Power Conversion Device Noise Reduction via Capacitor Overlap
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Solution Overview
Problem
Existing power conversion devices for electric and hybrid vehicles face increased noise levels due to higher inverter circuit frequencies and component densities, leading to vibration-related damage and high costs for vibration mitigation and substrate materials.
Innovation Solution
A power conversion device configuration with a transformer and smoothing reactor on a base, where the smoothing capacitors are mounted on a control substrate at a different height, overlapping with rectification elements to reduce noise impedance, and the transformer and reactor are easily supported to mitigate vibrations, using a base as both a support and a low-potential terminal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the smoothing reactor is supported only through connection between transformer and terminal, then the noise level is reduced, but the smoothing reactor is greatly shaken by vibrations and core and copper wire are damaged
Solution Approach 1:
The patent merges the support function with the existing structural components (base and housing) rather than adding separate support structures. The smoothing reactor is positioned to rest on the base and be surrounded by the housing, combining mechanical support with the enclosures already present in the system.
Solution Approach 2:
The base and housing structures serve dual purposes: they provide mechanical support for the smoothing reactor and simultaneously act as vibration-damping enclosures. The system uses its own structural components for support rather than requiring additional dedicated support elements.
2Reliability
If a support structure and cushioning members are added for the smoothing reactor, then vibration resistance is improved, but the cost increases significantly
Solution Approach 1:
The base and housing are designed to perform multiple functions simultaneously: structural support, vibration damping, and noise reduction. This multi-functionality eliminates the need for separate support structures and cushioning members, reducing overall manufacturing cost while maintaining vibration resistance.
Solution Approach 2:
The existing base and housing structures serve themselves by providing vibration support and damping without requiring additional dedicated components. The system uses its own structural elements for support rather than needing external support additions.
3Object-generated harmful factors
If a thick-copper pattern substrate is used for mounting rectification element and smoothing capacitor, then the noise level is reduced, but the substrate size and cost increase
Solution Approach 1:
The patent segments the capacitor mounting function from the high-current rectification element mounting. The smoothing capacitor is mounted on a separate control substrate rather than requiring the entire substrate to handle high currents, allowing the use of standard-cost substrates for capacitor mounting while maintaining noise reduction performance.
Solution Approach 2:
Different areas of the substrate system have different current handling requirements. The rectification element area uses thick-copper patterns for high current, while the capacitor area uses standard substrate materials. This local differentiation reduces overall substrate cost while maintaining noise reduction where high current flows.
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 reduces noise levels and costs by minimizing substrate expenses and providing effective vibration support for heavy components, while maintaining efficient noise reduction.
Implementation Method 1
a transformer for converting the high AC voltage into a low AC voltage
Implementation Method 2
a rectification element for rectifying the low AC voltage to convert the AC voltage into a DC pulse voltage
Implementation Method 3
a smoothing reactor and a smoothing capacitor for smoothing the DC pulse voltage
Implementation Method 4
a smoothing reactor and a smoothing capacitor for smoothing the DC pulse voltage
Implementation Method 5
a housing accommodating these components and including a water path for cooling heat-generating components such as the transformer and the rectification element
Data Source
AI summary
This power conversion device includes: a base; a control substrate; a first rectification element; a second rectification element; a smoothing reactor; an output filter circuit portion; a first main circuit wire; a second main circuit wire; and smoothing capacitors. As seen in a direction perpendicular to a surface of the control substrate, at least some of the smoothing capacitors and a target region obtained by combining a region in which the first rectification element is disposed, a region in which the second rectification element is disposed, and a region between the first rectification element and the second rectification element, overlap with each other, and a low-potential-side connection point of each smoothing capacitor connected to the second main circuit wire, is disposed so as to overlap with the control substrate and a region obtained by extending the target region in a specific direction and a direction opposite to the specific direction.