AC Busbar Layout for Balanced Current Sharing in Inverter Modules

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Solution Overview

Problem

Existing AC busbar configurations for high voltage applications fail to achieve equal current sharing and balancing among parallelly connected semiconductor switches, leading to potential damage and reduced reliability of inverter modules.

Innovation Solution

The AC busbar is designed with a terminal-side conductor, a load-side conductor, two connecting conductors, and an orthogonally projecting conductor, where the distance between the terminal-side and load-side conductors is optimized to minimize the inductance difference between connection points, ensuring balanced current distribution among phases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If inductance is added between the output of the terminals of the respective pairs of semiconductor switches and the busbar to improve current sharing, then current balancing is improved, but the size of the inverter module increases

Engineering Contradiction:

Improvecurrent balancingVSAvoidinverter module size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The busbar structure implements local quality by creating different geometric configurations for different phases. The first busbar has a different shape than the second busbar, with varying distances between connection points and the central axis. This local geometric variation compensates for inherent inductance differences in each phase path, achieving current balancing without adding external inductance components that would increase module size.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention changes the geometric parameters of the busbar structure itself to control inductance. By adjusting the distance between connection points and the central axis, and by varying the busbar shapes, the path inductances are modified to achieve balancing. This parameter adjustment approach achieves current sharing improvement without adding separate inductance components, thus avoiding increased module size.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If equal current path lengths are used in the busbar configuration, then manufacturing simplicity is improved, but current balancing among parallelly connected semiconductor switches is not achieved

Engineering Contradiction:

Improvebusbar configurationVSAvoidcurrent sharing

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention deliberately introduces asymmetry in the busbar configuration. Instead of symmetric equal-length paths, the busbars have different shapes and different distances from the central axis. This asymmetric design is specifically engineered to compensate for phase-specific inductance differences, achieving current balancing while maintaining manufacturing simplicity through a single busbar structure type.

Inventive Principle:

Principle #4Asymmetry

3Reliability

If the distance between terminal-side conductor and load-side conductor is reduced to minimize inductance, then inductance difference is reduced, but the space for other components is reduced

Engineering Contradiction:

Improveinductance differenceVSAvoidinverter module area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The invention optimizes the spatial arrangement of busbars in multiple dimensions. By positioning busbars at different distances from the central axis and arranging them in a multi-dimensional configuration, the design achieves low inductance difference while effectively utilizing available space. This dimensional optimization allows for reduced inductance without proportionally reducing the overall module area, as space is efficiently allocated across different spatial dimensions.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 configuration effectively balances current sharing among semiconductor switches, reducing the risk of damage and enhancing the reliability and efficiency of inverter modules by maintaining inductance differences below a predetermined percentage.

Implementation Method 1

A distance between the terminal-side conductor and the load-side conductor is such that a difference in an inductance between a connection point for a respective AC terminal of each phase and a common point on a middle of the load-side conductor is less than a predetermined percentage with respect to an average of the respective inductances

Methodology Applied

Scientific EffectInductance: Inductor

Data Source

PatentUS12327991B2AC busbar for current sharing between parallelly connected semiconductor switching pairs

Publication Date: 2025.06.10 BAE SYSTEMS CONTROLS INC

AI summary

An AC busbar for connecting at least three phases from a semiconductor switching unit to a load is provided. The AC busbar parallelly connects the at least three phases and provides current balancing. The AC busbar has a terminal-side conductor mechanically connectable to each AC terminal of the semiconductor switching unit and a load-side conductor positioned between the terminal-side conductor and the load. A distance between the terminal-side conductor and the load-side conductor is such that a difference in an inductance between a connection point for a respective AC terminal of each phase and a common point on a middle of the load-side conductor is less than a predetermined percentage with respect to an average of the respective inductances.