EV Quick-Charge Protection Circuit for Relay Double Welding
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Solution Overview
Problem
Existing electric vehicle systems fail to ensure reliable protection of the battery when a double welding failure occurs in the relay circuit, leading to potential risks such as difficulty in disconnecting the power supply and possible electric shock.
Innovation Solution
The system includes a third protection circuit on the power supply line capable of disconnecting both positive and negative lines, a detection section to identify double welding, and a control section to manage power disconnection based on detection results, ensuring safe operation by preventing power supply when double welding is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the control apparatus does not configure disconnection capability for double welding state, then the system structure remains simple, but battery protection cannot be ensured when double welding occurs
Solution Approach 1:
The detection section detects welding failures in advance before they can cause battery damage. The system identifies when both the first and second relay circuits have welding failures, and the control section proactively controls the third relay circuit to disconnect the battery from the power supply line, preventing potential battery damage from double welding conditions.
Solution Approach 2:
The third relay circuit acts as an intermediary backup mechanism. When the first and second relay circuits both fail due to welding, the third relay circuit serves as a mediator to disconnect the battery, providing an additional layer of protection without requiring complex control logic for normal operation.
Data Source
AI summary
An electric vehicle includes: a third power supply line that supplies power from a quick charger placed outside the vehicle body to a battery, a positive-side line being on an upstream side of a current flowing from the quick charger to the battery, a negative-side line being on a downstream side the current flowing from the quick charger to the battery; a third protection circuit that is capable of cutting off the power via the third power supply line by electrically disconnecting the positive-side line and/or the negative-side line; and a control section that executes control for electrically disconnecting between the battery and the third power supply line when determining, based on a detection result of a third detection section, that the third protection circuit is in a state where each of the positive-side line and the negative-side line is not disconnectable.