Battery String Switching Sequences to Limit Inrush Current
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Solution Overview
Problem
The increasing complexity of battery systems leads to wear and tear on battery cells and switches due to inrush currents when connecting or disconnecting strings with different energy storage levels, necessitating a controlled sequence for connection and disconnection to extend their useful life.
Innovation Solution
A battery control system with electrically controllable switches and a controller that manages the connection and disconnection of strings based on states of charge, charge capacities, electric currents, and polarities to minimize inrush currents, using precharging sequences and diodes to reduce wear and tear on components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If strings of battery cells with different energy storage levels are connected simultaneously, then the battery system achieves higher power output, but inrush currents damage switches and battery cells over time
Solution Approach 1:
The system performs preliminary actions by pre-charging the conductive bus before connecting battery strings with different energy levels. The controller charges the bus to a predetermined voltage level prior to connection, which prevents inrush currents from damaging switches and battery cells while still enabling high power output when multiple strings are connected.
2Adaptability or versatility
If switches are closed to connect battery cells with different voltages, then the battery system achieves greater flexibility in energy distribution, but inrush currents increase wear and tear on switches and cells
Solution Approach 1:
The conductive bus serves as an intermediary element between battery strings with different voltages. Instead of directly connecting strings with different energy levels (which causes inrush currents), the system uses the bus as a mediator that can be pre-charged to match voltage levels, thereby enabling flexible energy distribution without damaging switches or cells.
3Device complexity
If battery strings are connected without sequence control, then the system structure remains simple, but switches and battery cells suffer from increased wear and tear
Solution Approach 1:
The controller monitors the voltage levels of the conductive bus and battery strings, using feedback signals to determine when to close or open switches. This feedback mechanism enables sequence-controlled connections that extend switch and cell lifespan while maintaining relatively simple system architecture through automated control based on real-time electrical conditions.
Data Source
AI summary
A battery control system and method selectively connect battery strings to one or more conductive buses by plural electrically controllable switches. The switches are controlled to one or more of (a) connect the strings with one or more of the load or the power source via the one or more conductive buses in a first sequence and/or (b) disconnect the strings from one or more of the load or the power source via the one or more conductive buses in a second sequence. The first sequence and the second sequence are based on one or more of states of charge between the strings, different charge capacities between the strings, different electric currents conducted through the strings, different polarities of the electric currents conducted through the strings, and/or a speed of a vehicle that is powered by the one or more loads.