In a world focused on improving efficiency and delivering net zero, viable eVTOL and UAM vehicles need to be cleaner, more efficient and less invasive. Gary Rodgers, CEO of Magnomatics, explains how innovative magnetically geared motors offer a reliable, efficient, cost-effective solution for urban air transport.
Gary Rodgers, Magnomatics CEO.
Manufacturing considerations
eVTOL and UAM aircraft have incredible potential, to increase efficiencies whilst cutting journey times and helping to reduce congestion on roadways. However, to develop viable products that have market traction, manufacturers will need to ensure these aircraft are compliant with both safety and environmental regulations while being energy efficient, cost-effective to operate and requiring low maintenance. This means developing, quiet, reliable and lightweight aircraft that use the minimum electrical power.
At present, all UAM solutions rely on multiple electric motors to deliver electric power. The conventional way to provide the necessary power density is to operate permanent magnet motors at high speeds, often in excess of 10,000rpm. In UAM aircraft, where output speed needs to be slowed by up to 1/7 of the original motor speed, the traditional method of using a mechanical gearbox offers a less than satisfactory result, increasing the potential for mechanical failure, wear and noise, as well as raising the need for costly maintenance.
A Smarter Approach
A more effective solution for UAM applications and one which would mitigate these issues, is to use a concentric combination of a magnetic gear and permanent magnetic motor – an approach endorsed by NASA in its ‘Outer Stator Magnetically Geared Motors for Urban Air Mobility Vehicles’ paper in 2020.
Magnetically geared motors can play an instrumental role in improving performance and efficiency. Industrial scale models have already been successfully deployed in offshore and onshore wind, light rail, off-highway vehicles (OHVs) and marine propulsion applications, and smaller-scale drives offer the same advantages for UAM aircraft.
Engineered to overcome the torque limitations of traditional direct-drive electrical machines, magnetic gear systems feature a magnetic gear mounted inside a stator. Here, the gear’s outer magnetics are attached to the stator’s inner bore, with the stator’s copper windings driving the magnetic gear’s inner rotor.
The intelligent system design, which results in a low-load, high-speed electric motor that operates with low currents and at low temperatures, does not require a liquid cooling system.
The exclusion not only decreases the weight and complexity – removing potential cooling system failure modes – but it also reduces maintenance costs, as well as the real estate required to house and feed the cooling system, in turn making the whole solution a more cost-effective end product.
Moreover, by gearing up the inner rotor torque between 5:1 and 10:1 in the novel polepiece rotor, the product is a highly efficient, compact and durable electric motor, immune to outer magnet array demagnetisation.
For UAM aircraft, magnetically geared systems are much smaller, lighter and more efficient than conventional systems and thus deliver greater energy savings and improved sustainability. Furthermore, they are easier to install, require less maintenance, have no minimum cooling demands and without a mechanical gearbox, gearbox losses and wear are eradicated. Being quieter, they also reduce internal and external noise, providing more comfortable journeys and reducing environmental noise pollution.
UAM and eVTOL aircraft have the potential to transform urban transport, offering fast, affordable and convenient journeys for users, while cutting highway congestion and traffic pollution. Magnetic gear technology has a valuable role to play in the development of these aircraft, reducing manufacturing, maintenance and operating costs while enabling them to be energy-efficient, reliable, quieter and environmentally friendly.
For more information, visit the Magnomatics website.
