Parallel Battery Junction Box to Prevent Energy Dumping
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Solution Overview
Problem
Existing high-energy battery packs, such as lithium iron phosphate (LiFePO4) battery packs, face issues with parallel connection due to varying voltage and power levels, leading to energy dumping and requiring system shutdown for battery exchange, disrupting power to the load.
Innovation Solution
A modular, scalable energy storage system with a junction box allowing parallel connection of energy sources, featuring active or passive current sharing, and protection circuitry to prevent unwanted current flow, enabling continuous power delivery and independent charging of depleted batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If battery packs are connected in parallel to achieve continuous power delivery, then system availability is improved, but energy dumping occurs from higher state of charge packs to lower state of charge packs
Solution Approach 1:
The patent introduces a junction box as an intermediary device between parallel-connected battery packs. This junction box includes a control circuit that monitors the state of charge of each battery pack and actively manages current distribution. The control circuit prevents energy dumping by detecting voltage differences and controlling the connection state of internal relays, thereby eliminating the harmful energy transfer while maintaining parallel operation for continuous power delivery.
2Loss of energy
If series connection of battery packs is used to avoid energy dumping, then energy loss is reduced, but the entire system must be shut down when one pack is depleted
Solution Approach 1:
The patent segments the battery system into multiple independent battery packs that can operate autonomously. Each pack has its own protection circuitry and can be independently connected or disconnected via the junction box. This segmentation allows one pack to be depleted and disconnected without affecting the operation of other packs, enabling continuous power delivery while avoiding the energy loss associated with parallel connection.
3Reliability
If parallel operation of battery packs is implemented, then continuous energy delivery is enabled, but device complexity increases due to need for current sharing management
Solution Approach 1:
The patent combines multiple functions into a single junction box device. The junction box integrates the battery management system, protection circuitry, current sharing control, and connection management all in one unit. This merging approach simplifies the overall system architecture by centralizing control functions, reducing the number of separate components needed, and providing a unified interface for managing parallel battery pack operations.
Data Source
AI summary
An energy storage system is provided, including: a plurality of energy storage devices, wherein each energy storage device includes an energy source; a junction unit for connecting the plurality of the energy storage devices in parallel to a common power bus, the junction unit including a control circuit; a power conversion unit coupled to the common power bus; and protection circuitry coupled to the control circuit for preventing current from one of the energy storage devices from flowing to another of the energy storage devices.