Automotive Battery Voltage Estimation Using Dual-Path Filtering
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Solution Overview
Problem
Conventional automotive battery charging systems fail to adapt to dynamic changes in electrical resistance due to current, temperature, and other time-varying factors, leading to potential overcharging or undercharging, which can reduce battery life.
Innovation Solution
A battery charging system that uses a positive (B+) terminal voltage sensor and an intelligent battery sensor to generate filtered signals, which are then used by a controller to estimate battery voltage and adjust the target voltage for charging, employing high and low pass filters and a proportional-integral control scheme to mitigate overcharging and undercharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a fixed voltage offset compensation is applied to compensate for voltage drop along the electrical connection, then the packaging and weight distribution can be optimized with alternator and battery in different areas, but the system cannot adapt to dynamic changes in electrical resistance caused by current, temperature, and other time-varying factors
Solution Approach 1:
The system transitions from a fixed voltage offset compensation approach to a dynamic adaptation mechanism using high-pass and low-pass filters. The high-pass filter captures rapid voltage changes at the alternator, while the low-pass filter processes the battery voltage signal to remove high-frequency noise. This dynamic filtering approach allows the system to adapt to time-varying electrical resistance caused by current, temperature, and other factors, resolving the contradiction between fixed packaging design and dynamic adaptability requirements.
Solution Approach 2:
The system implements a feedback mechanism by continuously monitoring both alternator B+ terminal voltage and battery terminal voltage, processing these signals through complementary filters, and using the combined information to dynamically adjust charging control. This feedback loop enables real-time adaptation to changing electrical conditions while maintaining the physical separation between alternator and battery for optimal packaging.
2Device complexity
If conventional fixed offset compensation is used, then the system structure remains simple, but overcharging or undercharging may occur which reduces battery life
Solution Approach 1:
The patent introduces dynamic filtering processing (high-pass and low-pass filters) to the charging control system, transforming the simple but inaccurate fixed offset compensation into a more complex yet reliable adaptive system. This dynamic approach accurately tracks voltage differences under varying electrical conditions, preventing overcharging and undercharging, thereby extending battery life despite the increased processing complexity.
Solution Approach 2:
The system changes the parameter processing approach by applying frequency-based filtering transformations to the voltage signals. The high-pass filter extracts transient voltage changes while the low-pass filter provides stable baseline voltage information. This parameter transformation enables accurate battery voltage estimation under dynamic conditions, improving charging reliability and battery longevity.
3Measurement precision
If high pass and low pass filters are applied to process voltage signals, then accurate battery voltage estimation can be achieved under dynamic conditions, but the processing complexity and computational requirements increase
Solution Approach 1:
The voltage signal processing is segmented into two complementary filtering paths: high-pass filtering for the alternator B+ voltage signal to capture transient changes, and low-pass filtering for the battery voltage signal to extract stable baseline information. This segmentation allows each filter to be optimized for its specific function, achieving accurate battery voltage estimation under dynamic conditions while keeping individual processing stages relatively simple.
Solution Approach 2:
The filtering system acts as an intermediary between the raw voltage signals and the charging control decision-making process. By introducing these intermediate processing stages, the system transforms noisy, dynamic voltage measurements into reliable estimation data without requiring complex computational algorithms, thus achieving high measurement precision with moderate processing complexity.
Data Source
AI summary
Techniques for controlling charging of a battery of a vehicle comprise receiving, from a positive (B+) voltage sensor, a B+ voltage signal indicative of a voltage at a B+ terminal of an alternator of the vehicle, receiving, from an intelligent battery sensor (IBS), an IBS voltage signal indicative of a voltage at a positive terminal of the battery, applying high pass and low pass filters to the B+ voltage signal and the IBS voltage signals, respectively, estimating a voltage of the battery using both the filtered B+ voltage signal and the filtered IBS voltage signal, adjusting a target voltage for the battery based on the estimated battery voltage, and controlling charging of the battery using the adjusted target voltage to mitigate overcharging and undercharging of the battery.