Diametrically Mounted Power Capacitors for AC Motor Transmissions
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Solution Overview
Problem
In automotive vehicles, the space-efficient packaging of power capacitors for AC motors integrated with transmissions is challenging due to their significant volume, which complicates the packaging of other drive components and increases the risk of heat-related issues and electromagnetic interference.
Innovation Solution
The power capacitors are mounted diametrically on the transmission, allowing for annular or arcuate configurations with gaps, providing a large surface area for cooling and EMI shielding, and can be cooled by air or liquid, thereby optimizing space usage and reducing component volumes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If power capacitors are mounted inside the transmission housing, then EMI shielding is improved, but packaging space is insufficient and heat dissipation is poor
Solution Approach 1:
The patent transitions the capacitor mounting from a two-dimensional internal placement to a three-dimensional external arrangement on the transmission housing surface. By utilizing the external surface area of the transmission housing, the capacitor is positioned in a different spatial dimension that provides adequate packaging space while maintaining proximity to the motor for EMI shielding effectiveness.
Solution Approach 2:
The patent segments the transmission system into distinct functional zones: the motor assembly, the transmission housing, and the externally mounted capacitor. This segmentation allows each component to be optimized independently - the capacitor can be positioned for optimal EMI shielding without constraining the internal packaging of the transmission or motor components.
2Volume of moving object
If power capacitors are mounted externally on the transmission, then packaging space is improved, but heat dissipation becomes insufficient
Solution Approach 1:
The patent applies local quality enhancement by adding dedicated cooling features specifically at the capacitor mounting location on the transmission housing. The housing is designed with increased surface area, cooling fins, or thermal pathways in the local region where the capacitor is mounted, providing enhanced heat dissipation capability precisely where needed without affecting the overall packaging efficiency.
Solution Approach 2:
The patent employs liquid cooling systems (hydraulic principle) to manage heat dissipation from the externally mounted capacitor. Cooling channels or heat exchanger pathways are integrated into the transmission housing, allowing coolant flow that efficiently removes heat from the capacitor while maintaining a compact external configuration.
3Volume of moving object
If capacitor volume is reduced to improve packaging, then packaging efficiency is improved, but capacitance performance and reliability deteriorate
Solution Approach 1:
The patent changes the physical parameters of the capacitor by transitioning from traditional cylindrical wound construction to flat panel or layered configurations. This parameter change in geometry allows achieving the same or higher capacitance values with reduced volume, improving packaging efficiency while maintaining or enhancing reliability through better surface-area-to-volume ratios for heat dissipation.
Solution Approach 2:
The patent utilizes composite material structures in the capacitor construction, combining multiple dielectric layers, conductive materials, and cooling interfaces. These composite structures enable high capacitance density in a compact form factor while providing integrated thermal management pathways that maintain reliability despite the reduced overall volume.
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 the reliability and efficiency of the drive system by allowing for better heat dissipation and reduced capacitance derating, while also providing effective EMI shielding and space savings, leading to improved packaging and reduced component costs.
Implementation Method 1
capacitors are used as energy storage devices providing power buffers to maintain relatively smooth dc link voltages
Implementation Method 2
the power capacitor is cooled by circulating liquid which transfers heat from the power capacitor to a radiator
Implementation Method 3
the power capacitor is cooled by circulating liquid which transfers heat from the power capacitor to a radiator
Implementation Method 4
the power capacitor is cooled by air flowing over the power capacitor
Data Source
AI summary
Power capacitors for AC motors are mounted diametrically on associated transmissions. The power capacitors are in one embodiment annular and in another embodiment, arcuate. By having power capacitors mounted on transmission housings diametrically, cooling of the power capacitors is facilitated for both air and liquid cooling.