Vehicle Main Relay Control for Charging Safety
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Solution Overview
Problem
Existing vehicles equipped with power storage devices that can be charged externally face safety issues due to potential adhesion-related closing failures in the charging relay, which may lead to high voltage application from the power storage device to the power receiving connector even when the external charger is not supplying power.
Innovation Solution
Incorporating a control device that determines whether electric power is supplied from the external charger to the power receiving connector during charging, and opening the main relay if no power is supplied, thereby preventing high voltage application to the power receiving connector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the charging relay is closed during charging, then charging function is enabled, but high voltage may be applied to the power receiving connector due to relay adhesion even when external power is not supplied
Solution Approach 1:
The control device continuously monitors whether electric power from the external charger is actually supplied to the power receiving connector during charging. When power supply is detected to be absent despite the charging relay being closed, the control device automatically opens the main relay to prevent high voltage application, thus resolving the contradiction between maintaining charging reliability and preventing harmful high voltage exposure
Solution Approach 2:
The control device acts as an intermediary between the charging relay and the main relay. It monitors the actual power supply status and controls the main relay based on this information, creating a safety layer that prevents direct harmful effects on the power receiving connector while preserving normal charging operation
2Object-affected harmful factors
If the main relay is opened immediately when charging is completed, then safety is improved, but false opening may occur due to relay adhesion without actual power supply issue
Solution Approach 1:
The control device uses feedback from power supply detection to determine when to open the main relay. Instead of opening it immediately upon charging completion, it waits to confirm that power supply has actually stopped, thereby avoiding false openings due to relay adhesion while still preventing high voltage application when power supply truly ceases
Solution Approach 2:
The control device performs preliminary verification of power supply status before opening the main relay. By detecting whether power is actually supplied and confirming the cessation of power flow, it ensures that the main relay is opened only when necessary, preventing premature operation while maintaining safety
Data Source
AI summary
A vehicle comprises a motor configured to output a power for driving; a power storage device configured to supply electric power to the motor; a main relay provided between the motor and the power storage device; a power receiving connector configured to be connectable with a power feed connector of an external charger; and a charging relay connected with the power receiving connector and connected with the power storage device via the main relay. This vehicle further comprises a control device configured to determine whether electric power from the external charger is supplied to the power receiving connector during charging of the power storage device with the electric power from the external charger in closed positions of the main relay and the charging relay and to open the main relay when it is determined that the electric power from the external charger is not supplied to the power receiving connector.