EV Refrigerant Charge Detection Using Suction Pressure and Speed
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional low refrigerant charge protection systems in refrigeration systems of electrified vehicles fail to detect low refrigerant charge early enough, leading to insufficient cooling of traction batteries and other components, due to reliance on high-pressure sensors and delayed detection.
Innovation Solution
A system and method that utilize a controller to detect low refrigerant charge by combining suction pressure, compressor speed, and ambient temperature, implementing variable thresholds and speed adjustments to accurately identify low refrigerant levels and prevent damage, using sensors for suction pressure, compressor speed, and ambient temperature to initiate corrective actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional high-pressure sensor-based detection is used, then the system structure is simple, but the detection timing is delayed and detection accuracy is insufficient
Solution Approach 1:
The patent combines suction pressure sensor data, compressor speed sensor data, and ambient temperature sensor data into a unified detection system. The controller integrates these multiple parameters to detect low refrigerant charge conditions, achieving more accurate detection than single-parameter systems while maintaining reasonable system complexity through the use of existing sensors in the refrigeration system.
Solution Approach 2:
The patent changes the detection parameters from relying solely on high-pressure sensor readings to using a combination of suction pressure, compressor speed, and ambient temperature parameters. This parameter transformation enables earlier and more accurate detection of low refrigerant charge conditions by monitoring how these parameters change in relation to each other during system operation.
2Reliability
If early detection of low refrigerant charge is implemented, then cooling protection is improved, but detection complexity increases
Solution Approach 1:
The system performs preliminary detection of low refrigerant charge conditions by continuously monitoring suction pressure, compressor speed, and ambient temperature before actual cooling failures occur. The controller compares real-time parameter values against predetermined thresholds to identify early signs of refrigerant charge problems, enabling preventive action before the cooling system becomes unreliable.
Solution Approach 2:
The patent implements a feedback mechanism where the controller continuously monitors the relationship between suction pressure, compressor speed, and ambient temperature, and adjusts its detection decisions based on how these parameters interact. This feedback approach improves reliability by confirming low refrigerant charge conditions through multiple correlated parameter changes rather than relying on a single sensor reading.
3Measurement precision
If variable thresholds based on ambient temperature and compressor speed are used, then detection accuracy is improved, but control complexity increases
Solution Approach 1:
The patent implements dynamic detection thresholds that automatically adjust based on ambient temperature and compressor speed conditions. Rather than using fixed pressure thresholds, the system calculates variable thresholds that account for how suction pressure naturally varies with operating conditions. This dynamic approach maintains high detection precision while the controller automatically manages the complexity of threshold adjustments.
Data Source
AI summary
A system and method for protecting against low refrigerant charge of a refrigerant subsystem in a vehicle includes a controller configured to control a component of the vehicle in response to detecting a low refrigerant charge based on an ambient temperature of the refrigerant subsystem, a suction pressure of refrigerant entering a compressor of the refrigerant subsystem, and a speed of the compressor.