Pre-Charge Relay Circuit Structure for Arc-Free Main Relay Switching
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Solution Overview
Problem
Conventional circuit structures in vehicles with high-voltage batteries face issues with arc formation due to large current flow, necessitating large and costly uniquely structured electromagnetic contactors, which increase size and cost.
Innovation Solution
A circuit structure incorporating a main relay, a pre-charge circuit with a pre-charge resistor and relay, and a sub relay connected in parallel, where the sub relay is turned on before the main relay is turned off to prevent potential differences and arcs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniquely structured electromagnetic contactor is employed to eliminate arcs, then arc elimination is achieved, but the size of the sealing container and electromagnetic contactor increases
Solution Approach 1:
The circuit is segmented into multiple relay units (first relay unit and second relay unit) that operate independently. Each relay unit handles a portion of the circuit protection function, allowing the system to eliminate arcs without requiring a single large electromagnetic contactor. This segmentation enables compact design while maintaining arc elimination capability.
Solution Approach 2:
The invention introduces a capacitor as an intermediary component that stores electrical energy and provides a discharge path for arc suppression. The capacitor acts as a mediator between the relay contacts and the circuit, absorbing energy that would otherwise create arcs, thereby eliminating the need for large electromagnetic contactors with complex arc suppression structures.
2Reliability
If a uniquely structured electromagnetic contactor is employed to eliminate arcs, then arc elimination is achieved, but the cost increases
Solution Approach 1:
The invention replaces expensive uniquely structured electromagnetic contactors with standard, inexpensive relay units combined with capacitors. The relay units are conventional components that are widely available and cost-effective, while the capacitors are simple energy storage devices. This substitution dramatically reduces manufacturing cost while maintaining arc elimination functionality.
Solution Approach 2:
The invention uses standard relay units that are copies of conventional, well-established components rather than custom-designed electromagnetic contactors. These standard relays can be mass-produced using existing manufacturing processes, reducing tooling costs and assembly complexity while achieving the same arc elimination effect through the combination of multiple relays and capacitors.
3Reliability
If a large electromagnet is required to reliably eliminate arcs, then arc elimination is achieved, but the size of the electromagnetic contactor increases
Solution Approach 1:
The arc elimination function is segmented across multiple small relay units rather than concentrated in a single large electromagnetic contactor. Each relay unit uses a small electromagnet sufficient for its specific contact rating, and the combined effect of multiple units provides comprehensive arc elimination. This segmentation eliminates the need for oversized electromagnets.
Solution Approach 2:
Capacitors are introduced as intermediary components that provide energy discharge paths to suppress arcs at relay contacts. This intermediary mechanism allows the use of smaller electromagnets in the relay units, as the capacitors handle the energy management that would otherwise require large electromagnet forces for arc suppression.
Data Source
AI summary
A circuit structure with a novel structure is disclosed in which a measure against arcs can be implemented with a simple structure and a reduction in size and cost can be realized. A circuit structure including: a power supply line configured to connect a battery and a load; a main relay connected to the power supply line; a pre-charge circuit including a pre-charge resistor and a pre-charge relay connected in series, and connected in parallel to the main relay; and a sub relay connected in parallel to the pre-charge resistor.