Redundant Battery Current Determination via Voltage Variation
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Solution Overview
Problem
Current battery current measurement systems in vehicles face challenges in ensuring accurate and safe operation due to potential defects in current sensors, which can compromise vehicle safety and efficiency, especially in high-safety requirement applications like ISO 26262 ASIL D standards.
Innovation Solution
A redundant battery current determination system using a combination of current and voltage measuring means, where a current sensor and a voltage sensor work together with an evaluating unit to infer battery current from variations in single-cell voltage, allowing for validation of current measurement values and providing a qualified output without the need for multiple current sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple current sensors are used for redundant measurement, then measurement reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces voltage measuring means as an intermediary to indirectly determine battery current through voltage variations across battery cells. Instead of adding another current sensor, the system uses voltage measurements combined with battery models to calculate and validate current values, thereby maintaining reliability without increasing device complexity
Solution Approach 2:
The patent replaces the physical current sensing mechanism (second current sensor) with an electrical calculation approach using voltage measurements and battery models. This substitution eliminates the need for additional current sensors while achieving redundant current determination through mathematical relationships
2Reliability
If multiple current sensors are used for redundant measurement, then measurement reliability is improved, but cost increases
Solution Approach 1:
The patent creates a virtual copy of current measurement through calculation rather than using a physical duplicate sensor. By computing current from voltage measurements and battery models, the system achieves redundant measurement capability without the cost of manufacturing and installing additional current sensors
Solution Approach 2:
The patent substitutes expensive current sensing hardware with more economical voltage measurement hardware and computational processing. This replacement reduces material costs, manufacturing complexity, and system integration costs while maintaining the essential function of redundant current measurement
3Productivity
If a shunt with very small resistance is used, then circuit performance is improved, but measurement precision deteriorates due to small voltage drop
Solution Approach 1:
The patent introduces voltage measuring means as an intermediary to determine current indirectly. By measuring voltage variations across battery cells and using battery models, the system calculates current without relying on the small voltage drop across the shunt, thereby overcoming the measurement precision limitation
Solution Approach 2:
The patent substitutes the direct voltage drop measurement method (which suffers from low precision due to small shunt resistance) with an alternative electrical measurement approach using voltage sensors and computational modeling to determine current with higher precision
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances safety and flexibility by reducing system complexity and cost, allowing for accurate battery current measurement with a single current measuring means, leveraging existing voltage measuring capabilities, and enabling flexible software implementation.
Implementation Method 1
a voltage measuring means for separately detecting a variation with time of a single-cell voltage of at least one battery cell and providing at least one variation with time of a voltage measurement value
Data Source
AI summary
A device comprises a battery having a multiplicity of battery cells and a sensor system for the redundant determination of a battery current flowing through the poles of the battery. The sensor system comprises a current measuring device for detecting the battery current and providing a current measurement value. Furthermore, the device comprises a voltage measuring device for separately detecting a variation with time of the single-cell voltage of at least one battery cell and providing at least one variation with time of a voltage measurement value. Furthermore, the device comprises an evaluating unit which is configured for determining the battery current from the at least one variation with time of the voltage measurement value, providing a corresponding current value and comparing the current value with the current measurement value.