Research

BRIDGE programme and the Maxwell 3D model of the 5 kW, 1 m link.

University of Coimbra

Laboratory coil — Fig. R-01Litz conductor and a precision coil — reference laboratory photograph, not the 5 kW energised test.

FEM setup for the 5 kW / 1.00 m link (simulated). Degrees of freedom and run times are from the last accepted adaptive pass.
Solver	Physics	f	Unknown	Mesh	Acceptance
Ansys Maxwell 3D	Eddy Current	85 kHz	A	tetra + prism	M, k, R_ac, P_eddy
COMSOL AC/DC	Magnetic Fields	85 kHz	A_φ (2D-axi)	mapped + refine	J_Litz, \|B\|, ferrite
COMSOL 3D	Magnetic Fields	85 kHz	A	adaptive tetra	k(Δx), F_Lorentz

COMSOL |B| — Fig. FEM-01COMSOL AC/DC — |B| on an axisymmetric cut. Post-processing style illustration; figures simulated.

COMSOL mesh — Fig. FEM-02FEM mesh (COMSOL): refinement in copper and in the 1.00 m air gap.

COMSOL J Litz — Fig. FEM-03Current density J in Litz at 85 kHz (COMSOL) — skin and proximity.

COMSOL A_phi — Fig. FEM-04COMSOL — vector potential A_φ on an axisymmetric cut, 85 kHz. Simulated.

COMSOL misalignment — Fig. FEM-05COMSOL — |B| under lateral misalignment (~150 mm). Parametric study, simulated.

COMSOL ferrite |B| — Fig. FEM-06COMSOL — |B| in ferrite backing (saturation). Simulated.

Ansys eddy loss — Fig. FEM-07Ansys Maxwell 3D — eddy-current loss density in copper/ferrite. Simulated.

Ansys streamlines — Fig. FEM-08Field lines of the three-coil relay (Maxwell 3D). Simulated.

Ansys ICNIRP — Fig. FEM-09ICNIRP contours in plan (Maxwell). Radii 3.3 m and 6.3 m: simulated.

Ansys 3D mesh — Fig. FEM-10Ansys Maxwell 3D — adaptive tetrahedral mesh on coils and air gap.

Ansys |B| slice — Fig. FEM-11Ansys Maxwell 3D — |B| slice through the 1.00 m gap. Simulated.

Ansys force density — Fig. FEM-12Ansys Maxwell 3D — Lorentz force density. Simulated.

BRIDGE programme

Research at the University of Coimbra, DEI: Maxwell 3D model, coupled-mode analysis and the manufacturing package of the 5 kW / 1 m / 85 kHz link.

The corpus is the Maxwell 3D model, a COMSOL AC/DC cross-check, coupled-mode analysis, manufacturing package and hardware specification of the 5 kW / 1 m / 85 kHz link. Collaboration: research@nwpt.pt.

Formulation and cross-check

Maxwell: A-formulation (eddy-current) in the frequency domain. COMSOL: Magnetic Fields in 2D-axisymmetry for A_φ and the Litz mesh, and 3D when misalignment breaks symmetry.

Mutual inductance is the Neumann integral; FEM replaces it by energy extraction W = ½ Iᵀ L I. Acceptance quantities are k and R_ac — not how the field looks.

Research in high-power inductive transfer: Maxwell 3D, coupled-mode analysis and the manufacturing package of the 5 kW, 1 m link.

The work behind the 5 kW, 1 m, 85 kHz three-coil relay link: Ansys Maxwell 3D model, COMSOL AC/DC cross-check (A_φ, mesh, Litz J), coupled-mode analysis, manufacturing package and hardware specification.

The formulation is eddy-current in A; mutual inductance is Neumann / energy extraction. Model acceptance is convergence of M and R_ac, not how the field looks. No number on this page is a measurement above 1 kW.

5 kW across one metre: design complete and verified in Ansys Maxwell 3D, 97.18 % simulated coil-to-coil efficiency. Testing under way.

Collaboration and publications: research@nwpt.pt.

Model card — 5 kW link

Acceptance quantities: M and R_ac. How the field looks is not a criterion.
Geometry	Ø 1.10 m, axial stack, three-coil relay
Air gap	1.00 m (design)
Frequency	85 kHz
Solver	Ansys Maxwell 3D eddy-current; COMSOL AC/DC
Boundary	A × n = 0 at ≥ 5 coil radii
Mesh	tetra / prism; refine to δ/3 at 85 kHz
Convergence	ΔM and ΔR_ac < 0.5 % between adaptations
k (simulated)	0.117 relay / 0.037 direct
η coil-to-coil	97.18 % (simulated)
Measured (G0)	not posted

Cite this work

There is no journal DOI. Cite the site technical report until a preprint exists.

@techreport{nwpt2026link5kw,
  title       = {5 kW inductive link at 1.00 m: Maxwell 3D specification},
  author      = {{NOVEA Wireless Power Transmission, Lda}},
  year        = {2026},
  institution = {NWPT},
  address     = {Coimbra, Portugal},
  url         = {https://www.nwpt.pt/en/research/},
  note        = {Coil-to-coil efficiency 97.18 percent is simulated. Not energised above 1 kW.}
}

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