Propelling alternative mobility solutions
As concerns over urban congestion and the related effects continue to rise, there is a growing interest in finding alternative and sustainable methods of transportation. David Latimer, CEO of Magnomatics, investigates urban air mobility (UAM) and micromobility solutions and highlights the role innovative magnetically geared motors play in these developing markets.
As the world looks to decarbonise, alternative mobility solutions are appearing. Not only is there a mounting interest in flying cars – which was once the stuff of science fiction – but there has also been an explosion in the popularity of (lightweight electric vehicles) LEVs such as e-bicycles and e-scooters around the world, particularly in cities.
Whilst UAM vehicles, or electric vertical take-off and landing (eVTOL) vehicles, are envisioned to provide an affordable alternative to ground transport in congested urban areas in the next few years – some industry players are citing plans to start operating as early as 2024 – the adoption of micromobility solutions such as LEVs has steadily been on the rise in cities across the globe due to ease of accessibility and the promise of micromobility vehicles being able to fill gaps in public transport routes, providing a practical and popular answer to the perennial first-and-last-mile need.
The appeal of LEVs has been boosted by the fact that they help reduce road congestion and contribute to the more efficient use of parking and other shared public spaces. Of course, they also boast several environmental benefits.
Looking at micromobility
Road transportation is one of the biggest contributors to carbon emissions in cities – in 2019, transport was responsible for 122 metric tons of the 455 metric tons of CO2 emissions produced in the UK.
LEVs have great potential to significantly reduce CO2 emissions from the transport sector as their increased adoption means fewer vehicles that emit smoke, carbon, and other harmful gases. In fact, a study by shared e-scooter platform Lime found that using e-scooters in Paris for a year helped save over 330 metric tons of carbon emissions in the city.
Additionally, the use of LEVs can help reduce noise levels. While noise pollution, which is caused by excessive noise from people, transportation, construction equipment, neighbourhoods, and nightlife in cities may seem trivial, long-term exposure has an impact on residents’ health and wellbeing.
Whilst traditional micromobility solutions such as conventional bicycles have been used for decades, the primary factor behind the current micromobility trend is electrification. Thanks to advances in technology, complete electric powertrains can be easily integrated into micromobility platforms.
The question, however, is whether LEVs are efficient? For many e-bicycles and e-scooters, powertrains have already become commodities. In this instance the priority is cost, not efficiency. However, low efficiency reduces payload and range, which means more charging, which is the opposite of the objective of introducing LEVs in the first place, namely lower energy use.
Considering urban air mobility
The race to develop UAM solutions has gathered momentum over the past few years, with eVTOL gaining traction due to potential benefits such as easing traffic congestion and enabling efficient passenger and cargo transportation. Additionally, it it believed that by improving connectivity and accessibility, UAM could trigger changes in land use and impact de-urbanisation.
Whilst the concept of flying cars is certainly exciting, these new aircraft bring with them many challenges. They need to operate in complex airspace and over congested urban areas, which means the need for reliability and redundancy is critical. There is also a strong driver for zero emissions and very low noise.
One common feature is that all these aircraft use multiple electric motors. The route to power density in electric machines has historically been to operate permanent magnet motors (PM) at higher speeds, often in excess of 10,000 rpm. To become useful for air mobility aircraft, these speeds need to be geared down by as much as seven times. Conventionally this introduces the requirement for a mechanical gearbox, raising the issues of reliability, wear, maintenance, and noise.
Powering alternative transport solutions
To ensure efficiency, reliable motors – in particular innovative magnetically geared motors – a are a key enabling technology for both LEVs and eVTOL aircraft. Magnomatics’ revolutionary magnetic gears have been implemented in a range of innovative industry solutions such as offshore wind, marine propulsion, and light rail. Having achieved success at large scale the company has turned its attention to much smaller machines, including drives for eVTOL aircraft and for personal micromobility vehicles such as e-scooters and e-bicycles.
The company’s patented Pseudo Direct Drive (PDD) consists of a magnetic gear mounted inside a stator. The outer magnetics of the magnetic gear are attached to the inner bore of the stator, and copper windings in the stator are used to drive the inner rotor of the magnetic gear.
This is a relatively high-speed electric motor with a relatively low load, which results in low currents and hence, low temperatures. This in turn brings great efficiency, long life, and prevents demagnetisation of the outer magnet array. The torque in the inner rotor is then geared up in the novel polepiece rotor, typically by between 5 and 10:1. The result is a very compact and highly efficient electric motor, which is perfect for eVTOL aircraft and LEV vehicles.
The benefits of innovative magnetically geared motors such as PDD against conventional generator technology, particularly for the micromobility and UAM markets, are drastic reductions in motor size, no minimum cooling requirements, and reduced maintenance requirements. Ultimately, the lower mass and compactness of the PDD generator, when combined with partial load superior efficiency, low speed, high torque technology and improved reliability, makes it ideal for meeting the requirements of the broad range of new transport solutions being developed.
In fact, NASA, which has been at the heart of UAM development, has identified magnetic gears as an effective technology for electric aircraft. In 2018 they embarked on a programme described in their paper Magnetic Gearing Research for Electrified Aircraft Propulsion. Their original focus was on pure magnetic gears, but in the 2020 paper Outer Stator Magnetically Geared Motors (OSMGM) for Urban Air Mobility Vehicles they stated that the concentric combination of a magnetic gear and a permanent magnet motor would be ideal for an eVTOL UAM aircraft, concluding that a magnetically geared motor was a highly effective solution to avoid the pitfalls of a mechanically geared high-speed electric motor.
The development of alternative transport solutions such as LEV and eVTOL is becoming an increasingly exciting space and does not appear to be slowing down. As it continues to gain momentum, employing the right generator technology will drive efficiency and reliability in these innovative and exciting markets.
David Latimer, CEO of Magnomatics
