Cell Stack Voltage Sensing RC Layout for Lower-Voltage Capacitors
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Solution Overview
Problem
Existing voltage measurement devices for cell stacks require capacitors with high withstand voltage characteristics due to the potential difference between the total voltage of battery cells and GND, leading to increased component costs and complexity.
Innovation Solution
A voltage measurement device that includes (n+1) resistor elements and (n+1) capacitors connected in an RC filter configuration, where the second terminals of two or more capacitors are connected to the positive electrode of a specific battery cell, reducing the potential difference across capacitors and thus their required withstand voltage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitors are connected to the upper battery cell with reference to GND, then voltage measurement can be performed, but the capacitors require high withstand voltage characteristics due to the potential difference between total voltage and GND
Solution Approach 1:
The voltage measurement system is segmented into multiple measurement paths, each handling a portion of the total voltage. Instead of measuring the entire cell stack voltage through a single capacitor referenced to GND, the system divides the measurement into segments across different capacitors (C1, C2, ..., Cn), where each capacitor only needs to withstand a fraction of the total voltage, thereby reducing the withstand voltage requirement for each individual capacitor.
Solution Approach 2:
Intermediate voltage reference points are introduced between the battery cells and GND. These intermediaries (such as the positive electrodes of individual battery cells or intermediate nodes in the voltage divider network) serve as local reference potentials, allowing capacitors to be connected across smaller voltage differences rather than the full range from maximum voltage to GND, thus reducing their withstand voltage requirements.
2Measurement precision
If high withstand voltage capacitors are used, then accurate voltage measurement is achieved, but component cost and device complexity increase
Solution Approach 1:
The system segments the voltage measurement function across multiple capacitors with lower individual voltage ratings. By dividing the total voltage measurement task into smaller segments, each capacitor can be specified with lower withstand voltage characteristics, which reduces both component cost and the complexity of selecting and managing high-voltage components.
Solution Approach 2:
The invention changes the voltage parameter specification of the capacitors from high withstand voltage to low withstand voltage by altering the connection topology. Instead of connecting capacitors across the full voltage range, the system reconfigures connections so that each capacitor operates within a smaller voltage window, thereby changing the required capacitor parameters to more economical specifications.
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 configuration reduces the required withstand voltage characteristics of capacitors, lowering component costs and simplifying the design while maintaining accurate voltage measurement of each battery cell in the cell stack.
Implementation Method 1
includes (n+1) first resistor elements, first terminals of which are connected to a positive electrode of an upper-end battery cell among the n battery cells, a negative electrode of a lower-end battery cell among the n battery cells, and connection points between the n battery cells; (n+1) first capacitors, first terminals of which are respectively connected to second terminals of the (n+1) first resistor elements
Data Source
AI summary
A voltage measurement device individually detects, in a cell stack of n (n is an integer greater than or equal to two) battery cells connected in series, a voltage of each of the n battery cells, and includes: n+1 resistor elements, first terminals of which are connected to a positive electrode of an upper-end battery cell among the n battery cells, a negative electrode of a lower-end battery cell among the n battery cells, and connection points between the n battery cells; n+1 capacitors, first terminals of which are respectively connected to second terminals of the n+1 resistor elements; and a voltage measurer connected to the second terminals of the n+1 resistor elements. Second terminals of two or more capacitors among the n+1 capacitors are connected to a positive electrode of a k-th battery cell (k is an integer; 1≤k≤n−1) among the n battery cells.