DC Link Capacitor Module With Stepped Center Tap Insulation
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Solution Overview
Problem
Existing intermediate circuit capacitor modules in electric vehicles face challenges with improved electrical insulation and reduced heat load due to close proximity of DC+ and DC- potentials, leading to increased short circuit risks and heating.
Innovation Solution
The solution involves connecting at least two windings in series with a center tap, using stepped or alternately stepped contact strips to separate end faces of windings connected to different connecting plates, along with a shielding plate and thermal connection to a base plate, which dissipates eddy currents and improves insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If windings are connected in series with center tap using common contact handle, then electrical connection is simplified, but electrical insulation deteriorates due to close proximity of DC+ and DC- potentials
Solution Approach 1:
The patent introduces a stepped contact strip that creates vertical separation between DC+ and DC- potentials in the z-dimension. The first contact region is positioned at a different height than the second contact region, transforming a two-dimensional planar contact into a three-dimensional stepped structure. This dimensional change increases the creepage distance and electrical insulation between opposite polarity contacts while maintaining the simplified series connection topology.
2Volume of moving object
If connecting plates are placed close together for compact design, then device size is reduced, but electrical insulation deteriorates increasing short circuit risk
Solution Approach 1:
The stepped contact strip creates vertical separation between DC+ and DC- potentials in the z-dimension. The first contact region is positioned at a different height than the second contact region, transforming a two-dimensional planar contact into a three-dimensional stepped structure. This dimensional change increases the creepage distance and electrical insulation between opposite polarity contacts while maintaining the simplified series connection topology.
Solution Approach 2:
The contact strip serves as an intermediary element between the windings and connecting plates. It provides isolated contact regions for DC+ and DC- potentials, mediating the electrical connection while maintaining electrical insulation. The stepped structure of the contact strip acts as a physical barrier and insulating mediator that prevents direct contact between opposite polarity terminals.
3Loss of energy
If current flow path is shortened for efficiency, then power loss is reduced, but heat generation increases due to eddy currents in connecting plates
Solution Approach 1:
The patent extracts the eddy current path from the connecting plates by introducing a thermally conductive base plate that provides an alternative heat dissipation path. The base plate absorbs and conducts away the heat generated by eddy currents in the connecting plates, separating the electrical connection function from the thermal management function. This extraction prevents heat accumulation in the windings while maintaining efficient current flow.
Solution Approach 2:
The base plate serves as a thermal intermediary between the connecting plates and the environment. It provides a dedicated thermal conduction path that mediates heat transfer from the eddy current sources in the connecting plates, preventing heat buildup in the windings while allowing efficient electrical connections to be maintained.
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 enhances electrical insulation, reduces short circuit risks, minimizes heat generation, and allows for a compact design with efficient heat dissipation, thereby maintaining capacitance and reducing the size of the DC link capacitor.
Implementation Method 1
This effectively dissipates eddy current effects caused by the close current flow through the connecting plates to the base plate, thus reducing the resulting heat load in the windings
Implementation Method 2
the contact strip is thermally and electrically connected to a base plate. This effectively dissipates eddy current effects
Data Source
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AI summary
The invention relates to a DC link capacitor module (1) for an inverter (100), wherein the DC link capacitor module (1) has at least two windings (2) connected in series and having a central tap, wherein the windings (2) are connected to connecting plates (5, 6), wherein a first connecting plate (5) has terminals (7) for a positive contact (DC+) and terminals (8) for semiconductor switches (17) of the inverter (100), and the second connecting plate (6) has terminals (9) for a negative contact (DC-) and terminals (10) for semiconductor switches (17), wherein the windings (2) have a first end face (3) and a second end face (4) each with a contact, wherein the DC link capacitor module (1) has at least one contact strip (26), wherein the at least one contact strip (26) contacts the central taps of the windings (2).wherein the contact strip (26) is stepped or alternately stepped such that the first end face (3) or the first end faces (3) of the winding(s) (2) connected to the first connecting plate (5) lie in a different plane than the first end faces (3) of the winding(s) (2) connected to the second connecting plate (6), and an inverter (100).