Flux-Modulated Coaxial Magnetic Gear Calculator

Enter the pole pairs of both rotors, ring and modulator sizes, air gaps and length for a preliminary maximum transmitted (pull-out) torque, gear ratio and torque density of a flux-modulated coaxial magnetic gear.

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Are yours two wheels meshing side by side (like AIC's CJ series)?Use the parallel-axis gear calculator

1Pole pairs

Cross-section (not to scale)

High-speed (inner) rotor pole pairs2–20.

Low-speed (outer) rotor pole pairsMore than the inner rotor; up to 60.

Modulator pole pieces 26 · gear ratio 5.5 : 1, rotors turn in opposite directions

2Rings, gaps and modulator

Inner magnet bore radiusmmRadius of the inner yoke the magnets sit on.

Inner magnet thicknessmm

Inner air gapmmInner magnets to modulator, running clearance included.

Modulator ring thicknessmm

Pole-piece shareFraction of the modulator circumference that is steel, 0.2–0.8 (0.5 typical).

Outer air gapmmModulator to outer magnets, running clearance included.

Outer magnet thicknessmm

Axial lengthmmActive length of magnets and modulator.

3Grade and temperature

Magnet grade (both rotors, NdFeB or SmCo)

Working temperature°CBoth rotors are taken at this temperature; if they differ, enter the hotter side.

Calculating…

Preliminary estimate for a flux-modulated coaxial magnetic gear — a custom configuration, different from AIC's standard CJ parallel, MGS orthogonal and CS bevel gears and the CDS/CDQ coaxial face couplings (for CJ use the parallel-axis gear calculator, for CDS/CDQ the magnetic coupling calculator; for MGS and CS ask us). 2D analytic (subdomain) solution with a stationary modulator, under idealised assumptions: radially magnetised magnets with full pole arcs, μr = 1, ideal steel yokes and pole pieces (μr → ∞, no saturation), both rotors at the same temperature, static (no speed, eddy-current or windage effects). The implementation agrees with an independent finite-volume solution of the same idealised problem to 0.1–1.5 % — a numerical check, not a measurement. The end-effect factor is an approximate, conservative correction (not 3D FEA); pole pieces leak axially, so short gears lose more. Upper end at maximum Br; lower end = upper × (Br min / Br max)² × 0.7, an engineering margin for segment gaps, the real magnetisation, saturation and assembly — not modelled item by item and not checked against measurements. We confirm prototype and production designs by FEA and a pull-out torque test.

Send us your torque, speed and ratio — we design the gear