Semiconductor Bridging Element for Defective Battery Cell Isolation

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Solution Overview

Problem

The reliability and operational security of energy storage systems, particularly in electric vehicles, are compromised when a single defective battery cell causes the entire system to fail, leading to excessive heating and potential system failure, as existing bridging elements are not effective in distinguishing between healthy and defective cells.

Innovation Solution

A bridging element with a semiconductor substrate and doped regions is designed, where an electrically conductive material diffuses to create a low-impedance current path when predefined conditions are met, reducing resistance and enabling reliable bridging of defective cells without overheating healthy ones.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a bridging element permanently short-circuits a defective battery cell, then the reliability of the energy storage system is improved by allowing continued operation, but the risk of excessive heating and system failure increases if a healthy cell is incorrectly bridged

Engineering Contradiction:
Improvesystem operational reliabilityVSAvoidexcessive heating
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention changes the triggering parameter from a simple voltage threshold to a time-dependent voltage threshold. The bridging element monitors the voltage of the battery cell and triggers the short-circuit only when the voltage remains below a predefined threshold for a predefined time period. This time-dependent parameter change allows the system to distinguish between temporarily low voltage in healthy cells and permanently low voltage in defective cells, preventing incorrect bridging of healthy cells and the associated excessive heating risk.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention performs a preliminary monitoring action before triggering the bridging. The control unit monitors the battery cell voltage continuously and evaluates whether the voltage has been below the threshold for the required time period before activating the short-circuit. This preliminary evaluation action ensures that only genuinely defective cells are bridged, preventing premature or incorrect bridging decisions that could lead to excessive heating in healthy cells.

Inventive Principle:
Principle #10Preliminary action

2Ease of operation

If existing bridging elements are used that permanently short-circuit upon triggering, then the bridging function is achieved, but the ability to distinguish between healthy and defective cells is insufficient leading to potential misbridging

Engineering Contradiction:
Improvebridging activationVSAvoidcell defect detection precision
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The invention enhances the measurement precision by changing from a simple voltage threshold parameter to a time-dependent voltage threshold parameter. The control unit measures the battery cell voltage over time and compares it against a time-dependent threshold, enabling more precise differentiation between healthy and defective cells. This improved measurement precision ensures that only cells with genuine defects are bridged, while healthy cells with temporary voltage dips remain operational.

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If the pn junction is located far from the connection region, then the semiconductor structure is more stable, but the resistance reduction upon triggering is insufficient for reliable bridging

Engineering Contradiction:
Improvesemiconductor structure stabilityVSAvoidbridging function reliability
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The invention applies local quality by creating a highly doped region with specific properties localized at the connection region. The first doped region has a doping concentration of at least 10^19 atoms/cm³, which is significantly higher than typical semiconductor regions. This localized high doping concentration creates a region with specific electrical properties that enable reliable low-resistance connection upon triggering, while the rest of the semiconductor structure maintains its stability. The local quality change allows the pn junction to be positioned close to the connection region without compromising overall structure stability.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention changes the doping concentration parameter in the first doped region to at least 10^19 atoms/cm³, which is an extreme value compared to typical semiconductor doping levels. This parameter change in the localized region enables the connection structure to achieve very low resistance when triggered, ensuring reliable bridging function. The high doping concentration parameter creates a highly conductive path that can reliably short-circuit the battery cell when activation is required.

Inventive Principle:
Principle #35Parameter changes

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 solution significantly reduces resistance between connection structures, allowing for reliable and cost-effective bridging of defective battery cells, preventing system failure and maintaining energy supply even with faulty cells, while minimizing heat dissipation and operational costs.

Implementation Method 1

the electrically conductive material provided for diffusion into the semiconductor substrate diffuses at least partially through the first doped region into the second doped region when predefined triggering conditions occur

Methodology Applied
Scientific EffectDiffusion: Diffusion

Implementation Method 2

The pn junction between the first doped region and the second doped region is at least partially arranged at a distance of less than 5 μm from a connection region of the first doped region

Methodology Applied
Scientific Effectpn junction: Diode

Data Source

PatentEP2947696B1Device and method for bridging an electrical energy store
Publication Date: 2020.09.02 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP2947696B1 patent drawingFigure 1
  • EP2947696B1 patent drawingFigure 2
  • EP2947696B1 patent drawingFigure 3A~3B

AI summary

A device 10 for bridging an electrical energy storage device comprises a semiconductor substrate with a first doped region 3 arranged on a surface of the semiconductor substrate and a second doped region 4 adjacent to the first doped region 3. The pn junction between the first doped region 3 and the second doped region 4 is located at least partially less than 5 µm from a connection area of ​​the first doped region 3 located on the surface of the semiconductor substrate. Furthermore, the device comprises a first connection structure 2 which is in contact with the first doped region 3 in the connection area of ​​the first doped region 3 and which at least partially comprises an electrically conductive material intended for diffusion into the semiconductor substrate.The first connection structure 2 is designed such that the electrically conductive material intended for diffusion into the semiconductor substrate diffuses at least partially through the first doping region 3 into the second doping region 4 when predefined triggering conditions occur. Additionally, the device has a second connection structure 5 which is in contact with the second doping region 4 in a connection area of ​​the second doping region 4.