Low-Inductance Capacitor Design for Multiphase Systems
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Solution Overview
Problem
In power electronics, intermediate circuit capacitors in polyphase systems experience high power losses due to alternating currents and magnetic interactions, leading to increased inductance and heat generation, which complicates cooling and affects the performance of switching semiconductor switches.
Innovation Solution
A capacitor design featuring parallel and overlapping voltage layers with a gap, where each layer is in electrical contact with a terminal via a contact-making element, reducing inductance by guiding current paths close to each other with opposite current flow directions, thereby minimizing magnetic coupling losses and enhancing cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional capacitor design with separate voltage layers is used, then manufacturing is simpler, but inductance increases leading to higher power losses
Solution Approach 1:
The patent merges the first and second voltage layers into a single plane, creating an integrated capacitor structure where both voltage layers coexist on the same substrate plane. This merging eliminates the need for stacked three-dimensional arrangements, reduces parasitic inductance by minimizing current loop areas, and simplifies the overall device structure while lowering power losses from magnetic interactions.
2Loss of energy
If voltage layers are placed close together to reduce inductance, then magnetic coupling losses increase, but if placed farther apart, then inductance increases
Solution Approach 1:
The patent transitions from a vertical stacking arrangement (three-dimensional separation) to a planar side-by-side arrangement (two-dimensional separation). By placing the first and second voltage layers adjacent to each other on the same substrate plane rather than stacking them vertically, the design minimizes the area enclosed by current loops, thereby reducing parasitic inductance and magnetic coupling losses without requiring large vertical distances.
3Use of energy by moving object
If alternating current flows through the capacitor, then energy storage function is achieved, but frequency-dependent high power losses occur
Solution Approach 1:
The patent changes the geometric parameters of the capacitor structure by adopting a planar configuration with minimized current loop areas. This parameter change reduces the parasitic inductance of the capacitor, which directly lowers the frequency-dependent power losses that occur during alternating current operation, while preserving the energy storage function through the capacitor's fundamental C-V relationship.
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 achieves low-inductance connections, reduces power losses, and simplifies cooling, allowing for the use of heat-sensitive capacitor structures while improving electromagnetic compatibility and reducing demands on switching semiconductor switches.
Implementation Method 1
the magnetic interaction between the current layers effected with an opposite direction of current flow
Implementation Method 2
the effects caused by magnetic coupling of the magnetic fields of conductors lying close next to one another
Implementation Method 3
the capacitor comprises at least one capacitor structure, which has at least one dielectric
Implementation Method 4
which has at least one dielectric and is arranged on an upper side of the first voltage layer
Implementation Method 5
The contributions to the losses of the first voltage layer and the second voltage layer owing to skin effects and proximity effects are reduced
Implementation Method 6
Proximity effects result in current constrictions or current displacements between conductors which are close next one another in the case of alternating currents
Data Source
AI summary
The invention relates to a capacitor (1), particularly an intermediate circuit capacitor for a multiphase system, with a first voltage layer (11) and a second voltage layer (21), the first voltage layer (11) and the second voltage layer (21) forming an overlapping region (4) in which the first voltage layer (11) and the second voltage layer (21) are parallel to each other and arranged directly one above the other, at a distance from each other by means of a gap (5), on a base side (6) of the capacitor (1), with at least one capacitor structure (3) comprising at least one dielectric (2), arranged on an upper side (13) of the first voltage layer (11), facing away from the second voltage layer (21), the first voltage layer (11) being in electroconductive contact with a first terminal (15) of the capacitor structure (3) and the second voltage layer (21) being in electroconductive contact with a second terminal (25) of the capacitor structure (3) by means of a contacting element (30). According to the invention, the first voltage layer (11) has at least one recess (14) through which the contacting element (30) is guided.