Compressor Frequency Adjustment to Reduce Protective Shutdown Restarts
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Solution Overview
Problem
Air conditioners experience frequent compressor restarts when operating in heating mode with high outdoor temperatures or cooling mode with low outdoor temperatures, leading to protective shutdowns and inefficiencies.
Innovation Solution
A method and device that adjust the compressor frequency and operation duration based on the number of protective stops, lowering the frequency and duration when protective stops exceed preset thresholds to reduce the compressor's restarts and prevent overheating or overcooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the compressor operates at preset frequency (60 or 90Hz) for over 1 minute after startup, then the compressor can establish stable operation, but the evaporator temperature reaches protective values quickly causing frequent protective shutdowns and restarts
Solution Approach 1:
The patent applies dynamics by making the compressor frequency adjustable rather than fixed. The control device dynamically changes the frequency based on operating conditions: using preset frequencies (60-90Hz) during normal operation for stability, and lowering to reduced frequencies (30-50Hz) when protective shutdowns are detected to extend operation time between shutdowns. This dynamic frequency adjustment resolves the contradiction between maintaining stable operation and avoiding frequent restarts.
Solution Approach 2:
The patent implements parameter changes by modifying the compressor frequency parameter based on the number of protective shutdowns. When the shutdown count exceeds a threshold, the system changes the frequency parameter from preset values (60-90Hz) to reduced values (30-50Hz). This parameter change allows the evaporator temperature to rise or fall more slowly, delaying reaching of protective temperature values and reducing restart frequency.
2Productivity
If the compressor frequency is lowered to reduce protective shutdowns, then the evaporator temperature reaches protective values more slowly reducing restarts, but the compressor operation duration at reduced frequency must be limited
Solution Approach 1:
The patent applies periodic action through cyclic frequency adjustment. The control device periodically monitors the number of protective shutdowns and alternates between preset frequency mode (for rapid cooling/heating when needed) and reduced frequency mode (for extending operation duration when protective shutdowns are frequent). This periodic switching between frequency levels optimizes both operational continuity and prevents excessive operation duration at reduced frequency that could affect system performance.
Data Source
Figure 1~3
AI summary
A method of controlling a compressor is disclosed. The method includes: after the compressor is stopped for protection, updating the number of protective stops of the compressor occurring during a current operation of the air conditioner; and when the number of protective stops of the compressor is greater than a first preset number, lowering the frequency of the compressor so that when the compressor restarts the compressor would start and operate at the lowered frequency. Disclosed also is a device for controlling a compressor. Thus, by lowering the frequency of the compressor, the compressor would reach the high or low temperature protective value comparatively slowly, so the number of restarts of the compressor can be reduced.