BMW, the German maker of high-end luxury and sports vehicles, has rarely remained out of technology news for long thanks to its unrelenting focus on continuous innovation. The same spirit of invention is now evident in BMW’s new electric motor housed in its iX M60 sports activity vehicle. The motor is at the cutting edge of technology and quite a bit old school at the same time. Makes for an exciting combo, doesn’t it?
The science and other stuff to know
If we delve into the very basics of electricity and how it helps move things, we find that all electric motors need a medium to convert electric energy into mechanical force. And that medium has always been a magnet. Once electricity is introduced to a magnetic field, the opposite poles of the magnet attract one another while the like poles repel each other, creating torque, or turning force, that results in the movement of a machine.
The use of stronger permanent magnets that provide machines with more and consistently dependable power is a straightforward solution as automakers compete to offer electric vehicles with higher power outputs. The problem is that these permanent magnets are made from rare earth minerals, which are getting harder to source.
So BMW looked to the past to get around the problem. Most electric devices, like drills and grinders, have always used brushed motors, which have brushes made of conducting materials that transmit electricity to the commutator to spin the rotor.
The disadvantage to these motors is the fine dust the brushes produce as they operate and the periodic replacements that the brushes require due to wearing out. Brushless motors that most EVs use nowadays do not face such problems. However, they are costlier and more difficult to control.
BMW engineers relied on the tested technology of brushed motors and did away with the permanent magnets that jack the cost considerably. BMW says the new system allows for “more energy density, faster switching frequency, and better heat management”, Motor Trend reported. “All of which translates to higher RPM, more torque, and even more power,” BMW told Motor Trend.
The basic reason manufacturers switched to permanent magnets was that despite their higher cost, the efficiency achieved over a longer period was worth it. However, that advantage might be on its way out given the spiraling costs of permanent magnets, their limited supply, and China’s near monopoly over the mining, extraction, and processing of the rare-earth elements that permanent magnets are made of.
Moreover, mining and extraction of permanent magnets from complex compounds is an expensive and extensive process, and incurs heavy financial and environmental costs, something electric vehicle manufacturers have received a lot of flak for from environmental activists.
While BMW’s new electric motor based on old technology is as powerful as they come (532 hp and 749 lb-ft of torque), questions remain over its maintenance needs. Brushes in brushed motors have a specific life, and BMW has so far not specified how long the brushes in its motors will last. It says the brushes are housed in “an enclosed and sealed compartment” that eliminates dust contamination.
The BMW motor might seem like an old wine in a new bottle, but for what it’s worth, it is certain to disrupt the electric vehicle industry with its unique take on an existing technology that is efficient, cost-effective, and environmentally friendly all at the same time.