Transport refrigeration apparatus
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Solution Overview
Problem
Container refrigeration apparatuses face difficulties in accurately determining motor abnormalities due to variations in supply voltage and frequency, leading to erroneous detection of lock and connection abnormalities.
Innovation Solution
A transport refrigeration apparatus with a threshold changer that adjusts current thresholds based on supply frequency and voltage to accurately determine motor abnormalities in fan motors, using a combination of detectors to monitor current values and differentiate between lock and connection abnormalities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fixed current thresholds are used for motor abnormality detection, then the detection method is simple, but the accuracy of determination deteriorates due to variations in supply voltage and frequency
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the current threshold based on supply voltage and frequency parameters. The threshold changer modifies the threshold value according to the detected power supply conditions, ensuring accurate abnormality detection across different operating environments without requiring complex additional hardware
Solution Approach 2:
The system implements feedback by using the power supply detector to continuously monitor voltage and frequency, then feeding this information to the threshold changer which adjusts the current threshold accordingly. This closed-loop feedback mechanism maintains detection accuracy despite variations in power supply conditions
2Measurement precision
If separate detectors are used for fan motor and compressor motor, then detection accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies universality by making the compressor motor detector serve multiple functions: it detects both compressor motor current and fan motor current. By detecting the total current and subtracting the compressor motor current component, the system obtains fan motor current without requiring a separate detector, thus reducing device complexity while maintaining detection accuracy
Solution Approach 2:
The system merges the detection function for both motors into a single detector unit. The compressor motor detector is combined with calculation logic to simultaneously monitor both motor currents, eliminating the need for separate physical detectors and reducing overall system complexity
Data Source
AI summary
According to the present disclosure, in a container refrigeration apparatus configured to cool the inside of a container, the accuracy of determination of occurrence of a lock abnormality and a connection abnormality of a motor is increased, and erroneous detection of the motor abnormalities is reduced or prevented. The container refrigeration apparatus of the present disclosure includes an abnormality determinator configured to compare a value for current flowing through an in-compartment motor with a preset current threshold to determine occurrence of the motor abnormalities of the in-compartment motor, and a threshold changer configured to change the current threshold of the abnormality determinator in accordance with a supply voltage for each supply frequency of a power supply configured to supply power to the in-compartment motor.