Battery Pack Contactor Switching to Minimize Disconnect Arcing
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Solution Overview
Problem
The existing energy storage systems in vehicles face premature contactor failure due to high electrical wear, particularly when disconnecting battery packs from the power apparatus, leading to increased maintenance costs and reduced system lifespan.
Innovation Solution
A method for operating a switching arrangement that involves identifying a battery pack to disconnect, reducing its current below a predetermined threshold before opening the associated contactor, thereby minimizing electrical wear and extending the contactor's lifespan by reducing arcing and inductive effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the contactor is opened under load to disconnect the battery pack, then the disconnection operation is completed quickly, but the electric wear of the contactor increases significantly
Solution Approach 1:
The control unit identifies a battery pack to be disconnected and actively reduces its current output to below a threshold value before the contactor is opened. This preliminary current reduction ensures that when the contactor switches, the low current minimizes electric wear and prevents harmful arcs, thereby extending contactor lifespan while maintaining efficient disconnection operation.
2Reliability
If the current of the battery pack is reduced before disconnection, then the electric wear of the contactor is minimized, but the disconnection process takes longer
Solution Approach 1:
The system proactively reduces current before the disconnection event, accepting a brief time extension as a necessary trade-off to prevent contactor failure. This preliminary action is performed only when needed, optimizing the balance between time and reliability.
Solution Approach 2:
The control unit dynamically changes the current parameter from its normal operating level to a reduced threshold level before disconnection. This parameter change is controlled and time-bound, minimizing the time penalty while ensuring contactor protection.
3Power
If multiple battery packs are connected in parallel to meet higher power requirements, then the power capability of the energy storage system increases, but the complexity of managing individual contactor disconnections increases
Solution Approach 1:
The control unit implements a universal disconnection strategy that works for any number of parallel battery packs. The same current reduction and sequencing logic applies regardless of system size, making the solution scalable and reducing operational complexity despite increased power capability.
Solution Approach 2:
The system uses current threshold parameters to automatically determine disconnection sequencing and timing. By relying on parameter-based control rather than complex hardwired logic, the system manages multiple contactors efficiently as the system scales.
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 approach reduces contactor wear and prolongs the life of the switching arrangement by minimizing electrical wear during disconnection, thereby reducing the likelihood of premature contactor failure and overall maintenance costs.
Implementation Method 1
Electric arcs typically appear when the voltage over the air gap exceeds the breakdown voltage of air (3kV/mm) or when an inductive circuit is broken
Implementation Method 2
when an inductive circuit is broken since an inductor opposes a change of the current through it
Data Source
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AI summary
A method for operating a switching arrangement of an energy storage system of a vehicle, the energy storage system comprising a plurality of parallelly arranged battery packs and the switching arrangement comprising an associated contactor for each battery pack, the contactors being configured to connect the battery packs to a power apparatus being a load and/or a power source by closing, and disconnect the battery packs from the power apparatus by opening. The method comprises: - identifying a battery pack to be disconnected from the power apparatus, the battery pack being one of a plurality of battery packs connected to the power apparatus, - providing measured current of the identified battery pack, - in response to that that the measured current of the identified battery pack is higher than a predetermined threshold value, reducing the current of the identified battery pack, and - in response to that the measured current of the identified battery pack is lower than the predetermined threshold value, or in response to that a predetermined time period has lapsed since the step of reducing the current of the identified battery pack, opening the contactor associated with the identified battery pack to disconnect the battery pack from the power apparatus.