EV Charging Relay Hold Control for Low-Voltage Battery Recovery
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Solution Overview
Problem
In electric vehicles, the dedicated charging relay configuration prevents high-voltage battery charging when the battery voltage drops below a certain threshold, leading to reduced durability and ineffective charging.
Innovation Solution
The charger is arranged in parallel with the electric-power control device, and a control apparatus maintains the relay in a closed state for a predetermined time after connection to an external power source, ensuring the high-voltage battery can be charged by inhibiting the relay from switching to an open state until charging begins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the charger is disposed on an electric path that is connected to and disconnected from the high-voltage battery by switching of the main relay, then the device complexity is reduced by eliminating the dedicated charging relay, but the reliability of battery charging is worsened when battery voltage drops below the threshold
Solution Approach 1:
The patent segments the charging control function from the main relay control by introducing a charging control device that independently manages the charging relay. This allows the charging system to operate autonomously when voltage drops occur, preventing the main relay from disconnecting the charging path while maintaining battery protection through dedicated voltage monitoring and control.
2Strength
If the main relay is switched to the open state when battery voltage drops below the threshold, then the battery cell durability is protected from further voltage drop, but the charging process is interrupted and the voltage cannot be recovered
Solution Approach 1:
The patent introduces a charging relay as an intermediary component that mediates between the main relay and the charging system. When voltage drops occur, the charging control device can independently control the charging relay to maintain or resume charging operations without affecting the main relay state, thus protecting battery durability while ensuring charging completion through layered relay control architecture.
Data Source
AI summary
An electric vehicle including a charger configured to charge a high-voltage battery with an electric power supplied from an external power source. The charger is disposed on an electric path that is to be connected to and disconnected from the high-voltage battery by switching of a relay. When the high-voltage battery is to be charged by the charger, a control apparatus executes a charging-start-stage control by which a closed state of the relay is maintained until a predetermined time elapses after the relay is switched to the closed state in response to connection of the external power source, wherein the predetermined time is predetermined as a period in which the charger actually starts charging the high-voltage battery and a voltage of battery cells included in the high-voltage battery is increased.