detection unit (110) for detecting a motor current applied to the motor, And a stroke operation unit (200) for calculating a stroke based on the motor current.

The control unit of the linear compressor further includes a power unit 800. The power unit 800 includes a rectifier unit that receives commercial AC power and converts the AC power into DC power and a smoothing capacitor that smoothes the DC power .

The current detection unit 110 detects a motor current applied to the motor 700 of the linear compressor according to a load of the compressor or a load of the refrigerator. The voltage detection unit 120 detects the motor current, And detects a motor voltage applied between both ends of the linear motor 700.

The relation between the motor voltage, the motor current, and the stroke is as follows. That is, the stroke calculation unit 200 calculates a stroke using the following equation based on the motor voltage detected through the voltage detection unit 120 and the motor current detected through the current detection unit 110 .

Where x is the stroke, α is the motor constant, Vm is the motor voltage, R is the resistance, L is the inductance, and i is the motor current.

The phase difference detection unit 300 detects the phase difference between the motor current detected as described above and the stroke calculated through the stroke calculation unit 200.

On the other hand, the power calculation unit 400 calculates the power by multiplying the motor current detected through the current detection unit 110 by the motor voltage detected through the voltage detection unit 120. Since the power at this time is a value determined according to the power input to the linear motor 700 or the load of the compressor, it is referred to as a load power.

The control unit 500 generates a first load curve from a point at which the phase difference output from the phase difference detection unit 300 coincides with the load power calculated through the power calculation unit 400. [ Also, the control unit 500 outputs a control signal for generating a power command based on the first load curve.

The point at which the phase difference and the load power coincide has the relationship as shown in FIG. 1 or FIG. 2, and can be represented by a single curve, that is, a load curve as shown in FIG. As shown in FIG. 1, the phase difference (180 -? _{I, x} ) decreases as TDC approaches and the load power increases. At a certain point, the phase difference curve and the load power curve cross each other do. FIG. 1 shows an example of a low-load operation. 2, the phase difference (180 ° -? _{I, x} ) decreases and the load power increases, and the constant point 78W decreases as the TDC approaches. The phase difference curve and the load power curve intersect with each other. Further, the phase difference increases as the load increases, and decreases as the load decreases. That is, the retardation (FIG. 2) at the time of high load has a larger value than the retardation (FIG. 1) at the time of low load in the same TDC. Fig. 3 shows a load curve. The point at which the load intersects with the load of the compressor or the load of the refrigerator also varies. Meanwhile, the power command can be varied by multiplying the predetermined value according to the characteristics of the system, for example, the capacity of the refrigerator.

The control unit 500 performs control by adjusting the power command to the load curve using the load curve. The control unit 500 obtains the characteristic points corresponding to the load requiring the maximum load and the minimum power consumption from the plurality of load curves, connects the characteristic points, and then outputs the actual load, for example, And controls the compressor corresponding to the heat load.

Wherein the control unit (500) comprises: a first load curve generation module (not shown) for generating at least one first load curve based on the phase difference and the load power; And a second load curve generation module (not shown) for connecting the characteristic points according to the load powers and the phase differences at the time of the load requiring the minimum power consumption to generate a second load curve .

The first load curve generation module generates a first load curve based on the phase difference between the current and the stroke detected by the phase difference detection unit 300 and the point of intersection of the load power calculated by the power calculation unit 400, Lt; / RTI > Wherein the second load curve generation module generates a second load curve using the first load curve, wherein the second load curve generation module calculates the second load curve from the first load curves at the time of the maximum load and at the time of the load requiring the minimum power consumption Connect the points to create a second load curve.

6, the characteristic point at the time of the maximum load exists in a curve obtained by multiplying the first load curve by? 2, and the characteristic point at the time of the load requiring the minimum power consumption is a curve obtained by multiplying the first load curve by? 1 Lt; / RTI > The control unit 500 generates a second load curve by connecting the characteristic points, and controls the compressor by adjusting the power command to the second load curve using the second load curve.

5, the control apparatus for a linear compressor according to the present invention further comprises a gas spring constant calculation unit 310 for calculating a gas spring constant based on the motor current, the stroke, and the phase difference. Here, the control unit 500 generates a power command based on the gas spring constants and the load powers at the time of the maximum load and at the time of the load requiring the minimum power consumption.

The linear compressor is installed so that a cylinder is fixed in a hermetically sealed container, a piston is reciprocatingly linearly movable in the cylinder, and as the piston reciprocates linearly within the cylinder, refrigerant flows into the compression space inside the cylinder And a suction valve assembly and a discharge valve assembly are installed in the compression space to regulate the inflow and discharge of the refrigerant according to the pressure inside the compression space. In addition, a linear motor for generating a linear motion force to the piston is installed so as to be connected to each other. In the linear motor, an inner stator and an outer stator are arranged with a predetermined clearance so that a plurality of laminations are stacked in the circumferential direction around the cylinder A coil is wound around the inner stator or the outer stator, and a permanent magnet is connected to the piston at the gap between the inner stator and the outer stator. At this time, the permanent magnet is installed to be movable in the direction of movement of the piston, and reciprocates linearly in the direction of movement of the piston by an electromagnetic force generated as a current flows in the coil. Generally, the linear motor operates at a constant operating frequency So that the piston reciprocates linearly with a predetermined stroke.

In the meantime, various springs are installed so that the piston can be elastically supported in the direction of movement even when reciprocating linear motion by the linear motor. Specifically, a coil spring, which is a kind of mechanical spring, And a cylinder, and the refrigerant sucked into the compression space also acts as a gas spring. At this time, the coil spring has a constant mechanical spring constant (Km), and the gas spring has a gas spring constant (Kg) that varies according to the load. The natural frequency fn of the linear compressor is determined in consideration of the mechanical spring constant Km and the gas spring constant Kg. The relationship between the natural frequency fn and the mechanical and gas spring constants Km and Kg is as follows.

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

That is, the gas spring constant calculation unit 310 calculates the gas spring constant according to the load of the linear compressor. The gas spring constant calculation unit 310 calculates the gas spring constant by multiplying the motor current detected through the current detection unit 110, And the gas spring constant (Kg) is calculated on the basis of the phase difference between the current and the stroke detected through the phase difference detection unit 300. The gas spring constant (Kg) can be calculated as follows.

Where I is the motor constant, ω is the operating frequency, Km is the mechanical spring constant, Kg is the gas spring constant, M is the mass of the piston, I (jω) | Represents the stroke peak value of one week.

The control unit 500 generates a first load curve from a point where the gas spring constant output from the gas spring constant calculation unit 310 matches the load power calculated through the power calculation unit 400 . Also, the control unit 500 outputs a control signal for generating a power command based on the first load curve.

The point where the gas spring constant and the load power coincide can be shown as one curve, i.e., a load curve. As the TDC approaches, the gas spring constant decreases and the load power increases. At a certain point, the gas spring constant curve and the load power curve intersect each other. 1 or 2, the phase difference (180 ° -? _{I, x} ) between the motor current and the stroke may be replaced by the gas spring constant (Kg), wherein at a certain point the gas spring constant curve and the load power curve And cross each other. Further, the gas spring constant increases when the load is large, and decreases when the load is small. That is, the gas spring constant at the time of high load is larger than the gas spring constant at the time of low load in the same TDC.

The control unit 500 performs control by adjusting the power command to the load curve using the load curve. The control unit 500 obtains the characteristic points corresponding to the load requiring the maximum load and the minimum power consumption from the plurality of load curves, connects the characteristic points, and then outputs the actual load, for example, And controls the compressor corresponding to the heat load.

The control unit (500) includes a first load curve generation module (not shown) for generating at least one first load curve based on the gas spring constant and the load power, A second load curve generation module (not shown) for generating a second load curve by connecting the characteristic points according to the load powers and the gas spring constants at the time of the load and at the time of the load requiring the minimum power consumption .

The first load curve generation module calculates a first load curve based on a load power command according to a load using a point crossing the gas spring constant detected by the gas spring constant calculation unit 310 and the load power calculated by the power calculation unit 400 Lt; / RTI > Wherein the second load curve generation module generates a second load curve using the first load curve, wherein the second load curve generation module calculates the second load curve from the first load curves at the time of the maximum load and at the time of the load requiring the minimum power consumption Connect the points to create a second load curve.

6, the characteristic point at the time of the maximum load exists in a curve obtained by multiplying the first load curve by? 2, and the characteristic point at the time of the load requiring the minimum power consumption is a curve obtained by multiplying the first load curve by? 1 Lt; / RTI > The control unit 500 generates a second load curve by connecting the characteristic points, and controls the compressor by adjusting the power command to the second load curve using the second load curve. In the embodiment using the phase difference and the load power, it is suitable for the case where the operation frequency is fixed, and in the embodiment using the gas spring constant and the load power, the operation frequency is more suitable for the environment where the operation frequency is variable.

7 or 8, a method of controlling a linear compressor according to the present invention detects a characteristic point at which a phase difference between a motor current and a stroke applied to a compressor motor coincides with a load power corresponding to a compressor load, A power command is generated on the basis of the phase differences and the load powers at the time of the load and at the time of the load requiring the minimum power consumption.

Referring to FIG. 7, a method of controlling a linear compressor according to the present invention includes a phase difference detection step (S300) of detecting a phase difference between a motor current and a stroke applied to the compressor motor, A first load curve generation step S500 of generating at least one first load curve based on the phase difference and the load power, a power calculation step S400 of calculating a load power based on a motor current applied to the motor, A second load curve generating unit for generating a second load curve by connecting the characteristic points according to the load powers and the phase differences at the time of the maximum load and the load requiring the minimum power consumption in the first load curves, 2 load curve generation step (S600), and a motor driving step (S700) for driving the motor based on the second load curve. Hereinafter, the configuration of the apparatus will be described with reference to FIG.

A control method of a linear compressor according to the present invention includes a voltage detection step of detecting a motor voltage applied to the motor, a current detection step (S100) of detecting a motor current applied to the motor, And a stroke calculating step (S200) of calculating the stroke based on the current.

The control device of the linear compressor detects a motor current applied to the motor 700 of the linear compressor and a motor voltage applied between both ends of the linear motor 700 according to a load of the compressor or a load of the refrigerator S100). The controller of the linear compressor calculates a stroke based on the detected motor voltage and the detected motor current (S200).

The control device of the linear compressor detects the phase difference between the detected motor current and the calculated stroke as described above (S300). The controller of the linear compressor calculates power by multiplying the detected motor current and the motor voltage (S400). Since the power at this time is a value determined according to the power input to the linear motor 700 or the load of the compressor, it is referred to as a load power.

The controller of the linear compressor generates a first load curve for generating a power command according to the load using the phase difference between the current and the stroke and the point at which the load power crosses (S500). Wherein the control device of the linear compressor generates a second load curve by using the first load curve, wherein a characteristic point at the time of the maximum load from the first load curves and a characteristic point at the time of the load requiring the minimum power consumption To generate a second load curve (S600). 6, the characteristic point at the time of the maximum load exists in a curve obtained by multiplying the first load curve by? 2, and the characteristic point at the time of the load requiring the minimum power consumption is a curve obtained by multiplying the first load curve by? 1 Lt; / RTI > The control device connects the characteristic points to generate a second load curve, and controls the compressor to adjust the power command to the second load curve using the second load curve.

The control device of the linear compressor outputs a control signal for generating a power command corresponding to the characteristic point, and supplies the power command to the motor 700 (S700). Here, the control signal is generally a PWM signal for controlling PWM (Pulse Width Modulation) voltage duty of the inverter unit.

Referring to FIG. 8, a method of controlling a linear compressor according to the present invention includes a phase difference detection step (S300) of detecting a phase difference between a motor current and a stroke applied to the compressor motor, A power calculating step S400 of calculating a load power based on a motor current applied to the motor, a gas spring constant calculating step S510 of calculating a gas spring constant based on the motor current, the stroke and the phase difference, , A first load curve generation step (S510) of generating at least one first load curve based on the gas spring constant and the load power, and a second load curve generation step (S510) A second load curve generation step (S600) of generating a second load curve by connecting the characteristic points according to the load powers to the gas spring constants at a load requiring a load And a motor driving step (S700) for driving the motor based on the second load curve. Hereinafter, the configuration of the apparatus will be described with reference to FIG.

A control method of a linear compressor according to the present invention includes a voltage detection step of detecting a motor voltage applied to the motor, a current detection step (S100) of detecting a motor current applied to the motor, And a stroke calculating step (S200) of calculating the stroke based on the current.

The control device of the linear compressor detects the motor current applied to the motor 700 of the linear compressor and the motor voltage applied across the linear motor 700 according to the load of the compressor or the load of the refrigeration system (S100). The control device calculates a stroke based on the detected motor voltage and the detected motor current (S200). The control device detects the phase difference between the motor current detected as described above and the calculated stroke (S300). On the other hand, the control device calculates the electric power by multiplying the detected motor current and the motor voltage (S400).

The piston is provided with various springs so as to be elastically supported in the direction of movement even when the linear motor reciprocates by the linear motor. Specifically, a coil spring, which is a kind of mechanical spring, And the refrigerant sucked into the compression space also acts as a gas spring. At this time, the coil spring has a constant mechanical spring constant (Km), and the gas spring has a gas spring constant (Kg) that varies according to the load. The natural frequency fn of the linear compressor is determined in consideration of the mechanical spring constant Km and the gas spring constant Kg. The relationship between the natural frequency fn and the mechanical and gas spring constants Km and Kg is expressed by Equation (3).

That is, the control device of the linear compressor calculates the gas spring constant according to the load of the linear compressor, and calculates the gas spring constant (Kg) based on the motor current, the stroke, and the phase difference between the current and the stroke (S510). The gas spring constant (Kg) can be calculated as shown in Equation (4).

The control device generates a first load curve for generating a power command according to the load using the point where the gas spring constant and the load power intersect (S520). The control device generates a second load curve by using the first load curve, and connects the characteristic points at the time of the maximum load from the first load curves and at the time of the load requiring the minimum power consumption A second load curve is generated (S600).

6, the characteristic point at the time of the maximum load exists in a curve obtained by multiplying the first load curve by? 2, and the characteristic point at the time of the load requiring the minimum power consumption is a curve obtained by multiplying the first load curve by? 1 Lt; / RTI > The control unit 500 generates a second load curve by connecting the characteristic points, and controls the compressor by adjusting the power command to the second load curve using the second load curve. Further, the control device outputs a control signal for generating a power command corresponding to the characteristic point (S700). Here, the control signal is generally a PWM signal for controlling PWM (Pulse Width Modulation) voltage duty of the inverter unit. The control device supplies the electric power command to the motor in accordance with the control signal (S700). In the embodiment using the phase difference and the load power, it is suitable for the case where the operation frequency is fixed, and in the embodiment using the gas spring constant and the load power, the operation frequency is more suitable for the environment where the operation frequency is variable.

The control device, the control method, and the refrigerator having the linear compressor according to the present invention calculate the stroke using the current and voltage using the stroke calculation unit 200, but can directly detect the stroke using the sensor .

On the other hand, the refrigerator according to the present invention includes the linear compressor and the control device of the linear compressor, incorporates a control method of the linear compressor, and the cooling power is changed by driving the motor.

As described above, the control device, the control method, and the refrigerator having the linear compressor according to the present invention can perform the control of the refrigerator by performing the variable cooling power control corresponding to the load without receiving the variable amount of the cooling power from the refrigerator control section Simplifies and reduces power consumption and improves system efficiency by performing cold-tuning control following close thermal loads.

110: current detection unit 120: voltage detection unit
200: Stroke calculation unit 300: Phase difference detection unit
400: power calculation unit 500: control unit
600: inverter unit 700: compressor motor
800: power source unit 310: gas spring constant calculation unit

Claims (11)

A phase difference detecting unit for detecting a phase difference between the motor current and the stroke applied to the motor;
A power calculation unit for calculating a load power based on a motor voltage applied to the motor and a motor current applied to the motor; And
And a control unit for detecting a characteristic point at which the phase difference and the load power coincide with each other and generating a power command based on the phase differences and the load powers at the time of the maximum load and at the time of the load requiring the minimum power consumption, Control device of the compressor. The apparatus according to claim 1,
A first load curve generation module for generating at least one first load curve based on the phase difference and the load power; And
A second load curve for generating a second load curve by connecting the characteristic points according to the load powers and the phase differences at the time of the maximum load and the load at the time of the load requiring the minimum power consumption in the first load curves, And a generation module. The method according to claim 1,
And a gas spring constant calculation unit for calculating a gas spring constant based on the motor current, the stroke, and the phase difference. 4. The apparatus according to claim 3,
And generates a power command based on the gas spring constants and the load powers at the time of the maximum load and the load requiring the minimum power consumption. The method according to claim 1,
A voltage detection unit for detecting a motor voltage applied to the motor;
A current detection unit for detecting a motor current applied to the motor; And
And a stroke calculating unit for calculating a stroke based on the motor voltage and the motor current. The method according to claim 1,
Wherein the load is a thermal load indicating the amount of heat required to maintain the outside temperature or the room temperature of the refrigerator. A linear compressor having a motor; And
A control apparatus for a linear compressor as set forth in any one of claims 1 to 6,
Wherein the cooling force is changed by driving the motor. A characteristic point at which the phase difference between the motor current and the stroke applied to the motor coincides with the load power corresponding to the compressor load is detected and based on the phase differences and the load powers at the time of the maximum load and the load requiring the minimum power consumption And a control unit for controlling the linear compressor. 9. The method of claim 8,
A phase difference detection step of detecting a phase difference between a motor current applied to the motor and the stroke;
A power calculating step of calculating a load power based on a motor voltage applied to the motor and a motor current applied to the motor;
A first load curve generation step of generating at least one first load curve based on the phase difference and the load power;
A second load curve for generating a second load curve by connecting the characteristic points according to the load powers and the phase differences at the time of the maximum load and the load at the time of the load requiring the minimum power consumption in the first load curves, Generating step; And
And a motor driving step of driving the motor based on the second load curve. 10. The method of claim 9,
A voltage detecting step of detecting a motor voltage applied to the motor;
A current detecting step of detecting a motor current applied to the motor; And
And a stroke calculating step of calculating the stroke based on the motor voltage and the motor current. 10. The method of claim 9,
And calculating a gas spring constant based on the motor current, the stroke, and the phase difference.

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