Parallel Battery Module Voltage Control via Switching
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Solution Overview
Problem
In electric storage systems, the voltage differential between modules connected in parallel can cause significant current flow, leading to deterioration or damage of lithium-ion batteries, especially with decreasing impedance, making module replacement challenging and time-consuming.
Innovation Solution
The electric storage system includes a system control unit that allows each module to switch its connection relationship with the wire based on a control signal, enabling modules to be replaced without precise voltage adjustment, by disconnecting the module before connection to prevent current flow during voltage differential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If modules are connected in parallel to increase system capacity, then system power output is improved, but voltage differential causes significant current flow leading to battery deterioration
Solution Approach 1:
The patent implements dynamic control of module connections through switching elements (transistors or relays) that adjust the connection state of each module based on real-time voltage differential detection. This dynamic approach allows the system to maintain parallel connection for high power output while preventing harmful current flow by disconnecting modules with excessive voltage differences, thus resolving the contradiction between system power and battery durability.
2Reliability
If voltage adjustment is performed before module replacement, then battery damage risk is reduced, but replacement time and complexity increase
Solution Approach 1:
The system performs preliminary voltage differential detection and comparison before module connection through the switching element. This preliminary action identifies modules with excessive voltage differences and prevents their connection, eliminating the need for time-consuming voltage adjustment procedures during module replacement while still protecting against battery damage.
Solution Approach 2:
The switching element acts as an intermediary between the module and the parallel connection, mediating the connection based on voltage differential conditions. This intermediary controls whether the module is connected or disconnected, providing automatic protection without requiring manual voltage adjustment, thus reducing replacement time while maintaining reliability.
3Power
If impedance decreases to improve efficiency, then power output increases, but current flow from voltage differential becomes more significant
Solution Approach 1:
The patent implements a feedback mechanism where the detection unit continuously monitors voltage differentials between modules and provides this information to the control unit. The control unit uses this feedback to dynamically control the switching element, opening the circuit when voltage differential exceeds the threshold. This feedback loop allows the system to maintain low impedance for high efficiency while automatically preventing harmful current flow conditions.
Data Source
AI summary
An electric storage system to which a first electric storage device and a second electric storage device connected in parallel can be mounted decides a rated voltage of the first electric storage device in an electric storage system having at least one of (A) a discharge standby stage and (B) a charge standby stage. It decides a large and small relationship between the rated voltage of the electric storage device for which at least one of (i) an accumulated time, (ii) an accumulated power amount, and (iii) an accumulated number is decided to be made higher among the first electric storage device and the second electric storage device, and the rated voltage of the other electric storage device. It decides the rated voltage of the first electric storage device such that the large and small relationship decided in the large and small relationship deciding step is achieved.