Adjustable Tap Location for Energy Storage Cell Voltage Balancing
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Solution Overview
Problem
Energy storage systems face issues with voltage differences between battery strings due to cell failures, leading to overvoltage and reduced cell life, as a failed cell can cause a string to operate at a lower voltage, affecting the entire system.
Innovation Solution
An energy storage system with selectively adjustable tap locations, where control devices monitor voltage changes and adjust the number of cells providing power to balance open circuit voltages among strings, either by activating reserve cells or de-activating cells in parallel strings to maintain voltage similarity within 0.5%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If battery strings are connected in parallel with fixed tap locations, then the system can operate continuously, but voltage differences between strings cause overvoltage and reduced cell life when cells fail
Solution Approach 1:
The patent implements dynamically adjustable tap locations that can be reconfigured based on real-time cell voltage monitoring. When a cell fails or voltage imbalances are detected, the control system automatically adjusts the tap locations to redistribute voltage across the battery strings, preventing overvoltage conditions and extending cell life while maintaining continuous operation.
Solution Approach 2:
The system changes the electrical parameters (tap locations) of the battery strings in response to detected voltage imbalances or cell failures. By adjusting which cells are included in each string's voltage contribution to the parallel connection, the system optimizes voltage distribution and prevents harmful overvoltage conditions that would reduce cell life.
2Reliability
If a cell fails short in a battery string, then the string can continue operating, but voltage differences create overvoltage in other strings
Solution Approach 1:
The patent employs a feedback control system that continuously monitors cell voltages and detects failures or imbalances. When a cell fails short, the system receives feedback about the voltage change and automatically adjusts the tap locations of affected and unaffected strings to maintain balanced voltage distribution, preventing overvoltage conditions in strings without failures.
Solution Approach 2:
The system converts the harmful effect of cell failure into a manageable condition by using the detected voltage imbalance as a trigger for tap location adjustment. The control system leverages the feedback from the failed cell to reconfigure the battery strings, transforming the potential harm of overvoltage into an opportunity to optimize overall system voltage balance and reliability.
3Device complexity
If tap locations are fixed, then the system structure is simple, but voltage balancing among strings cannot be achieved when cell failures occur
Solution Approach 1:
The patent transitions from fixed to dynamically adjustable tap locations controlled by a microcontroller or control system. This dynamic capability allows the system to maintain voltage balance among parallel strings even when cell failures occur, significantly improving reliability without adding excessive complexity through automated control logic and monitoring.
Solution Approach 2:
The control system performs multiple functions: monitoring cell voltages, detecting failures, calculating optimal tap locations, and executing adjustments. This multi-functional approach consolidates what could be multiple separate systems into a single integrated control unit, managing the complexity while achieving superior voltage balancing and reliability.
Data Source
AI summary
Systems and methods for controlling a tap location associated with a string of an energy storage system are provided. In one embodiment, an energy storage system can include one or more strings. Each of the one or more strings can include a plurality of energy storage cells coupled in series. Each of the one or more strings can be associated with a selectively adjustable tap location to control the number of cells in the string that provide power to a power system. The energy storage system can further include a one or more control devices that can be configured to detect a change in a voltage associated with one or more of the one or more strings. The one or more control devices can be configured to adjust the tap location for at least one of the one or more strings in response to the change in the voltage.