Contactor Coil Vibration for Releasing Welded Contacts
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Solution Overview
Problem
In electrified vehicles, contactor contacts can weld closed due to operating conditions, leading to temporary inoperability if not addressed, as high currents cause melting and sticking, disrupting the electrical connection between the traction battery pack and other powertrain components.
Innovation Solution
A contactor system with a controller that commands vibrations by repeatedly alternating the energization and de-energization of a coil to mechanically shock the contacts, dislodging welds and maintaining vehicle operability through a weld release control strategy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contactor is left closed due to welding, then the electrical connection is maintained, but the vehicle becomes inoperable and requires immediate servicing
Solution Approach 1:
The system applies mechanical vibration to the contactor contacts through the coil assembly to dislodge welded contacts. The coil is energized and de-energized repeatedly to create vibratory motion that mechanically shocks the contacts apart, resolving the welding issue and restoring normal operation without requiring vehicle servicing.
Solution Approach 2:
The controller implements periodic energization and de-energization of the coil to create repeated mechanical shocks. This periodic action continues for a predetermined number of cycles or until the weld is released, allowing the system to systematically work through the problem of welded contacts over time rather than requiring immediate intervention.
2Ease of operation
If the coil is repeatedly energized and de-energized to release welds, then the contactor can be freed, but the system complexity increases
Solution Approach 1:
The system uses the existing coil and armature assembly to service itself by generating the mechanical vibration needed to release welds. The same components that normally close the contactor are used to create the freeing action, eliminating the need for separate vibration generation hardware and simplifying the overall system architecture.
3Reliability
If the contactor remains closed due to welding, then electrical connectivity is maintained, but safety risks increase
Solution Approach 1:
The controller monitors the status of the contactor and detects when welding occurs. Based on this feedback, the controller automatically initiates the weld release sequence by periodically energizing and de-energizing the coil. After the release attempt, the controller continues to monitor to confirm the contactor has been successfully freed or requires further action, ensuring safety through continuous feedback.
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
The system effectively releases welded contacts by applying mechanical shocks, ensuring continued vehicle operation without immediate servicing needs, thereby maintaining the vehicle's electrical connectivity and functionality.
Implementation Method 1
a coil...repeatedly alternating between energizing and de-energizing the coil of the contactor to apply the vibration...moves the armature shaft to apply the vibration
Data Source
AI summary
Systems and methods are provided for releasing welded-shut contactors of a contactor system. An exemplary contactor system may include a contactor and a controller. The controller may be programmed to command a vibration across portions of the contactor as part of a weld release control strategy when the contactor is welded closed. The vibration may be achieved by repeatedly alternating between energizing and de-energizing a coil of the contactor in order to mechanically shock/vibrate a welded contact of the contactor.