Apparatus and method of controlling linear compressor

Abstract

A linear compressor control apparatus including a position detecting unit to detect the position of a piston and a compensation unit to compensate for output distortion of the position sensor. The compensation unit compensates for output distortion of the position sensor, caused by internal temperature of the linear compressor and load variation. Further, the compensation unit separates a high frequency signal and a DC signal from the output of the position detecting unit, and simultaneously performs position and temperature detecting operations using the separated high frequency signal and the DC signal.

What is claimed is:  
     
         1 . An apparatus to control a linear compressor having a piston reciprocating in a cylinder of the linear compressor, comprising: 
 a position detecting unit to detect a position of a piston reciprocating in a cylinder of the linear compressor; and    a compensating unit to compensate for output distortion of the position detecting unit due to internal temperature of the compressor and load variation.    
     
     
         2 . The linear compressor control apparatus according to  claim 1 , wherein said position detecting unit detects the position of the piston when alternating current (AC) power is supplied and detects the internal temperature of the compressor when direct current (DC) power is supplied.  
     
     
         3 . The linear compressor control apparatus according to  claim 2 , further comprising a power supply unit to selectively supply AC power and DC power to the position detecting unit.  
     
     
         4 . The linear compressor control apparatus according to  claim 3 , wherein said power supply unit supplies the AC power to the position sensor if the load is unstable and supplies the DC power to the position sensor if the load is stable.  
     
     
         5 . The linear compressor control apparatus according to  claim 1 , wherein said compensation unit comprises: 
 a temperature detecting unit to detect the internal temperature of the linear compressor;    a resonance point shift detecting unit to detect the amount of shift of a piston resonance point due to the load variation;    a position calculating unit to compensate for an error of a maximum stroke of the piston detected by the position detecting unit according to the internal temperature of the linear compressor and the amount of shift of the piston resonance point; and    an instruction value calculating unit to output a drive instruction to drive the linear compressor according to the maximum stroke compensated by the position calculating unit.    
     
     
         6 . The linear compressor control apparatus according to  claim 5 , wherein said compensating unit further comprises a load amount calculating unit to calculate the amount of load according to the amount of shift of the piston resonance point and the instruction value calculating unit drives the linear compressor by considering the calculated load amount.  
     
     
         7 . A method of controlling a linear compressor having a position detecting unit to detect a position of a piston of the linear compressor, comprising: 
 supplying alternating current (AC) power to the position detecting unit, detecting the position of the piston according to an output of the position detecting unit, and detecting a load according to the detected position of the piston;    supplying direct current (DC) power to the position detecting unit and detecting internal temperature of the linear compressor according to the output of the position detecting unit; and    compensating for output distortion of the position detecting unit according to the detected internal temperature of the linear compressor and the detected load.    
     
     
         8 . The linear compressor control method according to  claim 7 , wherein said internal temperature of the linear compressor is detected when an activating time of the compressor is counted and a counted activating time exceeds a preset time.  
     
     
         9 . A method of controlling a linear compressor having a position detecting unit to detect a position of a piston of the linear compressor, comprising: 
 detecting internal temperature of the linear compressor;    detecting the amount of shift of a resonance point of the piston;    compensating for an error of a maximum stroke of the piston detected by the position detecting unit according to the internal temperature of the linear compressor and the amount of shift of the piston resonance point; and    driving the linear compressor according to the compensated maximum stroke.    
     
     
         10 . An apparatus to control a linear compressor, comprising: 
 a position detecting unit to detect a position of a piston reciprocating in a cylinder of the linear compressor;    a power supply unit to supply drive power to the position detecting unit; and    a compensating unit to compensate for output distortion of the position detecting unit due to internal temperature of the linear compressor.    
     
     
         11 . The linear compressor control apparatus according to  claim 10 , wherein said power supply unit supplies drive power obtained by overlapping a high frequency signal for detecting the position of the piston and a direct current (DC) voltage for detecting the internal temperature of the linear compressor.  
     
     
         12 . The linear compressor control apparatus according to  claim 11 , wherein said power supply unit comprises: 
 a high frequency signal generating unit to generate the high frequency signal;    a DC voltage generating unit to generate the DC voltage with a predetermined level; and    an adder to overlap the DC voltage and the high frequency signal.    
     
     
         13 . The linear compressor control apparatus according to  claim 10 , wherein said compensation unit comprises a low pass filter to eliminate a high frequency component from an output of the position detecting unit, and compensates for output distortion of the position detecting unit using a signal whose high frequency component is eliminated by the low pass filter.  
     
     
         14 . The linear compressor control apparatus according to  claim 13 , wherein said compensation unit comprises: 
 a position calculating unit to amplify the internal temperature information and then correcting position information, if the temperature information whose high frequency component is eliminated by the low pass filter and the position information obtained from the output of the position detecting unit have a linear relationship; and    an instruction value calculating unit to output a drive signal to drive the linear compressor on the basis of the position information which is corrected by the position calculating unit.    
     
     
         15 . The linear compressor control apparatus according to  claim 13 , wherein said compensation unit further comprises: 
 an instruction value calculating unit to receive temperature information and position information, respectively, correct the position information according to the temperature information using a preset lookup table, and output a drive signal to drive the compressor on the basis of the corrected position information, if the temperature information whose high frequency component is eliminated by the low pass filter and the position information obtained from the output of the position sensor have a non-linear relationship.    
     
     
         16 . An apparatus to control a linear compressor, comprising: 
 a position detecting unit to detect a position of a piston reciprocating in a cylinder of the linear compressor;    a power supply unit to supply drive power to the position detecting unit; and    a compensating unit to calculate the amount of shift of a piston resonance point and a load from the position of the piston, and compensate for output distortion of the position detecting unit on the basis of the calculated load.    
     
     
         17 . The linear compressor control apparatus according to  claim 16 , wherein said power supply unit supplies alternating current (AC) power to the position detecting unit.  
     
     
         18 . The linear compressor control apparatus according to  claim 5 , wherein the temperature detecting unit determines the variation of the load according to a shift change rate of a resonance point (Δ resonance point shift data) and provides an AC supply instruction to the power supply unit  14  when the load is unstable so the power supply unit  14  supplies AC power, or the temperature detecting unit  31  provides a DC supply instruction to the power supply unit  14  when the load is stable so the power supply unit  14  supplies DC power.  
     
     
         19 . An apparatus to control a linear compressor comprising: 
 a high frequency signal generating unit;    a DC voltage generating unit;    an adder to add the outputs of both the high frequency signal generating unit and the DC voltage generating unit; and    a position sensor to receive the output from the adder a provide two sensor output signals.    
     
     
         20 . The linear compressor control apparatus according to  claim 19 , wherein the position sensor comprises: 
 a magnetic core; and    first and second coils symmetrically would around the magnetic core.    
     
     
         21 . The linear compressor control apparatus according to  claim 19 , wherein the position sensor is connected at one end to the a high frequency signal generating unit through a first resistor and at another end to a potential through a second resistor.  
     
     
         22 . The linear compressor control apparatus according to  claim 21 , wherein the adder overlaps DC voltage and the high frequency signal and supplies the overlapped voltage to the position sensor.  
     
     
         23 . The linear compressor control apparatus according to  claim 22 , further comprising: 
 a rectifier to rectify one of the sensor output signals;    a differential amplifier to receive the rectified sensor output signal from the position sensor and compare the rectified signal with a preset reference signal to provide a difference signal;    a low pass filter to receive the difference signal and provide position information;    a peak detecting unit to receive the position information and output the position information; and    a position calculating unit to receive the position information from the peak detecting unit.    
     
     
         24 . The linear compressor control apparatus according to  claim 23 , further comprising: 
 a low pass filter to receive the second sensor output signal having a characteristic that a value thereof is decreased if a surrounding temperature is increased, wherein a high frequency signal of the second sensor output signal is varied according to the position of the piston.    
     
     
         25 . The linear compressor control apparatus according to  claim 24 , wherein the low pass filter has a cutoff of several Hertz and separates only a DC signal.  
     
     
         26 . The linear compressor control apparatus according to  claim 24 , further comprising: 
 an amplifier to amplify the separated DC signal and provide the amplified signal to the position calculating unit as temperature information.    
     
     
         27 . The linear compressor control apparatus according to  claim 26 , wherein the position calculation unit corrects the position information on the basis of the temperature information.  
     
     
         28 . The linear compressor control apparatus according to  claim 27 , further comprising: 
 an instruction value calculating unit to receive the temperature-corrected position information and convert the temperature-corrected position information into digital information; and    a compressor driving unit driving the linear compressor based on the digital information output received from the instruction value calculating unit.    
     
     
         29 . The linear compressor control apparatus according to  claim 22 , further comprising: 
 a rectifier to rectify one of the sensor output signals;    a differential amplifier to receive the rectified sensor output signal from the rectifier and compare the rectified sensor output signal with a preset reference signal to provide a difference signal;    a low pass filter to receive the difference signal and provide position information; and    a peak detecting unit to receive the position information and output the position information.    
     
     
         30 . The linear compressor control apparatus according to  claim 29 , further comprising: 
 a low pass filter to output temperature information from determined from the second sensor output signal received from the position sensor, the temperature information output having a characteristic that a value thereof is decreased if a surrounding temperature is increased, wherein a high frequency signal of the second sensor output signal is varied according to the position of the piston.    
     
     
         31 . The linear compressor control apparatus according to  claim 30 , further comprising: 
 an instruction value calculating unit to receive the position information from the peak detecting unit and the temperature information output from the low pass filter and converts the position information and temperature information signals into digital information, and corrects the position information according to the digital temperature information; and    a compressor driving unit to drive the linear compressor according to the information received from the instruction value calculating unit.    
     
     
         32 . The linear compressor control apparatus according to  claim 31 , wherein the instruction value calculating unit uses a lookup table to correct the position information by the temperature information and the position information.  
     
     
         33 . A linear compressor control apparatus comprising: 
 a high frequency signal generating unit to generate a high frequency signal;    a DC voltage generating unit to generate a DC voltage;    an adder to overlap the high frequency signal and the DC voltage signal; and    a position sensor to receive the output from the adder and separate a high frequency signal and a DC signal to be used as a position detection signal and a temperature detection signal, respectively, such that position detection and temperature detection are performed simultaneously.