Battery Pack Contactor Switching with Pre-Disconnect Current Reduction
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Solution Overview
Problem
The existing energy storage systems in vehicles face premature contactor failure due to high electrical wear, leading to increased maintenance costs, as contactors are subjected to mechanical and electrical stress when connecting and disconnecting battery packs from the power apparatus.
Innovation Solution
A method is introduced where the current of a battery pack is actively reduced below a predetermined threshold before disconnection, allowing the contactor to be opened with reduced wear, thereby extending the life of the switching arrangement by minimizing electrical arcs and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If contactors are used to connect and disconnect battery packs from the power apparatus, then the energy storage system can be operated flexibly with individual battery pack management, but the contactors are subjected to mechanical and electrical wear leading to premature failure
Solution Approach 1:
The control system actively reduces the current in a battery pack to below a threshold value before opening its contactor. This preliminary current reduction prevents high-current arcing that would otherwise cause electrical wear and premature contactor failure, thereby extending contactor lifespan while maintaining flexible battery pack management
Solution Approach 2:
The control system acts as an intermediary between the battery pack and contactor operations. It monitors battery pack currents and coordinates current reduction actions before contactor opening, mediating the transition to minimize electrical stress on the contactor while preserving system flexibility
2Speed
If contactors are opened under load to disconnect battery packs, then the disconnection can be performed quickly, but high electrical arcs occur causing severe electric wear
Solution Approach 1:
Before opening the contactor, the control system actively reduces the current in the associated battery pack to below a threshold value. This preliminary action eliminates the need for high-current arc interruption, allowing the contactor to be opened quickly without generating severe electrical arcs or causing significant electric wear
Solution Approach 2:
The control system applies preliminary anti-action by reducing the current that would otherwise cause harmful electrical arcs. By counteracting the potential for high-current arcing before the contactor opens, the system prevents electric wear while maintaining fast disconnection capability
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 method reduces contactor wear, prolongs the life of the switching arrangement, and prevents premature contactor failure by reducing electrical stress during disconnection, thus lowering maintenance costs and improving system efficiency.
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 of a vehicle includesidentifying 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, andin 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.