LDC Controller Priority Logic for EV Overcurrent Prevention
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Solution Overview
Problem
Conventional LDC converter control systems in electric vehicles experience electrical load performance degradation and instantaneous overcurrent due to controllers stopping operations during state transitions, leading to user inconvenience and discomfort.
Innovation Solution
The proposed solution involves prioritizing controllers and connecting them in series, with a command voltage determiner that calculates the final command voltage based on the output voltages of multiple controllers, ensuring that higher-priority controllers continue to operate even when lower-priority ones are active, thereby preventing overcurrent and maintaining stable electrical load performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If controllers are stopped during state transitions to limit charging current, then auxiliary battery protection is improved, but electrical load performance degradation and instantaneous overcurrent occur
Solution Approach 1:
The command voltage determiner pre-calculates and determines the final command voltage by considering outputs from all controllers (variable voltage controller, voltage drop compensator, and charging current limiter) before state transitions occur. This preliminary determination ensures smooth transitions without instantaneous overcurrent when controllers stop or start operating.
Solution Approach 2:
The command voltage determiner acts as an intermediary component that receives command voltages from multiple controllers and synthesizes them into a final command voltage. This mediator ensures that the transition between different controller states is smooth and prevents harmful instantaneous overcurrent while maintaining auxiliary battery protection.
2Reliability
If variable voltage controller and voltage drop compensator stop operating when charging current limit is active, then charging current control is improved, but control stability deteriorates
Solution Approach 1:
The variable voltage controller and voltage drop compensator continue to operate and provide their output voltages even when the charging current limit is active. The command voltage determiner selectively uses these continuous outputs along with the charging current limiter output to determine the final command voltage, ensuring control stability while maintaining charging current control.
Solution Approach 2:
The command voltage determiner is designed to universally handle outputs from multiple controllers with different functions (variable voltage control, voltage drop compensation, and charging current limiting). It can synthesize these diverse inputs into a unified final command voltage, allowing the system to maintain stability across different operating conditions.
3Measurement precision
If multiple controllers operate simultaneously, then control precision is improved, but device complexity increases
Solution Approach 1:
Multiple controllers (variable voltage controller, voltage drop compensator, and charging current limiter) are merged into a unified control architecture where their outputs are combined by the command voltage determiner. This merging allows precise command voltage determination through systematic combination of multiple control inputs while managing device complexity through structured integration.
Data Source
AI summary
An apparatus and a method are provided for controlling a low DC-DC converter (LDC) in an electric vehicle by prioritizing respective controllers, connecting the controllers in series in ascending order according to priority, and determining a command voltage of the LDC on the basis of output voltages of the respective controllers. Accordingly, even when a controller with a highest priority is operating, controllers of lower priority continue operating. Thus, electrical load performance degradation caused by instantaneous overcurrent generated in state transitions is prevented.