Bus Bar Terminal Connector Current Shaping

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Solution Overview

Problem

In power electronic devices, semiconductor switches face challenges due to cyclic thermal stresses, leading to delamination, debonding, and electrochemical failures, and maintaining thermal and electrical balance is difficult, resulting in uneven heating and power losses.

Innovation Solution

The design of bus bars with reshaped supply and load terminal connectors to balance impedances and optimize mutual inductances, ensuring all terminals experience the same current flow and thermal environment, thereby minimizing stray inductance and resistive losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional terminal connectors are used to connect multiple terminals, then the electrical connection is established, but the current flow becomes unbalanced across terminals leading to uneven power losses

Engineering Contradiction:
Improveelectrical connection stabilityVSAvoidpower losses
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies local quality by creating non-uniform gap distributions in the terminal connector. Specifically, gaps between adjacent terminals are varied in size - some gaps are larger while others are smaller - to compensate for differences in terminal impedances. This localized adjustment of gap dimensions ensures that current flow is balanced across all terminals, preventing uneven power losses while maintaining reliable electrical connections.

Inventive Principle:
Principle #3Local quality

2Device complexity

If terminals are arranged in a conventional configuration, then the device structure is simple, but thermal and electrical balance cannot be maintained leading to delamination and debonding

Engineering Contradiction:
Improveterminal connector structureVSAvoidbonding integrity
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent employs parameter changes by systematically varying gap dimensions between terminals based on their specific impedance characteristics and thermal requirements. Each gap is designed with a specific width and length to achieve desired current distribution and thermal balance. This parameter optimization prevents excessive thermal stress that would otherwise cause delamination and debonding, while the overall connector structure remains relatively simple.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If uniform gaps are used between terminals, then the manufacturing process is simplified, but electrical balance is compromised leading to unequal current flow

Engineering Contradiction:
Improvegap fabricationVSAvoidelectrical balance precision
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent implements local quality by introducing controlled variations in gap dimensions at specific terminal locations. Rather than using uniform gaps throughout, the design specifies different gap sizes based on local electrical requirements - larger gaps where impedance is lower and smaller gaps where impedance is higher. This localized customization achieves precise electrical balance while remaining compatible with standard manufacturing processes.

Inventive Principle:
Principle #3Local quality

4Power

If terminal connectors are designed for high current capacity, then power handling is improved, but thermal stresses increase causing fatigue cracking

Engineering Contradiction:
Improvecurrent handling capabilityVSAvoidresistance to thermal fatigue
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent applies parameter changes by optimizing gap dimensions to balance current distribution and reduce thermal stress concentrations. The gap sizes are specifically calculated to ensure that high current flow does not create excessive localized heating. By distributing current more evenly across terminals through controlled gap variations, the design handles high power while minimizing thermal fatigue that would lead to fatigue cracking.

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

This approach reduces switching heat loss, improves response time, and ensures uniform power dissipation across terminals, enhancing the overall performance and reliability of power electronic devices.

Implementation Method 1

a conductive plate that extends from a first edge to an opposite second edge and extends from a third edge to an opposite fourth edge

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

The plate includes a window opening located between the first and second edges and between the third and fourth edges. The plate also includes a slot extending into the plate from the first edge to the window opening

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 3

The plate includes first and second sets of openings configured to receive connections with first and second power terminals of switch packages

Methodology Applied
Scientific EffectElectrical contact: Conduction (electrical)

Data Source

PatentUS11239618B2Bus bar and power electronic device with current shaping terminal connector and method of making a terminal connector
Publication Date: 2022.02.01 TRANSPORTATION IP HOLDINGS LLC
  • US11239618B2 patent drawing
  • US11239618B2 patent drawing
  • US11239618B2 patent drawing

AI summary

A bus bar includes a load terminal connector comprising a conductive plate that extends from a first edge to an opposite second edge and extends from a third edge to an opposite fourth edge. The third and fourth edges extend from the first edge to the second edge. The plate includes a window opening located between the first and second edges and between the third and fourth edges. The plate also includes a slot extending into the plate from the first edge to the window opening. The plate includes first and second sets of openings configured to receive connections with first and second power terminals of switch packages. The first set of openings and the second set of openings are located on opposite sides of the slot.