Battery Temperature Estimation for Vehicle Power Derating
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Solution Overview
Problem
Existing vehicle battery management systems struggle to accurately estimate internal battery cell temperatures, leading to inefficient power management and potential overheating, as surface temperature measurements do not reliably reflect internal cell conditions.
Innovation Solution
A system that uses a temperature sensor to measure surface temperatures and calculates internal cell bulk temperature through a compensation method, incorporating parameters like current output and a delay filter to adjust power output and cooling measures based on estimated internal temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If surface temperature measurements are used to monitor battery cell temperature, then the measurement system is simple and easy to implement, but the temperature measurement precision is insufficient because surface temperature does not reliably reflect internal cell conditions
Solution Approach 1:
The patent uses surface temperature as an intermediary measurement to infer internal cell temperature. Instead of directly measuring internal temperature (which would require complex internal sensors), the system measures surface temperature and uses it as a mediator to estimate internal conditions through thermal modeling and compensation algorithms.
Solution Approach 2:
The patent replaces physical internal temperature sensors with a computational model that substitutes mechanical/physical measurement with mathematical processing. The system uses thermal diffusion models and signal processing algorithms to substitute for direct internal measurement, reducing hardware complexity while improving measurement accuracy.
2Reliability
If power output is continuously adjusted based on real-time temperature monitoring, then battery performance and safety are improved, but energy loss increases due to frequent power adjustments and cooling requirements
Solution Approach 1:
The patent applies preliminary action by proactively adjusting power output before critical temperature thresholds are reached. The system uses predictive thermal modeling to anticipate temperature rises and pre-adjusts power levels, preventing overheating before it occurs and reducing the need for aggressive cooling interventions.
Solution Approach 2:
The system implements periodic monitoring and adjustment cycles rather than continuous control. By using delayed timers and periodic sampling of temperature data, the system makes adjustments at optimal intervals, reducing unnecessary power modulation while maintaining safety margins.
3Measurement precision
If delayed timers and filters are used to process temperature data, then the temperature estimation accuracy is improved by accounting for thermal lag, but the response time to detect and react to temperature changes is reduced
Solution Approach 1:
The system performs preliminary thermal modeling and lag compensation in advance. By pre-calculating thermal diffusion characteristics and storing compensation factors, the system can apply corrections without real-time computational delays, maintaining both accuracy and responsiveness.
Solution Approach 2:
The patent implements dynamic adjustment of filter parameters and delay times based on operating conditions. The system adapts its processing characteristics in real-time, using shorter delays during high-stress conditions and longer delays during normal operation, optimizing the balance between accuracy and response time.
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
This approach allows for more accurate temperature estimation and effective power management, reducing the risk of overheating and improving battery performance by adjusting power output and cooling strategies based on calculated internal cell temperatures.
Implementation Method 1
a temperature sensor located at a surface of one of the cells to measure a surface temperature
Implementation Method 2
The data is based on the surface temperature and a cell heating power parameter derived from a plurality of parameters and via a delay timer and a filter
Data Source
AI summary
A vehicle includes a battery, a motor, and one or more controllers. The controllers, responsive to data indicative of an internal cell temperature of one or more cells of the battery exceeding a threshold, decrease power output from the battery to the motor. The data is based on a surface temperature of at least one of the cells and a cell heating power parameter derived from a plurality of parameters and via a delay timer and a filter.