Battery Contactor Reclosing with Pre-Charge After Unintended Opening
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Solution Overview
Problem
The existing contactor management systems in electric vehicles face damage due to unintentional opening, leading to overcurrent issues when the driving voltage fluctuates, necessitating a method to determine whether to maintain the open state or re-close the main contactor based on the vehicle's operating state and driving signal.
Innovation Solution
A battery system with a main contactor and a pre-charge contactor, where a controller determines the state of the main contactor using a voltage measurer and applies the appropriate driving signal to manage the contactor's operation, closing the main contactor after pre-charging with the pre-charge contactor when the vehicle is in a driving mode and maintaining an open state when in a parking mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the main contactor is automatically re-closed after unintentional opening, then the electrical connection between battery and external device is restored, but the contactor may be damaged by overcurrent when DC-link load is large
Solution Approach 1:
The pre-charge contactor is activated before closing the main contactor to pre-charge the DC-link capacitor, reducing the inrush current when the main contactor closes. This preliminary action prevents overcurrent damage while ensuring reliable electrical connection restoration.
Solution Approach 2:
The pre-charge contactor serves as an intermediary component that mediates between the battery and the main contactor. It provides a controlled path for initial current flow, protecting the main contactor from direct exposure to high inrush current during re-closing operations.
2Productivity
If the main contactor is kept closed to maintain power supply, then the vehicle operation is continuous, but the contactor cannot be protected from damage during unintentional opening events
Solution Approach 1:
The control unit continuously monitors the contactor state and voltage fluctuations, providing feedback to detect unintentional opening events. Based on this feedback, the system determines whether to activate the pre-charge contactor before re-closing the main contactor, balancing operational continuity with contactor protection.
Solution Approach 2:
The system dynamically adjusts the contactor control strategy based on real-time operating conditions. When unintentional opening is detected, the system transitions to a protected re-closing mode using the pre-charge contactor, while maintaining normal closed-state operation for continuous vehicle performance.
3Strength
If a pre-charge contactor is added to protect the main contactor, then overcurrent damage is prevented, but the device complexity increases
Solution Approach 1:
The pre-charge contactor serves multiple functions: it pre-charges the DC-link capacitor, limits inrush current to the main contactor, and provides a protection mechanism during unintentional opening events. This multi-functionality justifies the added component by providing comprehensive contactor protection through a single additional element.
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 solution prevents damage to the main contactor by managing the contactor's state effectively, reducing the risk of overcurrent and ensuring safe operation in both driving and parking modes.
Implementation Method 1
a voltage measurer measuring an operation voltage supplied to the main contactor
Implementation Method 2
closing the main contactor after closing the pre-charge contactor
Data Source
AI summary
Disclosed is a contactor management method and a battery system providing the same, and the battery system includes: a main contactor connected between a battery pack and an external device; a pre-charge contactor connected to the main contactor; a voltage measurer measuring an operation voltage supplied to the main contactor; and a controller determining an open event of the main contactor based on a change of the operation voltage measured by the voltage measurer, wherein the controller, when the open event occurs, determines the level of the driving signal that controls the operation voltage to be applied to the main contactor in the driving mode in which the vehicle is running, and when the level of the driving signal is an enable level, closes the main contactor after closing the pre-charge contactor and opens the pre-charge contactor after a predetermined time is elapsed in the state that the main contactor is closed.