ISG Voltage Prediction Using Historical Data
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Solution Overview
Problem
The existing Idle Stop and Go (ISG) system's battery voltage prediction algorithm is limited in accurately predicting the lowest voltage during startup as batteries age, affecting the system's performance and fuel efficiency.
Innovation Solution
A vehicle system that uses a battery sensor to measure startup voltage, a controller to compare current and previous voltage values, calculate differences, and apply correction voltages to predict the lowest battery voltage, thereby determining whether to enter or prevent ISG system stops based on predetermined reference and determination values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the existing lowest voltage prediction algorithm is used, then the system structure remains simple, but the prediction accuracy deteriorates as batteries age
Solution Approach 1:
The system performs preliminary actions by storing historical lowest voltage values and accumulated current data before predicting the current lowest voltage. The controller uses previously stored voltage values (V1, V2, ..., Vn-1) and accumulated current (QAB) to calculate the current lowest voltage (Vn), thereby improving prediction accuracy without requiring complex real-time measurements during battery operation.
Solution Approach 2:
The system implements feedback by continuously comparing predicted lowest voltage with actual measured lowest voltage, calculating the difference, and using this feedback to refine future predictions. The controller stores historical data and uses it to adjust prediction calculations, creating a closed-loop system that improves accuracy over time while maintaining manageable complexity through systematic data reuse.
2Use of energy by moving object
If the ISG system frequently enters stop mode to improve fuel efficiency, then energy consumption decreases, but battery voltage may drop below safe levels
Solution Approach 1:
The system performs preliminary assessment of battery voltage conditions before allowing the ISG system to enter stop mode. By predicting the lowest voltage using historical data and accumulated current, the controller determines in advance whether the battery can safely support ignition-off operation, thereby preventing voltage drops below safe levels while maximizing fuel efficiency opportunities.
Solution Approach 2:
The system uses feedback from voltage prediction results to dynamically control ISG stop entry decisions. When the predicted lowest voltage indicates insufficient battery capacity, the controller prevents stop mode entry, thereby maintaining battery voltage stability while still allowing stop mode when conditions permit, thus optimizing the balance between fuel efficiency and reliability.
3Measurement precision
If the battery SOC and liquid temperature are used alone to determine battery state, then the measurement process remains simple, but the prediction accuracy deteriorates with battery aging
Solution Approach 1:
The system segments the battery state determination into multiple independent components: SOC measurement, liquid temperature measurement, historical lowest voltage value storage, and accumulated current calculation. Each component operates independently and contributes to the overall prediction, allowing the system to achieve high accuracy without requiring a single complex measurement system.
Solution Approach 2:
The system merges multiple data sources (SOC, liquid temperature, historical lowest voltage values, and accumulated current) into a unified prediction framework. By combining these measurements and calculations, the controller achieves comprehensive battery state assessment that maintains accuracy throughout battery life while keeping individual measurement processes relatively simple.
Data Source
AI summary
A vehicle and a method use an Idle Stop and Go (ISG) system. The vehicle includes: a battery; a battery sensor configured to measure a lowest voltage of the battery at a time of startup of the vehicle; a driving unit including an engine of the vehicle; and a controller. The controller is configured to: compare a first lowest voltage predicted using a current lowest voltage of the battery with a reference value to determine whether the lowest voltage of the battery has been changed; in response to determining the lowest voltage of the battery has been changed, calculate a difference between the current lowest voltage of the battery and an immediately previous lowest voltage of the battery; calculate an accumulated current between a current of the battery at the immediately previous time point and a current of the battery at the current time point; calculate a correction voltage for the accumulated current; predict a second lowest voltage using at least one of the difference between the current lowest voltage of the battery and the immediately previous lowest voltage of the battery or the correction voltage; compare the second lowest voltage with a second determination value; and control the driving unit to control entry into a stop of the ISG system according to a result of the comparison.