Battery Pack Bypass Control for Series ESS Charge Balancing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In energy storage systems using electrochemical cells, unbalanced states of health (SOH) and state of charge (SOC) among battery packs connected in series lead to inefficiencies, where a battery pack with higher remaining electricity cannot be fully discharged, and one with lower cannot be fully charged, limiting the current and causing waste.
Innovation Solution
An energy storage system with a controller that manages bypass circuits for each battery pack, balancing electricity quantities by bypassing packs with higher or lower SOC values, allowing remaining packs to operate at maximum current, thereby maintaining consistent cluster current and extending backup duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple battery packs are connected in series to form a battery cluster with high voltage and large capacity, then the backup capacity and voltage level requirement are improved, but the electricity quantity of battery packs becomes unbalanced, limiting the current and causing waste
Solution Approach 1:
The battery cluster is divided into multiple independently controllable battery packs, each with its own bypass circuit. This segmentation allows individual battery packs to be managed separately, enabling the controller to bypass specific packs that have reached their charge or discharge limits while keeping others active, thus preventing current limitation and waste.
Solution Approach 2:
The bypass circuits are pre-configured for each battery pack, allowing the system to proactively bypass packs before they become bottlenecks. The controller monitors the state of charge and state of health of each pack and activates bypass circuits in advance when necessary, ensuring continuous optimal current flow through the battery cluster.
2Stress or pressure
If multiple battery packs are connected in series to form a battery cluster, then the voltage level requirement is improved, but the electricity quantity of battery packs becomes unbalanced, leading to waste of electricity quantity
Solution Approach 1:
The battery cluster is segmented into independently controllable battery packs with individual bypass circuits. This allows the system to maintain the required high voltage through series connection while preventing energy waste by bypassing packs that have reached their charge or discharge limits, allowing other packs to continue operating at full capacity.
Solution Approach 2:
Battery packs that have reached their charge or discharge limits are extracted from the active circuit through bypass circuits. This removes the bottleneck packs from the current path, allowing the remaining packs to operate without limitation and preventing energy waste that would occur if the entire cluster's current was constrained by a single depleted pack.
3Quantity of substance
If battery packs with different states of health and original states of charge are connected in series, then the battery cluster can achieve high voltage and large capacity, but the current must be limited based on the minimum current of individual battery packs
Solution Approach 1:
The battery cluster is divided into independently controllable segments (battery packs) with individual bypass circuits. This segmentation allows the controller to selectively bypass packs that have reached their charge or discharge limits, enabling the remaining active packs to operate at their maximum current capacity rather than being constrained by the minimum current of all packs.
Solution Approach 2:
The bypass circuits provide dynamic reconfiguration capability, allowing the battery cluster's effective composition to change in real-time. As battery packs reach different states of charge or health thresholds, the controller dynamically activates or deactivates bypass circuits to optimize current flow, transforming a static series connection into a dynamically adaptable system.
Data Source
AI summary
In accordance with an embodiment, and energy storage system includes a battery cluster, a power conversion circuit, and a controller. An output end of the battery cluster is connected to a first terminal of the power conversion circuit, and a second terminal of the power conversion circuit is connected to an output end of the energy storage system. Each battery cluster includes at least two energy storage modules connected in series, each energy storage module includes one bypass circuit and one battery pack, and each battery pack includes a plurality of batteries. The controller controls each bypass circuit based on a first parameter value of each battery pack, so that electricity quantities of battery packs are balanced.