5 pro tips for in-wheel axial flux motors. Learn how to maximize torque density and reduce unsprung mass for high-performance EVs with Beyond Motors.
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5 pro tips for in-wheel axial flux motors. Learn how to maximize torque density and reduce unsprung mass for high-performance EVs with Beyond Motors.
The transition to distributed drive systems—specifically in-wheel configurations—represents the next evolution in vehicle dynamics and packaging. For CTOs and Lead Engineers, the promise is clear: total torque vectoring, the elimination of mechanical differentials, and significantly increased cabin or cargo volume.
However, the primary engineering hurdle remains the "unsprung mass" paradox. Increasing the mass at the wheel hub typically degrades suspension response and ride quality. At Beyond Motors, we have found that the axial flux motor is the only architecture capable of overcoming this limitation by offering the highest power-to-weight ratio in the industry.
Here are five pro tips for engineers looking to integrate axial flux technology into high-performance in-wheel applications.
In a traditional central-drive EV, motor weight is "sprung mass," supported by the suspension. In a hub motor, every gram counts double. To maintain handling parity with traditional systems, you must utilize a motor that pushes the physical limits of power density.
Pro Tip: Target a benchmark of 10 kW/kg.
By utilizing a yokeless and segmented armature (YASA) topology, the Beyond Motors AXM series eliminates the heavy iron yoke found in radial motors. This allows for high-performance e-motors that deliver 130 kW of peak power in a package weighing just 14.5 kg. This weight reduction is the primary lever in mitigating the negative effects of unsprung mass.
A significant portion of the weight in legacy hub motors comes from the planetary gearbox required to multiply torque. Gearboxes add mechanical complexity, friction losses, and an additional failure point.
Pro Tip: Use the geometric advantage of axial flux to run direct-drive.
Because torque density in an axial flux machine is proportional to the cube of the diameter (D3), you can generate massive low-end torque within the flat "pancake" form factor of a standard wheel rim.
In-wheel motors operate in a confined, high-heat environment, often surrounded by brake assembly heat and restricted airflow. Without sophisticated thermal management, the motor will suffer from rapid "thermal derating," leading to inconsistent performance during aggressive driving or long hill climbs.
Pro Tip: Integrate direct-to-winding liquid cooling.
We have engineered a patent-pending water-cooling system that extracts heat directly from the stator. Unlike air-cooled hub motors, our axial flux motor architecture maintains a high continuous (S1) power rating. This ensures that your electric propulsion remains at peak authority throughout the entire duty cycle.
In an in-wheel configuration, a total loss of power in one corner can create dangerous yaw moments. For safety-critical automotive and aerospace applications, redundancy is a non-negotiable requirement.
Pro Tip: Specify dual winding architectures.
Beyond Motors offers a Double Winding (2 x UVW) option, allowing a single motor to be driven by two independent inverters. If one inverter or controller path fails, the wheel continues to provide 50% torque, providing the necessary "limp-home" capability and preventing vehicle instability.
The immense attraction forces in an axial flux motor (between the rotor and stator) must be managed alongside the lateral forces experienced during high-G cornering.
Pro Tip: Prioritize housing stiffness and bearing selection.
A custom in-wheel integration requires a housing that maintains a consistent sub-millimeter air gap even when the wheel is under heavy lateral load. If your project requires custom specs, sizing, or specific project requirements, our technical team can provide the specific FEA data for rotor-stator deflection to ensure long-term mechanical reliability.
The shift to in-wheel electric propulsion is inevitable for platforms seeking the ultimate in packaging and performance. By selecting an axial flux architecture, you are choosing a system that provides 30-40% higher torque density while effectively neutralizing the weight penalties of distributed drive.
Ready to simulate your hub-drive assembly?Use the Beyond Motors Configurator to input your rim size and torque targets to receive a personalized data sheet and CAD baseline for your project.
Start Your Technical Configuration with the Beyond Motors Configurator
