Driving the future of transport with axial flux motor technology.
The drive for efficient, compact, and sustainable transportation solutions is steering the world toward innovative motor technologies. One such innovation at the forefront is the axial flux motor. Often hailed as the next big thing in electric vehicle propulsion, the axial flux motor is set to redefine the industry.
WHAT’S AN AXIAL FLUX MOTOR?
While most are familiar with the traditional radial flux motors where the magnetic flux runs radially, from the motor’s centre outward, the axial flux motor takes a different approach. Here, the magnetic flux operates along the motor’s axis. This change, while seemingly subtle, brings a suite of benefits to the table.
DESIGN AND BENEFITS
Axial flux permanent magnet machines redefine motor performance. They typically offer more torque for a given motor volume, thanks to the active magnetic surface area being on the face of the rotor as opposed to the exterior diameter, inherent to radial motors. Consequently, axial flux motors are considerably more compact. Their axial length is drastically shorter than radial machines, an aspect vital for applications like in-wheel motors. This compactness doesn’t sacrifice power; these motors boast a higher power and torque density than their radial counterparts, and they achieve this without needing to operate at extremely high speeds.
Their efficiency is another standout feature. Boasting efficiencies often exceeding 96%, they benefit from the shorter, one-dimensional flux path, which rivals or even surpasses the best 2D radial flux motors in the market. This efficiency leap is partly attributed to the grain-oriented electrical steel in axial flux machines, which facilitates the flux passage, enhancing the motor’s overall efficiency.
DISTINGUISHING FACTORS
The axial flux technology presents two primary topologies: the dual-rotor single-stator (often referred to as torus-style machines) and the single-rotor dual-stator. While most permanent magnet motors adopt a radial flux topology, the dual-rotor axial flux motor offers a shorter and more efficient flux path. In this design, the flux loop starts at a magnet, passes axially through a stator tooth, and promptly reaches the next magnet. This shorter path results in a motor that is both smaller in size for equivalent power and boasts heightened power density and efficiency.
Furthermore, the design intricacies of axial flux motors stand out. Radial motors have historically used distributed windings, leading to inefficiencies as significant portions of the winding overhang the magnets. In contrast, axial flux machines have minimal coil overhangs, with some designs using concentrated or segmented windings that are entirely active. This design nuance, particularly the winding configuration, is where suppliers distinctively mark their territory in the market.
POTENTIAL APPLICATIONS
Electric vehicles (EVs) are an obvious beneficiary of axial flux motors. Given the motor’s compact and efficient design, EVs could see improvements in range and performance. But it doesn’t stop at cars.
Urban mobility solutions, such as electric buses and trams, benefit from axial flux motors to deliver robust acceleration even when laden with passengers. Off-highway vehicles and construction equipment, traditionally reliant on diesel engines, can benefit from the efficiencies and reduced operational costs of electrification and axial flux motors. Commercial marine applications also stand to benefit immensely from zero emissions propulsion leading to a reduction in water, air, and sound pollution that help preserve our oceans and wildlife – and the list goes on.
With such diverse applications, it’s clear that the axial flux motor’s influence extends well beyond traditional transportation, heralding a new era of efficient and sustainable mobility solutions.
TOWARD A SUSTAINABLE FUTURE
The transport sector has long been under scrutiny for its environmental impact. Here’s where axial rotor motors can make a difference. Beyond their efficiency, the very nature of their compact design means less material use during manufacture. This, coupled with the potential weight savings in vehicles, can lead to overall reduced resource consumption. As these motors possibly lead to better-performing EVs, they might just be the nudge some consumers need to make the switch, reducing the sector’s carbon footprint.
With the myriad benefits and vast application potentials they offer, axial flux motors are more than just an alternative in the transportation industry; they’re a future-forward solution. As the transport sector grapples with evolving demands and environmental imperatives, this technology promises a sustainable way forward.
Matrishvan Raval is Head of Product at Turntide Technologies.
