Battery Pack Contactor Control for Current Limiting
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Solution Overview
Problem
Battery packs face challenges in managing current limits effectively, leading to potential degradation due to over-current conditions, which existing hardware and software solutions struggle to address without cumbersome access or precise external control.
Innovation Solution
A method that uses a contactor to electrically decouple the battery pack from external circuits when integrated current exceeds a threshold, allowing for dynamic adjustment of threshold levels based on operating conditions, thereby reducing degradation without relying on hardware fuses or external controllers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hardware fuses are used to limit current flow, then battery pack degradation is limited, but accessing the battery pack to replace a blown fuse is cumbersome
Solution Approach 1:
The patent replaces the mechanical hardware fuse system with an electronic control system using a contactor. The controller monitors battery current and opens the contactor when over-current conditions are detected, eliminating the need for physical fuse replacement and enabling remote or automated protection.
Solution Approach 2:
The battery pack system performs self-protection by monitoring its own current output and automatically opening the contactor when degradation or over-current conditions are detected, without requiring external intervention or manual fuse replacement.
2Productivity
If external controllers are used to manage battery current limits, then current control is achieved, but the load or source may not have the capacity to precisely follow battery limits during transient operation
Solution Approach 1:
The patent introduces a dedicated battery pack controller as an intermediary between the battery and the load/source. This controller directly monitors battery current and controls the contactor based on real-time battery conditions, providing precise control that bridges the gap between battery capabilities and external load demands.
3Reliability
If fixed current limits are imposed on the battery pack, then hardware protection is provided, but the degree of current limits cannot adapt to varying operating conditions including duration of over-current conditions
Solution Approach 1:
The patent implements dynamic current limiting where the controller continuously monitors battery current and adjusts the contactor state based on real-time conditions. The system can tolerate temporary over-current conditions by integrating current over time and only opening the contactor when the integrated value exceeds a threshold, allowing adaptation to varying operating conditions rather than using fixed rigid limits.
Solution Approach 2:
The patent changes the control parameter from a simple fixed current threshold to an integrated current value over time. This allows the system to differentiate between brief over-current spikes and sustained over-current conditions, adjusting protection behavior based on the duration and magnitude of current excursions.
Data Source
AI summary
Systems and methods for controlling the output of a battery pack are disclosed. In one example, a battery pack contactor is opened in response to battery pack current. The system and method may reduce battery pack degradation and increase system flexibility.