Smoothing Capacitor Mounting for Low-Impedance Vehicle Power Conversion
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Solution Overview
Problem
The existing power conversion devices for electric and hybrid vehicles suffer from decreased performance of the smoothing capacitor due to long connection lines, leading to impaired electromagnetic compatibility and increased impedance, which is not adequately addressed in previous patents.
Innovation Solution
An in-vehicle power conversion device design that integrates a smoothing coil and capacitor with conductive housing and resin members, providing additional electrical and mechanical connections to reduce impedance and enhance the smoothing capacitor's performance, while facilitating manufacturing and downsizing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the smoothing capacitor is arranged next to the integrated component, then the device can be downsized and manufacturing facilitated, but the connection lines become long and impedance increases, resulting in decreased capacitor performance
Solution Approach 1:
The patent integrates the smoothing capacitor directly into the molded member that houses the transformer, choke coil, and rectifier element. The capacitor is positioned inside the housing formed by the molded member, eliminating the need for external mounting and long connection lines. This merging of components resolves the contradiction by achieving downsizing while maintaining short connection paths and low impedance.
Solution Approach 2:
The patent introduces a terminal as an intermediary element that provides both mechanical connection and electrical connection between the smoothing capacitor and the external circuit. The terminal is integrated into the molded member structure, allowing the capacitor to be positioned optimally within the housing while maintaining low-impedance electrical connections through the terminal's direct integration with the conductive housing.
2Volume of moving object
If the smoothing capacitor is arranged next to the integrated component, then the device can be downsized, but the connection lines increase in length and electromagnetic compatibility characteristics deteriorate
Solution Approach 1:
The smoothing capacitor is merged with the integrated component housing, positioned inside the molded member structure. This integration eliminates long external connection lines that would act as antennas for electromagnetic radiation, thereby resolving the contradiction between downsizing and maintaining electromagnetic compatibility characteristics.
Solution Approach 2:
The conductive housing that could potentially act as an electromagnetic shield is converted into a beneficial element by providing a low-impedance return path for high-frequency currents. The housing's conductivity is utilized to suppress electromagnetic radiation from the capacitor connections, transforming a potential harmful factor into a benefit for EMC performance.
3Ease of manufacture
If the smoothing capacitor is arranged next to the integrated component, then manufacturing can be facilitated, but the connection lines become long and impedance increases
Solution Approach 1:
The smoothing capacitor is integrated into the molded member structure during the molding process itself, allowing all components (transformer, choke coil, rectifier element, and capacitor) to be assembled as a single unit. This merging maintains manufacturing simplicity while eliminating the need for separate capacitor mounting and short connection lines, thus preserving capacitor performance.
Solution Approach 2:
The molded member serves multiple functions: it houses the transformer, choke coil, and rectifier element, provides structural support, and integrates the smoothing capacitor mounting. This multi-functionality maintains ease of manufacture through a single molding process while ensuring optimal capacitor positioning and short connection paths.
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
The design effectively reduces impedance, maintains capacitor performance, and facilitates manufacturing and downsizing of the power conversion device, thereby improving electromagnetic compatibility.
Implementation Method 1
a rectifier circuit configured to rectify an AC voltage generated in the secondary winding into a pulsating voltage
Implementation Method 2
a smoothing circuit which includes a smoothing coil and a smoothing capacitor, and is configured to smooth the pulsating voltage rectified by the rectifier circuit
Data Source
AI summary
Provided is an in-vehicle power conversion device in which a smoothing capacitor includes a first electrical connection portion, a second electrical connection portion, a mechanical connection portion, and a smoothing capacitor main body. The first electrical connection portion is electrically connected to a first conductor. The second electrical connection portion is electrically connected to a second conductor. The mechanical connection portion functions as an additional electrical connection portion configured to fix the smoothing capacitor main body to the first conductor or the second conductor to be electrically connected to a fixing destination of the smoothing capacitor main body.