Refrigeration Apparatus Motor Current Monitoring for Defrost Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing refrigeration apparatuses face inefficiencies due to wasteful and inefficient defrosting methods that do not account for actual ice buildup, leading to increased energy consumption and reduced motor lifespan.
Innovation Solution
A refrigeration apparatus equipped with ambient and inner temperature sensors, a motor current controller, and a dynamic control system that adjusts the operation of the electric motor and initiates a defrost procedure based on the difference between ambient and internal temperatures, as well as changes in motor current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If periodic heating is used to prevent ice build-up, then ice prevention is achieved, but energy consumption increases and efficiency decreases
Solution Approach 1:
The system continuously monitors motor current and compares it against reference values to detect ice build-up conditions. This feedback mechanism allows the system to initiate defrosting only when ice is detected, rather than using periodic heating regardless of actual ice conditions, thereby reducing unnecessary energy consumption while maintaining reliable ice prevention.
Solution Approach 2:
The system uses the motor's own current characteristics as an indicator of ice build-up conditions. By monitoring changes in motor current that occur when ice forms on evaporator surfaces, the system can self-diagnose ice conditions and trigger defrosting only when needed, eliminating the need for separate sensors or continuous heating.
2Reliability
If periodic heating is used to melt ice, then ice build-up is prevented, but the process becomes wasteful and inefficient
Solution Approach 1:
The system employs feedback control by continuously monitoring motor current and comparing it to reference values. When the current deviation exceeds a threshold, indicating ice build-up, the system initiates defrosting. This ensures energy is only consumed when actually needed to prevent ice build-up, eliminating wasteful periodic heating.
Solution Approach 2:
The system dynamically adjusts its operation based on real-time motor current measurements. Rather than using fixed periodic heating, the defrosting timing and duration are dynamically determined by actual ice conditions detected through motor current analysis, optimizing energy efficiency while maintaining reliable ice prevention.
3Duration of action of moving object
If continuous operation monitoring is implemented, then motor lifespan is extended, but system complexity increases
Solution Approach 1:
The system uses feedback control by continuously monitoring motor current and comparing it against reference values. This relatively simple feedback mechanism provides continuous operation monitoring that extends motor lifespan by enabling timely defrosting operations, while avoiding the need for complex sensor arrays or sophisticated control algorithms.
Solution Approach 2:
The motor current serves as an intermediary parameter that indirectly indicates both ice build-up conditions and motor operational status. By using this single intermediary measurement, the system achieves multiple monitoring functions (ice detection and motor health monitoring) without increasing device complexity, thereby extending motor lifespan through simple, efficient monitoring.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables dynamic control of the refrigeration apparatus, optimizing energy use by only initiating defrost when necessary, thereby extending the lifespan of the electric motor and improving overall efficiency.
Implementation Method 1
an ambient temperature sensor for measuring ambient temperature in the neighbourhood of the refrigeration apparatus
Implementation Method 2
at least one inner temperature sensor for measuring a temperature of the interior of the refrigeration apparatus
Implementation Method 3
a compressor for compressing vaporised refrigerant
Implementation Method 4
an electric motor for driving operation of the compressor
Data Source
AI summary
A refrigeration apparatus (10) has one or more chambers (12′, 12″) in which items to be cooled can be located. A compressor (20 driven by an electric motor (22) compresses vaporised refrigerant as part of a refrigeration cycle. The refrigeration apparatus (10) has an ambient temperature sensor (34) for measuring ambient temperature and at least one inner temperature sensor (36, 38) for measuring a temperature of the interior of the refrigeration apparatus (10). A controller (40) receives outputs from temperature sensors (34, 36, 38). The controller (40) obtains measures of a motor current of the electric motor (22) at time intervals which are based on the ambient temperature and the inner temperature. Based on the measures of the motor current at the time intervals, the controller (40) at least one of (ii) controls operation of the electric motor (22) and (ii) initiates defrost procedure for the refrigeration apparatus (10).