Battery AFE Balancing Module for Isolated Cell-Set Voltage Drift
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Solution Overview
Problem
In battery packs, voltage differences between sets of battery cells managed by analog front ends (AFE) lead to uneven power consumption, causing voltage imbalance over time, which is detrimental to the overall recycling and performance of the battery pack.
Innovation Solution
A voltage balancing system is introduced, comprising a high-side and low-side analog front end, a microcontroller, and a communication isolating module, with a balancing module that uses constant value or switchable resistors and transistors to equalize voltages between the two sets of battery cells, ensuring consistent power consumption and minimizing voltage differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If two independent AFEs are used to manage battery cells, then the number of battery cells that can be managed is increased, but voltage imbalance occurs between battery cell sets due to inconsistent power consumption
Solution Approach 1:
An intermediary balancing module is introduced between the two independent AFEs to equalize voltage differences. This module includes balancing transistors and resistors that act as mediators to transfer charge from the higher voltage AFE to the lower voltage AFE, thereby maintaining voltage balance while allowing independent operation of both AFEs
Solution Approach 2:
The system dynamically changes the operating parameters of the balancing module based on detected voltage differences. When voltage imbalance exceeds a threshold, the balancing transistors are activated to adjust current distribution, effectively changing the electrical parameters to restore balance between the two AFE-managed battery cell sets
2Ease of operation
If isolation chip is used for communication between AFE and MCU, then communication between different voltage domains is enabled, but power consumption inconsistency between isolated power supplies worsens voltage imbalance
Solution Approach 1:
The system implements feedback by continuously monitoring the voltage outputs of both AFEs through the balancing module. When voltage imbalance is detected, the system adjusts the balancing circuit operation to correct the imbalance, creating a closed-loop control that compensates for power consumption differences in the isolated power supplies
Data Source
AI summary
The invention provides a voltage balancing system for balancing controlling of voltage of battery cells including a first set of battery cells and a second set of battery cells connected in series. The system includes a high-side analog front end (AFE) connected to the first set of battery cells, a low-side analog front end (AFE) connected to the second set of battery cells, a microcontroller communicating with the high-side AFE and the low-side AFE, and a communication isolating module interconnecting between the high-side AFE and the microcontroller. The system further includes a balancing module arranged at a back end of the low-side AFE or the high-side AFE to equalize voltages output by the low-side AFE and the high-side AFE. Compared with the prior arts, the system employs a balancing module to balance the voltages of the two sets of battery cells, which can shorten the voltage difference therebetween.