Battery SOC Reset via Dynamic Charge Current Modulation
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Solution Overview
Problem
Existing methods for resetting the state of charge (SOC) of traction batteries in vehicles, such as hybrid or electric vehicles, face challenges during active charging, leading to errors and customer dissatisfaction due to premature interruption of charge current, inaccurate SOC estimation, and inability to achieve 100% charge level, especially when electrical loads cannot be completely removed or when charging system guidelines restrict zero-current output.
Innovation Solution
A system and method that utilize an OCV-SOC reset strategy, where the battery controller adjusts the charge current to induce a zero or near-zero current condition, allowing for accurate SOC estimation by manipulating the charging current request and evaluating battery voltage, enabling SOC adjustment during active charging sessions and power-up, while ensuring compliance with global charging standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If charge current is interrupted to perform OCV-SOC reset, then SOC estimation accuracy is improved, but charging completion is prevented and user experience deteriorates
Solution Approach 1:
The system dynamically adjusts charge current based on operational context. During normal charging, full current is applied. When OCV-SOC reset is needed, the system temporarily reduces current to near-zero to enable accurate SOC measurement, then resumes charging. This dynamic current modulation resolves the contradiction between maintaining charging productivity and achieving accurate SOC reset.
Solution Approach 2:
The system performs preliminary assessment of charging state and SOC estimation accuracy before interrupting charge current. By predicting when SOC reset is necessary and preparing the control strategy in advance, the system minimizes charging interruption time while ensuring accurate SOC measurement, thus maintaining overall charging productivity.
2Measurement precision
If charge current is reduced to zero for SOC reset, then SOC measurement accuracy is improved, but charging time increases and productivity decreases
Solution Approach 1:
Instead of completely stopping charge current, the system applies partial current reduction to a near-zero level sufficient for accurate OCV measurement. This partial action achieves the necessary SOC reset condition while minimizing the time penalty compared to complete charge interruption, thus reducing charging time loss.
Solution Approach 2:
The system changes the charge current parameter dynamically during the reset process. By adjusting current magnitude rather than maintaining a fixed charging regime, the system enables accurate SOC measurement at near-zero current while quickly transitioning back to normal charging current, minimizing overall charging time impact.
3Measurement precision
If electrical loads are activated to consume charge current during SOC reset, then near-zero battery current is achieved for accurate SOC update, but system complexity increases
Solution Approach 1:
The system uses existing electrical loads (A/C compressor, heater, air conditioner) to consume charge current during SOC reset instead of adding dedicated test equipment. These loads are already part of the vehicle system, so utilizing them for SOC measurement purposes avoids increasing device complexity while achieving the required near-zero battery current condition.
Solution Approach 2:
Existing electrical loads serve dual purposes: their normal vehicle functions and their role in consuming charge current during SOC reset operations. This multi-functionality eliminates the need for separate SOC measurement equipment, maintaining system simplicity while enabling accurate SOC updates.
Data Source
AI summary
A system for a vehicle including a traction battery, electrical loads, and a controller configured to, during a charge operation, activate the loads such that charge current output by a charger is consumed by the loads and charge current input to the battery approaches zero to update a state of charge (SOC) value of the battery, and deactivate the loads upon completion of the update such that charge current input to the battery increases.