Half-Bridge Busbar Coating for Compact EV Inverter Isolation
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Solution Overview
Problem
Existing inverter designs for electric and hybrid vehicles require large distances between busbars to maintain electrical insulation, leading to increased space requirements that contradict the automotive industry's goal of compactness.
Innovation Solution
A half-bridge design with busbars partially covered by a current-insulating coating, extending creepage distances while allowing for reduced busbar spacing, ensuring reliable galvanic isolation and low inductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large distances are maintained between busbars to ensure electrical insulation, then galvanic isolation is improved, but the space requirements and device dimensions increase
Solution Approach 1:
An insulating coating is introduced as an intermediary substance between the busbars. This coating layer provides the necessary electrical insulation and galvanic isolation, allowing the busbars to be positioned closer together without compromising safety or performance. The mediator enables reduced spacing while maintaining isolation requirements.
Solution Approach 2:
The electrical insulation parameters are changed by applying an insulating coating with specific dielectric properties. This allows the creepage distance to be extended along the surface of the busbars through the coated path, enabling shorter air gaps between busbars while maintaining adequate insulation levels.
2Reliability
If large distances are maintained between busbars for electrical insulation, then insulation reliability is improved, but the inductance and space requirements increase
Solution Approach 1:
The insulating coating serves as a mediator that allows busbars to be positioned closer together. This reduced spacing directly decreases the loop area of current paths, thereby reducing parasitic inductance while the coating itself maintains adequate insulation reliability through its dielectric properties.
Solution Approach 2:
By changing the insulation approach from relying on air gaps to using an insulating coating, the design enables shorter busbar spacing. This parameter change simultaneously reduces inductance (due to smaller loop areas) while maintaining insulation reliability through the coating's material properties.
3Area of stationary object
If busbar spacing is reduced for compactness, then device dimensions are improved, but electrical insulation and galvanic isolation deteriorate
Solution Approach 1:
The insulating coating acts as a mediator that compensates for the reduced busbar spacing. It provides the necessary electrical insulation barrier, allowing compact busbar arrangement without sacrificing insulation reliability. The coating fills the insulation function that would otherwise require larger air gaps.
Solution Approach 2:
Instead of maintaining insulation through increased horizontal spacing between busbars, the solution transitions to providing insulation through a vertical dimension - the thickness of the insulating coating layer. This dimensional shift enables compact packaging while maintaining adequate insulation.
4Area of stationary object
If busbar spacing is reduced for compact design, then space requirements are improved, but creepage distance and electrical insulation are compromised
Solution Approach 1:
The solution shifts the creepage distance provision from the horizontal plane (air gap between busbars) to the vertical dimension (surface path along the insulating coating). The coating provides a controlled surface path for creepage, allowing reduced horizontal spacing while maintaining adequate creepage distance along the coated surface.
Solution Approach 2:
The insulating coating serves as an intermediary that defines and controls the creepage path. By providing a controlled surface with specific dielectric properties, the coating ensures adequate creepage distance even when busbars are closely spaced, enabling compact design without compromising insulation reliability.
Data Source
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Figure 3~4
AI summary
Method for manufacturing a half-bridge (110A-C) for an electric drive of an electric vehicle or a hybrid vehicle, the half-bridge (110A-C) comprising a substrate, semiconductor switching elements, power terminals (114, 214, 116, 216) and signal terminals (120, 220), wherein the power terminals (114, 214, 116, 216) and the signal terminals (120, 220) are formed from a flat conductor frame, preferably stamped out, wherein the signal terminals (120, 220) are electrically connected to the semiconductor switching elements in such a way that the semiconductor switching elements can be switched via the signal terminals (120, 220) and wherein the power terminals (114, 214, 116, 216) are electrically connected to the semiconductor switching elements in such a way that the semiconductor switching elements enable electrical power transmission between the power terminals (114, 214, 116, 216) allow or interrupt,wherein the semiconductor switching elements are embedded in a modular layer system comprising a contacting plane (122, 222) and a metallization for contacting the semiconductor switching elements, wherein the signal terminals (120, 220) and the power terminals (114, 214, 116, 216) are arranged on a first surface of the substrate, wherein the modular layer system, the signal terminals (120, 220) and the power terminals (114, 214, 116, 216) are encapsulated with a potting compound (112, 212), wherein external sections of the power terminals (114, 214, 116, 216) and/or the signal terminals (120, 220) formed in the conductor frame extend from a second surface orthogonal to the first surface out of the potting compound (112, 212), wherein the external sections each have an end which perpendicular to the first surface.