Power Converter Noise Filter Magnetic Core Saturation
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Solution Overview
Problem
The size of noise filters in DC-DC converters is increased due to the need for large magnetic cores to prevent magnetic saturation, hindering the downsizing of these converters, especially when high DC currents are involved.
Innovation Solution
A power converter with a noise filter featuring a magnetic core with a single through-hole forming a closed magnetic circuit, where first and second wiring are wound through the core, and capacitors are placed between the wiring and ground to cancel out magnetic flux, preventing magnetic saturation and allowing for downsizing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large-sized magnetic core is used to prevent magnetic saturation in high DC current applications, then magnetic saturation is prevented, but the size of the noise filter increases
Solution Approach 1:
The patent divides the single through-hole into two separate through-holes (first through-hole and second through-hole) in the magnetic core. This segmentation allows the magnetic flux paths to be separated, enabling the use of a smaller magnetic core by distributing the magnetic flux through multiple independent paths rather than requiring a single large core to handle all flux.
Solution Approach 2:
The patent introduces a third dimension by creating a closed magnetic circuit through the combination of two through-holes and the magnetic core structure. The first and second wirings pass through different through-holes and are connected at both ends, forming a three-dimensional closed loop that optimizes magnetic flux distribution and reduces the required core size.
2Volume of stationary object
If the magnetic flux density is increased to reduce core size, then the core size decreases, but magnetic saturation occurs more easily
Solution Approach 1:
By segmenting the magnetic core into two through-holes with separate wiring paths, the magnetic flux density in each individual path is reduced compared to a single concentrated path. This segmentation allows the core to handle higher overall currents without saturation, as the flux is distributed across multiple paths.
Solution Approach 2:
The patent creates different local magnetic flux paths through the two through-holes, allowing each region of the magnetic core to operate at optimized flux density levels. The first and second wirings are positioned to create localized magnetic circuits that prevent any single region from reaching saturation point.
3Object-affected harmful factors
If a closed magnetic circuit is formed to improve filtering efficiency, then noise filtering improves, but the structural complexity increases
Solution Approach 1:
The closed magnetic circuit is achieved through segmentation into two separate through-holes rather than a single complex hole structure. This segmented approach simplifies the manufacturing process while still forming a complete magnetic circuit, as each through-hole can be independently processed and the wirings can be separately routed.
Solution Approach 2:
The magnetic core with two through-holes serves multiple functions: it provides a closed magnetic circuit for efficient noise filtering, allows separate wiring paths for differential signals, and maintains structural simplicity through standardized hole patterns that can be manufactured using conventional techniques.
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 solution effectively prevents magnetic saturation in the power converter, enabling the downsizing of the noise filter and the overall DC-DC converter while maintaining effective noise filtering capabilities.
Implementation Method 1
A magnetic flux formed by current flowing in a coil of a noise filter forms a closed magnetic circuit inside a magnetic core
Implementation Method 2
a first capacitor provided between ground and a connecting portion of the first wiring and the second wiring; and a second capacitor provided between the other end of the second wiring and the ground
Data Source
AI summary
Provided is a power converter in which a magnetic core of a noise filter can be prevented from magnetic saturation and the noise filter can be downsized. A noise filter 140 provided in a power converter includes: a magnetic core 1 formed with a single through-hole 1A and forming a closed magnetic circuit; first wiring 11 having one end 81 connected to a power conversion circuit and the other end drawn out from the second opening 3, and running through the through-hole 1A from one first opening 2 to the other second opening 3; second wiring 21 having one end connected to the other end of the first wiring 11 and the other end 82 drawn out from the first opening 2 as a filter output end, and running through the through-hole 1A from the second opening 3 to the first opening 2; a first capacitor 41 provided between the ground and a connecting portion 31 of the first wiring 11 and the second wiring 21; and the second capacitor 51 provided between the other end 82 of the second wiring 21 and the ground.