Hybrid Vehicle Current Sensor Fault Detection via SoC Error
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Solution Overview
Problem
Current sensor faults in hybrid vehicles are difficult to detect when the sensor output is within a normal operating range, leading to reduced fuel economy, drivability, and increased emissions, as traditional methods rely on out-of-range conditions to identify faults.
Innovation Solution
A current sensor fault detection strategy that monitors the change in battery state of charge error by comparing two different calculations, one based on integrating battery current and another on open-circuit voltage, allowing for fault detection within a normal operating range and enabling adjustments to the electric machine's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional fault detection methods are used that rely on out-of-range conditions, then fault detection is simple, but fault detection capability is lost when sensor output is within normal operating range
Solution Approach 1:
The patent introduces an intermediary verification mechanism using a second calculation method (voltage-based SoC estimation) to validate the current sensor's measurements. This intermediary approach allows indirect verification of sensor accuracy without requiring out-of-range conditions, resolving the contradiction by enabling reliable fault detection within normal operating ranges through cross-validation.
Solution Approach 2:
The system implements feedback by continuously comparing two independent calculations of state of charge (one from current integration, one from voltage measurement) and using this comparison to detect sensor faults. This feedback loop enables ongoing validation of sensor accuracy, maintaining reliability without requiring complex additional hardware.
2Productivity
If current sensor faults are not detected within normal operating range, then vehicle operation continues normally, but fuel economy decreases and emissions increase
Solution Approach 1:
The patent applies preliminary action by detecting and addressing current sensor faults before they significantly impact vehicle performance and emissions. By continuously monitoring the consistency between current-based and voltage-based state of charge calculations, the system can identify and correct sensor drift early, preventing the accumulation of errors that would lead to reduced fuel economy and increased emissions.
3Reliability
If the system continuously monitors and compares state of charge calculations to detect faults, then fault detection reliability improves, but computational load increases
Solution Approach 1:
The system implements partial monitoring by focusing computational resources on comparing specific key parameters (state of charge calculations from two methods) rather than continuously analyzing all sensor data. This selective approach maintains high detection reliability while minimizing unnecessary computational energy consumption, applying monitoring intensity only where fault indicators are most likely to appear.
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
Enables reliable detection of current sensor faults even when outputs are within normal ranges, improving vehicle fuel economy, drivability, and reducing emissions by allowing for timely adjustments in battery operation.
Implementation Method 1
a first change in battery state of charge calculated by integrating battery current with respect to a time
Implementation Method 2
a second change in battery state of charge calculated based on the battery open circuit voltage during the time
Data Source
AI summary
A current sensor fault detection system is disclosed which enables detection of a current sensor fault while the current sensor is operating and providing a current sensor output which is within a normal operating range. The current sensor is monitored by at least one controller which compares a change in battery state of charge error with a predetermined threshold. The change in battery state of charge error is a difference between a first change in battery state of charge calculated by integrating battery current with respect to a time and a second change in battery state of charge calculated based on the battery open circuit voltage during the time.