PCB EI-Core Coupled Inductors to Limit Saturation in Converters
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Solution Overview
Problem
Conventional inductors in power converters face challenges with magnetic saturation and core losses, particularly in high-frequency applications, where reducing the volume and weight of magnetic components is crucial, and existing solutions do not effectively address the trade-off between saturation field and core losses.
Innovation Solution
The use of through-output coupled inductors designed using PCB technologies, where each inductor is wound around an EI-shaped magnetic core, and a conductive material connects the inductors, allowing magnetic coupling at specific frequencies while decoupling at others, thereby reducing low-frequency magnetic flux and alleviating saturation constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional inductors are used with DC or low frequency field components, then the inductor design is coupled to the current flowing through the device, but this leads to magnetic saturation constraints and increased volume and weight
Solution Approach 1:
The inductor is segmented into multiple windings (first winding and second winding) with different functions. The first winding handles high frequency components while the second winding compensates for low frequency flux, allowing each segment to be optimized independently for its specific frequency range.
Solution Approach 2:
A magnetic coupling element is introduced as an intermediary between the first and second windings. This mediator enables magnetic coupling at low frequencies for flux compensation while allowing high frequency signals to pass through with minimal coupling, thus resolving the saturation issue without compromising high frequency performance.
2Object-affected harmful factors
If magnetic coupling between inductors is increased to reduce low frequency magnetic field, then saturation constraints are alleviated, but this causes significant increase in current ripple at N·F sw due to reduced leakage inductance
Solution Approach 1:
The magnetic coupling between windings is made dynamic rather than static. The magnetic coupling element provides strong coupling at low frequencies for flux compensation but automatically reduces coupling at high frequencies, allowing the system to adapt its coupling characteristics based on the operating frequency.
Solution Approach 2:
Different coupling characteristics are applied to different frequency ranges. The magnetic coupling element is designed to provide strong magnetic coupling specifically for low frequency flux compensation while maintaining weak coupling for high frequency signals, creating locally optimized coupling behavior for each frequency band.
3Ease of manufacture
If traditional inductor designs are used, then manufacturing is simpler, but this results in higher core losses and inability to effectively trade-off between saturation field and core losses
Solution Approach 1:
The inductor structure is designed to perform multiple functions simultaneously: the first winding provides high frequency inductance, the second winding provides low frequency flux compensation, and the magnetic coupling element enables frequency-dependent coupling. This multi-functionality allows a single device to address both saturation and core loss issues.
Solution Approach 2:
The design allows independent optimization of multiple parameters including the number of turns in each winding, the magnetic coupling coefficient, and the core material properties. By changing these parameters, designers can optimize the trade-off between saturation field strength and core losses for specific application requirements.
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 the low-frequency magnetic field, decouples the inductor design from current flow, and allows for cost-effective and streamlined manufacturing, while maintaining effective filtering performance by tuning the magnetic coupling and leakage inductance.
Implementation Method 1
the at least two inductors are magnetically coupled through the conductive material for multiple frequencies of N·F sw
Implementation Method 2
each inductor is composed of turns wounded around a central leg of a respective EI shaped magnetic
Implementation Method 3
the phase shift can be evenly distributed according to the number of legs. If this condition is fulfilled, this structure allows to reduce the output current ripple by a factor of N 2
Data Source
Figure 1a~1b
Figure 2~3
Figure 4~6
AI summary
The present invention concerns a multiphase system comprising a power converter having at least two legs and a filtering device connected to the at least two legs of the power converter, the filtering device being composed of at least two inductors, characterized in that the each inductor is composed of turns wounded around a central leg of a respective EI shaped magnetic, each inductor is disposed in at least one printed circuit board that comprises connections of the inductors and in that the filtering device further comprises a conductive material composed of at least two parts, each part goes through each aperture of a respective EI shaped magnetic material, a first terminal of each inductor being respectively connected at one leg of the power converter and one terminal of the conductive material is connected to the second terminals of the inductors.