Battery Internal Resistance Control for Engine Restart
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Solution Overview
Problem
Existing power supply systems in vehicles struggle to accurately determine whether an engine can be restarted after an automatic stop state due to variations in battery internal resistance caused by changes in state of charge, temperature, and usage patterns, leading to potential power shortages.
Innovation Solution
A control device that calculates the internal resistance of a battery during regenerative power generation or power running drive before the engine enters an automatic stop state and uses the latest internal resistance value to determine if the engine can be restarted, incorporating error correction and state change considerations to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine is automatically stopped to save fuel, then fuel consumption is reduced, but the battery may not have sufficient capacity to restart the engine due to internal resistance changes
Solution Approach 1:
The control device calculates the internal resistance of the battery before the engine enters the automatic stop state, and determines whether the battery can support engine restart in advance. This preliminary assessment prevents automatic stop when the battery lacks sufficient capacity, ensuring reliable restart while still enabling fuel-saving automatic stop when conditions are favorable.
Solution Approach 2:
The system establishes a safety margin by comparing the calculated internal resistance against predetermined thresholds before permitting automatic stop. This cushioning approach accounts for potential variations in battery performance and ensures that even under suboptimal conditions, the battery will have sufficient capacity to restart the engine.
2Measurement precision
If the latest internal resistance value is used for determination, then the accuracy of automatic stop permission determination is improved, but the complexity of the control system increases
Solution Approach 1:
The control device utilizes existing sensors and processors already present in the vehicle's power supply system to calculate internal resistance and make determination. No additional dedicated hardware is required, as the system repurposes existing computational resources to perform the accuracy-enhancing measurements and decisions.
Solution Approach 2:
The system monitors changes in internal resistance as a key parameter to determine battery suitability for engine restart. By focusing on this specific parameter and its variation over time, the system achieves high measurement accuracy without requiring complex multi-parameter analysis, thus balancing precision with simplicity.
Data Source
AI summary
A control device comprises an acquisition unit that acquires a current to or from the battery and a voltage of a battery, a calculation unit that calculates an internal resistance of the battery based on the current and the voltage when the regenerative power generation is performed by a rotary electric machine, and a permission determination unit that determines whether to permit an automatic stop of an engine depending on whether restarting of the engine is enabled based on power running drive of the rotary electric machine. The calculation unit calculates a value of the internal resistance each time the regenerative power generation or the power running drive is performed before the engine enters an automatic stop state. The permission determination unit determines whether to permit the automatic stop based on a latest value of the internal resistance among values of the internal resistance calculated by the calculation unit.