Vehicle Battery Voltage Prediction for Start-Stop Reliability
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Solution Overview
Problem
Existing methods for determining the starting ability of a vehicle battery are limited in their informative value, as they do not effectively predict voltage drops that could lead to undervoltage in the on-board electrical system, potentially causing resets in electrical loads.
Innovation Solution
A method that records and forms a mean value of voltage dips during drive motor starts, normalizes it to a reference value based on battery temperature, and uses this to predict the expected voltage at the vehicle battery, allowing for adaptive learning and prevention of undesired undervoltages by determining whether the drive motor can be stopped safely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the drive motor is stopped during operation to save energy, then energy consumption is reduced, but undervoltage in on-board electrical system consumers may occur due to voltage drops during subsequent battery starts
Solution Approach 1:
The control device performs preliminary assessment by detecting voltage dip values during drive motor starts and forming a mean value to predict the voltage to be expected at the vehicle battery before actually stopping the drive motor. This preliminary prediction allows the system to determine in advance whether stopping would cause undervoltage, thereby preventing harmful effects while still enabling energy-saving stops when safe.
Solution Approach 2:
The system continuously detects voltage dip values during drive motor starts and uses this feedback to update the mean value and predict future voltage levels. This feedback mechanism allows the control device to adaptively determine whether the drive motor can be stopped without causing undervoltage, creating a closed-loop control system that balances energy savings with reliability.
2Reliability
If the mean value of voltage dips is used to predict voltage levels, then undervoltage can be prevented, but the complexity of the control device increases due to additional detection and calculation requirements
Solution Approach 1:
The control device performs multiple functions using the same detection and processing resources: it detects voltage dip values for prediction purposes, forms the mean value of these detections, and uses this mean value to determine whether the drive motor can be stopped. This multi-functionality approach avoids the need for separate dedicated systems for each function, thereby limiting the increase in device complexity while achieving reliable voltage prediction.
3Productivity
If start-stop operation is enabled to reduce energy consumption, then fuel efficiency improves, but the risk of undervoltage resets in electrical loads increases
Solution Approach 1:
The control device applies preliminary anti-action by predicting the voltage to be expected at the vehicle battery using the mean value of detected voltage dips before permitting start-stop operation. This prediction allows the system to preemptively prevent undervoltage resets by determining whether stopping the drive motor would cause harmful voltage drops, thereby enabling fuel-efficient start-stop operation only when safe.
Data Source
AI summary
The invention relates to a method for operating a vehicle having a vehicle battery, in which, on starting a drive motor (10) of the vehicle, the value of a voltage drop (38) at the vehicle battery is detected. A mean value is formed from a plurality of such values of the voltage drop (38), and said mean value is used to predict an expected voltage (40) at the vehicle battery at the next starting of the drive motor (10). This allows a start-stop operation of the vehicle while maintaining a predetermined minimum voltage at the next starting procedure. The invention further relates to a control device for implementing such a method.