Refrigerating apparatus and inverter device

Abstract

A refrigerating apparatus having a refrigerating cycle that comprises a compressor, an electric motor that drives the compressor, and an inverter device that variably controls the operating frequency of the electric motor. The inverter device includes a converter circuit that converts an A.C. voltage from an A.C. power supply into a D.C. current, an inverter circuit comprising a D.C./A.C converter, and a shunt resistance that detects a D.C. current flowing through a switching element of the inverter circuit. The shunt resistance detects a D.C. current, and the detected D.C. current value is calculated as a sine wave A.C. current for the electric motor in relation to action of the switching element.

1 . A refrigerating apparatus having a refrigerating cycle including a compressor driven by an electric motor, of which operating frequency is variably controlled by an inverter device, 
 wherein the inverter device includes a converter circuit that converts an A.C. voltage from an A.C. power supply into a D.C. current, an inverter circuit comprising a D.C./A.C converter, and a shunt resistance that detects a D.C. current flowing through a switching element of the inverter circuit, and    a D.C. value detected by the shunt resistance is calculated as a sine wave A.C. current for the electric motor in relation to action of the switching element.    
   
   
       2 . A refrigerating apparatus according to  claim 1 , wherein the inverter device comprises: 
 a first substrate on a surface of which the shunt resistance is mounted and an opposite surface of which radiating fins are closely attached;    a second substrate on which a microcomputer that controls the switching element, a current detection circuit that processes a detection value detected by the shunt resistance, a driver circuit that causes the switching element to perform a switching operation, a connector for communication circuit/interface that communicates with a high-order control substrate, and a power circuit that supplies control power to the microcomputer, the current detection circuit, the driver circuit and the communication circuit are mounted; and    a case that covers sides of the first substrate, the case being provided with terminal blocks for electric power input and motor output;    wherein the first substrate and the second substrate are arranged in an order of the first substrate and the second substrate in a layered manner from a bottom surface of the case, the first substrate and the second substrate are connected to each other by a lead pin, and gel is filled on a surface of the first substrate on which a power semiconductor is mounted.    
   
   
       3 . A refrigerating apparatus according to  claim 2 , wherein the operating frequency is output to the high-order control substrate via the connector for interface.  
   
   
       4 . A refrigerating apparatus according to  claim 2 , wherein refrigerating cycle information (temperature, pressure, opening degrees of expansion valves, rotating speeds of fans) is input into the microcomputer via the connector for interface, and the refrigerating cycle is controlled by the microcomputer.  
   
   
       5 . A refrigerating apparatus according to  claim 2 , wherein a nonvolatile memory is arranged on the second substrate and data of detection gain of the shunt resistance are stored and retained in the nonvolatile memory.  
   
   
       6 . A refrigerating apparatus according to  claim 1 , further comprising an active switching element that constitutes an active circuit, and a shunt resistance that detects an electric current of a single-phase power supply input, and a single-phase power supply is input into the converter circuit.  
   
   
       7 . An inverter device that variably controls the operating frequency of an electric motor, the inverter device comprising a converter circuit that converts an A.C. voltage from an A.C. power supply into a D.C. current, an inverter circuit comprising a D.C./A.C converter, and a shunt resistance that detects a D.C. current flowing through a switching element of the inverter circuit, wherein a D.C. value detected by the shunt resistance is calculated as a sine wave A.C. current for the electric motor in relation to action of the switching element.  
   
   
       8 . An inverter device according to  claim 7 , further comprising: 
 a first substrate on a surface of which the shunt resistance is mounted and on an opposite surface of which radiating fins are closely attached;    a second substrate on which a microcomputer that controls the switching element, a current detection circuit that processes a detection value detected by the shunt resistance, a driver circuit that causes the switching element to perform a switching operation, a connector for communication circuit/interface that communicates with a high-order control substrate, and a power circuit that supplies control power to the microcomputer, the current detection circuit, the driver circuit, and the communication circuit are mounted; and    a case that covers sides of the first substrate, the case being provided with terminal blocks for electric power input and motor output,    wherein the first substrate and the second substrate are arranged in an order of the first substrate and the second substrate in a layered manner from a bottom surface of the case, the first substrate and the second substrate are connected to each other by a lead pin, and gel is filled on a surface of the first substrate on which a power semiconductor is mounted.    
   
   
       9 . An inverter device according to  claim 8 , wherein a frequency change-over mechanism capable of changing and fixing the operating frequency of the compressor is mounted on the second substrate.  
   
   
       10 . An inverter device according to  claim 8 , wherein a nonvolatile memory is arranged on the second substrate and data of detection gain of the shunt resistance are stored and retained in the nonvolatile memory.  
   
   
       11 . An inverter device according to  claim 7 , further comprising an active switching element that constitutes an active circuit, and a shunt resistance that detects an electric current of a single-phase power supply input, and a single-phase power supply is input into the converter circuit.