Patent Publication Number: US-2004042904-A1

Title: Apparatus and method for controlling output of linear compressor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001] This application claims the benefit of Korean Patent Application No. 2002-52887 filed on Sep. 3, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002] 1. Field of the Invention  
       [0003] The present invention relates to an apparatus and a method of controlling an output of a linear compressor, and more particularly, to an apparatus and a method of controlling an output of a linear compressor by controlling an intensity of a current flowing through a coil of the linear compressor.  
       [0004] 2. Description of the Related Art  
       [0005] Generally, a linear compressor comprises a stator and a rotor. The stator is wound with a coil and provided around the rotor. The rotor is combined with a magnet and provided in the stator. With this configuration, an alternating current provided from a power supply outside of the linear compressor flows into the coil of the stator. Accordingly, a driving force is generated on the magnet of the rotor, thereby linearly reciprocating the rotor in the stator.  
       [0006]FIG. 1 shows an apparatus which controls an output of a conventional linear compressor. The apparatus comprises a triac  20  which is disposed between a power supply  30  and a coil  10  of the linear compressor. The triac  20  is turned on/off by a driving signal transmitted from a controller  40 , and controls a phase of a voltage supplied to the coil  10 , thereby controlling the output of the linear compressor.  
       [0007] A method of controlling an output of a conventional linear compressor is described as follows, applying the linear compressor to a cooling system of a refrigerator as an example.  
       [0008] Where the refrigerator is overloaded, for example, where the refrigerator initially starts an operation or food of a high temperature is placed into the refrigerator, a temperature inside the refrigerator detected by a temperature sensor (not shown) of the refrigerator is higher than a predetermined reference temperature. In this case, the controller  40  transmits a driving signal having a waveform shown in FIG. 2B to the triac  20 . Herein, the triac  20  is turned on/off so as to have a phase of an AC voltage provided from the power supply  30  be cut into a phase of an AC voltage having a waveform shown in FIG. 2A, and increase the output of the linear compressor.  
       [0009] Where the refrigerator is under a normal load, the temperature inside the refrigerator detected by the temperature sensor is within the predetermined temperature range. In this case, the controller  40  transmits a driving signal having a waveform shown in FIG. 2D to the triac  20 . Accordingly, the triac  20  is turned on/off so as to have an AC voltage having a waveform shown in FIG. 2C be transmitted to the coil  10 , and decrease the output of the linear compressor.  
       [0010] However, the apparatus which controls the output of the conventional linear compressor has, for example, the following problems. In the normal load, the phase of the voltage cut by the triac  20  according to the driving signal transmitted from the controller  40  is increased. As a result, a power factor of power is decreased conspicuously and the efficiency of the power is also decreased.  
       [0011] Additionally, the more the power factor is decreased, the more current is permitted to flow, thereby causing a copper loss and/or an iron loss on the coil  10 .  
       SUMMARY OF THE INVENTION  
       [0012] Accordingly, it is an aspect of the present invention to provide an apparatus and a method of controlling an output of a linear compressor which can prevent a decrease of a power factor of power provided to a coil of the linear compressor, increase the efficiency of the power and minimize a copper loss and/or an iron loss on the coil.  
       [0013] Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.  
       [0014] To achieve the above and/or other aspects of the present invention, there is provided an apparatus controlling an output of a linear compressor having a stator and a rotor, the apparatus comprising coil taps which are connected to a coil of the stator, a switching part which is selectively connected to a desired one of the coil taps so as to control an intensity of a current flowing through the coil, and a controller which controls the switching part.  
       [0015] The apparatus may further comprise a phase controller which changes a phase of a voltage supplied to the coil according to a driving signal transmitted from the controller.  
       [0016] The phase controller may includes a triac which is turned on/off according to the driving signal, and controls the phase of the voltage. The apparatus my further include a power supply to supply power to the coil, wherein the phase controller is provided in series between the switching part and the power supply.  
       [0017] To achieve the above and/or other aspects of the present invention, there is provided a method of controlling an output of a linear compressor having a stator, the method comprising detecting a temperature of a predetermined space to which the linear compressor is applied, controlling an intensity of a current flowing through a coil of the stator according to the detected temperature, and controlling a phase of a voltage supplied to the coil according to the detected temperature.  
       [0018] The controlling of the current intensity may include increasing the intensity of the current flowing through the coil in response to the detected temperature being higher than a predetermined temperature, and decreasing the intensity of the current flowing through the coil in response to the detected temperature being lower than the predetermined temperature.  
       [0019] The controlling of the phase of the voltage may comprise controlling the phase of the voltage according to a difference between the detected temperature and the predetermined temperature. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0020] These and/or other aspects and advantages of the present invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompany drawings of which:  
     [0021]FIG. 1 shows a schematic configuration of an apparatus which controls an output of a conventional linear compressor;  
     [0022] FIGS.  2 A- 2 D show waveforms of driving signals of a controller and waveforms of a voltage supplied to a coil of the apparatus shown in FIG. 1;  
     [0023]FIG. 3 shows a schematic configuration of an apparatus which controls an output of a linear compressor according to an embodiment of the present invention;  
     [0024]FIG. 4 shows a schematic configuration of an apparatus which controls the output of the linear compressor of FIG. 3, further comprising a phase controller according to another embodiment of the present invention; and  
     [0025]FIG. 5 shows a signal of a controller provided to the phase controller and a waveform of a voltage passed through the phase controller according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0026] Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.  
     [0027] As an illustrative purpose, an apparatus which controls an output of a linear compressor according to the present invention is described below with a refrigerator having the same.  
     [0028] A linear compressor comprises a stator and a rotor. The stator is wound with a coil and provided around the rotor. The rotor is combined with a magnet and provided in the stator. With this configuration, an electromagnetic driving force generated between the coil of stator and the magnet of the rotor linearly reciprocates the rotor in the stator.  
     [0029]FIG. 3 shows an apparatus which controls an output of a linear compressor according to an embodiment of the present invention. The apparatus comprises a pair of coil taps  5   a  and  5   b  connected to a coil  1 , a switching part  6  which controls the intensity of a current flowing through the coil  1  by being selectively connected to a desired one of the pair of coil taps  5   a  and  5   b , and a controller  4  which controls the switching part  6  to be selectively connected to the pair of coil taps  5   a  and  5   b.    
     [0030] Where the switching part  6  is selectively connected to the coil taps  5   a  and  5   b , the length of the coil  1  through which a current flows is varied. Accordingly, the resistance of the coil  1  is varied. With this variation of the resistance, the intensity of the current flowing into the coil  1  is varied under the same voltage supplied from a power supply  3 .  
     [0031] The switching part  6  is selectively connected to the pair of coil taps  5   a  and  5   b  by a driving signal transmitted from the controller  4 . Herein, the structure of the switching part  6  can be appropriately varied as necessary.  
     [0032] The controller  4  generates an appropriate driving signal by comparing a temperature inside the refrigerator, which is detected by a temperature sensor (not shown) of the refrigerator, with a predetermined reference temperature. The driving signal generated by the controller  4  is transmitted to the switching part  6 , and the switching part  6  is selectively connected to the coil taps  5   a  and  5   b  according to the driving signal.  
     [0033] With the above configuration, a method of controlling the output of the linear compressor according to the present invention is described as follows.  
     [0034] Where the refrigerator is overloaded, for example, where the refrigerator initially starts an operation or food of a high temperature is placed into the refrigerator, the temperature of the refrigerator detected by the temperature sensor is higher than a predetermined standard temperature. In this case, the controller  4  transmits a driving signal to the switching part  6  so as to have the switching part  6  be connected to the first coil tap  5   a , and accordingly, the resistance of the coil  1  becomes relatively low. Thus, the intensity of a current flowing through the coil  1  is increased, and the output of the linear compressor is thereby increased.  
     [0035] Where the refrigerator is under a normal load, the temperature inside the refrigerator detected by the temperature sensor in the refrigerator is within a predetermined temperature range. In this case, the controller  4  transmits a driving signal to the switching part  6  so as to have the switching part  6  be connected to the second coil tap  5   b , and accordingly, the resistance of the coil  1  becomes relatively high. Thus, the intensity of a current flowing through the coil  1  is decreased, and the output of the linear compressor thereby is decreased.  
     [0036]FIG. 4 shows an apparatus which controls an output of the linear compressor according to another embodiment to the present invention In addition to the features of FIG. 3, the apparatus further comprises a phase controller  2  which changes a phase of a voltage provided to the coil  1 . The phase controller  2  is prepared in series between the switching part  6  and the power supply  3  which supplies the electrical power to the coil  1 .  
     [0037] The phase controller  2  is turned on/off by a driving signal from the controller  4  and controls the phase of the voltage provided to the coil  1  of the linear compressor. A triac may be used as the phase controller  2 . Alternatively, other circuit configurations may be adopted for the phase controller  2 .  
     [0038] The controller  4  compares a temperature inside the refrigerator, which is detected by the temperature sensor of the refrigerator, with a predetermined standard temperature, determines a phase of the voltage supplied to the coil  1 , and generates an appropriate driving signal to obtain the determined voltage.  
     [0039] In controlling the output of the linear compressor, a relatively great increase and/or decrease of the output is carried out by the switching part  6 . However, where an accurate output control is needed, as compared to an output control of the linear compressor by the switching part  6 , an output control by the phase controller  2  is carried out.  
     [0040] For example, where the refrigerator is under a normal load, the switching part  6  is connected to the coil tap  5   b , thereby increasing the resistance and decreasing the output of the linear compressor. Then, in a state where the output of the linear compressor is decreased by the switching part  6 , the controller  4  transmits a driving signal having a waveform shown in FIG. 5A to the phase controller  2 , and the phase controller  2  controls the phase of the voltage so as to supply the coil  1  with the voltage having the waveform shown in FIG. 5A. Thus, although the refrigerator is under the normal load, cutting of the phase of the voltage supplied to the coil  1  is decreased, thereby controlling the output of the linear compressor. The controller  4  transmits the driving signal to the phase controller  2 , wherein the driving signal can generate a voltage having an appropriate phase on the basis of a difference between the temperature inside the refrigerator and the predetermined standard temperature.  
     [0041] Although the apparatus controlling the output of the linear compressor is applied to the refrigerator, it is understood that the apparatus controlling the output of the linear compressor according to the present invention can be applied to other equipment having a linear compressor, including an air conditioner.  
     [0042] Additionally, although the switching part  6  is selectively connected to the pair of coil taps  5   a  and  5   b , it is understood that the apparatus controlling the output of the linear compressor may have three or more coil taps.  
     [0043] As described above, the output of the linear compressor is controlled by changing the resistance of the coil  1 , to thereby minimize the decrease of the power factor and increase the efficiency of the power. Also, the intensity of the current flowing through the coil  1  is decreased, to thereby minimize the copper loss and/or the iron loss.  
     [0044] Therefore, according to the present invention, an apparatus and a method of controlling an output of a linear compressor may be provided in which a power factor of power provided to a coil is prevented from being decreased, and the efficiency of the power is increased while the copper loss and/or iron loss on the coil is minimized.  
     [0045] Although a few embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.