Parallel Compressor Surging Detection Using Operation Point Analysis
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Solution Overview
Problem
Existing refrigerator systems with parallel compressors face false detection of surging due to deviations in current values, leading to unnecessary protection operations, as the difference in current values can be caused by factors other than surging, such as droplet suction.
Innovation Solution
A control device that detects surging and droplet suction by analyzing the deviation in current values and operation points indicated by air volume and compression ratio, using a bypass pipe and valve to manage refrigerant flow, and adjusts the expansion valve accordingly to prevent false protection operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If surging detection is performed based only on current value deviation between compressors, then detection simplicity is improved, but detection accuracy deteriorates due to false detection from non-surging causes
Solution Approach 1:
The patent transitions from one-dimensional detection (current value only) to two-dimensional detection by introducing operation point information (air volume and compression ratio) as an additional dimension. This allows the system to distinguish between surging and non-surging causes of current deviation, resolving the contradiction between simplicity and accuracy.
Solution Approach 2:
The patent changes the detection parameters from solely electrical parameters (current values) to include thermodynamic parameters (air volume, compression ratio, operation point). This parameter expansion enables accurate differentiation between surging and other operational states that also cause current deviations.
2Reliability
If protection operation is performed based on false surging detection, then compressor protection is improved, but system efficiency deteriorates due to unnecessary bypass valve opening
Solution Approach 1:
The patent implements feedback control by continuously monitoring both current values and operation points, and only triggering protection operations when surging is genuinely detected. This feedback mechanism prevents unnecessary bypass valve openings, maintaining system efficiency while providing reliable compressor protection.
Solution Approach 2:
The patent introduces dynamic decision-making based on real-time operation point analysis. The system adapts its protection behavior according to the actual operational state, opening the bypass valve only when genuinely needed for surging protection, thereby balancing reliability and productivity dynamically.
Data Source
AI summary
The present invention provides a control device for detecting an abnormal operation state of a compressor in a parallel refrigerator. The control device is a control device for a refrigerator that includes a plurality of compressors connected in parallel, and detects occurrence of surging and occurrence of droplet suction on the basis of a deviation between values of currents flowing through electric motors that is configured to drive each of the plurality of compressors, and an operation point indicated by the air volume and the compression ratio of the plurality of compressors.