Power Relay Assembly Driving Apparatus Arc Prevention
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Solution Overview
Problem
The high cost and weight of special gas-charged high voltage relays in power relay assemblies for electric and hybrid vehicles, along with complex mechanical structures and potential for contact fusion during short circuits, pose challenges in terms of efficiency, safety, and reliability.
Innovation Solution
A power relay assembly driving apparatus using a battery management system (BMS) or main controller to control a general relay, incorporating a first and second relay unit, switching units, and a protection unit to manage current flow and prevent contact fusion, thereby replacing expensive special gas-charged relays and simplifying wire arrangements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a special gas-charged high voltage relay is used to prevent arc at relay contact, then reliability is improved, but weight increases
Solution Approach 1:
The patent extracts the arc prevention function from the special gas-charged relay by introducing a separate capacitor discharge circuit. The capacitor is charged during normal operation and discharged when the relay contacts open, creating a counter-electromotive force that prevents arc formation. This separates the arc suppression function from the relay structure itself, allowing use of lighter general relays.
Solution Approach 2:
The patent introduces a capacitor as an intermediary element that mediates between the relay switching action and the arc prevention requirement. The capacitor stores energy during normal operation and releases it as a controlled discharge current when the relay opens, acting as a buffer that prevents direct arcing at the contacts without requiring special gas charging.
2Reliability
If a special gas-charged high voltage relay is used to prevent arc at relay contact, then reliability is improved, but cost increases
Solution Approach 1:
The patent replaces the expensive special gas-charged relay with a combination of a standard general relay and a capacitor. The capacitor is a relatively inexpensive component that can be discharged and recharged multiple times. This substitution uses cheaper, readily available components to achieve the same arc prevention function.
Solution Approach 2:
The patent substitutes the mechanical/chemical arc suppression mechanism (special gas charging) with an electrical mechanism (capacitor discharge). Instead of relying on special gas properties to quench arcs, the system uses controlled electrical discharge to create a counter-voltage that prevents arc formation, replacing a complex mechanical system with a simpler electrical one.
3Weight of moving object
If a general relay is used to replace special gas-charged relay, then weight is reduced, but reliability deteriorates due to contact fusion risk
Solution Approach 1:
The patent performs preliminary action by charging the capacitor during normal operation before the relay needs to open. When the relay contacts are about to open, the capacitor is already charged and ready to discharge, providing immediate arc suppression. This preliminary charging ensures that the protective action is available exactly when needed, preventing contact fusion in general relays.
4Reliability
If protection unit is added to control current flow according to temperature, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent implements self-service by enabling the system to monitor its own temperature and automatically adjust current flow accordingly. The protection unit detects temperature conditions and controls the switching units to prevent overheating damage, allowing the system to self-regulate without external intervention. This reduces the need for complex external protection systems.
Data Source
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AI summary
According to one embodiment of the present invention, a power relay assembly driving apparatus comprises: a first relay unit which switches a connection between a first terminal of a battery unit and a first terminal of an inverter unit having a capacitor; a second relay unit which switches a connection between a second terminal of the battery unit and a second terminal of the inverter unit; a first switching unit connected in parallel to the second relay unit between the second terminal of the battery unit and the second terminal of the inverter unit; a second switching unit connected in parallel to the second relay unit between the second terminal of the battery unit and the second terminal of the inverter unit; and a battery management system (BMS) which controls the first relay unit and the first switching unit in order to pre-charge the capacitor with the power of the battery unit, controls the second relay unit in order to normal-charge the capacitor with the power of the battery unit and then controls the first switching unit in order to end the pre-charging of the capacitor, controls the second switching unit upon a power cutoff of the battery unit in order to form an equipotential between the second relay unit and the second terminal of the inverter unit, and controls the second relay unit in order to electrically separate the second terminal of the battery unit and the second terminal of the inverter unit from each other.