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.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to a refrigerating apparatus including a variable speed motor for compressor, and an inverter device to be used in the apparatus. [0002] Conventionally, in order to achieve miniaturization and to enhance a refrigerating cycle in reliability in a refrigerating apparatus and an inverter device to be used in the apparatus, it is known and described in, for example, JP-A-2003-289675 that a substrate with a power semiconductor and a microcomputer mounted thereon is enclosed by a box-shaped case and arranged in a layered manner with a connector substrate for interface disposed topmost. [0003] In the conventional art described above, since a current sensor (current detection mechanism) for detecting an electric current fed to an electric motor is used, a large mount area is needed. That is, the current sensor is a high function part to take in a current output to a motor once, to grasp magnetic flux generated by the flowing c...

AI Technical Summary

Benefits of technology

"The invention is a refrigerating apparatus with a refrigerating cycle that includes a compressor, an inverter device, and a shunt resistance for detecting current. The inverter device converts an A.C. voltage to a D.C. current and includes a converter circuit, an inverter circuit, and a shunt resistance for detecting current. The shunt resistance detects the current flowing through a switching element and the detection value is calculated as a sine wave A.C. current. The inverter device is designed to control the operating frequency of the electric motor and can be controlled by an external microcomputer. The invention also includes a layered arrangement of components and a connector for communication with a high-order control substrate. The invention provides a thinner and more reliable inverter device with improved overcurrent protection."

Problems solved by technology

That is, the current sensor is a high function part to take in a current output to a motor once, to grasp magnetic flux generated by the flowing current, to effect voltage conversion and to output to a control substrate, and so the part itself is large to become obstacles in miniaturization of the whole.

Also, in refrigerating apparatuses (air conditioners, refrigerating machines), an electric motor relatively consumes a large electric power and is in many cases driven by a three-phase electric source.

For inverter control, at least two phases (for example, U-phase and V-phase among three-phase output (U-phase, V-phase and W-phase)) of the current to be output to the electric motor must be detected, and to provide a space for detection is disadvantageous to miniaturization and enhancement in reliability.

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