Battery Over-Discharge Detection Using Temperature Rate of Change
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Solution Overview
Problem
Hybrid-electric vehicles face challenges in accurately detecting traction battery over discharge conditions, which can lead to irreversible damage and capacity deterioration, often due to errors in cell voltage measurement and state of charge estimation, resulting in false positive alerts and potential system shutdowns.
Innovation Solution
A system and method that utilize a controller to issue an over discharge alert and open contactors based on a battery temperature rate of change and state of charge exceeding predefined thresholds, integrating battery voltage and temperature data to prevent false positives and reduce discharge power to zero before disconnecting the traction battery from the load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If battery over discharge detection is based on cell voltage measurement and state of charge estimation, then the detection system is simple to implement, but false positive alerts occur due to measurement errors
Solution Approach 1:
The patent combines multiple detection parameters (cell voltage, state of charge, and temperature rate of change) into a unified over-discharge detection system. By merging these different measurement approaches, the system cross-validates readings and reduces false positives caused by individual measurement errors, thereby improving detection reliability without requiring overly complex individual sensors
Solution Approach 2:
The patent introduces temperature rate of change as an intermediary parameter to validate over-discharge conditions. Instead of relying directly on voltage measurements alone, the system uses temperature changes as a mediator to confirm whether actual over-discharge is occurring, filtering out false alerts caused by voltage measurement anomalies
2Reliability
If contactors are opened immediately upon detecting over discharge condition, then battery damage is prevented, but unnecessary system shutdowns occur due to false positives
Solution Approach 1:
The patent applies preliminary anti-action by using temperature rate of change as a pre-validation check before triggering the over-discharge protection response. The system anticipates false positives from voltage measurements and counteracts them by requiring temperature data to confirm the condition, preventing unnecessary contactor opening and system shutdowns
Solution Approach 2:
The system uses feedback from multiple sensors (voltage, state of charge, and temperature) to continuously monitor battery conditions. By feeding back temperature rate of change data into the detection algorithm, the system can distinguish between actual over-discharge events and measurement anomalies, ensuring contactors are only opened when truly necessary and maintaining system availability
3Measurement precision
If multi-parameter detection approach is used to reduce false positives, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent implements multi-functionality by having the battery management system perform multiple functions: voltage measurement, state of charge estimation, and temperature monitoring all within the same detection framework. This universal approach allows the system to use existing sensors for multiple purposes, improving detection accuracy without proportionally increasing device complexity
Solution Approach 2:
The patent changes the detection parameter from static voltage thresholds to dynamic temperature rate of change measurements. This parameter change allows the system to adapt to varying battery conditions and distinguish between normal operation and actual over-discharge, improving measurement precision while using standard temperature sensors already present in most battery systems
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
Effectively reduces instances of false positive over discharge indications, minimizes battery damage, and prevents unnecessary system shutdowns by using a multi-parameter approach to detect over discharge conditions, ensuring accurate and timely intervention.
Implementation Method 1
A battery management system that detects an over discharge condition of a traction battery may be based on a rate of change of temperature of the battery
Implementation Method 2
opening the contactors may cause the traction battery to be disconnected from a high voltage bus thereby powering down the hybrid electrified vehicle
Data Source
AI summary
A system includes contactors electrically connecting a traction battery and a vehicle bus when closed, and a controller configured to issue an over discharge alert and open the contactors responsive to a battery temperature rate of change, measured during battery discharge and while a battery state of charge (SOC) exceeds a first threshold, being greater than a predefined rate.