Axial Overlapping Busbars in Annular Capacitor Assemblies
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Solution Overview
Problem
Annular capacitors in power electronics devices of electrically driven vehicles experience high inductance due to terminal lug distances, leading to switching overvoltages and potential malfunctions in semiconductor switches.
Innovation Solution
A capacitor assembly design with busbars arranged in the axial direction of a space, overlapping and electrically isolated by an insulation layer, connecting capacitor windings in parallel to reduce inductance and provide low-inductance electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If terminal lugs are distributed in a circumferential direction of the annular capacitor, then the capacitor can be connected to semiconductor switches, but the distances between terminal lugs create large surface areas that increase inductance
Solution Approach 1:
The patent transitions from a two-dimensional circumferential arrangement of terminal lugs to a three-dimensional configuration where busbars extend in the axial direction and overlap. This dimensional change allows current paths to be stacked vertically rather than spread horizontally, reducing the effective surface area and thus the inductance while maintaining all necessary electrical connections.
Solution Approach 2:
The patent merges multiple current paths by overlapping busbars in the axial direction. Instead of having separate terminal lugs distributed around the circumference, the busbars are combined in space, creating parallel current paths that reduce overall inductance. The overlapping busbars for different potentials are electrically isolated by an insulation layer, allowing them to function as integrated current carriers.
2Object-affected harmful factors
If busbars are arranged overlapping in the axial direction, then inductance is reduced, but electrical isolation between different potentials must be maintained
Solution Approach 1:
The patent introduces an insulation layer as an intermediary between overlapping busbars of different potentials. This insulation layer enables the busbars to be in close proximity (reducing inductance) while maintaining electrical isolation. The insulation layer acts as a mediator that allows the conflicting requirements of low inductance and electrical isolation to coexist.
3Ease of operation
If terminal lugs are positioned at distributed locations, then connection to semiconductor switches is enabled, but switching overvoltages occur due to high inductance
Solution Approach 1:
By arranging busbars in the axial direction with overlapping configuration, the patent creates shorter and more direct current paths compared to the circumferential arrangement. This dimensional reorganization reduces the loop area for current flow, thereby reducing inductance and the resulting switching overvoltages while maintaining full connection capability to semiconductor switches.
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 minimizes inductance, reducing the risk of switching overvoltages and enhancing the reliability of power electronics devices by limiting malfunctions and failures.
Implementation Method 1
the first and the second busbar being arranged overlapping one another; there is an electrically isolating insulation layer; the first busbar (S1), the insulation layer and the second busbar (S2) being arranged overlapping one another; and the insulation layer being arranged between the first busbar (S1) and the second busbar (S2)
Data Source
AI summary
Various embodiments of the teachings herein include a capacitor assembly comprising: a capacitor extending at least partially around a space, the capacitor including first, positive-voltage-side current terminals and second, negative-voltage-side current terminals; a first bus bar electrically connected to the first current terminals; and a second bus bar electrically connected to the second current terminals. The first and the second busbar extend parallel to or obliquely to an end face of the space.