Electric motor technology

What Is an Axial-Flux Motor?

An axial-flux motor is an electric motor whose magnetic flux travels mainly along the axis of the motor shaft. The geometry is often flatter and more disc-like than the cylindrical radial-flux motors commonly used in EVs.

Illustration comparing axial-flux and radial-flux electric motor geometry and magnetic flux direction
Axial-flux versus radial-flux motor concept: the main distinction is magnetic-flux direction and the resulting motor geometry.
Simple definition

Axial flux describes the direction of magnetic flux through the motor. It is a motor topology, not a motor-count term. A car can be single-, dual- or tri-motor and still use radial-flux or axial-flux motors.

Axial-flux vs radial-flux

Axial-fluxRadial-flux
Flux directionMostly parallel to shaftMostly outward/inward across the radius
Typical shapeShort, wide, disc-likeLonger cylindrical package
Industry maturityGrowing in high-performance applicationsDominant EV motor architecture today
Key appealHigh torque/power density and compact axial lengthEstablished manufacturing and broad scalability

Why are axial-flux motors attracting attention?

YASA, a Mercedes-Benz subsidiary specializing in axial-flux motors, highlights high torque density, high power density and a much shorter axial package as major advantages. That can give vehicle engineers more freedom for packaging and performance.

Potential advantages

  • High torque density.
  • High power density.
  • Short axial length can save packaging space.
  • Lower mass is possible for a given performance target.
  • Useful for high-performance EV and hybrid applications.

Challenges and trade-offs

Axial-flux motors are not automatically superior in every application. Manufacturing cost, cooling, mechanical tolerances, rotor forces, magnet supply, production volume and integration with the inverter and gearbox all matter. Radial-flux motors remain extremely mature and widely manufactured.

Axial flux is not the same as tri-motor

Tri-motor tells you how many motors the vehicle uses. Axial flux tells you how a motor is built. A three-motor car could use three radial-flux motors, three axial-flux motors, or a mixed arrangement if the manufacturer designed it that way.

CEER has confirmed EXOBOT's Tri-Motor AWD layout, but CEER has not publicly identified EXOBOT's traction motors as axial-flux. CarGlossary therefore does not make that assumption.

Where is axial-flux used?

YASA supplies and develops axial-flux technology for performance automotive applications and is part of Mercedes-Benz. The technology is increasingly discussed for future high-performance EVs because of its compact size and power density.

Sources