Dynamic Discharge Voltage Control for High Impedance Batteries
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Solution Overview
Problem
As batteries age, they develop high internal resistance, leading to nonmonotonic charge or discharge voltage evolution, which restricts the utilization of electrochemical cell capacity due to a minimum discharge voltage threshold.
Innovation Solution
An electrochemical battery system with a processor and voltage limiting circuit that dynamically adjusts discharge voltages to maintain them above a threshold, utilizing a zener circuit to manage discharge and prevent cell reversal, thereby extending the discharge cycle and utilizing more cell capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high constant current discharge is applied to an aged battery with high internal resistance, then power delivery capability is maintained, but voltage becomes nonmonotonic and cell capacity utilization is restricted
Solution Approach 1:
The patent implements dynamic adjustment of discharge current based on real-time voltage monitoring. The controller modifies the discharge current profile during the discharge cycle to maintain monotonic voltage evolution while maximizing capacity utilization. This dynamic control allows the system to adapt to the battery's aging state and internal resistance changes, resolving the contradiction between maintaining power delivery and utilizing full cell capacity.
Solution Approach 2:
The patent changes the discharge current parameter from a constant high value to a variable profile that adjusts based on voltage feedback. By modifying the current parameter dynamically during discharge, the system maintains monotonic voltage evolution while extracting maximum capacity from aged batteries with high internal resistance, thus resolving the contradiction between power delivery and capacity utilization.
2Reliability
If discharge voltage is maintained above a minimum threshold to prevent cell reversal, then battery reliability is improved, but discharge cycle duration is reduced due to premature termination
Solution Approach 1:
The patent dynamically adjusts the discharge voltage threshold based on the battery's state of charge and aging characteristics. Rather than using a fixed minimum voltage threshold that causes premature termination, the controller adapts the threshold in real-time, allowing the discharge cycle to extend closer to the true capacity limits while maintaining reliability by preventing cell reversal. This dynamic threshold adjustment resolves the contradiction between reliability and discharge duration.
Solution Approach 2:
The patent implements a feedback control mechanism that continuously monitors discharge voltage and adjusts the discharge profile accordingly. The feedback loop prevents voltage from dropping to levels that would cause cell reversal while allowing maximum discharge duration. This feedback-based control resolves the contradiction by maintaining reliability constraints without unnecessarily limiting discharge cycle length.
3Stability of the object's composition
If internal resistance increases with battery aging, then voltage stability during discharge is maintained, but voltage drop increases and nonmonotonic voltage evolution occurs
Solution Approach 1:
The patent implements dynamic current adjustment during discharge to compensate for increased internal resistance. The controller modifies the discharge current profile in real-time based on voltage monitoring, preventing the nonmonotonic voltage evolution that occurs with constant high current discharge in aged batteries. This dynamic control maintains voltage stability while ensuring monotonic voltage evolution, resolving the contradiction between voltage stability and ease of operation.
Solution Approach 2:
The patent changes the discharge current parameter from constant to variable, adapting the current profile to account for increased internal resistance in aged batteries. By adjusting the current parameter dynamically during discharge, the system maintains monotonic voltage evolution and prevents nonmonotonic behavior, thus resolving the contradiction between voltage stability and operational simplicity.
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 increased access to electrochemical cell capacity by maintaining discharge voltages above a predetermined threshold, even as internal resistance changes, ensuring efficient power delivery and extended battery life.
Implementation Method 1
Batteries are a useful source of stored energy
Implementation Method 2
The power dissipated by the electrochemical cell due to internal resistance is a significant contributor to the temperature of the cell
Implementation Method 3
utilizing a zener circuit to manage discharge and prevent cell reversal
Data Source
AI summary
An electrochemical battery system in one embodiment includes a first electrochemical cell, a memory in which command instructions are stored, and a processor configured to execute the command instructions during a discharge cycle of the first electrochemical cell to (i) establish a first discharge voltage of the first electrochemical cell based upon a first sensed discharge voltage, and (ii) permit a second discharge voltage of the first electrochemical cell after establishing the first discharge voltage, wherein the second discharge voltage is greater than the first discharge voltage.