Battery Pack Contactor Sequencing for Even Disconnection Wear
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Solution Overview
Problem
Energy storage systems in vehicles face premature contactor failure due to excessive electric wear, particularly from electric arcs during the disconnection of battery packs from the load, leading to costly replacements.
Innovation Solution
A method for operating a switching arrangement that sequences the disconnection of battery packs to distribute increased disconnection wear among contactors, ensuring that one contactor is opened last to minimize electric arc formation and wear, thereby extending the life of the switching arrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If battery packs are disconnected simultaneously from the load, then the disconnection process is fast and simple, but all contactors are subject to increased electric wear from electric arcs at the same time, leading to premature contactor failure
Solution Approach 1:
The patent segments the simultaneous disconnection action into sequential operations. Instead of opening all contactors at once, they are opened one after another in a controlled sequence. This segmentation distributes the electric arc wear across different contactors at different times, preventing any single contactor from experiencing excessive wear while maintaining operational efficiency.
2Reliability
If one contactor is opened last to minimize its wear, then that contactor experiences reduced electric wear, but the other contactors still experience increased wear from being opened earlier, creating an uneven wear distribution
Solution Approach 1:
The patent implements periodic action by cycling through different contactors to be opened last in successive disconnection operations. Over multiple operation cycles, each contactor serves as the 'last opened' contactor an equal number of times, ensuring that the increased wear from being opened last is distributed evenly across all contactors. This periodic rotation achieves uniform wear distribution while protecting individual contactors from excessive wear.
3Reliability
If a controlled sequence of disconnection is implemented, then contactor wear is distributed more evenly, but the control system becomes more complex and the disconnection process takes longer
Solution Approach 1:
The patent applies preliminary action by pre-planning and pre-assigning the disconnection sequence before actual disconnection occurs. The control system determines in advance which contactor will be opened last in each disconnection cycle, and this information is stored or memorized. This preliminary determination simplifies the real-time control process, as the sequence is already established before the disconnection operation begins, reducing the complexity of real-time decision-making while achieving even wear distribution.
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 effectively distributes contactor wear, reducing the risk of premature failure and extending the lifespan of the contactors by evenly distributing electric wear across multiple contactors, thus reducing maintenance costs and improving system reliability.
Implementation Method 1
Electric arcs typically appear when the voltage over the air gap exceeds the breakdown voltage of air (3 kV/mm) or when an inductive circuit is broken
Data Source
AI summary
A method for operating a switching arrangement of an energy storage system, 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 and disconnect the battery packs relative a load by closing and opening, respectively. The method comprises disconnecting the battery packs from the load by means of the contactors such that the battery packs are disconnected in a sequence in which one contactor is opened last and thereby subject to increased disconnection wear, controlling the sequence in which the battery packs are disconnected in such a way that the increased disconnection wear is accounted for and used to distribute contactor wear among the contactors during subsequent disconnections of the battery packs from the load.