Parallel Resistor Current Sensing for Battery Thermal Management
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Solution Overview
Problem
Conventional methods for measuring current in battery cells using a single detection resistor generate heat, leading to reduced precision and potential damage to surrounding components during charging and discharging.
Innovation Solution
A system with multiple resistors of different resistance values connected in parallel, where the voltage across each resistor is detected, and a multiplexer switches between resistors to distribute current and prevent overheating, using Field Effect Transistors (FET) or Bipolar Junction Transistors (BJT) switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single detection resistor is used to measure current, then the device complexity is reduced, but heat generation increases causing reduced measurement precision and potential damage to surrounding components
Solution Approach 1:
The patent divides the single detection resistor into multiple resistors (first detection resistor, second detection resistor, third detection resistor) connected in parallel. Each resistor handles a portion of the total current, distributing the heat generation across multiple components. This segmentation allows the system to maintain measurement precision while reducing the thermal burden on any single resistor and surrounding components.
2Device complexity
If a single detection resistor is used, then the device complexity is reduced, but heat generation causes damage to surrounding components
Solution Approach 1:
The patent segments the current path into multiple parallel resistors, distributing the thermal load across multiple components. This prevents excessive heat concentration that would damage surrounding components, while the main chip integrates measurements from all resistors to maintain accurate current measurement.
Solution Approach 2:
The patent introduces a temporal dimension to the measurement process by sequentially activating different resistors through the multiplexer. The main chip measures current through resistors at different time intervals, allowing heat to dissipate between measurements and preventing thermal damage to surrounding components while maintaining measurement accuracy.
3Temperature
If multiple resistors are used in parallel, then heat generation per resistor is reduced, but the device complexity increases
Solution Approach 1:
The patent makes the main chip multi-functional by enabling it to perform multiple tasks: integrating current measurements from multiple resistors, controlling the multiplexer to switch between resistors, and processing the aggregated current data. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in device complexity while achieving effective heat distribution.
4Ease of operation
If current is continuously measured through the same resistor, then the measurement process is simple, but heat accumulation reduces precision over time
Solution Approach 1:
The patent introduces dynamic switching between different resistors using the multiplexer. Instead of continuously measuring through a single resistor, the system dynamically transitions to different resistors after a predetermined time interval. This dynamic approach allows heat to dissipate between measurements, maintaining measurement precision over extended periods while the main chip continues to integrate current data.
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 prevents damage from heat generation and enhances the precision of current measurement in battery cells by distributing current across multiple resistors, maintaining component safety and accuracy.
Implementation Method 1
increase of the current in the detection resistor 101 during charging or discharging causes an increase in temperature
Implementation Method 2
a multiplexer selecting one of the other resistors (R2 and R3) when the amount of current added up at the main chip exceeds a predetermined threshold value
Data Source
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AI summary
Disclosed is an apparatus for measuring an amount of current in battery cells. The apparatus includes: a plurality of resistors (Rl, R2, and R3) connected in parallel; a main chip connected to both ends of one (Rl) of the plurality of resistors, detecting voltage across the connected resistor, and adding up the amount of current on the basis of the detected voltage; a multiplexer selecting one of the other resistors (R2 and R3) when the amount of current added up at the main chip exceeds a predetermined threshold value; and a plurality of switches connected to the plurality of resistors respectively, and switched on/off by an output signal of the multiplexer. Thereby, it is possible to prevent damage to the surrounding components caused by the generation of heat from the single detection resistor, and detect a more precise amount of current in the battery cells.