Control method for variable volume ratio compressor
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Solution Overview
Problem
Existing variable volume ratio compressors experience high-frequency switching of volume ratios, leading to excessive wear on components and inconsistent performance under partial load conditions.
Innovation Solution
Implementing a controller that determines a switching parameter based on suction density and compressor speed, incorporating delay periods to stabilize volume ratio changes, reducing high-frequency switching by delaying volume ratio adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If automated switching of volume ratios is implemented without delay periods, then the compressor can respond quickly to changing operating conditions, but high-frequency switching occurs causing excessive wear on components
Solution Approach 1:
The patent implements periodic action by introducing delay periods between volume ratio switching operations. The controller is configured to wait for a specified delay period before allowing another volume ratio change, which prevents high-frequency switching while still enabling the compressor to adapt to changing operating conditions. This periodic restriction reduces wear on components while maintaining operational responsiveness.
2Reliability
If volume ratio switching is delayed to reduce high-frequency switching, then component wear is reduced, but the compressor may not respond quickly enough to optimal operating conditions
Solution Approach 1:
The patent employs feedback mechanisms where the controller continuously monitors operating conditions (such as suction pressure, discharge pressure, and temperature) and compares them against predetermined thresholds. This feedback system ensures that volume ratio changes are triggered only when genuinely needed, preventing unnecessary switching while maintaining optimal compressor efficiency under varying load conditions.
3Productivity
If the controller continuously monitors and adjusts volume ratio based on real-time conditions, then compressor efficiency is optimized, but the complexity of the control system increases
Solution Approach 1:
The patent applies parameter changes by adjusting the volume ratio of the compressor based on variations in operating parameters such as suction pressure, discharge pressure, and temperature. The controller modifies the volume ratio to specific predetermined values corresponding to different operating conditions, which optimizes compressor efficiency without requiring overly complex control algorithms or additional hardware components.
Data Source
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AI summary
A compressor system (100) comprises a variable volume ratio compressor (102) and a controller (106) which is configured to: determine a mass flow rate as a switching parameter; to determine whether to change the volume ratio of the compressor based on a switching condition and the switching parameter; and, when it is determined to change the volume ratio, direct a change in the volume ratio which the variable volume ratio compressor (102) is operated at.