A control unit having improved compressor control algorithm
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Solution Overview
Problem
Cooling appliances with existing control units fail to adjust compressor speeds effectively when loaded with high heat capacity articles, leading to insufficient cooling and customer dissatisfaction.
Innovation Solution
A control unit algorithm that measures and adjusts compressor speed by dividing on-cycles into intervals, comparing average current values, and increasing speed stepwise to match the heat capacity of loaded articles, while neglecting in-rush current for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the compressor runs at fixed speed determined by previous on-cycle, then the control algorithm is simple, but the cooling capacity is insufficient when high heat capacity articles are loaded
Solution Approach 1:
The on-cycle is divided into multiple time intervals (first time interval, second time interval, etc.) for separate current measurements. This segmentation allows the control unit to detect cooling demands at different stages of the compression cycle, enabling more accurate assessment of heat capacity articles without requiring a completely complex control system.
Solution Approach 2:
The control unit measures current during on-cycles, compares it with current from the previous on-cycle, and adjusts the duration of the next on-cycle based on this feedback. This closed-loop feedback mechanism dynamically adapts the compressor operation to the actual cooling demand, increasing cooling capacity while keeping the control algorithm relatively simple.
2Loss of time
If the compressor speed is increased rapidly to cool high heat capacity articles, then the cooling response is fast, but the energy consumption increases
Solution Approach 1:
The control unit dynamically adjusts the on-cycle duration based on real-time current measurements and comparisons. Instead of fixed or purely time-based control, the system adapts the compressor operation duration to match the actual cooling demand, achieving fast response when needed while conserving energy during normal operation.
Solution Approach 2:
The control algorithm changes the operational parameters (on-cycle duration) based on detected conditions. By measuring current at different time intervals and comparing with previous cycles, the system adjusts the on-cycle duration parameter to optimize both cooling response time and energy consumption.
3Stability of the object's composition
If the control unit uses average current value for speed adjustment, then the control is stable, but the response to sudden cooling demands is slow
Solution Approach 1:
The on-cycle is divided into multiple time intervals with different measurement approaches. The first time interval provides a stable baseline measurement, while the second time interval detects changes more rapidly. This segmented approach maintains stability through averaging while improving response speed through interval-specific analysis.
Solution Approach 2:
The control unit performs preliminary current measurement during the first time interval before making adjustment decisions. This preliminary action provides a stable reference point that enables faster and more accurate response to sudden cooling demands in subsequent intervals.
Data Source
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AI summary
The present invention relates to a cooling appliance (1) comprising a control unit (2) and a compressor (3) wherein the control unit (2) is configured to activate the compressor (3) by initiating an on-cycle wherein the coolant is compressed and during which the control unit (2) measures the current drawn by the compressor (3), followed by an off-cycle wherein the compressor (3) remains inactive.