Battery Pack Balancing Bus Control for Cascaded Energy Storage
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Solution Overview
Problem
High-voltage cascaded energy storage systems face limited electric energy balancing capability due to inconsistency among batteries, leading to inefficiencies and reduced capacity utilization, exacerbated by the low balancing current in passive balancing methods.
Innovation Solution
The introduction of a balancing bus connected to each battery pack via direct current/direct current conversion circuits, with a controller managing the energy transfer to achieve higher balancing currents, up to 100 amperes, and improve energy distribution across battery packs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If passive balancing with small balancing current (≤1A) is used, then the system structure is simple, but the electric energy balancing capability is limited and balancing time is excessive
Solution Approach 1:
The patent divides the battery cluster into multiple battery packs, each with independent DC/DC conversion circuits. This segmentation allows each battery pack to be balanced independently through active balancing, enabling much higher balancing currents (up to 100A) compared to passive balancing, thereby significantly improving balancing capability and reducing balancing time.
Solution Approach 2:
The patent introduces a balancing bus as an intermediary component that connects all battery packs. This balancing bus enables active energy transfer between battery packs through DC/DC conversion circuits, allowing high-current balancing while maintaining system modularity. The balancing bus acts as a mediator that facilitates efficient energy redistribution without requiring direct connections between all battery pairs.
2Quantity of substance
If a large quantity of batteries are integrated into one system, then the system capacity increases, but battery inconsistency becomes more prominent and SOH differentiation increases
Solution Approach 1:
The patent segments the large battery cluster into multiple smaller battery packs (e.g., 100 battery packs in the embodiment). Each battery pack is managed independently with its own DC/DC conversion circuit and control unit. This segmentation allows individual monitoring and balancing of each battery pack, preventing the propagation of inconsistency across the entire system while maintaining high overall capacity.
Solution Approach 2:
The patent implements a feedback mechanism where each battery pack's state (SOC, SOH, voltage, current) is continuously monitored by control units. The central controller receives this feedback information and dynamically adjusts the DC/DC conversion to balance energy distribution. This feedback loop enables real-time compensation for battery inconsistency, maintaining system reliability despite the large quantity of batteries.
3Productivity
If passive balancing is used, then the device complexity is low, but the balancing current is too small (≤1A) to effectively balance large capacity batteries (hundreds of Ah)
Solution Approach 1:
The balancing bus serves as an intermediary that enables active balancing between battery packs. By introducing this intermediate component, the system can achieve high balancing currents (up to 100A) through controlled DC/DC conversion, overcoming the limitation of passive balancing while maintaining a manageable system architecture through modular design.
Solution Approach 2:
The patent replaces the passive resistive balancing mechanism with active DC/DC conversion circuits. This substitution transforms the balancing process from a dissipative mechanical-like process (resistor consumption) to an active electrical conversion process, enabling high-current bidirectional energy transfer without excessive heat loss and with precise controllability.
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 solution enhances the electric energy balancing capability, allowing for quicker balancing and reducing the impact of battery inconsistencies, thereby improving the overall efficiency and capacity utilization of the energy storage system.
Implementation Method 1
each battery pack is connected to the balancing bus by using one direct current/direct current conversion circuit
Data Source
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AI summary
This application provides an energy storage system, a balancing control method for an energy storage system, and a photovoltaic power system, and relates to the field of energy storage system technologies. The energy storage system includes a controller and three power conversion branches. Each power conversion branch includes one power conversion circuit, or each power conversion branch includes at least two power conversion circuits connected in series. A second end of each power conversion circuit is connected to at least one battery cluster, each battery cluster includes at least two energy storage modules connected in series, each energy storage module includes one direct current/direct current conversion circuit and one battery pack, an output end of each battery pack is connected to an input end of a corresponding direct current/direct current conversion circuit, and an output end of each direct current/direct current conversion circuit is connected in parallel to a balancing bus. The controller controls each direct current/direct current conversion circuit, so that electric energy of battery packs in the battery cluster is balanced. By using this solution, an electric energy balancing capability of the energy storage system is improved, and impact caused by a Cannikin law of batteries is alleviated.