Adaptive Power Estimation for Li-Ion Battery Overvoltage Prevention
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Solution Overview
Problem
Existing battery power estimation techniques, particularly for Li-Ion batteries in hybrid systems, fail to accurately account for transient power demands, leading to potential overvoltage and system shutdown due to reliance on lagging indicators like state of charge and temperature, which do not adaptively regulate cell voltage within safe boundaries.
Innovation Solution
A method and system utilizing a feedforward estimator and PID feedback compensator to dynamically adjust power limits based on real-time cell voltage readings, ensuring the battery operates within a predetermined voltage threshold, thereby preventing over-shoot and maintaining efficient hybrid system operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If look-up tables are used to estimate battery available power based on state of charge and temperature, then historical information is provided, but the estimation lags behind transient power demand changes and cannot respond instantaneously
Solution Approach 1:
The feedforward estimator predicts future power limits by anticipating transient power demands before they occur. It uses a dynamic model that forecasts the battery's power capability in advance, allowing the control system to prepare appropriate power limits proactively rather than reactively, thus eliminating the time lag inherent in look-up table approaches.
Solution Approach 2:
The PID feedback compensator continuously monitors actual battery performance and adjusts power limits by comparing predicted values with actual measurements. This closed-loop feedback mechanism corrects deviations in real-time, ensuring accurate power estimation while maintaining rapid response to transient conditions, thereby resolving both accuracy and response time requirements.
2Reliability
If power limits are set conservatively to prevent exceeding working boundaries, then system reliability is improved, but the hybrid system cannot efficiently benefit from the battery's operation during transient periods
Solution Approach 1:
The system dynamically adjusts power limits in real-time based on actual battery conditions and transient demands. Rather than using fixed conservative limits, the feedforward estimator and PID compensator continuously adapt the power limits to match the battery's instantaneous capabilities, allowing maximum efficient operation while maintaining safety boundaries through active regulation.
Solution Approach 2:
The invention changes the parameter of power limits from static conservative values to dynamic values that adapt to transient conditions. By using a dynamic model that adjusts power limits based on real-time battery state and predicted transient demands, the system achieves both high reliability and maximum productivity during transient periods.
3Productivity
If the battery operates at high power output to meet instantaneous demand, then productivity is improved, but the cell voltage may exceed working boundaries causing system shutdown
Solution Approach 1:
The feedforward estimator predicts future power limits before transient demands occur, allowing the control system to set appropriate power limits in advance. This proactive approach enables the battery to operate at high power output when safe, while preventing voltage excursions by establishing protective limits before they become problematic.
Solution Approach 2:
The PID feedback compensator continuously monitors cell voltage and adjusts power limits to maintain operation within working boundaries. This real-time feedback ensures that even during high-power transient periods, the voltage remains within safe limits, preventing system shutdown while maximizing productivity.
Data Source
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AI summary
The present invention provides for a method and computer program product for estimating battery available power from a battery system in relation to a cell voltage, comprising: determining the cell voltage, a power command of the battery system; and a cell voltage threshold. The processes used by the present invention, include a static and a dynamic portion in which cell voltages, cell voltage thresholds and power command are associated and processed using a feed forward estimator and a proportional-integral-derivation (PID) controller to determine the final power command estimation for the requisite battery system.