Dual-Compressor Inverter Switching for Stable Refrigerator Control

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Solution Overview

Problem

Existing compressor control systems require separate inverters for each compressor, making them costly and inefficient, especially when controlling two compressors in a refrigerator, as they cannot simultaneously operate effectively with one inverter.

Innovation Solution

A compressor control apparatus using one inverter with three pairs of switching elements, where one pair is commonly connected to both compressors and switched at an operating frequency, while the others are switched at carrier frequencies, allowing for simultaneous operation and varying load management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If one inverter is used to control two compressors, then device complexity and cost are reduced, but control reliability and operational stability deteriorate due to shared switching elements

Engineering Contradiction:
Improveinverter quantityVSAvoidcompressor control stability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent segments the control of two compressors by assigning different switching frequency characteristics to different switching element pairs. The first pair operates at a lower frequency while the second pair operates at a higher frequency, allowing independent control characteristics for each compressor despite sharing a common inverter. This frequency-based segmentation resolves the contradiction by maintaining control reliability through differentiated operation modes while reducing overall device complexity.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If switching elements are operated at high frequency for precise control, then control precision improves, but switching losses increase and energy efficiency deteriorates

Engineering Contradiction:
Improvecompressor control precisionVSAvoidswitching loss
Core Design Contradiction:
Measurement precisionVSLoss of energy

Solution Approach 1:

The patent applies parameter changes by operating different switching element pairs at different frequencies. The first switching element pair operates at a lower frequency to minimize switching losses and improve energy efficiency, while the second pair operates at a higher frequency to provide precise control when needed. This frequency parameter differentiation allows the system to optimize between control precision and energy efficiency based on operational requirements.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If two compressors are controlled independently with separate inverters, then operational flexibility and control independence improve, but system cost and component quantity increase

Engineering Contradiction:
Improvecompressor operation flexibilityVSAvoidinverter quantity
Core Design Contradiction:
Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent implements universality by designing a single inverter that can control two different compressors with different operational requirements. The inverter contains multiple switching element pairs that can operate at different frequencies, enabling the same inverter unit to adaptively control both compressors independently. This multi-functional design achieves compressor operation flexibility while reducing the total number of inverters required.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP2620722B1Apparatus for controlling compressor and refrigerator having the same
Publication Date: 2019.04.24 LG ELECTRONICS INC
  • EP2620722B1 patent drawingFigure 1
  • EP2620722B1 patent drawingFigure 2
  • EP2620722B1 patent drawingFigure 3

AI summary

There is disclosed herein a compressor control apparatus, and a refrigerator including the same. According to the embodiments of the present disclosure, the operation of two compressors (C1, C2) may be controlled using one inverter (40), thereby minimizing the use of elements as well as increasing the compressor capacity and enhancing the operation efficiency of a system. According to the embodiments of the present disclosure, switching elements commonly used may be switched at an operating frequency contrary to the other switching elements in operating two compressors (C1, C2) using one inverter (40), thereby allowing the simultaneous operation of two compressors (C1, C2), reducing the switching loss, and improving the efficiency and stability of a system.