Contactor Weld Check Using Open-Circuit Voltage Measurement
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Solution Overview
Problem
Welding of contacts in contactors due to high power arcs or excessive currents during switching operations leads to operational failures in electrical energy storage systems, particularly in vehicles, causing unnecessary downtime and wear.
Innovation Solution
A computer system with processing circuitry performs a weld test by measuring voltages across open contactors to determine if welding has occurred, using voltage criteria to identify welded contacts without requiring active control or closure of the contactors, thereby reducing testing time and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional weld testing methods are used requiring contactor closing and opening operations, then welding detection can be performed, but testing time increases and contactor wear increases
Solution Approach 1:
The patent performs weld detection by measuring voltages across open contactors before any closing operation occurs. The control circuit measures voltages at multiple points (V1, V2, V3, V4) while contactors remain open, calculates contactor voltages (Vcontactor1 = V2 - V4, Vcontactor2 = (V1 - V2) - (V3 - V4)), and evaluates welding conditions immediately without requiring the contactors to close and open. This preliminary measurement approach detects welding in the open state, eliminating the need for active switching operations during testing.
2Reliability
If traditional weld testing methods are used requiring contactor closing and opening operations, then welding detection can be performed, but contactor wear increases
Solution Approach 1:
The patent performs weld detection by measuring voltages across open contactors before any closing operation occurs. The control circuit measures voltages at multiple points (V1, V2, V3, V4) while contactors remain open, calculates contactor voltages (Vcontactor1 = V2 - V4, Vcontactor2 = (V1 - V2) - (V3 - V4)), and evaluates welding conditions immediately without requiring the contactors to close and open. This preliminary measurement approach detects welding in the open state, eliminating the need for active switching operations during testing.
3Duration of action of stationary object
If voltage measurements are taken across open contactors without active control, then contactor wear is reduced, but the testing method must be sufficiently simple and robust
Solution Approach 1:
The patent replaces mechanical switching operations with electrical voltage measurements to detect welding. Instead of mechanically closing and opening contactors to test for welding, the control circuit electrically measures voltages at four different points (V1, V2, V3, V4) across the open contactors, calculates the voltage drop across each contactor using these measurements, and determines welding conditions based on whether the calculated voltages fall below a threshold. This electrical measurement approach substitutes for mechanical operation while maintaining detection reliability.
Data Source
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AI summary
A computer system (100) comprising processing circuitry (106) configured to: request opening of a positive contactor (102) and a negative contactor (104), acquire measurements of a first voltage (v1), a second voltage (v2), a third voltage (v3), and a fourth voltage (v4) between a positive pole (124) and a negative pole (126), and ground, calculate a first contactor voltage (Vcontactor1) across one of the negative contactor (104) and the positive contactor (102) and a second contactor voltage (Vcontactor2) across the other one of the negative contactor (104) and the positive contactor (102), determine that one or more of the positive contactor (102) and the negative contactor (104) is welded when the respective one of the first contactor voltage (Vcontactor1) and the second contactor voltage (Vcontactor2) fulfill the voltage criterion.