Coupled Inductor Winding Offset for Magnetic Leakage Reduction
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Solution Overview
Problem
Multi-level parallel converters face significant magnetic leakage issues due to common mode currents, leading to eddy current losses and stray losses, which affect the normal operation of magnetic components like Hall effect sensors and current transformers.
Innovation Solution
The coupled inductor design features windings twisted in opposite directions on each magnetic cylinder, ensuring that common mode magnetic potentials generated by first and second windings offset each other, reducing magnetic leakage and associated losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If common mode current flows through coils on two magnetic cylinders of the coupled inductor, then the magnetic fluxes generated by the coils are in opposite directions, but a high common mode magnetic potential is generated causing magnetic leakage
Solution Approach 1:
A magnetic isolation component (non-magnetic material) is introduced between the upper and lower magnetic yokes to block the magnetic flux path. This intermediary prevents the magnetic flux generated by common mode current from forming a closed loop through the magnetic yokes, thereby reducing magnetic leakage and the associated high common mode magnetic potential.
Solution Approach 2:
The magnetic coupling path for common mode flux is extracted or removed from the system by introducing non-magnetic material that breaks the magnetic circuit. This separates the magnetic flux paths of the two magnetic cylinders, preventing the formation of a shared magnetic leakage path through the magnetic yokes.
2Reliability
If magnetic leakage occurs in the air, then the magnetic fluxes generate high common mode magnetic potential, but eddy current loss and stray loss increase
Solution Approach 1:
The magnetic isolation component acts as an intermediary that blocks the magnetic leakage path, preventing magnetic flux from extending into the surrounding air. This eliminates the conditions that cause eddy current loss in windings and stray loss in external metal parts, while ensuring normal operation of surrounding magnetic components like Hall effect sensors and current transformers.
3Loss of energy
If windings are arranged to generate opposite magnetic potentials, then common mode magnetic flux is reduced, but the structure becomes more complex
Solution Approach 1:
Instead of relying solely on complex winding arrangements to achieve magnetic isolation, a magnetic isolation component made of non-magnetic material is introduced. This simplifies the overall structure by providing a straightforward physical barrier to magnetic flux, while maintaining the benefit of reduced common mode magnetic flux.
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 design significantly reduces magnetic leakage, minimizing eddy current losses and stray losses, while ensuring the normal operation of surrounding magnetic components.
Implementation Method 1
at least two first windings L11, L21, . . . and Ln1, and at least two second windings L12, L22, . . . and Ln2, which form mutually coupled inductances with the at least two input ends 121, 122, . . . and 12n and an output end 130 and make the at least two first windings L11, L21, . . . and Ln1 and the at least two second windings L12, L22, . . . and Ln2 on each cylinder generate opposite magnetic potentials when currents that flow into the at least two input ends 121, 122, . . . and 12n are equal
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention provides a coupled inductor and a power converter. The coupled inductor includes: at least two input ends, an output end, a common magnetic core, at least two first windings, and at least two second windings. The common magnetic core includes at least two cylinders, and the number of the at least two cylinders corresponds to the number of the at least two input ends; and one first winding and one second winding are twined in parallel on each cylinder among the at least two cylinders, and the first windings and the second windings on the at least two cylinders are mutually connected between the at least two input ends and the output end to form mutually coupled inductances and when currents that flow into the at least two input ends are equal, make the first winding and the second winding on each cylinder generate opposite magnetic potentials. In technical solutions of the present invention, the first winding and the second winding on each cylinder generate opposite magnetic potentials when currents that flow into the input ends are equal. In this way, the magnetic potentials generated by common mode currents offset each other, so that a magnetic leakage is reduced.