Apparatus and method for controlling operation of reciprocating compressor

An apparatus for controlling an operation of a reciprocating compressor comprising:

• a current detector for detecting a current applied to a motor of a reciprocating compressor;
• a voltage detector for detecting a voltage applied to the motor;
• a stroke calculator for calculating a stroke estimate value of the reciprocating compressor based on the detected current value, the detected voltage value and a parameter of the motor;
• a first comparator for comparing the calculated stroke estimate value and a pre-set stroke reference value, and outputting a first difference value according to the comparison result;
• a current amplitude value generator for generating a current amplitude value for compensating the first difference value and outputting the current amplitude value in a sine wave form;
• a current controller for comparing the current amplitude value and the detected current value and generating a pulse width modulation signal used for compensating a second difference value according to the comparison result;
• and
• an inverter for varying amplitude of the current to be applied to the motor according to the pulse width modulation signal.

An apparatus for controlling an operation of a reciprocating compressor comprising:

• a current detector for detecting a current applied to a motor of a reciprocating compressor;
• a voltage detector for detecting a voltage applied to the motor;
• a stroke calculator for calculating a stroke estimate value of the reciprocating compressor based on the detected current value, the detected voltage value and a parameter of the motor;
• a first comparator for comparing the calculated stroke estimate value and a pre-set stroke reference value, and outputting a first difference value according to the comparison result;
• a first proportional integral (PI) controller for generating a current amplitude value for compensating the first difference value by performing proportional-integral controlling based on the first difference value;
• a controller for reading a previously stored current sine table value corresponding to the current amplitude value from a storage unit, and generating a current amplitude value having a sine wave based on the read sine table value;
• a second comparator for comparing the current amplitude value having the sine wave and the detected current value, and outputting a second difference value according to the comparison result;
• a second PI controller for performing proportional-integral controlling based on the second difference value outputted form the second comparator and applying a pulse width modulation signal used for compensating the second difference value to an inverter;
• and
• the inverter for varying amplitude of a current to be applied to the motor according to the pulse width modulation signal,
• wherein the controller outputs the current amplitude value having the sine wave by synchronizing a current waveform corresponding to the current amplitude value with an operation frequency corresponding to an operation frequency reference value.

A method for controlling an operation of a reciprocating compressor comprising:

• generating a first current value for compensating a difference value between a stroke reference value of the reciprocating compressor and a stroke estimate value;
• and
• outputting the first current value in a sine wave form to the reciprocating compressor,
• wherein the step of generating the first current value comprises:
• comparing the stroke estimate value and the pre-set stroke reference value and outputting a first difference value according to the comparison result;
• outputting the first current value for compensating the first difference value in the sine wave form;
• comparing the first current value and a second current value of the current applied to the reciprocating compressor and generating a pulse width modulation signal used for compensating the second difference value according to the comparison result;
• and
• varying the current to be applied to the reciprocating compressor according to the pulse with modulation signal.

A method for controlling an operation of a reciprocating compressor comprising:

• detecting a current applied to a motor of a reciprocating compressor;
• detecting a voltage applied to the motor;
• calculating a stroke estimate value of the reciprocating compressor based on the detected current value, the detected voltage value and a parameter of the motor;
• comparing the calculated stroke estimate value and a pre-set stroke reference value and outputting a first difference value according to the comparison result;
• generating a current amplitude value for compensating the first difference value and outputting the current amplitude value in a sine wave form;
• comparing the current amplitude value and the detected current value and generating a pulse width modulation signal used for compensating a second difference value according to comparison result;
• and
• varying amplitude of a current to be applied to the motor according to the pulse width modulation signal.