KR100588719B1 - Controlling apparatus of linear compressor and its method - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control apparatus and a control method of a linear compressor, and more particularly, to a control apparatus and a control method of a linear compressor for improving output by applying a sine wave voltage in the form of a square wave to the linear compressor.

The control apparatus of the linear compressor according to the present invention includes a rectifying unit which receives an AC voltage and converts it into a DC voltage, an inverter unit which receives the DC voltage and generates a sinusoidal voltage according to the inverter control signal, and a predetermined maximum voltage limit value according to the load. The control unit is configured to receive a voltage command value and set a sinusoidal wave voltage thereto, and to generate an inverter control signal for the set sinusoidal wave voltage and transmit the generated inverter control signal to the inverter unit.

Description

CONTROLLING APPARATUS OF LINEAR COMPRESSOR AND ITS METHOD             

1 is a block diagram of a control apparatus of a linear compressor according to the prior art,

2 is a waveform of a voltage and a current applied to the linear compressor according to FIG.

3 is a configuration diagram of a linear compressor according to the present invention;

4 is a block diagram of a control device of the linear compressor according to the present invention;

5 is a waveform of a voltage and a current applied to the linear compressor according to FIG. 4, and

6 is a graph showing a change in input power of the linear compressor according to the voltage command value.

<Explanation of symbols on main parts of the drawings>

51: rectifier 52: inverter

53: linear compressor 54: control unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control apparatus and a control method of a linear compressor, and more particularly, to a control apparatus and a control method of a linear compressor for improving output by applying a sine wave voltage in the form of a square wave to the linear compressor.

In general, a compressor is a mechanical device that increases pressure by receiving power from a power generator such as an electric motor or a turbine to compress air, refrigerant, or various other working gases. It is widely used throughout.

These compressors are classified into a reciprocating compressor which compresses the refrigerant while linearly reciprocating the inside of the cylinder by forming a compression space in which the working gas is absorbed and discharged between the piston and the cylinder. And a rotary compressor for compressing the refrigerant while the roller is eccentrically rotated along the inner wall of the cylinder to form a compression space in which the working gas is sucked and discharged between the eccentrically rotating roller and the cylinder. As a scroll compressor that compresses the refrigerant while the rotating scroll rotates along the fixed scroll to form a compression space in which the working gas is absorbed and discharged between the orbiting scroll and the fixed scroll. Divided.

Recently, among the reciprocating compressors, in particular, the piston is directly connected to the reciprocating linear motion drive motor, so that there is no mechanical loss due to the motion conversion to improve the compression efficiency as well as a simple linear compressor has been developed a lot.

In general, a linear compressor sucks, compresses, and discharges a refrigerant by using a linear driving force of a motor. A compression unit including a cylinder and a piston for compressing a refrigerant gas is large, and a linear motor supplying driving force to the compression unit. It is divided into included driving parts.

Specifically, the linear compressor is installed so that the cylinder is fixed inside the sealed container, the piston is installed in the cylinder to reciprocate linear movement, the compression space in the cylinder as the piston reciprocating linear movement in the cylinder It is configured to compress and then discharge the refrigerant into the inlet, the inlet and outlet valve assembly is installed in the compression space to adjust the inflow and discharge of the refrigerant in accordance with the pressure in the compression space.

In addition, the linear motor for generating a linear movement force to the piston is installed to be connected to each other, the linear motor is installed in the inner stator and the outer stator configured to have a plurality of laminations circumferentially stacked around the cylinder with a predetermined gap. The coil is wound around the inner stator or the outer stator, and a permanent magnet is installed in the gap between the inner stator and the outer stator so as to be connected to the piston.

At this time, the permanent magnet is installed to be movable in the direction of movement of the piston, and the reciprocating linear motion in the direction of movement of the piston by the electromagnetic force generated as the current flows in the coil, the linear motor is a constant operation Not only is it operated at a frequency f _c but also causes the piston to reciprocate linearly with a predetermined stroke S.

Therefore, in the linear compressor configured as described above, when a current is applied to the linear motor, an electromagnetic force is generated by interacting with the outer stator and the inner stator as a current flows in the coil, and the permanent magnet and The piston connected to this causes the reciprocating linear motion.

As such, the pressure inside the compression space is changed as the piston reciprocates linearly in the cylinder, and the refrigerant is sucked into the compression space according to the pressure change of the compression space, and then compressed and discharged.

1 is a block diagram of a control apparatus of a linear compressor according to the prior art. As shown in the drawing, the control device receives an external AC power and supplies AC power below a predetermined maximum voltage limit to the linear compressor 42, and receives AC power from the power supply 41 to compress the AC power. And a linear compressor 42 that performs a suction stroke, and a controller 43 that controls the power supply unit 41 and adjusts an AC power applied to the linear compressor 42 according to a load (or cold force). The maximum voltage limit is set for the protection of the control device and the protection of the linear compressor.

The control unit 43 receives a command value (voltage and / or current command value) from an external separate control means and controls the power supply unit 41 accordingly. However, since the control unit 43 controls only the command value less than or equal to the maximum voltage limit, the power supply unit 41 is controlled so that the command value exceeding the maximum voltage limit is not processed or only the maximum voltage limit is processed. Therefore, even when a high load is generated according to the load and high cooling power is required, the controller 43 may receive a command value within the maximum voltage limit and allow the AC voltage within the maximum voltage limit to be applied to the linear compressor 42. There is nothing else.

2 shows waveforms of voltage and current applied to the linear compressor according to FIG. 1. As shown, since the command value is limited within the maximum voltage limit v _p , the AC voltage v according to this command value is also limited within this maximum voltage limit v _p . In addition, since the alternating voltage v is limited, the alternating current i is thus limited, and the power applied to the linear compressor 42 is also limited due to this limited alternating voltage v and current i.

Such a prior art according to the limited AC voltage and current i has a problem in that a cooling force of a predetermined size or more is not realized even when a high cooling force is required according to a high load.

In addition, the control apparatus according to the prior art allows a resonant power mode to be performed in order to output a high cooling force upon overload in a refrigeration cycle, and a low or medium cold force at a low load or a medium load in a refrigeration cycle. In order to output the normal mode (saving mode) is performed. In this normal motion, as shown in FIG. 2, the control device does not increase the AC voltage v input to the linear compressor 42 above the maximum voltage limit v _p , so that the piston has a top dead center TDC. It will not reach until. Therefore, the control device has a problem in that the piston reaches the top dead center (TDC) by controlling by the resonance motion despite the decrease in the efficiency of the linear motor.

In view of these problems, it is an object of the present invention to provide a control apparatus and a control method for a linear compressor that realizes power more than the electric power according to the prior art and significantly improves the cooling power.

It is also an object of the present invention to provide a control apparatus and a control method for a linear compressor which generates a voltage within the maximum voltage limit while significantly improving the cooling power.

In addition, an object of the present invention is to provide a control apparatus and a control method of a linear compressor in which a high cold power and a top dead center (TDC) motion is implemented by controlling a voltage command value.

The control apparatus of the linear compressor according to the present invention includes a rectifying unit which receives an AC voltage and converts it into a DC voltage; The control unit is configured to set a sine wave voltage according to the voltage command value and generate an inverter control signal for the set sine wave voltage to the inverter unit.

In this case, the set sinusoidal voltage is preferably limited by the maximum voltage limit.

The controller may generate the inverter control signal according to a switching cycle limit value of the inverter control signal corresponding to the maximum voltage limit value.

In addition, the set sinusoidal voltage is preferably a sinusoidal voltage clamped by the maximum voltage limit.

In addition, the clamped sinusoidal voltage is preferably in the form of a square wave.

In addition, the control method of the linear compressor according to the present invention includes the steps of receiving a voltage command value of a predetermined maximum voltage limit value according to the load, setting the sine wave voltage for the voltage command value, and the inverter control signal for the set sine wave voltage Generating.

In this case, the setting step preferably further includes the step of limiting the sinusoidal voltage by the maximum voltage limit.

In addition, the generating step preferably generates the inverter control signal according to the switching period limit value of the inverter control signal corresponding to the maximum voltage limit.

In addition, the set sinusoidal voltage is preferably a sinusoidal voltage clamped by the maximum voltage limit.

In addition, the clamped sinusoidal voltage is preferably in the form of a square wave.

In the above, the present invention has been described in detail by taking an example of the control device of the linear compressor based on the embodiments of the present invention and the accompanying drawings. However, the scope of the present invention is not limited by the above embodiments and drawings, and the scope of the present invention will be limited only by the contents described in the claims below.

3 is a block diagram of a linear compressor according to the present invention. As shown, the linear compressor is provided with an inlet tube 2a and an outlet tube 2b through which refrigerant flows in and out of one side of the sealed container 2, and the cylinder 4 is fixed inside the sealed container 2. The piston 6 is installed inside the cylinder 4 so as to reciprocate linearly so as to compress the refrigerant sucked into the compression space P inside the cylinder 4. Various springs are installed to be elastically supported in the direction of movement), the piston (6) is installed to be connected to the linear motor 10 for generating a linear reciprocating drive force, the linear motor (10) is a variable compression capacity The stroke S of the piston 6 is controlled.

In addition, a suction valve 22 is installed at one end of the piston 6 in contact with the compression space P, and a discharge valve assembly 24 is provided at one end of the cylinder 4 in contact with the compression space P. ) Is installed, and the suction valve 22 and the discharge valve assembly 24 are automatically adjusted to open and close according to the pressure inside the compression space P, respectively.

Here, the airtight container (2) is installed so that the upper and lower shells are coupled to each other so that the inside is sealed, the inlet pipe (2a) and the outlet pipe (2b) for the coolant flow in one side is installed, the The piston 6 is installed inside the cylinder 4 so as to be elastically supported in the movement direction for reciprocating linear movement, and the linear motor 10 is assembled to each other by the frame 18 outside the cylinder 4. The assembly is constructed, and this assembly is installed to be elastically supported by the support spring 29 on the bottom surface of the sealed container 2.

In addition, a predetermined oil is contained in the bottom surface of the airtight container (2), and an oil supply device (30) for pumping oil is installed at the bottom of the assembly, and oil is provided in the lower frame (18) of the assembly. An oil supply pipe 18a is formed to be supplied between the 6 and the cylinder 4, so that the oil supply device 30 is operated by vibration generated by the reciprocating linear motion of the piston 6. The oil is pumped, and this oil is supplied along the oil supply pipe 18a to the gap between the piston 6 and the cylinder 4 for cooling and lubrication.

Next, the cylinder 4 is formed in a hollow shape so that the piston 6 can reciprocate linearly, and a compression space P is formed at one side thereof, and one end is located close to the inside of the inflow pipe 2a. It is preferable to be installed on the same straight line as the inflow pipe (2a) in the state.

Of course, the cylinder (4) is installed in one end close to the inlet pipe (2a) so as to reciprocate linear movement, the discharge valve assembly ( 24) is installed.

At this time, the discharge valve assembly 24 is provided to open and close the discharge cover 24a which is installed to form a predetermined discharge space on one end side of the cylinder 4, and one end of the compression space P side of the cylinder. And a discharge valve 24b and a valve spring 24c, which is a kind of coil spring that imparts an elastic force in the axial direction between the discharge cover 24a and the discharge valve 24b. The O-ring (R) is installed in the fitting so that the discharge valve 24a is in close contact with one end of the cylinder (4).

In addition, a bent loop pipe 28 is installed between one side of the discharge cover 24a and the outlet pipe 2b. The loop pipe 28 guides the compressed refrigerant to be discharged to the outside. In addition, the vibration caused by the interaction of the cylinder 4, the piston 6, and the linear motor 10 buffers the transmission of the entire sealed container 2.

Therefore, when the pressure of the compression space P becomes equal to or greater than a predetermined discharge pressure as the piston 6 reciprocates linearly in the cylinder 4, the valve spring 24c is compressed and the discharge valve ( 24b) is opened, and the refrigerant is discharged from the compression space P, and then completely discharged along the loop pipe 28 and the outlet pipe 2b.

Next, the piston 6 has a coolant flow path 6a formed at the center thereof so that the coolant flowing from the inlet pipe 2a flows, and one end close to the inlet pipe 2a is connected to the connection member 17. In addition, the linear motor 10 is installed to be directly connected to each other, and the suction valve 22 is installed at one end of the inflow pipe 2a opposite to the inflow pipe 2a, and is elastically formed by various springs in the movement direction of the piston 6. It is installed to be supported.

At this time, the suction valve 22 is formed in a thin plate shape so that the center portion is partially cut to open and close the refrigerant passage 6a of the piston, and one side is screwed at one end of the piston 6a. It is installed to be fixed.

Therefore, as the piston 6 reciprocates linearly in the cylinder 4, when the pressure of the compression space P becomes lower than or equal to a predetermined suction pressure lower than the discharge pressure, the suction valve 22 is When the refrigerant is opened and sucked into the compression space P, and the pressure in the compression space P becomes equal to or greater than a predetermined suction pressure, the refrigerant in the compression space P is closed while the suction valve 22 is closed. Is compressed.

4 is a block diagram of a control device of the linear compressor according to the present invention. As shown, the control device includes a rectifying unit 51 for receiving an external alternating voltage and converting it into a direct current voltage, an inverter unit 52 for receiving the direct current voltage and generating a sine wave control voltage according to an inverter control signal; The sine wave control voltage is set according to the linear compressor 53 which receives the sine wave control voltage from the inverter unit 52 and performs the compression and suction stroke, and the voltage command value equal to or greater than a predetermined maximum voltage limit value according to the load (or cooling force). The controller 54 generates an inverter control signal for the set sine wave control voltage and transmits the generated inverter control signal to the inverter unit 52. At this time, the determination of the load (or cold force) may be made according to the load (or cold force) information received by the control unit 54 from other control means, or may be made by independently determining the load in the linear compressor 53.

In detail, the inverter unit 52 generates a sine wave control voltage set by the controller 54 in accordance with an inverter control signal (for example, a PWM signal) from the controller 54.

In addition, when the load (or cold force) is a high load (or high cold force), the controller 54 sets the sine wave driving voltage according to the voltage command value v ^* equal to or greater than the maximum voltage threshold value v _p mentioned in the prior art. The inverter generates a control signal for the set sine wave driving voltage. The set sinusoidal drive voltage is first set to a peak value corresponding to the voltage command value v ^* , but the peak value is limited by the maximum voltage limit value v _p . This restriction process is shown in FIG.

5, the control unit 54 sets the sine wave drive voltage, first in accordance with a voltage command value (v ^*), and then the maximum voltage threshold value in (v _p) Maximum voltage limit was added limited by (v _p Drive voltages exceeding are set to the maximum voltage limit v _p . That is, there is no restriction on the magnitude (or peak value) of the voltage command value v ^* , but a restriction on the magnitude (or peak value) of the sinusoidal drive voltage applied to the linear compressor 53 is applied. The controller 54 generates and applies an inverter control signal corresponding to the clamped sinusoidal drive voltage v 'set as described above to the inverter unit 52. At this time, as the sine wave driving voltage v 'becomes large, it is natural that the sine wave driving current i' also increases.

In other words, the control section 54 has a switching cycle limit value of the inverter control signal corresponding to the maximum voltage limit value v _p . Thus, after the sinusoidal drive voltage corresponding to the voltage command value v ^* equal to or greater than the maximum voltage limit v _p is set, when the set sinusoidal drive voltage is converted into the inverter control signal, the switching cycle limit value of the inverter control signal is increased. Applied to prevent generation of sinusoidal drive voltages above the maximum voltage limit v _p .

As described above, the control unit 54 has no limitation on the voltage command value v ^* , and has only a switching cycle limit value of the inverter control signal, so that the sinusoidal drive voltage generated by the actual inverter unit 52 is always the maximum voltage limit value. to be kept below (v _p ).

When comparing the power according to the voltage v and the current i in FIG. 2 and the power according to the voltage v 'and the current i' in FIG. 5, the voltage v 'according to the present invention and It is apparent that the power according to the current i 'is greater, thereby improving the maximum value of the cooling force made in the linear compressor 53. That is, larger power can be applied to the same external AC voltage, which improves power efficiency.

In addition, ideally, when the voltage v 'according to the present invention is in the form of a square wave, the efficiency of power accordingly increases significantly, and thus the maximum value of the cooling power can be improved.

6 is a graph showing a change in input power of the linear compressor according to the voltage command value. This graph shows the results of an experiment on a linear compressor with an ambient temperature of 43 degrees, with a maximum voltage limit (v _p ) of 220V (RMS).

As shown, the X axis represents a change in the voltage command value v ^* set by the control unit 54 according to the load, and the Y axis represents the input power ratio (%) of the linear compressor. Here, the input power ratio (%) is defined as (the input power at the time of the current input power / TDC movement).

In the first section, when the voltage command value v ^* of the control unit 54 sets the sinusoidal AC voltage at 220 V or less, which is the maximum voltage limit v _p , and applies the linear compressor 53 to the linear compressor 53 through the inverter unit 52. Represents the input power ratio (%) of the linear compressor. As the voltage command value v ^* increases in this first section, the input power ratio (%) also increases, but since the piston 6 does not perform a reciprocating linear motion to the top dead center (TDC), the input power ratio ( %) Is only about 78%.

In the second section, the voltage command value v ^* of the control unit 54 is set to be equal to or greater than the maximum voltage limit value v _p , and sets the clamped sinusoidal AC voltage (that is, an AC voltage in the form of a square wave). The input power ratio (%) of the linear compressor at the time of applying to the linear compressor 53 through) is shown. It is shown that the input power ratio (%) increases as the voltage command value v ^* increases in this second section. In particular, the voltage command value (v ^* ) before reaching the third section in the second section increases rapidly from about 310V to the degree of the increase of the previous input power percentage (%), which is the beginning of the third section. At 330V, the input power percentage reaches 100%. Immediately before the third section, the piston 6 performs a reciprocating linear motion in close proximity to the top dead center TDC, so that the input power ratio (%) is rapidly increased, and in the third section, the piston 6 The reciprocating linear motion reaching the top dead center (TDC) is performed, so that the input power ratio (%) becomes 100%.

The present invention has the effect of realizing a power more than the power according to the prior art, significantly improving the cooling power.

In addition, the present invention has the effect of generating a voltage within the maximum voltage limit while significantly improving the cooling power.

In addition, the present invention has the effect of implementing a high cold power and top dead center (TDC) movement by controlling the voltage command value.

Claims (10)

A rectifying unit receiving an AC voltage and converting the same into a DC voltage; An inverter unit receiving the DC voltage and generating a sine wave voltage according to an inverter control signal; The control unit of the linear compressor, characterized in that the control unit for setting the sine wave voltage according to the voltage command value more than the predetermined maximum voltage limit value according to the load, and generates an inverter control signal for the set sine wave voltage to the inverter unit . The method of claim 1, And said set sine wave voltage is limited by said maximum voltage limit. The method of claim 2, And the control unit generates the inverter control signal according to the switching period limit value of the inverter control signal corresponding to the maximum voltage limit value. The method according to any one of claims 1 to 3, And said set sinusoidal voltage is a sinusoidal voltage clamped by said maximum voltage limit. The method of claim 4, wherein The clamped sinusoidal voltage is a control device of the linear compressor, characterized in that the square wave shape. Receiving a voltage command value equal to or greater than a predetermined maximum voltage limit according to the load; Setting a sinusoidal voltage for the voltage command value; And generating an inverter control signal for the set sine wave voltage. The method of claim 6, The setting step further comprises the step of limiting the sinusoidal voltage by the maximum voltage limit value. The method of claim 7, wherein The generating step of the control method of the linear compressor, characterized in that for generating the inverter control signal in accordance with the switching period limit value of the inverter control signal corresponding to the maximum voltage limit. The method according to any one of claims 6 to 8, The set sinusoidal voltage is a control method of a linear compressor, characterized in that the sinusoidal voltage clamped by the maximum voltage limit. The method of claim 9, The clamped sinusoidal voltage is a control method of the linear compressor, characterized in that the square wave shape.

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