Battery Voltage Detection Controller with Current Mirroring
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Solution Overview
Problem
Conventional battery voltage detection systems suffer from low accuracy due to significant voltage drops across resistors, leading to imbalanced voltage readings across battery cells over time, which affects the accuracy and longevity of battery packs.
Innovation Solution
A controller system that couples converters to battery cells through switching units, utilizing mirroring units to equalize currents through first and second paths, and a compensation circuit to maintain balance among cells, ensuring accurate voltage detection and prolonged battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional voltage detection systems use resistors for current sampling, then the detection system can be implemented with simple circuit structure, but the voltage drop across resistors causes low measurement precision
Solution Approach 1:
The patent divides the current path into separate first and second paths, with sampling resistors placed only in the first path. This segmentation allows the sampling current to be measured without requiring resistors in both paths, reducing voltage drop while maintaining detection accuracy.
Solution Approach 2:
The patent introduces a compensation current generated by a current mirror circuit as an intermediary to compensate for the sampling current. This compensation current flows through the second path to balance the current distribution, eliminating the need for large resistors in the second path and reducing voltage drop.
2Measurement precision
If compensation current is used to balance sampling current, then measurement precision can be improved, but the device complexity increases due to additional current mirror circuits
Solution Approach 1:
The current mirror circuit serves multiple functions: it generates the compensation current, provides current mirroring to balance the sampling current, and enables accurate voltage detection. This multi-functionality reduces the need for separate compensation components, offsetting the added complexity with functional consolidation.
3Quantity of substance
If large resistors are used for current sampling, then the sampling current can be adequately measured, but the voltage drop increases causing low measurement precision
Solution Approach 1:
The patent segments the current measurement function to only the first path, where the sampling resistor is placed. The second path does not require a sampling resistor, eliminating the voltage drop issue. The segmentation allows adequate sampling current measurement in the first path without compromising the second path's voltage integrity.
Solution Approach 2:
The compensation current acts as an intermediary that flows through the second path to replace the need for a sampling resistor there. This intermediary current balances the current distribution, allowing the first path's sampling resistor to function effectively without causing excessive voltage drop in the second path.
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
The system achieves precise voltage detection across battery cells by equalizing currents and maintaining balance, thereby enhancing accuracy and extending battery pack lifespan.
Implementation Method 1
duplicating, by a mirroring unit, an operating current and a sampling current of a first converter
Data Source
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AI summary
A controller for detecting voltages of battery cells in a battery pack includes converters coupled to the battery cells and switching units. An anode of each battery cell is coupled to a respective converter through a respective first path, and a cathode of each battery cell is coupled to the respective converter through a respective second path. The switching units are coupled between the battery cells and the converters. The converters are coupled to anodes of the battery cells through the switching units. When a switching unit corresponding to a battery cell is turned on, an anode of the battery cell provides an operating current and a sampling current through a respective first path to a respective converter, and the operating current flows from the anode of the battery cell through the respective converter to ground.