Parallel Battery Relay Contact Welding Detection
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Solution Overview
Problem
In power-supply systems with multiple batteries connected in parallel, existing methods cannot effectively detect contact welding in main relays, leading to the need for replacing all relays if any one suffers from contact welding.
Innovation Solution
A control apparatus that performs a battery charge/discharge process to identify which main relay is experiencing contact welding by comparing the state of charge of batteries connected in series with each main relay, using a controller to turn on one relay while turning off others and analyzing the voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple batteries are connected in parallel to increase total battery capacity, then the battery capacity increases, but it becomes impossible to detect contact welding in main relays using existing methods
Solution Approach 1:
The detection process is segmented into multiple sequential steps: first turning off the target main relay, then performing battery charge/discharge processes, and finally identifying contact welding based on voltage changes. This segmentation allows detection in parallel battery systems where simultaneous operation of all relays masks individual relay faults.
Solution Approach 2:
The target main relay is turned off before performing the battery charge/discharge process. This preliminary action isolates the target relay's circuit, enabling subsequent voltage measurements to specifically reflect the state of the target relay rather than the combined state of all parallel relays.
2Reliability
If all main relays are replaced when contact welding is suspected in parallel battery systems, then reliability is maintained, but cost and complexity increase significantly
Solution Approach 1:
The mechanical replacement of all main relays is replaced with an electrical detection system. The controller performs voltage measurements and analyzes charge/discharge characteristics to electrically identify which specific relay has contact welding, substituting physical replacement with intelligent detection and targeted replacement.
Solution Approach 2:
The system performs self-diagnosis by automatically detecting contact welding in main relays through voltage measurements during battery charge/discharge processes. The controller identifies the faulty relay without external intervention, enabling targeted maintenance rather than blanket replacement of all relays.
3Ease of operation
If existing detection methods are used in parallel battery systems, then system operation is simple, but contact welding cannot be accurately detected
Solution Approach 1:
The system uses feedback from voltage measurements during battery charge/discharge processes to determine the state of main relays. The controller monitors voltage changes and uses this feedback information to identify contact welding, maintaining operational simplicity while achieving accurate detection through intelligent analysis of system responses.
Data Source
AI summary
A control apparatus is used for a power-supply apparatus with power-supply systems connected in parallel between a pair of power wires connected to a load. Each power-supply system has a series circuit of a battery and a contact of a relay. When the control apparatus determines that at least one relay suffers from a contact welding, the control apparatus performs a battery charge/discharge process to charge/discharge the batteries through the pair of power wires by turning ON one of possible relays while turning OFF the others of the possible relays. The possible relay is defined as having a possibility of suffering from the contact welding. After the battery charge/discharge process, the control apparatus identifies which possible relay actually suffers from the contact welding based on a change in a state of the battery connected in series with the contact of each possible relay.