Although there are electric motor designs that do not use permanent magnets, they typically work with an AC or alternating current supply. As such, these induction motors, as is their popular name, are not suitable for EVs or electric vehicles running on batteries, and are therefore, DC or direct current systems. Magnets in EV motors are permanent types, typically made of rare-earth elements like ferrite, samarium-cobalt, or neodymium-boron-iron, and are heavy and expensive.
The extra weight of the PM or permanent magnet EV motors tends to reduce the efficiency of the drive system, and it would be advantageous if the weight of the EV motor could be reduced somehow. One of the ways this can be done is to use motors that did not use heavy magnets.
A Stuttgart-based automotive parts manufacturer has done just that. MAHLE has developed a highly efficient magnet-free induction motor that works on DC systems. They claim the new motor is environmentally friendly and cheaper to manufacture as compared to others. Moreover, they claim it is maintenance-free as well.
According to a press statement from MAHLE, the new type of electric motor developed by them does not require any rare earth elements. They claim to have combined the strength of various concepts of electric motors into their new product and to have achieved an above 95% efficiency level.
The new motor generates torque via a system of contactless power transmission. Its fine-tuned design not only makes it highly efficient at high speeds but also wear-free.
When working, a wireless transmitter injects an alternating current into the receiving electrodes of the rotor. This current, in turn, charges wound copper coils, and they produce a rotating electromagnetic field much like that inside a regular three-phase induction motor. The rotating electromagnetic field helps to spin the rotor, thereby generating torque.
The magnetic coils take the place of permanent magnets in regular motors. MAHLE typically leaves an air gap between the rotating parts of the motor to prevent wear and tear. According to the manufacturer, it is possible to use the new concept in many applications, including subcompact and commercial vehicles.
MAHLE claims to have used the latest simulation processes to adjust and combine various parameters from different motor designs to reach an optimal solution for their new product. Not using rare earth element magnets allowed them to make lighter motors and has gained them a tremendous advantage from a geopolitical perspective as well.
Electric vehicles, and therefore PM electric motors, have seen a recent boom. But PM electric motors require rare earth metals, and mining these metals is not environmentally friendly. Moreover, with the major supply of these PM electric motors coming from China, automakers outside of China, are understandably, uncomfortable.
Although MAHLE used the latest simulation processes to design their new motor, the original concept is that of induction motors, invented by Nikola Tesla, in the 19th century. Other automakers have also developed EV motors sans permanent magnets, the MAHLE design has a rather utilitarian approach, making it more sustainable as compared to others
