Reciprocating compressor, driving unit and control method for the same

Abstract

A driving unit and control method for a reciprocating compressor for controlling a frequency of input power so that an operational frequency of the compressor follows a resonant frequency, which varies depending on a variation of the load applied to the compressor. The reciprocating compressor includes an inverter to adjust the frequency of the input power, so that the frequency of the input power is set at a value corresponding to the resonant frequency by the inverter. The resonant frequency is set in a range of 60% to 90% of the normal power frequency. The compressor further includes a controller to control the frequency of the input power so that the operational frequency of the compressor follows the resonant frequency, which varies depending on the operation of the compressor.

1 . A reciprocating compressor comprising: 
 an inverter to receive a power and adjust a frequency of the received power and to input the adjusted power to the compressor, wherein:    a resonant frequency of the compressor is less than a typical frequency of the received power, and    a frequency of the input power corresponds to the resonant frequency.    
   
   
       2 . The compressor according to  claim 1 , wherein the resonant frequency is between 60% to 90% of the typical frequency of the received power.  
   
   
       3 . The compressor according to  claim 2 , further comprising: 
 a controller to control an operation of the compressor,    wherein the controller controls the frequency of the input power so that an operational frequency of the compressor follows the resonant frequency as the resonant frequency varies depending on the operation of the compressor.    
   
   
       4 . The compressor according to  claim 3 , wherein the controller determines a phase difference between the frequency of the input power and the operational frequency of the compressor, thereby controlling the inverter to increase or decrease the frequency of the input power according to a correction value corresponding to the phase difference.  
   
   
       5 . The compressor according to  claim 4 , further comprising: 
 a piston mounted in the compressor;    a current detector to detect the frequency of the input power; and    a displacement detector to detect a displacement of the piston to determine the operational frequency.    
   
   
       6 . The compressor according to  claim 5 , further comprising: 
 a load detector to detect a load applied to the compressor    wherein the controller controls the inverter so that the frequency of the input power is equal to the resonant frequency when the load detected by the load detector is a normal load, and the frequency of the input power is greater than the resonant frequency when the detected load is higher than the normal load.    
   
   
       7 . A reciprocating compressor comprising: 
 an inverter to adjust a frequency of power input to the compressor; and    a controller to control the inverter so that an operational frequency of the compressor coincides with the frequency of the input power according to a determined phase difference between the operational frequency and the frequency of the input power.    
   
   
       8 . The compressor according to  claim 7 , wherein the controller controls the inverter to increase or decrease the frequency of the input power according to a correction value corresponding to the phase difference, thereby allowing the operational frequency to follow a resonant frequency of the compressor which varies depending on an operation of the compressor.  
   
   
       9 . A driving unit for driving a reciprocating compressor, comprising: 
 an inverter to adjust a frequency of input power to be applied to the compressor;    a load detector to determine a load applied to the compressor; and    a controller to control the inverter so that the frequency of the input power is equal to a resonant frequency of the compressor when the load determined by the load detector is a normal load, whereas the frequency of the input power is greater than the resonant frequency when the determined load is greater than the normal load.    
   
   
       10 . A driving unit for driving a reciprocating compressor, comprising: 
 a piston;    an inverter to adjust a frequency of input power to be applied to the compressor;    a current detector to detect the frequency of the input power;    a displacement detector to detect a displacement of the piston to thereby determine an operational frequency of the compressor; and    a controller to control the inverter to thereby determine a phase difference between the operational frequency and the frequency of the input power and then increase or decrease the frequency of the input power based on the determined phase difference, wherein the operational frequency follows a resonant frequency, which varies depending on an operation of the compressor.    
   
   
       11 . A control method for a reciprocating compressor comprising: 
 determining whether a load applied to the compressor is a high load or normal load;    applying a power, having a frequency equal to a resonant frequency of the compressor, to the compressor if the load applied to the compressor is the normal load; and    applying a power, having a frequency greater than the resonant frequency of the compressor, to the compressor if the load applied to the compressor is the high load.    
   
   
       12 . A control method for a reciprocating compressor having an inverter, comprising: 
 determining a phase difference between a frequency of input power and an operational frequency of the compressor; and    controlling the inverter to increase or decrease the frequency of the input power with a correction value corresponding to the phase difference.    
   
   
       13 . The compressor according to  claim 4 , wherein the controller maintains the frequency of the input power when the determined phase difference is zero.  
   
   
       14 . The compressor according to  claim 5 , wherein the resonant frequency varies according to a gas pressure acting on the piston.  
   
   
       15 . A control method for a reciprocating compressor: 
 inputting a power having a frequency greater than a resonant frequency of the compressor;    adjusting the input power to the resonant frequency of the compressor; and    driving the compressor with the adjusted power.