ESS Contactor Welding Detection Through Parallel Relay Paths
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Solution Overview
Problem
Existing methods for checking the welding of a contactor in an energy storage system (ESS) require blocking the flow of current, which is difficult due to the ESS's constant connection to a power grid.
Innovation Solution
A method and device that utilize a first and second relay system with photo couplers to detect welding without interrupting current flow by measuring current through parallel paths and using optical signals to determine relay status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the flow of current is blocked to check whether the contactor is welded, then the welding state can be accurately detected, but the ESS cannot maintain continuous operation and the power grid connection is interrupted
Solution Approach 1:
The contactor is divided into multiple relays (first relay, second relay, third relay) that can be independently controlled. This segmentation allows the system to open only the necessary relay for detection while keeping others closed, enabling welding detection without completely blocking current flow and maintaining continuous operation.
Solution Approach 2:
The system changes the operational state parameters of relays dynamically - opening specific relays for detection purposes while maintaining others in closed state. This parameter change allows the system to achieve welding detection accuracy while preserving continuous current flow through alternative paths, thus maintaining productivity.
2Measurement precision
If the contactor is opened to check for welding, then the welding state can be detected, but the electrical path between battery racks and positive output terminal is interrupted
Solution Approach 1:
The contactor is segmented into multiple independently controllable relays. When detecting welding in one relay, only that specific relay is opened while others remain closed, maintaining electrical path continuity through alternative relays and ensuring system reliability during detection.
Solution Approach 2:
The detection units act as intermediaries that enable welding detection without requiring complete contactor opening. By using detection units to monitor relay states and control individual relays, the system can detect welding while maintaining electrical path continuity through other relays.
3Productivity
If multiple relays are used to enable detection without blocking current, then continuous operation is maintained, but the device complexity increases
Solution Approach 1:
The multiple relays and detection units serve multiple functions: they enable welding detection, maintain continuous current flow, and provide redundant detection capabilities. This multi-functionality justifies the increased device complexity by delivering significant operational benefits.
Solution Approach 2:
The detection units provide continuous feedback on relay welding states, enabling the BSC to make informed decisions about relay operation. This feedback mechanism allows the system to maintain continuous operation while detecting welding, as the feedback information guides the control strategy for multiple relays.
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
Enables reliable and economical welding detection of ESS contactors without disrupting current flow, ensuring efficient operation of the ESS.
Implementation Method 1
the first detection unit includes a first photo coupler, wherein the first photo coupler is connected in parallel with the first relay so that when the first relay is open, current flows to the first photo coupler to emit light
Data Source
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AI summary
The present invention relates a device and method for checking the welding of a contactor of an energy storage system without blocking the flow of current. Specifically, the present invention relates a device and method for checking the welding of a contactor of an energy storage system using a contactor of two relays connected in parallel without blocking the flow of current.