Overlapping Conductive Layer Bus Assembly for Stray Inductance Reduction
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Solution Overview
Problem
Circulating currents generated by stray inductances in electric drive systems of vehicles with alternating current (AC) drive systems cause component stress and reduce the operational life of components, leading to increased heat and voltage ripples.
Innovation Solution
A bus assembly with overlapping conductive layers and insulator sheets reduces stray inductance by aligning conductive layers and using capacitors to couple arms to the bus bar, forming a capacitor bus with multiple capacitors, which decreases circulating currents and increases resonance frequency and damping factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If bus bars are used to connect multiple inverters to a DC bus, then the connection is simple and direct, but stray inductances are generated between the inverters causing circulating currents
Solution Approach 1:
The patent transitions from a single-plane bus bar connection to a multi-layer conductive structure with overlapping conductive layers separated by an insulator sheet. This dimensional change creates multiple parallel current paths, reducing stray inductance and circulating currents while maintaining connection simplicity.
Solution Approach 2:
The invention uses a composite structure combining multiple conductive layers (e.g., copper or aluminum) with an insulator sheet (e.g., fiberglass or plastic) to create a laminated bus assembly. This composite design reduces inductance while providing electrical isolation and mechanical strength.
2Ease of manufacture
If conventional bus bars are used for inverter connection, then manufacturing is straightforward, but circulating currents generate excessive heat reducing component life
Solution Approach 1:
The patent employs multiple overlapping conductive layers separated by insulator sheets, creating a three-dimensional laminated structure. This multi-layer configuration reduces stray inductance and circulating currents, thereby reducing heat generation and extending component operating life while remaining manufacturable using standard lamination techniques.
3Device complexity
If traditional bus bar connections are used, then the structure is simple, but voltage ripples are generated causing control problems
Solution Approach 1:
The patent uses multiple overlapping conductive layers with insulator sheets to create a multi-plane connection structure. This dimensional approach distributes current paths and reduces voltage ripples, improving inverter control stability without significantly increasing structural complexity.
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 reduces circulating currents, extends the operational life of components, and decreases manufacturing complexity and costs by minimizing heat generation and voltage ripples.
Implementation Method 1
The first and second conductive layers are at least partially aligned with respect to each other to form a first overlap region of the insulator sheet
Implementation Method 2
an insulator sheet interposed between the first and second conductive layers
Implementation Method 3
decreases circulating currents and increases resonance frequency and damping factor
Implementation Method 4
increases resonance frequency and damping factor
Data Source
AI summary
A bus assembly is provided having a bus bar with first and second conductive layers extending along an insulator sheet interposed between the first and second conductive layers. The first and second conductive layers are partially aligned with respect to each other to form a first overlap region of the insulator sheet. The bus assembly includes a first set of arms having a set of diodes and a second set of arms having a set of switches. The bust bar includes a plurality of bus links coupling the plurality of arms to the bus bar forming a plurality of inverters. Each of bus links include a respective first bracket and a respective second bracket aligned with each other forming a second overlap region of the insulator sheet. The first bracket is electrically coupled to the first conductive layer and the second bracket is electrically coupled to the second conductive layer.