Apparatus and method for controlling a compressor

Abstract

An apparatus and method for controlling a compressor are provided. An input voltage of a commercial power source, a motor voltage of a compressor motor, and a motor current of the compressor motor are detected, based on which voltage values of a capacitor and voltage values of a triac may be calculated. Thus, an additional operational amplifier or a sensor to measure a capacitor voltage is not required, reducing costs.

What is claimed is: 
     
         1 . An apparatus for controlling a compressor, the apparatus comprising:
 one or more capacitors connected to a compressor motor;   a triac that operates the compressor motor according to a gate driving signal; and   a microcomputer that generates the gate driving signal, and calculates voltage values of the one or more capacitors and the triac using an input voltage of a commercial power source, a motor voltage of the compressor motor, and a motor current of the compressor motor.   
     
     
         2 . The apparatus of  claim 1 , wherein the microcomputer includes a capacitor voltage calculator that calculates voltage values of the capacitor, wherein when the motor current is 0, the capacitor voltage calculator calculates a predetermined capacitor voltage value. 
     
     
         3 . The apparatus of  claim 1 , wherein the microcomputer includes a capacitor voltage calculator that calculates voltage values of the capacitor, wherein when a value of the motor current is not 0, the capacitor voltage calculator calculates a value obtained by subtracting the motor voltage from the input voltage, as a voltage value of the capacitor. 
     
     
         4 . The apparatus of  claim 2 , wherein the microcomputer includes a triac voltage calculator that calculates triac voltage values using the input voltage, the motor voltage, and the capacitor voltage value. 
     
     
         5 . The apparatus of  claim 4 , wherein the triac voltage calculator subtracts a value of the motor voltage from a value of the input voltage, and subtracts the capacitor voltage value from the resultant subtraction value to calculate the triac voltage values. 
     
     
         6 . The apparatus of  claim 1 , further comprising:
 an input voltage detector that detects an input voltage of the commercial power source;   a motor voltage detector that detects a motor voltage applied to the compressor motor; and   a motor current detector that detects a motor current flowing in the compressor motor.   
     
     
         7 . The apparatus of  claim 7 , further comprising:
 a zero voltage detector that detects a zero voltage from the detected input voltage.   
     
     
         8 . The apparatus of  claim 1 , further comprising:
 a commercial power source that supplies power to the compressor motor; and   a rectifyier that rectifies and smooths the power provided from the commercial power source.   
     
     
         9 . The apparatus of  claim 1 , further comprising:
 a switch connected to the triac, the switch connecting the triac to the compressor motor or directly connecting the commercial power source to the compressor motor according to a control signal.   
     
     
         10 . The apparatus of  claim 9 , wherein the microcomputer generates the control signal for controlling an operation of the switch and provides the generated control signal to the switch. 
     
     
         11 . The apparatus of  claim 1 , wherein the compressor comprises a reciprocating compressor. 
     
     
         12 . A method for controlling a compressor, the method comprising:
 detecting an input voltage of a commercial power source, a motor voltage of a compressor motor, and a motor current of the compressor motor;   calculating a voltage of a capacitor connected to the compressor motor using the input voltage, the motor voltage, and the motor current;   calculating a voltage of a triac operating the compressor motor according to a gate driving signal using the calculated capacitor voltage; and   controlling the compressor using the detected input voltage, the motor voltage, and the motor current, and the calculated voltages of the capacitor and the triac.   
     
     
         13 . The method of  claim 12 , wherein in the calculating of the voltage of the capacitor, when the motor current is 0, a predetermined voltage is calculated. 
     
     
         14 . The method of  claim 12 , wherein in the calculating of the voltage of the capacitor, when the motor current is not 0, a voltage value obtained by subtracting the motor voltage from the input voltage is calculated. 
     
     
         15 . The method of  claim 12 , wherein in the calculating of the voltage of the triac, a value is obtained by subtracting the motor voltage from the input voltage, and the calculated voltage of the capacitor is subtracted from the obtained value to calculate the voltage of the triac. 
     
     
         16 . The method of  claim 12 , further comprising:
 detecting whether the compressor has an error by monitoring the motor voltage, the capacitor voltage, and the triac voltage.   
     
     
         17 . The method of  claim 12 , wherein the compressor comprises a reciprocating compressor.