Learn electric motor design
Practical guides on the fundamentals — written for engineers who want to understand the physics behind the calculations.
Cogging torque — causes, slot-pole selection, and reduction
Why permanent-magnet motors feel "notchy" at low speed, how LCM(Q,P) sets the cogging frequency and amplitude, and which slot-pole combinations minimise it for servo and hub motors.
Read article →Winding distribution factor — why spreading conductors costs EMF
How distributing a phase across multiple slots staggers EMF phasors and gives kd = sin(q·α/2) / (q·sin(α/2)). Includes a worked numerical example for 12, 24, and 36-slot machines.
Read article →Coil pitch factor — how a winding captures rotor flux
How slot electrical angles, coil span, and induced voltage combine into kp = sin(β/2). Includes a worked numerical example for a 12-slot / 4-pole machine with three valid coil pitches.
Read article →What is winding factor and why does it matter in motor design?
Understand how the distribution factor and pitch factor combine to determine how efficiently a winding converts current into torque-producing flux.
Read article →MMF harmonics in three-phase AC windings
Learn how the spatial distribution of conductors creates a magnetomotive force spectrum — and why higher harmonics cause torque ripple and additional losses.
Read article →Integer-slot vs fractional-slot windings — when to use each
The slots-per-pole-per-phase ratio q determines fundamental winding behaviour. Learn the trade-offs between distributed and tooth-coil winding configurations.
Read article →How to read an electrical steel B-H curve
Decode the magnetisation curve: what saturation, permeability, and the hysteresis loop tell you about a steel grade's suitability for your motor core.
Read article →NdFeB magnet grades explained — remanence, coercivity, and energy product
A practical guide to navigating the N35 to N52 grade system, temperature class suffixes, and how to select the right magnet for your operating conditions.
Read article →12s/14p vs 12s/10p: a mirror-image winding pair explained
Both configurations share an identical winding factor of 0.933, yet differ significantly in cogging torque, operating frequency, and MMF harmonic structure. A side-by-side breakdown for drone and EV motor designers.
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