Updated on 08/04/2023 08:29
It has been 200 years since the British scientist Michael Faraday developed the first functional electric motor. The Faraday rotor was a significant step forward in understanding the conversion of electrical energy into mechanical energy, but it was primitive and had no practical application. It was in the 1830s when William Sturgeon developed the first electromagnet, inspiring Thomas Davenport and Thomas Edison improvement of modern electric motors. The way to its wide application in industry and transport was opened.
Although electric traction motors were developed primarily in the 1800s, they continue to evolve today, two centuries later. thanks to the spread of electric vehicles, offering new technologies that respond to new opportunities driven by demand. In recent years, more and more attention has been paid to materials used for electric motors, as well as for topology underlying.
The goals of each development are different. some are looking for improve characteristics such as power density and torque, with technologies such as axial flow. Others are looking for profitability and sustainability, reduction or complete elimination of rare earth elements. In an ideal world, both goals can be achieved at the same time, but in reality they need to be balanced. In a report by the consulting company IDTechEX, “Electric motors for electric vehicles 2024-2034”, delves into technology, demand, material usage and market forecasts.
The beginning of the end of the rare earths
A key element of the electric motor market are magnetic materials. Between 2015 and 2022, the share of permanent magnet (PM) motors in the electric vehicle market has consistently exceeded 75%. However, the need to use rare earth metals with a very limited supply chain to China has led to a sharp increase in prices in 2021 (as well as in 2011/2012).
Several European manufacturers have opted for a free design of these magnets, as is the case with wound-rotor motors (AC and synchronous with external excitation), which use Renault and BMW or using induction motors Audi. While the choice to use non-rare earth magnets has a significant impact on performance, other manufacturers’ choices have been to reduce their content through advanced materials development and optimized motor design.
This year, Tesla announced a new generation of motors, which it defines as a rare earth-free permanent magnet machine based on alternative magnetic materials such as ferrite magnets. Without requiring significant design changes, their implementation would lead to a loss of power and torque by more than 60%. This decrease in performance can be compensated for by optimizing various aspects of the design. There are also manufacturers looking for new magnetic alloys such as iron nitride magnets from Niron.
IDTechEx predicts that Engines on the PM will remain predominant, especially with China’s dominance of the electric vehicle market. However, he predicts that the number of rare earths per engine will decrease and alternative magnetic materials will move into the market.
Technological alternatives: axial motors and wheel motors
Engines radial flow They are traditionally integrated into electric vehicles. But there are two new alternatives that are generating a lot of interest in their first market approach: axial flow motors and wheel motors.
V axial flow motors, the magnetic field is parallel to the axis of rotation (which is perpendicular in machines with radial flow). Advantages of axial flow motors higher power and torque density and very suitable form factor for integration in various scenarios. Technologies have evolved towards market penetration. Daimler has acquired YASA, one of the companies that pioneered these engines, for use in AMG’s upcoming electric platform. In addition, Renault is partnering with WHYLOT to use axial flow engines in its hybrids starting in 2025.
motors in wheels was a technology adopted by some brands. Protean is the most advanced of all. Dongfeng has demonstrated the first homologated ProteanDrive (power-in-wheel platform) passenger car, which will continue into 2023 with further testing.
In addition, new manufacturers have been created, such as Rivian who already sells the R1T electric pick-up and has demonstrated the tremendous control offered by this technology.
Israeli startup. REE Automotive developed a modular electrical platform based on wheel motors, structural battery and cable control systems. modules REEcorner they combine all transmission, transmission, suspension and steering components in one unit. So the platform REEboard becomes completely flat and modular electric chassis reduced weight, which will offer more free space release the design of the vehicles that use it.
Very similar is the modular e-Corner system, which the Koreans from Hyundai introduced through their technology company Hyundai Mobis. In each of them, the suspension, braking and steering systems are located inside the wheel hub. Thus, each of them can be controlled independently. Externally, a vehicle equipped with four e-Corner modules will not be aesthetically different from a conventional one. And in normal use it won’t be any different, although things change when it comes to maneuvering.
Finally, there is the case of American electric pickups. Lordstown, at this time in serious economic problems, who also chose this solution. His only model shown, an electric pickup called the Endurance, had an all-wheel drive powertrain based on electric motors mounted in the wheels.
IDTechEx predicts significant growth in demand for axial flow motors and wheel motors in certain vehicle categories, but does not expect them to completely replace traditional radial flow machines in the near future.