Battery Pack Current Estimation from Inter-Cell Voltage Drops
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Solution Overview
Problem
Current battery power systems in vehicles face challenges in accurately estimating battery currents, leading to potential damage from incorrect readings and unnecessary battery stoppages, due to the reliance on high-integrity current sensors which can be costly and prone to errors.
Innovation Solution
A computer system with processing circuitry that estimates battery pack current by obtaining resistance data and inter-cell voltage drops across inter-cell connectors, determining inter-cell currents, and calculating a battery pack current estimate, which can converge to a normal distribution, allowing for detection of malfunctioning sensors and continued power transfer without relying solely on current sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-integrity current sensors are used to monitor battery current, then measurement reliability is improved, but system cost and complexity increase
Solution Approach 1:
The patent introduces voltage sensors as intermediary measurement devices that indirectly measure battery current by detecting voltage drops across known resistance values of inter-cell connectors. This mediator approach replaces direct current measurement with a derived calculation method, reducing sensor requirements while maintaining measurement reliability through Ohm's law (I=V/R).
Solution Approach 2:
The patent substitutes electrical current sensing with a voltage-based measurement system. Instead of using current sensors (amperometers) to directly detect current flow, the system uses voltage sensors to measure voltage drops across resistive elements, then calculates current through mathematical relationships. This substitution reduces hardware complexity while achieving the same measurement objective.
2Difficulty of detecting and measuring
If current sensors are relied upon for battery current measurement, then current detection is simplified, but measurement accuracy and integrity deteriorate due to sensor errors
Solution Approach 1:
The battery pack's inter-cell connectors, which inherently possess resistance as part of their normal construction, are utilized to serve a dual purpose: their primary function of electrical connection and their secondary function as built-in sensing elements for current measurement. The voltage drop across these connectors naturally provides the measurement signal, eliminating the need for separate sensing components and reducing measurement error sources.
Solution Approach 2:
Instead of directly measuring current with a single sensor point, the system creates multiple voltage measurement copies across different inter-cell connectors. By measuring voltage drops at multiple locations and using statistical analysis, the system generates multiple estimates of the same current value, then converges these estimates to improve accuracy and detect sensor malfunctions through redundancy.
3Measurement precision
If multiple inter-cell current measurements are averaged, then measurement accuracy improves through convergence to normal distribution, but processing complexity increases
Solution Approach 1:
The system implements feedback through statistical monitoring of multiple current measurements. By continuously calculating mean values and standard deviations from multiple inter-cell measurements, the system creates a feedback mechanism that converges toward the true current value. This feedback loop also enables malfunction detection when measurements deviate beyond statistical thresholds, improving reliability without requiring complex external monitoring systems.
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 the accuracy and reliability of current measurements, reduces the risk of erroneous readings, and allows the battery to continue providing power even if the current sensor malfunctions, potentially eliminating the need for additional sensors and improving battery health monitoring.
Implementation Method 1
determine inter-cell currents based on the resistance data and associated inter-cell voltage drops
Data Source
AI summary
A computer system comprising processing circuitry is presented. The processing circuitry is configured to obtain resistance data of a plurality of inter-cell connectors of a battery pack comprising a plurality of battery cells, and obtain inter-cell voltage drops across the plurality of inter-cell connectors. The processing circuitry is further configured to determine inter-cell currents based on the resistance data and associated inter-cell voltage drops; and determine a battery pack current estimate of a battery pack current of the battery pack based on the inter-cell currents.