Battery Management System Local SOC Calculation
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Solution Overview
Problem
Existing battery management systems require high bandwidth for data transmission between cell monitoring units and a central control unit, which is particularly problematic in vehicles where this can lead to increased complexity and cost, especially when determining the state of charge of battery cells or modules.
Innovation Solution
The method involves measuring electrical voltage and current by cell monitoring units, calculating the state of charge locally, and transmitting only a single current value, reducing data rate and eliminating the need for local current sensors, thereby simplifying the system and reducing hardware complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a central battery management system collects all voltage and current data from cell monitoring units, then the state of charge can be determined centrally, but the data transmission bandwidth requirement increases significantly
Solution Approach 1:
The patent applies local quality by enabling each cell monitoring unit to independently calculate the state of charge for its monitored battery cells using locally available voltage measurements and received current values. This distributes the computational function from a centralized location to multiple local units, reducing the data transmission burden on the communication bus while maintaining accurate SOC determination capability at each location.
2Measurement precision
If each cell monitoring unit has its own current sensor, then local state of charge calculation is more accurate, but the hardware cost and system complexity increase
Solution Approach 1:
The patent implements universality by using a single current sensor that serves multiple functions: it measures the current for the entire battery pack and provides this current value to all cell monitoring units. Each monitoring unit then uses this shared current measurement combined with its local voltage measurements to independently calculate state of charge. This eliminates the need for multiple current sensors while maintaining the capability for accurate local SOC calculation.
Data Source
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AI summary
The invention relates to a method for determining the charge state (SOC) of battery cells (14) or battery modules of a battery. Said method is carried out using a plurality of cell monitoring units (16, 32), each unit monitoring several battery cells (14) or at least one battery module, and comprises the following steps: the respective electric current of the battery cells (14) or battery modules is measured by cell monitoring units (16, 32), the battery current is measured, the measured current value is transmitted to the plurality of cell monitoring units (16, 32), and a charge state (SOC) is calculated in each of the cell monitoring units (16, 32) for the respective monitored battery cells (14), or respectively, the at least one battery module. The invention also relates to a battery management system (21, 31) which is designed to carry out the claimed method. The invention further relates to a battery and a motor vehicle comprising a battery management system (21, 31) for carrying out said method.