Apparatus for controlling driving of reciprocating compressor and method thereof

Abstract

Disclosed are an apparatus for controlling a driving of a reciprocating compressor capable of enhancing an efficiency by differently controlling a frequency and a stroke voltage according to a load size and capable of reducing consumption power, and a method thereof. The apparatus comprises a controlling unit for judging a load size by comparing a phase difference between a detected current and a stroke with a reference phase difference, and outputting a frequency control signal and a stroke control signal according to the judged load size.

1 . An apparatus for controlling a driving of a reciprocating compressor, comprising a controlling unit for judging a size of a load by comparing a phase difference between a detected current and a stroke with a reference phase difference, and for outputting a frequency control signal and a stroke control signal according to the judged load size. 
   
   
       2 . The apparatus of  claim 1 , wherein when the phase difference between the detected current and the stroke is less than the reference phase difference, the controlling unit outputs a stroke control signal to vary a current stroke into a full stroke. 
   
   
       3 . The apparatus of  claim 1 , wherein when the phase difference between the detected current and the stroke is larger than the reference phase difference, the controlling unit outputs a stroke control signal for varying a capacity. 
   
   
       4 . The apparatus of  claim 1 , wherein when the phase difference between the detected current and the stroke is larger than the reference phase difference, the controlling unit outputs a frequency control signal for varying a current driving frequency into a resonance frequency. 
   
   
       5 . An apparatus for controlling a driving of a reciprocating compressor, comprising:
 a controlling unit for judging a load size by comparing a phase difference between a current and a stroke with a reference phase difference, and outputting a frequency control signal and a stroke control signal according to the judgment result;   a driving frequency command value determining unit for determining a driving frequency command value according to the frequency control signal;   a stroke command value determining unit for determining a stoke command value according to the stroke control signal;   a first comparing unit for comparing the driving frequency command value with a current driving frequency, and outputting a frequency compensation signal according to the comparison result;   a second comparing unit for comparing the stroke command value with a current stroke, and outputting a stroke compensation signal according to the comparison result;   a PWM controlling unit for outputting a PWM control signal to vary a driving frequency and a stroke according to the frequency compensation signal and the stroke compensation signal; and   an inverter for varying a voltage and a driving frequency applied to a motor according to the PWM control signal.   
   
   
       6 . The apparatus of  claim 5 , wherein when the phase difference between the detected current and the stroke is less than the reference phase difference, the controlling unit outputs a stroke control signal to vary a current stroke into a full stroke. 
   
   
       7 . The apparatus of  claim 5 , wherein when the phase difference between the detected current and the stroke is less than the reference phase difference, the controlling unit outputs a stroke control signal for varying a current stroke into a full stroke and outputs a frequency control signal for varying a current driving frequency into a driving frequency larger than a resonance frequency. 
   
   
       8 . The apparatus of  claim 5 , wherein when the phase difference between the detected current and the stroke is larger than the reference phase difference, the controlling unit outputs a stroke control signal for varying a capacity. 
   
   
       9 . The apparatus of  claim 5 , wherein when the phase difference between the detected current and the stroke is larger than the reference phase difference, the controlling unit outputs a frequency control signal for varying a current driving frequency into a resonance frequency. 
   
   
       10 . The apparatus of  claim 5 , wherein when the phase difference between the detected current and the stroke is larger than the reference phase difference, the controlling unit outputs a stroke control signal for varying a capacity and outputs a frequency control signal for varying a current driving frequency into a resonance frequency. 
   
   
       11 . A method for controlling a driving of a reciprocating compressor, comprising:
 driving a reciprocating compressor with a capacity corresponding to a certain stroke command value;   detecting a current and a voltage applied to a motor of the reciprocating compressor, and calculating a stroke by the detected current and voltage;   detecting a phase difference between the calculated stroke and the detected current; and   comparing the detected phase difference with a reference phase difference, and varying a stroke command value and a driving frequency command value according to the comparison result.   
   
   
       12 . The method of  claim 11 , wherein in the step of varying a stroke command value and a driving frequency command value, when the detected phase difference between the current and the stroke is less than the reference phase difference, a current stroke is varied into a full stroke. 
   
   
       13 . The method of  claim 11 , wherein in the step of varying a stroke command value and a driving frequency command value, when the detected phase difference between the current and the stroke is larger than the reference phase difference, a stroke is varied thus to vary a driving capacity of the reciprocating compressor. 
   
   
       14 . The method of  claim 11 , wherein in the step of varying a stroke command value and a driving frequency command value, when the detected phase difference between the current and the stroke is larger than the reference phase difference, a current driving frequency is varied into a resonance frequency. 
   
   
       15 . The method of  claim 11 , wherein in the step of varying a stroke command value and a driving frequency command value, when the detected phase difference between the current and the stroke is less than the reference phase difference, a current driving frequency is varied into a driving frequency larger than a resonance frequency and a current stroke is varied into a full stroke. 
   
   
       16 . The method of  claim 11 , wherein in the step of varying a stroke command value and a driving frequency command value, when the detected phase difference between the current and the stroke is larger than the reference phase difference, a stroke is varied thus to vary a driving capacity of the reciprocating compressor and a current driving frequency is varied into a resonance frequency. 
   
   
       17 . A method for controlling a driving of a reciprocating compressor, comprising:
 driving a reciprocating compressor with a capacity corresponding to a certain stroke command value;   detecting a current and a voltage applied to a motor of the reciprocating compressor, and calculating a stroke by the detected current and voltage;   detecting a phase difference between the calculated stroke and the current;   comparing the detected phase difference with a reference phase difference, and varying a stroke command value and a driving frequency command value according to the comparison result;   comparing the varied driving frequency command value with a current driving frequency, and generating a frequency compensation signal according to the comparison result;   comparing the varied stroke command value with a current command value, and generating a stroke compensation signal according to the comparison result;   generating a PWM control signal to vary a stroke voltage and a driving frequency according to the frequency compensation signal and the stroke compensation signal; and   varying a stroke voltage and a driving frequency applied to a motor of the reciprocating compressor according to the PWM control signal.   
   
   
       18 . The method of  claim 17 , wherein in the step of varying a stroke command value and a driving frequency command value, when the detected phase difference between the current and the stroke is larger than the reference phase difference, a stroke control signal for varying a capacity is outputted and a frequency control signal for varying a current driving frequency into a resonance frequency is outputted. 
   
   
       19 . The method of  claim 17 , wherein in the step of varying a stroke command value and a driving frequency command value, when the detected phase difference between the current and the stroke is smaller than the reference phase difference, a stroke control signal for varying a current stroke into a full stroke is outputted and a frequency control signal for varying a current driving frequency into a driving frequency larger than a resonance frequency is outputted.