Compressor Fault Diagnosis Using Pressure and Temperature Signals
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Solution Overview
Problem
Conventional compressor protection systems in refrigeration systems lack precision in diagnosing faults, often requiring multiple tests to identify issues due to the need for numerous sensors and lack of direct indication of specific faults, leading to inefficient and sometimes incorrect diagnosis.
Innovation Solution
A diagnostic system that uses a pair of sensors to generate high-side and low-side signals, processing these signals to indirectly determine non-measured operating parameters, allowing for the differentiation between high-side and low-side faults and enabling the compressor to toggle between normal, reduced-capacity, and shutdown modes based on sensed parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors are used to monitor various operating parameters, then measurement precision and reliability improve, but device complexity increases
Solution Approach 1:
The patent applies multi-functionality by enabling a reduced set of sensors to perform multiple diagnostic functions through advanced signal processing. The system uses two sensors (discharge pressure and discharge temperature) to detect multiple fault types (high-side faults, low-side faults, compressor faults) by analyzing complex relationships between parameters rather than requiring one sensor per parameter.
Solution Approach 2:
The patent introduces processing circuitry as an intermediary that mediates between the limited sensors and the diagnostic functions. This intermediary component performs sophisticated signal processing, pattern recognition, and parameter correlation to extract multiple fault diagnoses from minimal sensor inputs, effectively acting as a bridge that multiplies the informational value of each sensor.
2Reliability
If conventional protection systems shut down compressor at predetermined thresholds, then compressor protection is provided, but diagnostic precision deteriorates requiring multiple tests
Solution Approach 1:
The patent applies preliminary action by performing comprehensive diagnostic analysis continuously during normal operation before faults develop or escalate. The system proactively identifies emerging fault conditions through trend analysis and parameter correlation, enabling early intervention and precise fault identification before the compressor requires shutdown or multiple diagnostic tests become necessary.
Solution Approach 2:
The patent implements feedback mechanisms where the processing circuitry continuously monitors sensor outputs, compares them against expected relationships and fault patterns, and provides real-time diagnostic feedback. This feedback loop enables the system to distinguish between different fault types (high-side vs. low-side vs. compressor faults) and provide precise diagnostic information rather than simple threshold-based shutdown signals.
3Device complexity
If discrete switches are used for temperature and pressure sensing, then system simplicity is maintained, but measurement precision and diagnostic capability are limited
Solution Approach 1:
The patent applies parameter changes by transforming the way temperature and pressure information is utilized. Instead of using discrete switches that detect only threshold crossings, the system employs continuous analog sensors (discharge pressure sensor, discharge temperature sensor) that provide varying signal levels corresponding to actual parameter values. The processing circuitry then analyzes these continuous parameters and their relationships to derive precise diagnostic information about multiple fault conditions.
Data Source
AI summary
A system and method includes a compressor operable in a refrigeration circuit and including a motor, a current sensor providing a high-side signal indicative of an operating condition of a high-pressure side of the refrigeration circuit, a discharge line temperature sensor providing a low-side signal indicative of an operating condition of a low-pressure side of the refrigeration circuit, and processing circuitry processing the high-side signal and the low-side signal to indirectly determine a non-measured operating parameter of the refrigeration circuit.