BMS IC Layout for Shared ESD Protection and Cell Balancing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing battery management system integrated circuits (BMS ICs struggle to provide effective electrostatic discharge (ESD) protection and cell balancing while accommodating bus bars, leading to increased footprint and material costs, and potential measurement errors due to parasitic serial resistance.
Innovation Solution
A BMS IC design with bi-directional ESD protection elements and dual polarity switches, separated cell-measurement and cell-balancing modules, and centralized ESD protection, allowing safe monitoring and balancing even with bus bars, reducing die size and material requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional ESD protection elements are used for each measuring pin, then ESD protection is provided, but the IC footprint and material costs increase
Solution Approach 1:
Multiple ESD protection elements are merged into a single shared ESD protection circuit that serves all measuring pins simultaneously. This consolidation reduces the total number of discrete protection components needed, thereby reducing IC footprint and material costs while maintaining comprehensive ESD protection across all measurement points.
Solution Approach 2:
The ESD protection circuit is designed with multi-functionality to handle protection requirements for multiple measuring pins through a single unified structure. This universal protection mechanism can protect against ESD events on any or all measuring pins without requiring separate dedicated protection elements for each pin, optimizing both space and material usage.
2Adaptability or versatility
If bus bars are used instead of battery cells, then monitoring is enabled, but measurement errors occur due to parasitic serial resistance
Solution Approach 1:
The measuring pins are designed with asymmetric characteristics where pins connected to bus bars have different electrical characteristics compared to pins connected to battery cells. The system compensates for the parasitic serial resistance by implementing asymmetric measurement and calculation algorithms that account for the different impedance paths, thereby maintaining measurement accuracy across both bus bar and battery cell configurations.
3Reliability
If more protecting components are added around the IC, then ESD protection is improved, but the bill of material increases
Solution Approach 1:
Multiple ESD protection functions are merged into integrated protection circuits within the IC itself, eliminating the need for numerous discrete protecting components on the external circuit board. This integration maintains robust ESD protection while dramatically reducing the bill of material by consolidating protection functionality into the IC chip.
Solution Approach 2:
The IC incorporates self-service ESD protection mechanisms that provide protection without requiring external protecting components. The internal ESD protection circuits are designed to handle discharge events autonomously, reducing dependency on external components and thereby lowering the overall bill of material while maintaining protection effectiveness.
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 design ensures safe and efficient monitoring and balancing of battery packs with bus bars, reducing IC footprint and costs, while maintaining accurate measurements and compliance with safety standards like ISO26262.
Implementation Method 1
a plurality of bi-directional ESD protection elements, each one connected between a pair of adjacent cell-measuring-pins in the sequence
Implementation Method 2
a plurality of dual polarity switches, each one connected between a pair of adjacent cell-balancing-pins in the sequence
Implementation Method 3
a plurality of cell-measurement-first-diodes, one for each of the cell-measuring-pins; a plurality of cell-measurement-second-diodes, one for each of the cell-measuring-pins
Data Source
AI summary
A battery management system, BMS, integrated circuit, IC, (102) for a battery pack. The battery pack (101) comprises a sequence of battery cells connected in series; and a sequence of battery-cell-connection-nodes between adjacent battery cells. The BMS IC (102) comprises: a sequence of cell-measuring-pins (104) for connecting to corresponding battery-cell-connection-nodes; a plurality of bi-directional ESD protection elements (105), each one connected between a pair of adjacent cell-measuring-pins (104) in the sequence; a sequence of cell-balancing-pins (106) for connecting to corresponding battery-cell-connection-nodes; and a plurality of dual polarity switches (107), each one connected between a pair of adjacent cell-balancing-pins in the sequence.