Charging Relay Control for Electric Vehicles
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Solution Overview
Problem
Existing automobile systems experience delays in restarting external charging when the charger is disconnected from the external power source during simultaneous external charging and preliminary air conditioning, leading to increased wear on the charging relay due to frequent on-off cycles.
Innovation Solution
An electronic control unit is implemented to manage the charging relay, turning it off only after a longer period when preliminary air conditioning is in progress, and ensuring no current flows through the relay when it is turned off, thereby reducing the frequency of on-off cycles and extending the relay's service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the charging relay is turned off immediately when the charger is disconnected from the external power source, then the charging relay is protected from unnecessary wear, but external charging cannot be restarted quickly when the charger is reconnected
Solution Approach 1:
The charging relay control strategy is made dynamic by adjusting the turn-off timing based on the system state. When preliminary air conditioning is detected, the charging relay maintains an on-state for a longer period after charger disconnection, whereas in other states it turns off immediately. This dynamic adaptation resolves the contradiction by optimizing relay longevity without sacrificing charging restart speed when needed.
Solution Approach 2:
The control system changes the parameter of charging relay on-time based on the detected system state. By identifying whether preliminary air conditioning is in progress, the system adjusts the relay's operational duration accordingly, allowing the relay to remain on longer during AC operations to enable faster charging resumption while maintaining normal immediate turn-off behavior in other scenarios.
2Loss of time
If the charging relay remains on for a longer period after charger disconnection during preliminary air conditioning, then external charging can be restarted faster, but the charging relay experiences increased wear from prolonged operation
Solution Approach 1:
The charging relay control applies different quality standards to different operational contexts. During preliminary air conditioning, the relay maintains an extended on-state to prioritize charging restart capability. In other operational states, the relay follows standard immediate turn-off procedures. This localized quality adjustment resolves the contradiction by applying prolonged operation only when it provides genuine benefit.
Solution Approach 2:
The system dynamically adjusts the charging relay's operational characteristics based on real-time system state detection. By monitoring whether preliminary air conditioning is in progress, the control system adaptively modifies the relay's duty cycle, extending operation only when necessary for maintaining charging readiness while minimizing unnecessary wear during other operations.
3Use of energy by moving object
If the charging relay is turned off during simultaneous external charging and preliminary air conditioning, then energy is saved, but the system cannot quickly resume charging when the charger is reconnected
Solution Approach 1:
The system prepares for potential charging resumption by maintaining the charging relay in an on-state during preliminary air conditioning operations. This preliminary preparation ensures that when the charger is reconnected, the relay is already positioned to immediately resume charging without requiring a turn-on cycle, thus resolving the contradiction between energy savings and charging productivity.
Solution Approach 2:
The control system modifies the charging relay's operational parameter (on-time duration) based on the detected system state. During preliminary air conditioning, the relay parameter is extended to prioritize charging readiness, while in other states the parameter returns to standard energy-saving modes. This parameter adaptation resolves the energy-productivity contradiction contextually.
Data Source
AI summary
An electronic control unit is configured to i) turn off a charging relay when a charger is disconnected from an external power source while external charging is in progress which is started when the charger is connected to the external power source and the charging relay is turned on while a system is off and in which a battery is charged with electric power from the external power source by the charger, and ii) set the period from the disconnection of the charger from the external power source to the turn-off of the charging relay to be longer when preliminary air conditioning is in progress than when preliminary air conditioning is not in progress.