Linear Induction Motor Design Services

Requirement capture

Good motors start from an honest brief. We work through the loads, speeds, gaps and duty that actually define the problem: the mass to be moved, the target speed profile and acceleration, the available packaging and running gap, the track or fin length, and the supply you can realistically provide. We also fix the topology early, because a single-sided motor (primary over a plate on steel back-iron, with a significant normal pull toward the steel) and a double-sided motor (two primaries either side of a bare fin, with the normal pulls largely cancelling in the frame) lead to very different structural and thermal designs.

Electromagnetic sizing

With the requirement fixed, we size the electromagnetics using equivalent-circuit models. A linear induction motor is a rotary motor unrolled: a straight primary winding creates a magnetic field that travels along the track instead of rotating, dragging a conductive reaction plate with it. The field speed is set by the drive frequency and the pole spacing, and the slip is the small difference between field speed and vehicle speed that helps set the thrust. Thrust ultimately comes from the air-gap power divided by the field speed, so we trade winding layout, pole pitch, gap and current density to land the thrust and efficiency you need within the packaging and supply envelope.

End-effect and edge-effect corrections

A short, open-ended motor does not behave like an ideal infinite machine, so the first-pass sizing is refined with two corrections. The longitudinal end-effect accounts for the field building up and decaying at the entry and exit of a finite primary, which typically erodes thrust and efficiency, more so at higher speeds. The transverse edge-effect accounts for reaction-plate current spreading beyond the active width. We carry both corrections through the sizing so the predicted thrust reflects a real finite motor rather than an idealised one.

FEA validation

Equivalent-circuit models are fast and honest for exploring the design space, but they are lumped. We cross-check the chosen design with finite-element analysis (FEA), resolving the field in the primary, gap and reaction plate to confirm the thrust and normal-force predictions, check for local saturation, and look at how the design behaves across the working slip and speed range. Where the two methods disagree, that disagreement is information: we reconcile it before committing to the geometry.

Route/duty simulation

A motor sized for a peak point can still fall short over a real journey, so we run the full duty in route simulation. The velocity profile, grades, dwell times and repeat cycles drive a time-domain run that tells us the real force demand, the energy drawn and the losses accumulated across a representative cycle rather than a single worst-case instant. Because the drive is adhesion-independent, thrust does not rely on wheel-rail grip, so rain, ice and grades change the load but not the drive-slip limit that constrains a friction drive.

Thermal limits

Losses set the real limit on a linear motor far more often than magnetics do. We feed the duty-cycle losses into thermal modelling of the primary winding and the reaction plate to check that temperatures stay within the insulation class and material limits under the specified cooling, typically for the continuous duty as well as the short overload bursts. If the thermal picture is tight, we loop back to the sizing rather than quietly relying on optimistic assumptions.

Drive and supply sizing

The motor and its drive are one system, so we size them together. Most applications use an inverter or variable-frequency drive, which sets the field speed by varying frequency across the speed range; for niche fixed-speed duty a direct-on-line arrangement can suit. We match the voltage, current and frequency range to the winding, and we check that the current, gap and thermal limits are consistent with the supply you can provide, so the delivered thrust curve is one the drive and supply can actually sustain.

Deliverables — what you get back

You get an engineering package you can build to and defend, not a headline number.

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