This motor design also offers more power density and lower weight than radial motors.
One of the arguments traditional carmakers use for the survival of combustion engines is that it still has many development possibilities. Variable compression and the SPCCI cycle would be examples of that. Electric motors' energy efficiency is around 90 percent. But a new concept from Belgium promises to offer 98 percent of energy efficiency. It is from Magnax and consists of a yokeless axial flux motor.
The new engine, according to the manufacturer, is very capable because of the way it has been conceived. Its wiring has rectangular section other than round, which saves space, makes filling more effective (90 percent), and prevents copper loss.
There are two permanent magnet rotors and the stator is yokeless, something that makes flux paths the shortest possible, according to Magnax.
The coils also count on a cooling system that helps them keep the lowest possible temperature, but it is the axial flux that allows the Magnax motor to have a high power-to-weight ratio. And this image shows that in the best way possible.
While the radial electric motor used on the BMW i3 offers 168 hp (125 kW), 184.4 lb-ft (250 Nm), and weighs 101 lb (46 kg), a Magnax axial flow with the same torque would offer 268 hp (200 kW) and weigh only 35 lb (16 kg).
Since mass is one of the three pillars of efficient vehicles, and EVs already have to deal with heavy battery packs, any weight advantage is always welcome. It is a classic example of more for less.
This inherent lightness also makes the Magnax less demanding in natural resources. While the magnet of BMW’s radial engine weighs 4.4 lb (2 kg), the one in the axial motor is just 2.7 lb (1.2 kg).
This may be something crucial in the future, with more and more vehicles demanding more and more neodymium for permanent magnets. And more rare earth, or RE, as some call it.
Magnax claims its motors are ideal for cars, motorcycles, and airplanes. We can’t wait to see the first EV equipped with one of them. Or four of them, in case it is an AWD model.