Battery Cell Voltage Measurement for Active Balancing
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Solution Overview
Problem
Conventional energy storage systems face challenges in continuous battery cell balancing, especially in scenarios with limited idle periods, as existing methods require accurate open circuit voltage (Voc) estimation during active operation, which is computationally complex and not feasible for cost-effective battery cell level estimation.
Innovation Solution
An energy storage system with a battery management unit and controller that starts idle and steady condition timers to measure voltages, calculates total resistance, and estimates open circuit voltage, enabling efficient battery cell balancing, state-of-charge, and health prediction with reduced computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If extended Kalman filter or ARX modeling is used to estimate battery cell open circuit voltage during active operation, then continuous battery cell balancing capability is achieved, but computational complexity increases significantly making it infeasible for cost-effective implementation
Solution Approach 1:
The patent replaces complex computational models (EKF, ARX) with a simpler, more computationally efficient approach that uses basic voltage measurements and timer-based idle condition detection. This simpler estimation method is analogous to using a disposable, low-cost solution that achieves the required function without the overhead of expensive, complex computational resources.
Solution Approach 2:
The patent extracts the essential function of Voc estimation from complex computational models and implements it through a simplified method that only requires measuring battery cell voltage during idle conditions and using timer-based logic to determine when idle conditions exist. This extraction removes the computational burden while retaining the core functionality needed for continuous cell balancing.
2Measurement precision
If battery cell balancing is performed only during idle periods using traditional methods, then Voc measurement is easier to obtain, but balancing adequacy is insufficient for systems without long idle periods
Solution Approach 1:
The patent implements a dynamic balancing approach that adapts to the operational state of the battery system. By using timers to detect idle conditions and dynamically switching between idle-period balancing and active-period balancing modes, the system maintains Voc measurement accuracy while ensuring continuous balancing adequacy regardless of idle period duration.
Solution Approach 2:
The patent ensures continuous balancing action by implementing logic that operates during both idle and active periods. The system continuously monitors battery cell voltages and performs balancing operations whenever voltage differences exceed thresholds, eliminating gaps in balancing protection that would occur with idle-period-only approaches.
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 effective battery cell balancing and health prediction during active operation, extending battery life and ensuring safer operation by providing accurate estimates of battery cell energy and state, even in systems with limited idle periods.
Implementation Method 1
calculate a total resistance of the battery cell, and calculate an open circuit voltage of the battery cell using the total resistance
Data Source
AI summary
An energy storage system is provided and comprises a battery management unit; a controller configured to start an idle condition timer, measure a voltage of a battery cell of a battery connected to the battery management unit while the battery is idle, after the idle condition timer has expired, start a steady condition timer, measure the voltage of the battery cell while the battery is on, after the steady condition timer has expired, calculate a total resistance of the battery cell, and calculate an open circuit voltage of the battery cell using the total resistance.