Full-Bridge Inverter Module Layout for Low Loop Inductance
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Solution Overview
Problem
Inverters for electric vehicles face challenges due to loop inductance associated with phase switches, which affect switching losses, especially with the use of silicon carbide devices, leading to inefficiencies in motor driving.
Innovation Solution
A power module design with overlapping DC power rails and optimized switch configurations reduces loop inductance by placing positive and negative DC power rails in separate planes and using dual-sided cooling, along with a balanced internal geometry to minimize stray inductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional power module design is used, then device complexity is reduced, but loop inductance increases causing higher switching losses
Solution Approach 1:
The patent transitions from a conventional planar single-sided layout to a three-dimensional multi-layer configuration with DC power rails extending through multiple layers of the substrate. This dimensional change allows the DC power rails to be positioned directly beneath the switches, minimizing the loop area and reducing loop inductance, thereby decreasing switching losses while maintaining a compact form factor
Solution Approach 2:
The patent embeds the DC power rails within the substrate layers, nesting them directly underneath the switches in a vertical arrangement. This nesting approach minimizes the distance between power supply and switching elements, reducing the loop inductance and associated switching losses without increasing the overall footprint of the power module
2Loss of energy
If DC power rails are positioned close to switches, then loop inductance decreases, but manufacturing precision requirements increase
Solution Approach 1:
The patent merges the DC power rails with the substrate structure itself, integrating them as inherent features of the substrate rather than separate components. This integration allows for precise positioning to be achieved through the substrate fabrication process itself, reducing the need for additional high-precision assembly steps while maintaining low loop inductance
Solution Approach 2:
The substrate serves multiple functions: it provides mechanical support for the switches, contains and positions the DC power rails, and facilitates thermal management. This multi-functionality allows the same structural element to achieve both low loop inductance through integrated rail positioning and ease of manufacturing through a unified fabrication process
Data Source
AI summary
A system including: first switches to receive positive DC power to generate the AC power, a positive DC power rail to provide the positive DC power to the first switches, positive DC power tabs connected to the positive DC power rail, second switches to receive negative DC power to generate the AC power, a negative DC power rail to provide the negative DC power to the second switches, negative DC power tabs connected to the negative DC power rail; and AC power tabs to receive the AC power from the first switches and the second switches, wherein the positive DC power rail is provided in a first plane on a first side of the first switches and the second switches, and the negative DC power rail is provided in a second plane on a second side of the first switches and the second switches and opposite to the first side.