EV Battery Rapid Charging Relay Welding Detection and Control
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Solution Overview
Problem
The existing series-connected structure of main and rapid charging relays in eco-friendly vehicles does not consider safety during rapid charging, leading to potential damage from inrush currents when the rapid charging relay is welded.
Innovation Solution
An apparatus and method that include a battery unit with a first relay, a second relay interposed between the first relay and the rapid charging port, and a charging controller that determines the welding state of the second relay to control the charging sequence, preventing damage by employing either a compensation or basic charging sequence based on the welding state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the main relay and rapid charging relay are series-connected to protect the battery, then the battery is protected from overcurrent, but the rapid charging relay may be welded due to inrush current when both relays are on
Solution Approach 1:
The patent applies preliminary action by controlling the main relay to be turned on before the rapid charging relay is turned on. This sequence ensures that the circuit path is already established through the main relay before the rapid charging relay closes, thereby preventing inrush current from damaging the rapid charging relay while maintaining battery protection through the series connection structure.
2Productivity
If the rapid charging relay is used to control charging current, then rapid charging capability is achieved, but the relay welding state cannot be detected by conventional charging sequences
Solution Approach 1:
The patent applies preliminary action by performing a relay welding state detection before initiating the charging process. The charging controller detects whether the rapid charging relay is welded by measuring voltage across the relay terminals before closing the relay. This preliminary detection prevents attempting to charge through a welded relay, which would be ineffective and potentially dangerous.
Solution Approach 2:
The patent applies feedback by continuously monitoring the voltage across the rapid charging relay terminals and using this information to determine the relay's welding state. The charging controller adjusts the charging sequence based on this feedback - if welding is detected, the controller prevents charging; if no welding is detected, the controller proceeds with the charging process. This closed-loop control enables reliable detection and response to relay conditions.
Data Source
AI summary
An apparatus for controlling charging of a battery includes a battery unit including a battery, a first relay connected with the battery, and a second relay interposed between the first relay and a rapid charging port to charge the battery with charging power from a rapid charger connected with the rapid charging port, if the first relay and the second relay are controlled to be on. The apparatus includes a charging controller that controls the first relay and the second relay to be on or off and to determine a welding state of the second relay, if the rapid charger is connected with the rapid charging port, to control charging of the battery in a charging sequence corresponding to the welding state of the second relay. A method of controlling charging of a battery includes determining the welding state of the second relay, controlling the first relay to be on or off in a compensation charging sequence, if the second relay is determined to be welded, or controlling the first relay and the second relay to be on or off in a basic charging sequence, if the second relay is not determined to be welded.