EV Thermal Management Controller Fault Detection Logic
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Solution Overview
Problem
Previous thermal management systems for electrified vehicles fail to accurately identify faults in the electric air conditioning compressor and pressure sensors, leading to incorrect deactivation and impact on high-voltage battery and cabin cooling.
Innovation Solution
A vehicle thermal management system with a controller programmed to monitor compressor operation, detect pressure sensor faults, and perform system checks to identify faults in the electric air conditioning compressor and refrigerant levels, using timers and pressure differentials to determine operational states and power outputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the system monitors eAC compressor operation and pressure sensor readings continuously, then fault detection capability is improved, but system complexity and false fault indications increase
Solution Approach 1:
The fault detection system is segmented into distinct monitoring modes: a first mode that activates system checks only after the eAC compressor has been off for a predetermined time period, and a second mode that operates continuously. This segmentation reduces false fault indications by avoiding monitoring during transient operational states while maintaining reliability through targeted checks.
Solution Approach 2:
The system performs preliminary actions by waiting for the eAC compressor to be off for a predetermined time period before initiating system checks. This preliminary waiting period ensures the system is in a stable, at-rest state before monitoring begins, preventing false fault detections that would occur during dynamic operation transitions.
2Loss of time
If the system performs system checks during eAC compressor operation transitions, then fault detection speed is improved, but false fault indications increase
Solution Approach 1:
The monitoring system dynamically adjusts its operation based on eAC compressor state. System checks are enabled only when the compressor has been off for a predetermined time period, and disabled during operational transitions. This dynamic adjustment prevents false fault indications during transient states while maintaining rapid fault detection capability when the system is stable.
3Productivity
If the system deactivates eAC compressor based on pressure sensor readings, then cooling performance is improved, but incorrect deactivation occurs due to sensor faults
Solution Approach 1:
The system implements feedback mechanisms where system checks monitor pressure sensor readings and eAC compressor operation status. When the compressor is in an at-rest state (off for predetermined time period), the system checks pressure differential and power output to determine if the pressure sensor is faulty. This feedback loop prevents incorrect deactivation by verifying sensor accuracy before acting on pressure readings.
Solution Approach 2:
The system applies preliminary anti-action by performing system checks to detect pressure sensor faults before they cause incorrect eAC compressor deactivation. The predetermined time period requirement ensures the compressor is truly at rest before checks occur, preventing false fault detection that would lead to unnecessary compressor shutdown and impact cooling performance.
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
Accurately identifies and addresses faults in the thermal management system, ensuring effective thermal management of the high-voltage battery and vehicle cabin by differentiating between operational states and faults, preventing incorrect deactivation and maintaining optimal cooling performance.
Implementation Method 1
The chiller selectively thermally links the circuits
Implementation Method 2
an electric air conditioning (eAC) compressor to move refrigerant throughout the second thermal loop
Implementation Method 3
a pressure sensor to monitor refrigerant pressure
Implementation Method 4
calculation of an eAC compressor power output being less than a predetermined power threshold
Data Source
AI summary
A vehicle thermal management system including a refrigerant circuit, a coolant circuit, a chiller, and a controller is provided. The refrigerant circuit may include an electric air conditioning (eAC) compressor and a pressure sensor. The coolant circuit may include a high-voltage battery. The chiller selectively thermally links the circuits. The controller may be programmed to, responsive to receipt of a sensor signal indicating refrigerant pressure exiting the eAC compressor is greater than a high threshold, output a pressure sensor fault error indicating the pressure sensor is faulty. The system may further include a timer to monitor operational timing of the eAC compressor. The controller may be further programmed to direct the system to operate without monitoring the eAC compressor responsive to the timer indicating the eAC compressor has been off for a time-period less than a time threshold reflective of the eAC compressor not being in an at rest state.