Battery Rack Discharge Switching Without External Load Dependence
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Solution Overview
Problem
Existing energy storage systems (ESS) face safety issues due to continuous high voltage states when the state of charge (SOC) is at the top or discharge is not possible, leading to reduced battery life and swelling phenomena, necessitating an independent discharge solution without reliance on external loads.
Innovation Solution
A battery rack discharging system with a battery management system (BMS) and battery protection unit (BPU) that allows individual discharge by connecting at least two battery racks in parallel, with a BMS determining discharge conditions and controlling the BPU to switch between external and internal loads for independent discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If charging/discharging is performed by an external device (PCS), then the energy storage device can operate in a passive system with centralized control, but the system cannot discharge independently when the external device is unavailable or when the battery rack is overcharged, leading to continuous high voltage states and safety problems
Solution Approach 1:
The patent divides the energy storage system into independent battery rack units, each equipped with its own BMS and discharge circuitry. This segmentation allows each rack to operate independently with autonomous discharge capability, eliminating the mandatory dependence on the external PCS while maintaining system modularity.
Solution Approach 2:
Each battery rack is equipped with self-contained discharge functionality through integrated BMS and internal discharge circuits. The system can perform self-discharge when overcharged or when external PCS is unavailable, providing self-service capability that eliminates the harmful continuous high voltage state without requiring external intervention.
2Adaptability or versatility
If the battery rack is connected to external load through main contactor, then the discharge path is established, but the system cannot switch to internal discharge when external load is unavailable, causing safety issues
Solution Approach 1:
The patent implements dynamic switching between external and internal discharge paths using contactors and control circuits. The system can adaptively change the discharge configuration based on real-time conditions such as external load availability and battery rack charge state, ensuring reliable discharge under various operating scenarios.
Solution Approach 2:
The patent introduces an intermediary internal discharge circuit with associated contactor that acts as a backup discharge path. When the external discharge path through the main contactor is unavailable or when overcharge conditions exist, the intermediary internal discharge path can be activated to safely discharge the battery rack.
3Measurement precision
If the BMS sequentially determines discharge conditions, then the discharge control is precise and safe, but the response time may be increased due to multiple determination steps
Solution Approach 1:
The BMS continuously monitors battery parameters and pre-evaluates discharge conditions before actual discharge is needed. This preliminary action allows the system to be prepared for rapid discharge response while maintaining precise condition checking, as the evaluation process is already underway or completed before critical situations arise.
Solution Approach 2:
The BMS performs continuous monitoring and sequential determination of discharge conditions without interruption. This continuous useful action ensures that all discharge criteria are constantly evaluated, enabling rapid response when discharge is needed while maintaining high precision through uninterrupted measurement and assessment.
Data Source
AI summary
The present invention relates to an individual discharging system and method of a battery rack, and more particularly, to an individual discharging system and method of a battery rack capable of individually discharging a battery rack without dependence on an external load.