Compressor Capacity Stage Control Using Averaged Set Value Feedback
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Solution Overview
Problem
Existing control logic methods for refrigerant compressor systems in heat pumping circuits are not responsive enough to changes in capacity set values, leading to inefficient operation.
Innovation Solution
A method that determines a capacity set value, calculates a decision quantity, and uses a calculated capacity average value to adjust compressor capacity stages, incorporating a change rate limitation action to prevent excessive switching, allowing for a closed-loop feed forward control mechanism that reacts to changes in load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional control logic methods are used for compressor capacity adjustment, then the control system is simple to implement, but the system is not responsive enough to changes in capacity set value
Solution Approach 1:
The control system calculates a capacity average value in advance by averaging the capacity set value over multiple control cycles. This preliminary calculation allows the system to anticipate future capacity requirements and respond more quickly to changes, improving responsiveness without requiring complex real-time analysis
Solution Approach 2:
The system compares the calculated capacity average value with the current operating capacity stage and uses this feedback to determine whether to adjust the compressor capacity. This closed-loop feedback mechanism enables responsive control while maintaining a relatively simple control structure through systematic decision-making
2Speed
If the compressor capacity stage is changed frequently to match capacity set value changes, then the system responsiveness improves, but the component lifespan decreases due to excessive switching
Solution Approach 1:
By pre-calculating the capacity average value before making capacity adjustment decisions, the system can identify genuine capacity changes that persist over multiple cycles rather than transient fluctuations. This allows responsive control while avoiding unnecessary switching that would reduce component lifespan
Solution Approach 2:
Instead of changing capacity immediately when the set value changes, the system inverts the approach by waiting for the averaged capacity value to confirm a sustained change trend. This reverse sequencing of operations ensures responsiveness to real changes while filtering out noise that would cause excessive switching
Data Source
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AI summary
Method for controlling a compressor system, arranged in a heat pumping circuit, said compressor system being designed to be operated at at least two different compressor capacity stages, said compressor capacity stages being adjusted by a capacity adjustment system enabling switching from one compressor capacity stage to another compressor capacity stage, said capacity adjustment system being controlled by a capacity selection signal defining the compressor capacity stage to be selected, said method comprising determining a capacity set value, determining a decision quantity on the basis of said capacity set value, determining a calculated capacity average value on the basis of capacity selection signals generated before, comparing said calculated capacity average value with said decision quantity and changing said compressor capacity stage to the next higher stage if the calculated capacity average value is below the decision quantity or changing said compressor capacity stage to the next lower stage if the calculated capacity average value is above the decision quantity, or not changing said compressor capacity stage if the calculated capacity average value meets said decision quantity.