Asymmetric Magnetic Core for Energy Recovery on Multiphase Cables
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Solution Overview
Problem
Existing electrical energy recovery devices are invasive and restrictive, unable to be installed directly on multi-conductor power cables without disassembling the protective sheath, and are ineffective when positioned around all phase conductors due to zero or weak magnetic fields generated by differential currents.
Innovation Solution
A non-invasive method using a toroidal magnetic core with air gaps or magnets to create asymmetrical magnetic flux, allowing for the recovery of electrical energy from power cables with multiple phase conductors by maximizing the output voltage through heterogeneities and asymmetries in the magnetic circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a magnetic core is placed around all phase conductors of a power cable, then the device can be installed non-invasively without isolating individual conductors, but the magnetic field becomes zero or very weak due to the vector sum of differential currents
Solution Approach 1:
The patent introduces local heterogeneity into the magnetic circuit by creating air gaps at specific positions on the magnetic core, or by using magnetic materials with different permeabilities in different regions. This local modification creates asymmetry in the magnetic flux distribution, allowing the detection coil to generate a non-zero output voltage even when the power cable carries balanced differential currents. The local quality change enables the device to function on multi-conductor cables without requiring conductor isolation.
Solution Approach 2:
The patent deliberately creates asymmetry in the magnetic circuit through air gaps positioned at specific angular locations on the toroidal magnetic core, or through the use of magnets arranged asymmetrically. This asymmetry breaks the symmetry of the magnetic flux paths that would otherwise cancel each other out in a balanced three-phase system. The asymmetric configuration ensures that the magnetic flux detected by the coil does not sum to zero, enabling energy recovery from cables with differential currents.
2Reliability
If a magnetic core is fixed on one phase conductor, then sufficient magnetic field is generated for energy recovery, but the installation becomes invasive requiring isolation of individual conductors
Solution Approach 1:
The patent merges the magnetic core structure to encompass all phase conductors simultaneously within a single toroidal configuration, rather than requiring separate installations on individual conductors. By combining multiple conductors into one integrated magnetic circuit with strategically placed air gaps or magnets, the device achieves sufficient magnetic field strength while simplifying installation to a single non-invasive operation around the entire cable assembly.
3Power
If air gaps or magnets are introduced to create heterogeneity in the magnetic circuit, then output voltage is maximized, but the device complexity increases
Solution Approach 1:
The patent modifies key parameters of the magnetic circuit, specifically introducing air gaps with controlled dimensions (width, position, angular distribution) or magnets with specific magnetic moments and orientations. These parameter changes create the necessary heterogeneity to maximize output voltage while maintaining a relatively simple overall device structure. The air gaps or magnets serve as controlled modifications that significantly enhance performance without proportionally increasing complexity.
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
Enables flexible and simple installation on power cables, both during manufacturing and on-site, while ensuring sufficient voltage for powering additional electrical systems without the need to isolate individual phase conductors, overcoming the limitations of existing solutions.
Implementation Method 1
a magnetic core in the form of a torus, arranged to be installed around said power cable and form a magnetic circuit capable of capturing a magnetic field induced by the primary current passing through the phase conductors
Implementation Method 2
a detection winding wound around said magnetic core and arranged to induce a secondary voltage from said induced magnetic field and deliver to the terminals of said detection winding an output voltage
Data Source
Figure 1
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AI summary
The invention relates to a device (10) for recovering energy from a single-phase power cable (1) comprising two phase conductors (C1, C2). It comprises a magnetic core (20) in the form of an open torus, installed around said power cable (1) so as to form a magnetic circuit able to capture a magnetic field induced by a primary current flowing through said phase conductors, and a detection winding (30) wound around said magnetic core (20) so as to induce a secondary voltage from said induced magnetic field and deliver, to the terminals of said winding, an output voltage able to be used to supply electrical systems. It comprises a heterogeneous magnetic circuit for inducing a flow of an asymmetric magnetic flux in said magnetic circuit and maximizing the output voltage of said detection winding (30). In one of the variants, the magnetic core (20) is off-centre with respect to the power cable (1), the magnetic core (20) comprises two air gaps (E1, E2) of different widths, including a main air gap (E1) positioned facing and in alignment with the phase conductors (C1, C2), and the detection winding (30) is located in an area of the magnetic core (20) opposite said main air gap (E1).