EV Charging Relay Welding Diagnosis via Voltage Differential
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Solution Overview
Problem
Electric vehicle charging controllers face challenges in diagnosing relay welding and preventing over-discharge of batteries, which can lead to relay malfunction and safety hazards.
Innovation Solution
An electric vehicle charging controller with sensors to measure voltage differences across the relay and a control unit that determines relay malfunction by applying a low voltage to the high voltage line, allowing for quick relay shutdown and preventing over-discharge by communicating with the vehicle's ECU and EVSE.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a relay is used to interrupt EV battery current during charging, then charging control is enabled, but the relay may weld due to overcurrent, causing battery over-discharge and potential battery failure
Solution Approach 1:
The patent applies preliminary action by performing a relay welding diagnosis test before normal charging operations begin. The control unit measures voltage across the relay in a high-voltage state and compares it to a reference voltage to detect welding conditions in advance, preventing potential battery damage before it occurs.
Solution Approach 2:
The patent uses voltage measurement as an intermediary indicator to indirectly detect relay welding. Instead of directly detecting the welding condition, the system measures the voltage across the relay terminals and uses this intermediate electrical parameter to infer the relay's operational state, enabling safe charging control.
2Difficulty of detecting and measuring
If voltage measurement is performed to diagnose relay welding, then relay malfunction detection is enabled, but additional sensors and control complexity are required
Solution Approach 1:
The patent applies universality by using the existing voltage measurement capability of the EV charging controller to serve multiple functions: both normal charging control and relay welding diagnosis. The same control unit and voltage sensing circuitry used for charging management are also utilized for relay health monitoring, eliminating the need for separate dedicated diagnostic hardware.
Solution Approach 2:
The system performs self-diagnosis by using its own built-in voltage measurement resources to detect relay welding conditions. The control unit leverages the existing voltage sensing infrastructure already present in the charging system to monitor relay health, making the system self-sufficient for diagnostic purposes without requiring external specialized equipment.
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 easy diagnosis of relay welding and prevention of over-discharge, ensuring safe and efficient charging operations by quickly identifying and addressing relay malfunctions.
Implementation Method 1
a first sensor configured to measure a second voltage value between a first battery having a first voltage value and a relay in a high voltage line
Implementation Method 2
a second sensor configured to measure a third voltage value between the electric vehicle supply equipment and the relay in the high voltage line
Data Source
AI summary
An electric vehicle charging controller according to an embodiment comprises: a first sensor for measuring a second voltage value between a first battery having a first voltage value and a relay in a high voltage line connected to electric vehicle charging equipment; a second sensor for measuring a third voltage value between the electric vehicle charging equipment and the relay in the high voltage line; and a control unit for controlling on/off of the relay, wherein if a difference between the second voltage value and the third voltage value is less than a preset fourth voltage value when the control unit applies a second battery voltage between the relay and the electric vehicle charging equipment in the high voltage line after controlling the relay to be turned off, the control unit determines that an operation of the relay is abnormal.