Vehicle ESS Power Limits Based on Battery Temperature Rise
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Solution Overview
Problem
Existing energy storage systems in vehicles face challenges in accurately determining operational power levels due to varying battery cell capacities and temperatures, leading to uneven state-of-charge distribution and reduced vehicle performance, especially during high power demand situations.
Innovation Solution
A method that determines the state temperature of the energy storage system, calculates an acceptable temperature increase based on safety and operational life time thresholds, and uses this to determine the maximum operational power level, ensuring reliable and efficient vehicle operation by considering temperature effects on power output and input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the battery is operated with a safety margin in relation to the actual operational SOC level, then the reliability of power supply is improved, but the available energy supply and vehicle range are reduced
Solution Approach 1:
The patent applies dynamics by transitioning from static SOC-based power limits to dynamic temperature-based power limits. The maximum operational power level is continuously adjusted based on real-time temperature measurements and predicted temperature increases, allowing the system to adapt power capability to actual thermal conditions rather than relying on conservative fixed margins
Solution Approach 2:
The patent changes the key parameter for power limitation from state of charge (SOC) to temperature. By determining maximum operational power level based on current temperature and predicted temperature increase rather than SOC levels, the system achieves more accurate and less conservative power capability assessment, resolving the contradiction between reliability and energy availability
2Power
If the battery operates at high power levels, then the vehicle performance is improved, but the temperature increase and risk of exceeding safety thresholds are worsened
Solution Approach 1:
The patent applies preliminary action by predicting future temperature increase before it occurs. The system calculates the predicted temperature increase based on current temperature, environmental conditions, and requested power level, then uses this prediction to proactively limit the maximum operational power level to prevent exceeding safety thresholds
Solution Approach 2:
The patent implements feedback by continuously monitoring current temperature, calculating predicted temperature increase, and adjusting the maximum operational power level accordingly. This closed-loop control ensures that power delivery is continuously adapted to thermal conditions, preventing temperature excursions while maximizing power capability
3Productivity
If the state of charge distribution across battery cells becomes uneven, then the operational performance of the battery is limited, but continuing to operate with uneven distribution accelerates aging and reduces battery life
Solution Approach 1:
The patent changes the control parameter from SOC-based limits to temperature-based limits. This allows the battery management system to operate at higher power levels without unnecessarily restricting performance due to conservative SOC margins, thereby maintaining operational performance while preventing conditions that would accelerate aging
Data Source
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AI summary
The invention relates to a method for determining an operational parameter indicative of the power capability of an energy storage system (ESS) of a vehicle, wherein the method comprises the steps of determining a state temperature of the ESS;determining an acceptable temperature increase of the ESS for a given time period based on the determined state temperature of the ESS and a maximum temperature threshold of ESS, the maximum temperature threshold being indicative of any one of a safety temperature level of the ESS and an operational life time temperature level of the ESS; and determining a maximum operational power level of the ESS for the given time period based on the determined acceptable temperature increase of the ESS.