Refrigerator and method for controlling the same

Abstract

A refrigerator is provided. The refrigerator includes a storage compartment, an evaporator, a compressor, a first electrode arranged in the storage compartment, a second electrode arranged spaced apart from the first electrode in the storage compartment, a radio frequency (RF) power supply configured to apply an RF signal to the first electrode and the second electrode, a voltage control circuit configured to adjust an input voltage of the RF power supply, a frequency control circuit configured to generate a switching signal for turning the RF power supply on or off, a voltage-current detector configured to detect an output voltage between the first electrode and the second electrode and an output current of the first electrode, memory storing instructions, and at least one processor operatively couple to the compressor, the at least one voltage control circuit, the frequency control circuit, the voltage-current detector, and the memory, wherein the instructions, when executed by the at least one processor individually or collectively, cause the refrigerator to operate the compressor, identify an impedance change rate of food placed between the first electrode and the second electrode based on the output voltage and the output current, and adjust a reference voltage applied to the at least one voltage control circuit or an on-off duty ratio of the frequency control circuit, based on the impedance change rate of the food.

What is claimed is: 
     
         1 . A refrigerator, comprising:
 a storage compartment;   an evaporator configured to cool the storage compartment;   a compressor configured to supply a refrigerant to the evaporator;   a first electrode arranged in the storage compartment;   a second electrode arranged spaced apart from the first electrode in the storage compartment;   a radio frequency (RF) power supply configured to apply an RF signal to the first electrode and the second electrode;   at least one voltage control circuit configured to adjust an input voltage of the RF power supply;   a frequency control circuit configured to generate a switching signal for turning the RF power supply on or off;   a voltage-current detector configured to detect an output voltage between the first electrode and the second electrode and an output current of the first electrode;   memory storing instructions; and   at least one processor operatively couple to the compressor, the at least one voltage control circuit, the frequency control circuit, the voltage-current detector, and the memory,   wherein the instructions, when executed by the at least one processor individually or collectively, cause the refrigerator to:
 operate the compressor to cool the storage compartment, 
 identify an impedance change rate of food placed between the first electrode and the second electrode based on the output voltage and the output current periodically detected by the voltage-current detector, and 
 adjust a reference voltage applied to the at least one voltage control circuit or an on-off duty ratio of the frequency control circuit, based on the impedance change rate of the food. 
   
     
     
         2 . The refrigerator of  claim 1 , wherein the instructions, when executed by the at least one processor individually or collectively, further cause the refrigerator to:
 adjust the reference voltage applied to the at least one voltage control circuit, based on the impedance change rate of the food being greater than or equal to a reference value, and   adjust the on-off duty ratio of the frequency control circuit, based on the impedance change rate of the food being less than the reference value.   
     
     
         3 . The refrigerator of  claim 2 , wherein the instructions, when executed by the at least one processor individually or collectively, further cause the refrigerator to:
 reduce the reference voltage to reduce the input voltage, and   reduce the on-off duty ratio of the frequency control circuit, based on a decrease in the impedance change rate of the food.   
     
     
         4 . The refrigerator of  claim 2 , wherein the instructions, when executed by the at least one processor individually or collectively, further cause the refrigerator to:
 adjust a frequency of the switching signal, based on the impedance change rate of the food being less than the reference value.   
     
     
         5 . The refrigerator of  claim 4 , wherein the instructions, when executed by the at least one processor individually or collectively, further cause the refrigerator to:
 reduce the frequency of the switching signal, based on a decrease in the impedance change rate of the food.   
     
     
         6 . The refrigerator of  claim 2 ,
 wherein the reference value is a first reference value, and   wherein the instructions, when executed by the at least one processor individually or collectively, further cause the refrigerator to:
 maintain the on-off duty ratio of the frequency control circuit to be constant, based on the impedance change rate of the food being within an error range of a second reference value that is less than the first reference value. 
   
     
     
         7 . The refrigerator of  claim 2 ,
 wherein the instructions, when executed by the at least one processor individually or collectively, further cause the refrigerator to:
 apply the reference voltage to the at least one voltage control circuit to generate an electric field between the first electrode and the second electrode, based on the impedance change rate of the food being less than or equal to a threshold value after the compressor starts operating, and 
   wherein the threshold value is greater than the reference value.   
     
     
         8 . The refrigerator of  claim 1 , further comprising:
 a food sensor configured to identify the food,   wherein the instructions, when executed by the at least one processor individually or collectively, further cause the refrigerator to:
 obtain food information corresponding to the identified food and electric field control information corresponding to the food information from the memory or a user device, and 
 determine the on-off duty ratio of the frequency control circuit or the reference voltage applied to the at least one voltage control circuit based on the electric field control information. 
   
     
     
         9 . The refrigerator of  claim 1 , further comprising:
 a direct current (DC) converter configured to apply a voltage to the RF power supply; and   a power factor correction (PFC) circuit configured to deliver power factor compensated power to the DC converter,   wherein the at least one voltage control circuit is connected to at least one of the DC converter or the PFC circuit.   
     
     
         10 . The refrigerator of  claim 1 , further comprising:
 an impedance matching circuit through which the RF power supply applies the RF signal to the first electrode and the second electrode,   wherein the instructions, when executed by the at least one processor individually or collectively, further cause the refrigerator to:
 control the impedance matching circuit to match an output impedance of the RF power supply and an electrode impedance of the first electrode and the second electrode. 
   
     
     
         11 . A method performed by a refrigerator comprising a storage compartment, an evaporator configured to cool the storage compartment, a compressor configured to supply a refrigerant to the evaporator, a first electrode arranged in the storage compartment, a second electrode arranged spaced apart from the first electrode in the storage compartment, a radio frequency (RF) power supply configured to apply an RF signal to the first electrode and the second electrode, a direct current (DC) converter configured to apply a voltage to the RF power supply, and a power factor correction (PFC) circuit configured to deliver power factor compensated power to the DC converter, the method comprising:
 operating the compressor to supply the refrigerant to the evaporator so as to cool the storage compartment;   identifying an impedance change rate of food placed between the first electrode and the second electrode, based on an output voltage between the first electrode and the second electrode and an output current of the first electrode, the output voltage and the output current being periodically detected by a voltage-current detector; and   adjusting a reference voltage applied to at least one voltage control circuit configured to adjust an input voltage of the RF power supply, or an on-off duty ratio of a frequency control circuit configured to generate a switching signal for turning the RF power supply on or off, based on the impedance change rate of the food.   
     
     
         12 . The method of  claim 11 , wherein the adjusting of the reference voltage or the on-off duty ratio comprises:
 adjusting the reference voltage applied to the at least one voltage control circuit, based on the impedance change rate of the food being greater than or equal to a reference value; and   adjusting the on-off duty ratio of the frequency control circuit, based on the impedance change rate of the food being less than the reference value.   
     
     
         13 . The method of  claim 12 ,
 wherein the adjusting of the reference voltage comprises reducing the reference voltage to reduce the input voltage, based on a decrease in the impedance change rate of the food, and   wherein the adjusting of the on-off duty ratio comprises reducing the on-off duty ratio based on the decrease in the impedance change rate of the food.   
     
     
         14 . The method of  claim 12 , further comprising:
 adjusting a frequency of the switching signal, based on the impedance change rate of the food being less than the reference value.   
     
     
         15 . The method of  claim 14 , wherein the adjusting of the frequency of the switching signal comprises reducing the frequency of the switching signal based on a decrease in the impedance change rate of the food. 
     
     
         16 . The method of  claim 12 ,
 wherein the reference value is a first reference value, and   wherein the adjusting of the on-off duty ratio comprises maintaining the on-off duty ratio of the frequency control circuit to be constant based on the impedance change rate of the food being within an error range of a second reference value that is less than the first reference value.   
     
     
         17 . The method of  claim 12 , further comprising:
 applying the reference voltage to the at least one voltage control circuit to generate an electric field between the first electrode and the second electrode, based on the impedance change rate of the food being less than or equal to a threshold value after the compressor starts operating,   wherein the threshold value is greater than the reference value.   
     
     
         18 . The method of  claim 11 , further comprising:
 identifying, by a food sensor of the refrigerator, the food; and   obtaining food information corresponding to the identified food and electric field control information corresponding to the food information from memory or the refrigerator or a user device,   wherein the adjusting of the reference voltage or the on-off duty ratio includes determining the on-off duty ratio of the frequency control circuit or the reference voltage applied to the at least one voltage control circuit based on the electric field control information.   
     
     
         19 . The method of  claim 11 , wherein the at least one voltage control circuit is connected to at least one of the DC converter or the PFC circuit. 
     
     
         20 . The method of  claim 11 , further comprising:
 controlling an impedance matching circuit of the refrigerator, through which the RF power supply applies the RF signal to the first electrode and the second electrode, to match an output impedance of the RF power supply and an electrode impedance of the first electrode and the second electrode.