EV Charging Outlet Contactor Guarding Against Battery Parallel Shorting
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Solution Overview
Problem
Existing electrical vehicle charging systems lack a reliable, cost-effective method to detect welded contactors and prevent short circuits caused by parallel connections of multiple vehicle batteries, which can lead to overloading, overheating, and potential battery explosions.
Innovation Solution
A system with a guarding wire and control device that monitors current flow through parallelization switches and outlet switches, using voltage sources and current sensors to detect unintended connections and trigger a fail-safe state by opening switches if excessive current is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If auxiliary contacts are provided for welding detection, then contactor welding can be detected, but system cost increases
Solution Approach 1:
The system uses its own existing current sensors and control signals to detect contactor welding, without requiring external auxiliary contacts. The control device monitors the control signal current through the contactor coil, and the existing current sensors detect abnormal current patterns that indicate welding, allowing the system to self-diagnose the fault using its own components.
Solution Approach 2:
The system creates a virtual model of normal contactor operation by comparing the actual control signal current waveform against expected patterns. By analyzing the shape, duration, and magnitude of the control signal current, the system can infer the contactor's operational state without physical auxiliary contacts, effectively copying the detection function through signal analysis.
2Reliability
If leakage current measurement is used for welding detection, then welding can be detected, but system complexity and environmental dependency increase
Solution Approach 1:
The invention extracts the welding detection function from complex external measurement systems and integrates it into the existing control circuitry. By monitoring the control signal current that already flows through the contactor coil, the system separates the detection function from the power control function, using the same current path for both purposes without adding separate measurement infrastructure.
Solution Approach 2:
The control signal current serves dual purposes: it activates the contactor coil and simultaneously provides the measurement signal for welding detection. The existing current sensors, originally intended for power monitoring, are also used to detect abnormal current patterns indicating welding, making the system components multi-functional and eliminating the need for separate detection hardware.
3Reliability
If coil inductance measurement is used for welding detection, then welding can be detected, but reliability and simplicity decrease
Solution Approach 1:
The system performs welding detection during the normal energization process of the contactor, before the contactor completes its closing action. By monitoring the control signal current waveform during the coil activation phase, the system can detect welding conditions early in the process, preventing the harmful parallel connection before it fully develops.
Solution Approach 2:
The system continuously monitors the control signal current and provides immediate feedback about contactor status. When the current sensors detect abnormal current patterns indicating welding, the control device receives real-time feedback and can immediately respond by preventing outlet switch closing or alerting operators, creating a closed-loop safety system.
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
Prevents unintended parallel connections by ensuring the system goes into a safe state, avoiding overloading and potential battery explosions, providing a simple and reliable solution for protecting charging infrastructure.
Implementation Method 1
current sensors to detect unintended connections
Data Source
AI summary
A system and method for electrical vehicle charging includes a plurality of outlets, at least one parallelization switch, a guarding wire running in parallel along a DC path formed by outlet switches and at least one parallelization switch and comprising a plurality of outlet guarding switches, a plurality of current sensors, a plurality of voltage sources and at least one parallelization guarding switch, and a control device connected to the current sensors. Each voltage source, current sensor and outlet guarding switch is associated to each one outlet. Each outlet guarding switch is associated to one outlet switch. The control device is configured for opening at least one of the outlet switches and/or the at least one parallelization switch when at least one of the current sensors measures a current greater than zero.