Inverter Capacitor Bus Plate Layout for Low-Inductance Power Modules
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Solution Overview
Problem
The existing inverter structures in electric vehicles are hindered by large size and weight due to high-voltage power handling, leading to increased heat generation, electromagnetic interference, and energy loss, which complicates space management and balance in vehicle design.
Innovation Solution
The inverter structure incorporates a smoothing capacitor with columnar unit capacitors and plate-shaped bus plates, arranged parallel to each other, allowing for reduced inductances and improved layout flexibility, which shortens bus bar lengths and reduces inductances, enabling size reduction and efficient power module placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional bus bars with complex shapes are used to connect power modules and smoothing capacitor, then the inverter can handle high voltage and large current, but the inductances of the bus bars increase causing noise, vibration, electromagnetic interference, and energy loss
Solution Approach 1:
The smoothing capacitor is divided into multiple columnar unit capacitors arranged side by side, each connected to bus plates. This segmentation allows for shorter bus bar connections from each power module to individual unit capacitors, reducing overall inductance while maintaining high voltage handling capability through parallel configuration
Solution Approach 2:
The unit capacitors are arranged in a planar configuration side by side, allowing power modules to be positioned optimally in the same plane. This two-dimensional layout reduces the vertical distance and wiring length compared to traditional three-dimensional stacking, thereby reducing inductance and electromagnetic interference
2Quantity of substance
If the wiring length of bus bars is increased to connect power modules and smoothing capacitor, then the inverter can accommodate larger components, but the electric resistance increases causing copper loss and heat generation
Solution Approach 1:
By segmenting the smoothing capacitor into multiple unit capacitors distributed in a planar arrangement, the bus bar wiring length is reduced for each connection. This segmentation allows larger total capacitance to be achieved with shorter individual bus bar lengths, reducing electric resistance and copper loss
Solution Approach 2:
Multiple unit capacitors are merged in parallel configuration to achieve the required total capacitance value. This merging allows the system to obtain large capacitance capacity while maintaining short connection lengths, as the parallel arrangement reduces the distance from power modules to capacitor terminals
3Volume of moving object
If the inverter size is reduced to improve vehicle space management, then fuel economy and power consumption improve, but the inductances of bus bars may increase due to constrained wiring length and width
Solution Approach 1:
The planar arrangement of unit capacitors side by side enables optimized two-dimensional layout within the inverter housing. This allows power modules and capacitors to be positioned in the same plane with minimal vertical spacing, reducing bus bar length and inductance while maintaining compact overall inverter volume
Solution Approach 2:
The invention changes the physical arrangement parameters from traditional vertical stacking to horizontal planar distribution. This parameter change in spatial configuration reduces wiring length and inductance, allowing smaller inverter size without compromising electrical performance
Data Source
AI summary
In an inverter that includes a smoothing capacitor and a plurality of power modules, the smoothing capacitor includes a plurality of columnar unit capacitors each having electrodes at both ends thereof, a one-end-side bus plate connected to the electrode at one end of each unit capacitor, and an other-end-side bus plate connected to the electrode at the other end of the unit capacitor. The unit capacitors are arranged, with axes thereof parallel to each other, side by side in a direction perpendicular to the axes. The plurality of power modules is arranged, with respect to the smoothing capacitor, side by side in a direction perpendicular to the axes of the unit capacitors.