Adaptive SoC Window Control for Aging ESS Usable Energy
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Solution Overview
Problem
Existing Energy Storage Systems (ESS) face challenges in maintaining optimal usable energy delivery due to aging battery packs, leading to inefficient energy utilization and accelerated aging, particularly in vehicles like trucks and buses, where fixed SoC windows fail to adapt to changing battery health.
Innovation Solution
An adaptive SoC window control strategy iteratively adjusts the SoC window limits by predefined amounts to match the target usable energy, minimizing abrupt changes and errors, ensuring consistent energy delivery throughout the ESS's lifetime while avoiding under/overcharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the SoC window is fixed, then the control strategy is simple and stable, but the usable energy delivery deteriorates as battery packs age
Solution Approach 1:
The SoC window is transformed from a fixed static value to a dynamic adaptive value that automatically adjusts based on battery aging state. The control unit iteratively adapts the SoC window based on actual usable energy delivery and battery health status, allowing the system to maintain optimal performance throughout the battery's lifecycle without manual intervention.
Solution Approach 2:
The system changes the parameters of the SoC window (upper and lower limits) based on battery aging characteristics and actual performance. By monitoring the difference between target and actual usable energy, the system dynamically adjusts the SoC window parameters to compensate for capacity fade and impedance increase, ensuring consistent energy delivery from beginning-of-life to end-of-life.
2Reliability
If the SoC window is adapted aggressively to compensate for aging, then usable energy is maintained, but abrupt changes occur that are noticeable to users
Solution Approach 1:
The system applies partial adaptation by limiting the maximum adjustment amount of the SoC window in each iteration. Instead of making full compensatory adjustments that would cause abrupt changes, the system makes gradual incremental adjustments that stay below user perception thresholds while still achieving the goal of maintaining consistent usable energy delivery over time.
3Measurement precision
If large instantaneous changes are made to the SoC window, then errors in input parameters are propagated directly, but robustness against errors is reduced
Solution Approach 1:
The system implements error cushioning by limiting the maximum adjustment amount of the SoC window in each iteration. This pre-set constraint prevents large instantaneous changes that would amplify input parameter errors, thereby protecting the system against robustness issues while still allowing gradual convergence to the optimal SoC window that maintains accurate usable energy delivery.
Data Source
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AI summary
A computer system (200) for adapting a State-of-Charge (SoC) window of an Energy Storage System (ESS) is provided, including processing circuitry (210) configured to: obtain a target usable energy value for an ESS (220), and improve a matching between i) the target usable energy value and ii) a current usable energy value of the ESS in accordance with a SoC window for the ESS, by iteratively adapting the SoC window for the ESS over a plurality of iteration steps, wherein the processing circuitry is further configured to, for each iteration step, update the SoC window for the ESS with no more than a predefined maximum amount. A corresponding electric vehicle including the ESS and computer system and computer-implemented method for iteratively adapting the SoC window of the ESS are also provided.